Episode 190: Jane's five rules for houseplant care, plus the lowdown on aphids
Transcript
Episode 190
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Jane: Hello and welcome to On The Ledge podcast, the podcast about houseplants. I'm your host, Jane Perrone. Greetings to you all, whether you're a first-time listener or an OG fan. I'm still in self-isolation here at On The Ledge Towers and my plants have been well and truly saving my sanity. When I felt a bit stressed, I've been able to escape down to my greenhouse to do some re-potting of various plants and lots of propagating too, so thank goodness for plants! In this week's show, I'm going to be bringing you my talk from the LEAF houseplant festival, which encapsulates my five rules for houseplants and, also, I answer some questions which, hopefully, will prove of interest. Plus I'm answering a question about aphids, those dastardly little creatures that cause problems with our houseplants and finding out a little about their incredible life cycles.
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Jane: Thank you to Kathy who became a Crazy Plant Person and Maria who became a Ledge-end this week. Marnie77 and PennyWin, both from the UK, left five-star reviews for the show, so pats on the back all round for you individuals! You are all helping to support this here podcast, which is a very welcome and lovely thing, so thank you very much for your support! If you want to find out how to support the show, it's simple: janeperrone.com is the place to go. All the information should be at the bottom of any of the show notes you click on. Whether you want to drop me a couple of quid or leave a review, there are lots of ways to support On The Ledge. You can also buy my merch - T-shirts, mouse mats, even Wolfie is getting excited over here! - T-shirts, mouse mats, hats, lots of cool stuff that you can get, I think there might even be a face mask, you know, with the On The Ledge logo on it! It's a great way of supporting the show and you can show it off on your Insta, as we all love to do.
A few weeks ago, I was a guest speaker at the LEAF Houseplant Festival, which took place at the Eco Village that's in Market Harborough, in the UK in the county of Leicestershire, and this was a great event, one of the first ones since the UK kind of started opening up after the pandemic. There were lots of great stores and the Windowsill Plants shop, which is in the Eco Village, was also open for business. Soil Ninja was there, which is an interesting UK-based business selling substrates for houseplants and it was interesting to have a chat to them and I gave a talk and that's what you're going to be hearing in this episode.
I'm sure that if you're a regular listener some of the things I'm going to say will be familiar to you, but if you're a new listener, well, this is a useful episode for boiling down the tenets of how I look after my houseplants and there's also some questions at the end which throw up a few interesting issues and I hope you get something out of that too.
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Jane: Before we get onto the talk, I'm going to tackle the Question of the Week, which comes from Lori and concerns aphids on her String of Dolphins. Now, aren't there just so many different string plants out there that it gets rather confusing? I think that String of Dolphins is probably referring to Curio radicans, which is a trailing succulent, also sometimes known as String of Bananas - I kind of like the idea of a string of dolphins, although I'm not sure dolphins would be particularly happy to be on a string! Nonetheless, this particular species Curio radicans, also known as Sinecio radicans, a close relative of the String of Pearls, it's a lovely plant, it's a South African native and it has its moments in terms of you need to make sure this plant doesn't have wet roots but it can grow into a lovely trailing succulent.
If you're looking for aphids on your plant, where do you start and what do you look for? Well, the first thing to say is aphids love a bit of tender new growth, so look first at the newest leaves and the tender buds and growth points on your plant because that is where aphids will be gathered. What do they look like? Well, the good thing about aphids is that you can see them with your naked eye, unlike the red spider mite, unless your vision is very poor, you should be able to spot them on your plants. These little sap suckers have got oval-shaped bodies and they'll vary in size because they grow very fast and have lots of babies. They'll probably be about 1mm/2mm long and they can be a variety of different colours. Sometimes they're green or black, yellow, pink and orange. So these are just different species of the same family, which is the Aphidoidia - that's really not that easy to say! -- Aphidoidia. There we go! I've had a go!
Oftentimes, when you have aphids, you will find that they come along with ants. The reason for that is that the ants will come along and farm the aphids. Basically, they collect the honeydew, which is the sweet sticky stuff that the aphids produce. Maybe I'm going to call it a secretion instead of a poo! You can get ants inside as well, in fact, I've got some ants wandering around my kitchen right now! The other thing you get with the honeydew, is that they can encourage a black powder, which is a sooty mould that can build up on honeydew-secreted areas of your leaves. So there's a few issues with aphids and it's certainly a pest that you're wise to control.
If you're wondering how they've got into your house? Well, some of the females can fly, so that's one way they're getting in, and also, if you're bringing in flowers from the garden, they can come in on other plants and they will find your plants. I've found that this spring has been a particularly bad one. I don't know if that's just me, but aphids are around. Look for clusters of them on those growing tips. They have got a pretty hectic life cycle, they can reproduce by what's called parthenogenesis, which basically means nothing has to be fertilised in order for babies to be born. They are born as babies, they're born as young, rather than eggs, and their life cycle is extremely short. Some of the aphids will develop wings at different seasons of the year and some will overwinter as eggs on plants outside and some stay active. There are loads, I think there's about 500 species in the UK, so they've all got slightly different things going on, but what you need to know is that they reproduce very, very quickly.
The other problem with aphids is they can transmit viruses. They're sucking sap out of plants and, obviously, their mouth parts are getting right in there, in the plant, and so they can transmit viruses from one plant to another and that can affect all kinds of things, including edible crops, houseplants and garden ornamentals. So they really are something you should be aware of.
How can you treat them? The simplest thing to do, if you see aphids on a plant, is just to take your fingers and carefully brush them off. You can run the plant under the tap if that's possible, you will kill a lot of aphids this way and you will need to repeat the exercise because you'll probably miss a few and they will reproduce very quickly, as I've said. Normally, if you're dealing with garden aphids, I would say make sure you've got lots of natural biological controls out there, so things like lace wings and hover flies which do brilliant work at controlling aphid populations. Indoors, that's not going to be something you can do. You can use lots of organic sprays to deal with aphids. Some of them are based on fatty acids or plant oils and these can control aphids quite well. You do need to repeat, as I've said before, with any pest treatment. Repeat, repeat, repeat and that will help.
Things like eco-effective bug control and SB Plant Invigorator, which are all available in the UK, which are called plant invigorator sprays, these can help to control aphids as well. It's not considered organic, that treatment, but it does work on aphids. There are neonicotinoid-based insecticides that are available for aphids. I have never had an aphid infestation that I felt was serious enough to warrant using neonics, but that is an option for you if you want to use those kind of chemicals. The other thing that you may find with plants that have been affected by aphids, and this for me is the most annoying thing about aphids on houseplants, is they do promote distorted growth. So I've got some on my Hoya polyneura at the moment and it's making all of those lovely fishtail shaped leaves go all weird. Lori, this might be what you're finding on your String of Dolphins as well - that the growth of the new leaves just doesn't look quite right and that is often due to the presence of aphids. It weakens a plant. They're not particularly happy. In this scenario, if I can, I tend to remove the distorted leaves and deal with the infestation and then, hopefully, the plant will kick into growth again and the new growth will be healthy. The other thing about distortion is that when a leaf is curled over, sometimes that means the aphids can hide inside that leaf and you might not get them with a spray so easily. So if you have got distorted leaves, do check all sides of them to make sure there aren't any aphids hiding there. When they're sucking the sap, they're also leaving behind a little gift in the form of some toxins that, basically, affect the development of the leaf, which is rather annoying, I think you'll agree.
Now, if you've listened to my biological control episode, you may be wondering what biological controls are available for aphids. I think we did mention these briefly in the episode? You can get lace wings. Their larvae eat a heck of a lot of aphids, so they're a good choice, or, indeed, ladybirds. These are popular solutions. The only thing is, obviously, in the home rather than in a greenhouse setting, are they going to land in the right place? Are they going to get right to the source of the problem and have you got enough plants to deem it worthwhile investing in this biological control? Those are the things to think about with biological controls. I'm not sure where I would put aphids on my sort of pest top five when it comes to houseplants. This spring I'd probably put them at the top because they have been really troublesome. I think the problem is that because I don't treat them with the seriousness that I treat, say, seeing some thrips, or some mealybugs, is they tend to then be allowed to proliferate and then I get distorted growth and the rest is rather annoying.
So do keep an eye out for aphids. Lori, I would suggest that you spray them off to start with and just look at that new growth all the time for any signs of a presence of aphids and deal with them as quickly as you can. That way, you can get them under control quite easily. If they do decide to start producing winged individuals, then that makes life a lot easier for them to spread to other plants. So nip aphids in the bud is my message on this front.
I hope that's helped, Lori, and if you've got a question for On The Ledge then let me know: ontheledgepodcast@gmail.com Send me pictures, information, everything you can think of - your inside leg measurement! No, don't bother with that! Just the details of your plants would be great! Now it's time to get on with my talk from the LEAF houseplant Festival. Do check out the show notes as you listen, for the pictures that I mention in this chat.
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Jane: Thank you very much for coming and listen to me waffle on about plants! So I'm the host of a podcast called On The Ledge, which is a houseplant podcast and it's been going since February 2017, so I'm quite tired now! I've done 186 episodes and covered everything from James Wong's apartment, to soil science and everything in between. What I'm going to try to do in this talk is just give you a bit of a potted summary, if you'll excuse the pun, of my philosophy of looking after your plants and then I'm going to leave lots of time for questions. As I've just said, I do have, on this table, some lovely plants, but also some little tiny baby plants that I've brought with me. I'm just going to tell you what they are before we start. So if you ask a question, you can come and take a plant and you can come and take some On The Ledge stickers if you want to. The plants I've got here are... I've got a baby, baby, baby, very small Pachyphytum oviferum, which is a lovely Jelly Bean succulent. I've got two Saxifraga stolonifera, the Strawberry Saxifrage, which is one of my absolute favourite plants. I've got two very baby, oh no, actually one very baby Hoya serpens plant, which is a lovely foliage, tiny-leaved foliage plant and I've got a Begonia soli-mutata, which is another lovely foliage plant and I've got an Agave as well. So there's lots of choice there. At the end, if you ask a question, please feel free to come and take a plant. I will be eternally grateful and so will my husband! So that's who I am and I hope that things will come to your mind as you listen to me talk, but let's go with the slides. I don't have loads of slides because I don't really favour slides but please feel free to ask questions afterwards.
Okay, so I've got five rules for houseplant care here and I think one of the things that frustrates us all, and I'm sure it's not the case at any of the plants sold at this festival, but one of the problems is you go to a garden centre or you see a cheeky plant in the supermarket that is an impulse buy and you look at the label and it says "Foliage plant" and that's really annoying because that doesn't help you at all! This is a foliage plant, the lovely orange Chlorophytum, and this is a foliage plant, the lovely Sansevieria, and this is a foliage plant, the Monstera and yet care is quite different for them all, so just because it's foliage doesn't mean the care is going to be the same.
Oftentimes, this is one of the things that I rant on about occasionally, sometimes the labels have a name but the name is wrong and that's also really annoying. So one of the things you can do is, obviously, put your picture of your plant on Google Lens or ask in a Facebook group and find a name, but there are also lots of things you can do before you even get to the stage of identifying that plant - to just look at it and figure out a little bit about how to care for it.
What are we looking at in terms of figuring out the signs the plant is giving us that tell us where it might have come from and how it lives? So, the picture we've got here on the left hand side of the screen is cacti and succulents. This is really quite a broad group of plants, but the one thing we can say about all of them is that they've got succulent leaves, fleshy, fleshy succulent leaves. The reason why they're fleshy is because inside each of those leaves there's a special kind of tissue called parenchyma, a bit of a technical word, but it's a useful word because that basically means it's storing loads of moisture, of water and nutrients being stored in those leaves. So we know that succulent plants are adapted to cope with periods where there might not be a load of moisture at the root level, they're adapted to periods of drought. So that's telling us a little bit about how we might be looking after them. We also can tell, from looking at those cacti and succulents, that a lot of them have got either furry surfaces or flowery surfaces or grey surfaces, all of which reflect the sun really nicely, so they're used to high light conditions.
If we get deeper into the world of succulents, you realise that not all succulents require exactly the same amount of high light but, generally speaking, your sunniest windowsill is going to be the place to put those cacti and succulents because they're used to a really high light environment. Even the sunniest windowsill in your house will be nothing. If you've got a light meter and you measured that sunniest windowsill against outside, on a sunny patio, light levels inside are always going to be less because you've got so many things in the way, i.e. your walls and the window and the curtains. So you need lots of light for those succulents.
On the other end of the slide, we've got the Maidenhair Fern and it's the opposite end of the scale in that you've got this incredibly tracing-paper-thin leaf. I don't know if any of you have tried to grow Maidenhair Ferns, but they really do challenge a lot of houseplant growers because those very, very fragile leaves are used to having a nice moist environment, a constant, set level of moisture. They need moisture around the roots and they need moist air and some of us struggle to provide that. Because they're paper thin, those leaves can't store water in the same way that the cacti and succulent leaves can and, therefore... Actually, they do really well in a self-watering pot. That's what I'd really recommend, if you want to grow a Maidenhair Fern, or a lot of the other members of the fern family. A self-watering pot is a really good way to go. It doesn't have to be an expensive one, self-watering pots are quite pricey but you can just get a piece of nylon cord about 10 cm - 15 cm long, or a couple of pieces ideally, stick one end through the bottom of the pot and stick the other end into a vessel of water underneath the pot and you've got yourself a very simple self-watering pot.
So, we've got those two extremes there and in the middle, I just put this picture of a Staghorn Fern, slightly to remind myself of my own past errors! So the Staghorn Fern, it's another kind of fern but it lives a very different life. It's actually got really quite thick, leathery leaves. I don't know if you can see there, but it's actually mounted onto a board and that's because this plant is an epiphyte, which means a plant that grows on another plant, basically, and that means it's got quite a small root system. It doesn't have a huge amount of roots going hither and thither. Its root system is small. It's in the nook of a tree and it's used to having moisture but it's used to that moisture running away quite quickly.
So, again, that's how we learn how to look after a Staghorn Fern. Dunk it in a bucket of water once a week and make sure it drains thoroughly and, hopefully, you do well. Unfortunately, I killed mine because I left it outside for the summer and forgot to bring it in and it's my biggest plant regret to this day that I killed that plant. So, yes, RIP Staghorn Fern! I haven't grown another one since because I just can't bear the thought of killing another one, but they are actually quite easy plants, if you can say that. If you remember to bring it in before the frosts, they're actually quite easy plants because they have got these leathery leaves that appreciate water but they don't really worry if they have a dry period because the plant is adapted to grow in those conditions where water drains very, very quickly and then wait till the next bout of rain.
So that's my first suggestion for you - just look at the plant. The more time you can spend looking at your plants, the better. I know you may sort of think, "I've put them on this very high shelf". If you've got plants that are new, or that you're not familiar with, the care regime for put them somewhere really right in front of where you are working, or doing the washing up, or making a cup of tea, and you'll find that you very quickly spot things that you wouldn't necessarily spot if you had them on a high shelf. I know hanging plants are really, really popular right now, but the trouble is, if you're not quite sure on the care front, you won't spot that very first thrip or that very first bit of wilting that's starting trouble. So you have to be careful to make those plants that you're most worried about very accessible, so you can see things as they occur.
We worry a lot about the leaves. I get a lot of questions about, "Oh, the leaves are looking a bit sad! I'm worried about..." and the first thing I say is, "Have you looked at the roots?" because the roots are actually just as important as the leaves, possibly more important actually, because it's quite possible, with certain plants, to actually kill the whole set of foliage and the plant still be very much alive and able to re-shoot from the roots. I don't know if you've ever grown one of these guys, the Marantas, and had trouble with spider mites? I had one of these recently except it was, typically, the rarer, white-ribbed form and it got spider mites and it was only small and all the foliage died off and I was so angry that I'd nearly killed this plant, but I thought, "No! I think that this has got potential to re-sprout. It's got some kind of rhizome in there, which is a storage organ, which is storing water and nutrients, I think it's going to regrow!" So I wrapped it in a clear plastic bag and I put it on the windowsill and I waited, still grumpy for a long time, and finally it re-shooted. So don't give up hope, particularly with plants that have got some kind of chunky bit of root system. You can regrow!
So roots are really, really important and the picture here shows a couple of different types of root ball, a couple of different species and their root ball. On the left we've got an Aloe vera, which was one I repotted a while back, and on the right I think that is a Ctenanthi, which is another member of the family that this plant is in, the Prayer Plant family. We can see that we've got the major roots and then you've got little roots going off that. Most plants have this amazing network, going right down to a very, very small level of tiny root hairs and that's why they can draw up nutrients from the soil and get the moisture they need from the soil, but it's really important that we give them the room they need to do that and the right substrate.
So if you look at your roots, you can tell a lot and that's why I always say, "If you've got a problem with the leaves, have a look at the roots!" because that will tell you what's going on. It's quite difficult because lots of times, people say, "Well, my plant's wilted. It needs more water" but, unfortunately, over-watering can look very much like under-watering. So the classic one is the Peace Lily, where you get it wilting and you think, "Oh it's wilting! It needs more water". You put some more water on it, it keeps wilting, and actually, what's happening, is the roots are drowning in water. Air can't get to those roots and, as a result, the plant is wilting because there's no transport of moisture up to the top of the plant and down at root level things are rotting.
What's that going to look like? Well, that's going to look like smelly, sliminess 'round those roots. It's not going to look very attractive. The roots aren't going to be firm and they're going to show signs that rot has set in. So that's one thing you need to look out for if your plant is wilting. Don't just assume, without touching the soil, that it needs more water. When you also look at the roots, you can look at the situation in terms of "Does this plant need a bigger pot?" This is a bit of a judgment call. People often say, "Oh this plant, this species, likes to be snug in its pot." Well how snug? How do I know when it really needs a new pot?
My rule is always to have a look at that root ball and to see what surface area of soil you can still see and make a judgment as to whether it needs a new pot. When you do repot though, don't think that bigger is better. So, you often see a really tiny plant with a really massive pot. Somebody has thought, "I'm going to really give it a luxurious, big pot because it deserves it!" and that's the worst thing the plant doesn't want you to do! What you end up with then, is a tiny little plant and its little root system in the middle around it every time you water you're ending up with a kind of like sump of water that doesn't actually have anywhere to go. There's no roots able to pull moisture from that area and so that tends to make plants quite unhappy.
So then people say, "Pot it one size up." Have you ever heard that phrase? "Pot it one size up!" and I go, "What does that actually mean?" What sizes? Someone tell me about pot sizes! I don't know what the rule is! Is this a size 10? Where's the numbers on the bottom?" I don't know, I've never figured that out. I think every pot company has a different system, so what my judgement on that is just to say, "Okay, if I can put the two pots together, one smaller pot inside a larger pot, if I can just get my finger in between the two pots, that's probably about right" unless it's a massive pot, in which case it might be my fist if it's a really large container, but, generally, you just want to give the plant that little bit of extra room to put its roots into without allowing it to have this big cold wet ring of compost around it.
So have a look at those roots, don't be afraid to poke your finger into the pot. People often say, "Well, your finger will be able to tell if it's moist." Well, no! Your finger does not sense moisture actually! What you will be able to do is take your finger out and look at the end of your finger and see if there's some moist compost on there, or if it's completely dry and there's nothing there. That will tell you whether there's moisture right down at that root level. That is the key thing for when you're deciding whether a plant needs watering - not whether it's moist at the surface - whether it's moist right down at that root level. So always don't be afraid to poke your finger in. You can get a moisture meter. I find them quite inaccurate; a lot of the cheap ones are not that accurate. I kind of prefer to rely on my finger. If you don't like the idea of using your finger, just get a wooden kebab stick, or a wooden lollipop, stick it in there for about half-an-hour, pull it out and see if it's damp or if it's totally dry. That does the same thing for you.
So, while you're rooting about in there, you can also do your houseplant a favour, if it doesn't need repotting, and just have a little bit of a poking session! It's good for moments where you need a little bit of de-stressing! Just get a knitting needle, kebab stick, or something, and give that root ball a poke. Because what happens when you have a plant in a pot for a few months, it tends to slump, you're losing the air holes in there that the roots need to survive, so you get this compacted compost which is not good in terms of absorbing more water. So, just poke a few holes in there, it's quite satisfying, you won't do anything too damaging to the roots and you will introduce some air. It's quite therapeutic, I find!
I've told you everything from this slide already. Yes, use your finger and if you've got a pot that is really quite small, not a massively heavy pot, but what you can also do, is just lift it up. I do know people who literally weigh their pots to find out, so they've got a constant record of how much water is in there. I don't have time to do that! I really don't have time! You can get to know from feeling a pot. If it's a plastic pot, you'll be able to lift it up and go, "Oh yes, that's feeling a bit light" and that probably means that it needs watering. Water is quite heavy and adds to the weight of a pot quite considerably. So you can just do a little experiment and if your hand shoots up - I'm feeling these two; that one feels considerably heavier than that one, so I think this one is probably more in need of a drink than this. So you can use little techniques like that and you'll just start to be more aware of really small elements of looking at your plants and deciding when they need moisture.
I often find, particularly with cacti and succulents, that they get to a point where they just look a little bit dull and a little bit wan and that's the point at which they definitely need a drink. You can tell also that with the String of Pearls, on the left-hand side there, when they start to go slightly, slightly, slightly shrivelled, that's when you know they need a drink. You need to be particularly careful with cacti and succulents in the winter time because those root systems that they've got, which are designed to be around very free draining compost, if you water them too much then you rot those roots really easily. This time of year, though, don't be afraid to water your cacti and succulents because they do actually like a decent amount of water. If your cactus or succulent just hasn't grown in about two years it's probably because you've not been giving it any water, so don't be afraid to water generously when it's the summer months and your plants are growing. Just make sure that you don't leave a load of water in the bottom of the pot and that you check the cache pot for water because that's the other thing that's a lethal thing to do. By doing that you're basically water-logging the plant, there's no air getting to those roots and rot will set in. The picture on the right is one of my favourite species within the Gesneriad family and it's a Primulina. I just say this for everybody just because I want everyone to grow them because they're amazing. That one's not in flower but they produce these beautiful flowers and they're really easy, beautiful plants, so that's my little speech about Gesneriads.
Going back to my point about keeping plants where you can see them. This is my windowsill. This looks totally different now because it's changing all the time. I just chuck any plants up here that need something in the way of daily attention. They might be poorly, they might be something propagating, they might be something I'm just waiting for it to come into flower because there I can see exactly what's going on when I'm doing the washing up. I don't do the washing up particularly well as a result, but it means you can just see what's happening to every single plant and you will just spot things that you never would have spotted otherwise, if the plants were at ground level, or if they were high up. It's so, so handy, so keep your plants where you can see them!
On the right hand side there - I'll just mention this in case anyone hasn't come across it before - I've got four clear plastic pots. If you've ever struggled with propagating things, or you want to do a bit of propagation experimentation, lots of things do really well just chucked in a plastic hummus pot with a tiny dribble of water at the bottom! You'd be amazed the things I've grown in there! I started off doing this with Peperomias**, which was the plant that was recommended to me when I went to visit a Peperomia collector, but it works with loads of things, including unexpected things like some cacti and succulents will grow roots really quickly and well in those pots - also good for ferns and Begonias. If you struggle to remember to keep your propagation unit looking good then that's a really good solution, so check that out. If you've got a few empty hummus pots, you can start your own propagation station.
The final one is a common thing that plant parents get bamboozled by is they come to me and they say.... Actually, there's two categories of people who come to me, category one is this person and they say: "I bought this plant but I've got a yellow leaf and I'm really worried about it, what am I going to do?" Nothing, it's fine. When you've got yellowing leaves you need to think about what leaf is it and how many leaves are yellowing and where are they on the plant? Now if it's the oldest leaf on the plant, and if it's one, then it's just the plant saying: "This has done its turn, it's produced, it's performed photosynthesis beautifully and now it's going to retire from life, the plant has withdrawn all of its resources from that leaf and that leaf is going to die," and in nature that would be, obviously, landing on the ground and going back into the soil and providing nutrients for the next load of leaves. So don't worry if it's one leaf and people panic about this.
The other group of people that get in touch with me are the people who've got, literally, a dead stick, who say, "What do I do? My plant's not looking very good!" I just say, "There's nothing you can do!" but we tend to go to these two extremes. But if you've got one yellow leaf, don't worry! It's probably fine. If you've got a lot of yellow leaves and they're not the oldest leaves on the plant, then you might need to be more concerned. Now, when I say oldest, how do you know how old the leaves are? Well, on something like this, this is a Monstera, usually you can tell because the early leaves are the smallest and the simplest, they usually haven't got any holes in them and they're the ones that the plant produced first. Depends on your plant's growth method and how it grows, so for example, on something like this, it would probably be the outer leaves on the rosette that would be the oldest because it's growing from the centre. So have a look at the form of your plant and that will help you to know how old the leaves are.
The other thing I would say, if you do have more than one yellowing leaf, then look at your watering, but also, always, always, always look at the backs of your leaves because that's where the pests like to hang out. Get yourself a magnifying glass, or a botanist hand lens, and have a look at the backs of the leaves and that's where you'll see the trouble brewing and it might be something like spider mites, which usually manifests itself as little grainy bits on the back of the leaves, which rather unpleasantly are the shed skins of the spider mites as they grow, or you might see some little black dash-like creatures, which are thrips. Or you might see something like a group of aphids. The backs of the leaves are very educational, so check out the backs of the leaves and make sure you haven't got a pest problem. That way, hopefully, you can remove those old leaves but they won't do any harm to your plant; it's just your plant doing its thing. It's like us shedding dead skin from our bodies. It's just part of life's rich tapestry!
So that is my five rules and that's my podcast list. I'm coming up on half an hour, so I will hopefully have some questions from you guys. I hope that's thrown up something in the way of a question, but if you haven't got a question, just make something up because you get a free plant!
Person: I would like to start, actually! So here at LEAF Houseplant Festival, our theme is houseplants and happiness. So why do houseplants bring you happiness?
Jane: That's a really good question. Well, I think that, for me, I just love seeing plants thrive and just boasting about it endlessly and being so pleased. It's actually quite disappointing because my family just don't care! I'll be, like, "Have you seen this amazing flower?" They're, like, "Yes, mum. Whatever!" but I just love having plants do cool stuff that I can then look at and observe. This Maranta that I grew, it was just so exciting to see these new leaves coming out of literally nothing and regrowing. So that, for me, is what's really exciting, is seeing those changes happen. I just love pottering about with them and learning more about them, which is probably good because I do spend a good proportion of my week talking about them and talking to experts. The other great thing about my podcast is if ever I've got a question about something, I can just literally go, "Oh, I'm just going to go and have a chat with somebody because it's my job!" which is very handy! So I do, sort of, often ask listeners to come up with ideas for episodes and they usually do because they want to learn about some specific type of plant. It's been a lifelong thing for me. I've been doing it since I was a little kid, so I can't imagine not doing it. I'm also very excited when I see people discovering houseplants at any age and it's enormous fun. Something can set you off. You go into a garage and you see a really abandoned-looking plant and you pick it up and you start tending to it and then, ten months later, you've got a jungle in your house! I'm sure some people can relate to that! So yes, it's a lovely thing to do and I'm really excited that more and more people are adopting the houseplant growing hobby. So yes, thank you for supporting this festival and, hopefully, getting more people on board with all of that scene.
Person: Thanks, Jane. How do you feel about showering with your plants?
Jane: That's a really good one. I don't have any plants in my shower. I'm quite an accident-prone person and I think I'd probably end up with disastrous things happening. I think it's a really nice idea to do the whole spa day thing. I'm kind of spoiled in that I've got a garden and I've got a potting shed, so if I've got to do that kind of process of taking plants outside and really washing them down, I do that outside. I can appreciate not everyone has that space and so it's fine to put all your plants into the shower. It is good to wash off dust and you'll be maybe washing off some pests in the process. If you live in a hard water area, I don't know what the water's like around here, but it can leave you with marks on the leaves. So if you want to get a little bit over the top, you ideally want to be getting some rain water or some distilled water, just for that washing process, just so you don't get those mineral salt streaks left on the leaves. Yes, showering with my plants? Yes, I have the shower incredibly hot and soapy, so I think generally that would be a bad idea, for me personally, but I can see why people want to have an environment in their bathroom that's full of greenery and the bathroom can be a really good place for plants. It tends to be humid, so if you've got plants that need humidity, it's definitely worth looking at putting them in your bathroom for a while.
Just bear in mind that often light levels are quite low in your bathroom, so you can't necessarily provide enough light for them, so it's a balance. The other thing, is it's a great idea to have a couple of the same plant. You've got these two plants and you can switch them in and out of low light areas, like the bathroom, if you don't have a big window in there, and have a lighter place to put the other one and that one's kind of recovering and then you move and you switch them around and that way your plant will do better in that low-light place. Washing your plants down is a really good idea and, for pests, people often want a silver bullet solution for pests, like, "I want to fix thrips now!" Well, no, you're not going to do that, but if you wash them every single day, you will solve the problem eventually, it's just a long road.
Person: I mentioned it to some people this morning, the fact that I occasionally throw plants in the shower, just a cool shower...
Jane: It's also good if you're watering your plants with tap water, and you have hard water, it's a really good idea to wash that substrate through every now and again because you get a build-up of mineral salts in the soil, which can be problematic for some plants. So just washing the soil through will, hopefully, solve that problem and, if you want to avoid that altogether, if you can collect rain water to use on your houseplants, that's kind of the Dom Pérignon of the houseplant world, in terms of watering, if you happen to have access to a water butt, or whatever. That's what I use because I've got lots of water butts, but I appreciate not everyone has that option. I've got a vision now of you and your shower with all these plants around! Not in there with them, yes. I think it's a great idea and there's nothing more depressing than a dusty houseplant, I just think, if you see someone, going to someone's house and... I say this, I'm probably going to go home and realise that I've got lots of dusty houseplants, but I did actually get one of my Sansevierias out yesterday it was covered in spider webs, not spider mite, spider webs! I was, like, "Oh, I'm a bad plant parent!" but it didn't care!
Person: It's particularly good for big specimen cacti because how else are you going to get the dust out from in between the spines and so on? So a quick scooch in the shower...
Jane: Exactly, yes, exactly, and people say, "Oh, use a paintbrush". I'm, like, "I ain't got the time for that! I haven't got time to be brushing cacti!" Exactly - just give them a blast and they'll be absolutely fine. Okay, anyone else got a question for me? Come on, ask a question! Look - I've got all these beautiful plants here! I want somebody to take one of these! Should I tell you a bit about these plants that you could win? Okay, give me a question and you can come and get a plant afterwards.
Person: We just bought an Oxalis triangularis from the festival. We've not had one before, so we just wondered if you could give us any tips?
Jane: Yes, really good plant. What you have to bear in mind with this plant is that it might lose leaves in winter, but that's okay because this is one of these plants that grows from... I don't know, officially, what it's called. Is it a corm? I think it might be a corm, or a bulbil. Oxalis: so it's got an underground storage organ, which is really handy, because it means those leaves can die back and oftentimes Oxalis, in certain conditions, in the winter, will start to lose some leaves, but it will come back. In fact, I had one, not that species one with a ridiculous Latin name of aureoreticulata, anyway, it died back completely and then I forgot it was there and I ended up using some of the soil for something else and now I've got it popping up in all my plants because these tiny little bulbs have got in with everything else. But that's a really good thing because it just means that if you lose a few leaves, don't panic.
You've got a choice to make with that plant, do you like small pink flowers? I don't like small pink flowers, so I just pull them all out brutally. Some people love them. So you've got a choice whether you want to do that. If you love the leaves and you want all the energy of your plants to go in the leaves, you can literally just snip off those flowers or even just pull them out. If you like the flowers, obviously, you can keep them going. Oh, yes, also the leaves are edible. Now, warning, they contain Oxalic acid, so don't eat a pound of them, or anything, but they taste like lemon, or it tastes a bit like sorrel. Don't go eating random houseplant leaves, please, because lots of them are poisonous! Almost all Aroids are going to be toxic to some level, so please don't go and eat loads of houseplant leaves, but that particular Oxalis -- triangularis - the leaves are edible and you could put them on a salad. That looks quite nice. They're a really good plant and, yes, I'm sure you'll love it and just enjoy the leaves. It needs, I would say, reasonably moist soil, don't let it drown, but at the same time, probably more moist soil than you'd be looking at for a cactus or a succulent, those leaves are quite thin...
Person: Does it need much humidity?
Jane: No. In your house it'll be fine, unless your house is a very, very dry place. I'm sure it'll be absolutely fine. Just stick it on a windowsill and enjoy it, really. It's not a difficult houseplant at all. As I say, if it all goes pear-shaped, have faith that it will re-shoot. What you can do, once it's going, you can just take it out of its pot and take off one or two of those little bulbs and just pot them up separately and then it's a nice little gift for somebody. I'm always doing that, which is why mine never gets any bigger because I'm always stealing bits off it! Yes, it's a great plant, so good choice!
Person: Can I just ask you one other thing? When you're talking about cacti and succulents and watering them in the summer, we're quite good at not watering them in the winter, but then when it comes to the summer, I don't know how often, because I don't want to over water them in the summer.
Jane: What I would say with watering cacti and succulents, it's better to give them a good soaking and let the compost get really soaked and then allow it to dry out, rather than just a dribble of water on the surface. If you allow them to do the first method, that way you're encouraging the roots to grow throughout the root ball, if you just put a trickle of water on top it never really penetrates. Whether this is true or not, I don't know, but the idea is that you're always encouraging the roots to come to the surface in search of that moisture. So, yes, with my cacti and succulents, in the summer, I will put them in an old washing up bowl or a tray and I'll literally fill it with water and let them sit there for half an hour, make sure they're fully wet, drain them off, especially if they're in an outer pot, drain them off thoroughly and then put them back and that way you know they've had a good drink. Then just observe and wait for the next time that they're... I don't do a schedule, like, "Oh, it's Sunday, so I've got to water," but just keep an eye on them and when they look like they're getting dry, do that again. If they're in terracotta pots, which is what I prefer for cacti and succulents, the pot will evaporate moisture but it will also take up moisture when you water that way.
Person: So it could be quite frequently, if it's a little one that's in sun and dries out really quickly?
Jane: Yes, that's the thing about these small pots. This size of pot dries out really quickly. I think small plants are sometimes quite hard because you've got to really keep an eye because that can dry out fast and you need to observe it, whereas a big pot will take a long time to dry out. Just observe your plants carefully and, yes, in the summer, just start tailing it off towards September/October and keep your cacti and succulents cool, if you can, over the winter. If they're in a really hot centrally heated room in the winter that's when things like spider mite can take hold, so put them in a cool room and cut back on that watering, reflecting the fact they're just having a rest period, really. Marvellous! Well, I want you to come and get a plant, please! Do you want to choose something? Come and choose something because I cannot go home with these! If you like the Oxalis, the little round-leaf plant with the silver veins, that's called Saxifraga stolonifera, the Strawberry Begonia; really nice and produces all these little baby plants on little stems, so it's kind of fun. [Thank you] No worries! Okay, any other questions for me? Who has bought a gorgeous Begonia? It's like a member of the audience! I love it!
Person: I don't know how you feel about naming plants, but it does have a name!
Jane: What's its name?
Person: It's Leelee, because it was given to me by my neighbor, Aaliyah. Her nieces will call her Leelee, so it's Leelee the Begonia!
Jane: I don't name my plants because I don't see them in that way, but I have absolutely no shade for anyone who does and it's a lovely thing. If it helps you to put more energy into understanding your plant by naming it, then I think it's a really good thing.
Person: I do worry that she's a bit sad though. It's popping out new leaves all the time but as soon as a new leaf comes out, one dies back.
Jane: Yes that's a really Begonia thing to do.
Person: That's what I'm worried about. So you can probably see how much growth... so it was at the top, here, and so it's had loads of growth. Each leaf keeps coming out, but then I keep losing leaves. It's just growing taller.
Jane: It's a cane Begonia, so, in a way, that's kind of how it goes. I think it's probably Lucerna, a cane Begonia. That's what they tend to do. They like really constant moisture around the roots, Begonias, and that also kind of translates into air humidity as well, but it's more important that you don't let them completely dry out. They just protest if they get an erratic watering regime. So I would maybe suggest putting it into some kind of self-watering pot system, maybe, but also, as it gets bigger, it just gets easier with Begonias like that. You see the really big ones that will get six foot tall, and it, just then, as the plant gets bigger, it gets easier. Yes, it will be fine, it's looking really healthy, it will be fine. I could suggest all crazy things about increasing air humidity and stuff, but actually, it's much better for it to get used to the conditions of your house, and it should be fine, but maybe a self-watering pot might be one way to go with it. Begonias do have that tendency: "Hey, I'm making a new leaf, so I'm going to kill this one!" and it's a little bit annoying, but it's a beautiful plant, with that lovely silvery marking, which is gorgeous. I don't think we really know why plants do that, other than, possibly, well, it's a few different theories, but one theory is it's mimicking pest damage, so the pests go away and think the leaves are already damaged, which is kind of interesting. Begonias are great! This little Begonia I've got in here is called soli-mutata. If you're a terrarium person, please take that because it's a really lovely plant for terrariums. Don't grow it outside of a terrarium because you will cry. Begonias - there are easier ones and harder ones. That is an easier one, the cane Begonias, because they don't tend to have such fragile root systems and they tend to be more able to cope with conditions in the home. Oftentimes, those are really lovely heirloom plants that people have for decades and decades and will give away cuttings of, so it's really nice the way it continues on, throughout generations, so yes, it's a nice thing to have, a really nice thing to have. Okay, any more questions? I've got more plants here. Come on guys, any more questions? Yes, go on!
Person: So, like you, I've been growing houseplants for a very long time, probably 40/45 years, and it seems to me that plants have come into fashion, come out of fashion, but also, I think we've probably lost some plants that were grown commonly as houseplants in the 60s or the 70s. Are there any plants that you miss now that you would like to see back in cultivation?
Jane: That's a really good point. I think Swedish Ivy is the one that... everyone had a Swedish Ivy when I was a kid. No, Swedish Ivy is not that popular now, despite the fact it's such a good houseplant. It's an amazingly good houseplant - really, really tolerant and excellent and looks beautiful. I think probably the old Cast Iron Plant, Aspidistra elatior, which is coming back in now, actually. There's a lot to be said for the these plants. They're not called the Cast Iron plant for nothing, but they're really, really easy and a lot of them have amazing stories behind them and you can get some variegated forms too. So Aspidistra elatior, but quite expensive to buy because they're so slow-growing is the only downside. What about you, any other ones?
Person: Well, the Swedish Ivy, definitely. We had one on the stall earlier on that somebody bought and it hadn't occurred to me that, actually, you very rarely see it for sale now.
Jane: I don't think I've ever really... somebody needs to get on to that!
Person: Asparagus ferns, as well. They don't seem to be as popular as they used to be. There are plants which I wish people wouldn't grow or sell, things like Boston Ferns, which just drop their leaflets everywhere.
Jane: You see people on Instagram with these amazing Boston Ferns and I just go, "I don't have time to be sweeping up all those dead leaves all the time!". They're really tedious, but they're lovely! Some people just have the knack of growing them, but not me!
Person: I'm not a big fan of Begonias either.
Jane: I don't have massive amounts of Begonias. People keep trying to make me grow more Begonias but, for me, they are not my home plant. I'm more of cacti and succulent type person, really, and Hoyas and Gesneriads. So yes, but I've got a bit of everything, as you can imagine. Any more questions before I let you all go and release you into this sunny afternoon? Seriously, please come and take a plant because I can't take them home with me! Oh, question coming up...
Person: With your podcast, you have quite the extensive backlog. What's the most surprising thing you've discovered on your journey?
Jane: That's a really good question. The most surprising thing is that there is such an appetite for knowledge about houseplants and that people assume that you get a plant and that you might just find out the name of it, but the people's enthusiasm is just never-ending. The more you get into it, the deeper you go. I thought, four years ago, I knew quite a lot about houseplants and I realise now that there was just so much more. The journey that I'm on, of discovering more, has been so exciting and also that people are just very generous and I love the way that houseplant people are so keen to help other people out, with information and cuttings, and spread this wonderful world. Also, plants continue to totally blow my mind! I've had some amazing guests on the show, telling me about amazing plants and they're just incredible.
I've been exploring the world of extrafloral nectaries recently. Extrafloral nectaries are, basically, points on a plant that aren't flowers, that produce nectar. Oftentimes, it's to do with a relationship with something like an ant, where the plant develops a symbiotic relationship with an ant and the ant protects it. I'm now looking, with a glass, on a lot of my plants and checking out which ones have got extrafloral nectaries. Jeff, you probably know a million things about this, but there's just these incredible things that plants can do that we don't really understand. I think there's a lot of unanswered questions out there, so I've found that really fascinating, to just delve into that and find out that we've got a lot more that we need to learn and, hopefully, inspire some people to become botanists and answer some of these questions that we don't know the answers to. That's the exciting thing for me.
Well, I'm going to stop now unless anyone's got another burning question? Please come and take a plant so I don't have to take them home and thank you very much for joining me. There's some stickers in there as well, if anyone likes stickers, and I hope that's been vaguely entertaining and educational and do listen to my podcast if you haven't already, if you're not already sick of the sound of my voice! Thank you very much! [Applause].
[music]
Jane: That's all for this week's show! I'll be back next Friday. Keep your peckers firmly in the up position and remember to breathe and set aside just a few minutes a day to enjoy your plants. Bye!
[music]
Jane: The music you heard in this episode was Roll Jordan Roll, by The Joy Drops, The Road We Used To Travel When We Were Kids, by Komiku and I Snost, I Lost, by Doctor Turtle. The ad music was Dill Pickles, by the Heftone Banjo Orchestra. All tracks are licensed under Creative Commons. Visit janeperrone.com for details.
Subscribe to On The Ledge via Spotify, Apple Podcasts, Player FM, Stitcher, Overcast, RadioPublic and YouTube.
Hear my talk on houseplant care from the Leaf Houseplant Festival and I answer a question about aphids.
Thanks to Windowsill Plants at the Eco Village in Market Harborough, Leicestershire in the UK for hosting my talk at their houseplant festival in May 2021.
Jane’s five rules for houseplant care
Become a houseplant detective
It’s annoying how often plants are sold without any kind of name label beyond ‘foliage plant’. But if you have a mystery plant that you want to figure out how to care for, there are some clues as to how it grows in the wild. Plants with thick, fleshy leaves have the capacity to store water in tisues known as parenchyma, which means they are adapted to survive periods of dryness. They may also have furry or silvery leaves, or a thick waxy cuticle that prevents foliage from drying out quickly, and also helps to reflect the sun in high light conditions. From this information, you can guess that your plant needs your sunniest windowsill, and a free-draining potting mix that will allow water to drain away quickly.
On the other hand, ferns such as the maidenhair fern (Adiantum raddianum) has thin, filmy leaves, telling us that these plants like moist air and moisture around their roots. Not all ferns are made equal though - staghorn ferns grow as epiphytes, nestling nooks in trees, so they have a small rootball and leathery leaves, as they are used to deal with a cycle of wetting and drying, so these can be soaked in a bucket then allowed to dry between waterings.If in doubt, check the roots
Whenever I get a houseplant query, the first thing I almost inevitably say is - have you checked the roots? What’s going on at root level is just as important as what’s happening with the leaves. Healthy roots should be firm and not smelly. Slimy roots usually indicates there is too much water sitting in the rootball. If you see a mass of roots covering the surface of the rootball, that means the plant needs repotting. If your plant doesn’t need repotting, there’s still something you can do - get a chopstick or knitting needle and poke some holes into the rootball. Roots need air as well as water, and as potting mixes get older they start to slump in the pot, removing air pockets. Adding some holes like this may seem brutal but it does work, and you’ll find water is much more easily absorbed afterwards.
Your finger is your best houseplant tool
You can buy moisture meters to test how much water is in your soil, but your finger works just as well - stick it right into the heart of the roots and pull it out - is it dry or damp? This tells you whether it’s time to water your plant. If your plant is really small you can use a wooden lollypop stick instead - stick it in for about half an hour, pull out and see if it’s soaked up any water.
Keep plants where you can see them
Putting plants by the kitchen sink, on your desk or next to the place where you make a cup of tea, you’re much more likely to spot any problems developing before they become serious. Hanging plants high up or placing on high shelves may look good, but you’ll take longer to spot an issue when you can’t see the surface of the soil, or the leaves up close.
One yellow leaf does not a dead plant make
If you get the occasional yellow leaf, don’t worry - this is normal, as leaves have a lifespan and will die back once they have served their purpose. Wait until the leaf has gone dried out and brown before removing if you wish, as this will give the plant the best chance to withdraw all its resources from the leaf, but if you want to cut it off sooner for aesthetic purposes, that’s OK too! Do not believe the social media ‘hack’ that you should remove yellowing leaves from the plant as they are sapping its resources: this isn’t true!
There are hundreds of species of aphids, and they come in a range of colours. Photograph: Martin Cooper on Flickr.
QUESTION OF THE WEEK
Lori wanted to know what to do about aphids on a string of dolphins, eke Curio radicans. There are more than 500 species of aphids in the UK, all part of the aphid superfamily Aphidoidea, but they all work in the same way: gathering on tender new growth of your plant, and sucking its sap, causing distortion and weakening growth. Here’s a look at their lifecycle, which allows them to reproduce really quickly. They give birth to live young, who already carry another generation inside them, so one or two aphids can turn into many very quickly.
Some of the females develop wings, so they can fly in through open windows, or you may bring them in on cut flowers or other flowers. As soon as you see aphids, rub them off gently between your fingers, or wash off under the tap. Fatty acid sprays, plant oil sprays and invigorator sprays (eg SB Plant Invigorator) can all be used to keep aphids in check. If you want to try biological controls, lacewings and ladybirds can work, if you have enough of an infestation to provide food, and your little workers don’t fly off. Neonicotinoid sprays ie systemic insecticides can work, but I’d try everything else first before using these. There’s an excellent page on aphids and their control on the RHS website if you want to find out more.
Want to know more about houseplant pests? Check out my thematic guide for more episodes on this topic.
Want to ask me a question? Email ontheledgepodcast@gmail.com. The more information you can include, the better - pictures of your plant, details of your location and how long you have had the plant are always useful to help solve your issue!
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CREDITS
This week's show featured the tracks Roll Jordan Roll by the Joy Drops, The Road We Use To Travel When We Were Kids by Komiku and I Snost, I Lost by Doctor Turtle. The ad music was Dill Pickles by the Heftone Banjo Orchestra. All tracks licensed under Creative Commons.