Episode 244: visiting the National Collection of Hoyas
Felix Horne with some of his collection of Hoyas. Photograph: Jane Perrone.
Transcript
Episode 244
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Jane: Hello, welcome, this is On The Ledge podcast! I'm Jane Perrone, we're talking about Hoyas - what's not to like!? Well, a very fine day to you all and in this week's show I'm going to be visiting the National Collection of Hoyas in Newcastle, curated by the wonderful Felix Horne, and I answer a question about a languishing lime.
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Jane: Love that; a languishing lime! Alliteration - you just can't beat it! Thanks for joining me this week. It's episode 244 and I do hope this audio is finding you in a reasonable state. Now, if you've listened to On The Ledge for any length of time, you will probably know that I'm quite keen on Hoyas, so, no surprises - there are a couple of Hoya episodes coming up in the next few weeks and the first of those is this episode. I travelled to Newcastle, to meet Felix Horne, who holds the National Collection of the Hoya genus here in the UK.
What's a National Plant Collection you may ask? Well, this is a UK charity that helps to conserve plants by gathering together plants of a particular genus and looking after them. The people looking after them are a huge range of volunteers who study them, keep great records and generally keep the flame alive for their plant of choice. In the case of Felix Horne, that happens to be Hoya. So whether you're a Hoya fan or a Hoya disbeliever, I have a feeling that after listening to Felix you may want a few of these wonderful epiphytic plants. If you hear a little bit of noise in the background during the interview, most likely it's one of Felix's two cats, one of whom got very interested in our chat and joined in delightfully, so a little bit of extra action there, for you cat lovers!
Felix: My name is Felix Horne. I'm the National Collection holder for Hoyas.
Jane: We're here in your house, Felix, and I'm feeling the Hoya love here! How did this come about? I seem to remember seeing the call-out from the National Collections people, saying "We need somebody for Hoya!". Presumably you just were alerted to that and thought, "This is for me!"?
Felix: Yes, pretty much! I very naively thought, "I could do that!" My mum had grown a Hoya, which I'm sure lots of people can relate to, that we've had growing in our house when I was little and it flowered all the time and it smelled amazing. Then it just suddenly stopped flowering and got pushed further and further back in her collection and then kind of forgotten about. Then, just before Covid hit, I started collecting them myself and rediscovered them. She gets the RHS magazine and when I saw that call go out, I was, like, "Oh, I could do that!"
Jane: Here we are! I don't know how long ago that was, but you've got a collection of Hoyas that's presumably growing all the time?
Felix: Yes, a lot!
Jane: One of the things I find fascinating about Hoya is the diversity of this genus. There are just so many interesting variations on the theme. Of the ones that you've got in this particular room, are there any that are your absolute favourites, that you're going to be taking from the house as you go to your desert island?
Felix: I've got a Hoya Sunrise. Off the top of my head, I can't remember what its parent plants are, but it is a cultivar cross-breed. That one, I think, is really beautiful, just with... often when Hoyas have the visible veins, they're darker than the rest of the leaf and sunrise is the other way around. It has these really beautiful flowers that smell amazing as well. Probably Lacunosa is always a really safe bet. That flowers profusely and has gorgeous flowers. They're scented flowers as well, but then I think my most favourite one in here is also the most pathetic one, the one that has most actively been trying to die on me for three years and that is my Hoya archboldiana! I got that as a two-leaf cutting, one of the leaves then died, then I spent two years trying to stop the rest of it from dying and then this year it finally rewarded me by growing two new leaves and a whole bit of stem. It has a grand total of three leaves!
Jane: With Hoyas, it's one of those things, when you hear one of those stories, people who don't grow are, like, "Why are you getting so excited?" but when you've grown Hoyas and you know that pain . . .
Felix: That was the one that I always wanted the most and I have no idea why. It always really called to me! It's fine, it looks fine, but I don't know why. Just the fact that it just wanted to die so bad and I stopped it and it seems to be quite happy now. I'm never going to get flowers from it. I'll be lucky if I get five leaves off it. I've got other Hoyas in here that are just huge and super-prolific and I feel kind of bad for them because this little pathetic, three-leaf Hoya is out-competing all of them!
Jane: One of the things you were telling me before I started recording was about growing for the National Collection and how you try to, as far as you can, emulate what listeners' rooms might be like, rather than growing them into a rarefied environment where you're tweaking humidity and stuff. These are in a regular room, as are the vast majority of your collection. Why is that, that you want to promote that kind of growing?
Felix: I don't know if it's standard for National Collection holders, but I feel like part of what your role is, is growing plants for the nation, that the nation could grow. So one of the things I do, is I don't import plants from outside the UK because that seems to be outside of my remit, but also, what's the point of having all of these plants if I'm the only person that can grow them? I've got a few, more specialist areas that are "ideal settings" for a plant to grow, but I'll also have copies of that plant growing in, say, your bathroom, or somewhere else, to see if they can grow in normal household conditions because it's expensive to do the specialist stuff and that's something that not a lot of people are going to have access to and I think that that shouldn't be a barrier for people to enjoy these really amazing plants; they should be for everybody.
Jane: I think that's a really good point. You have got an Ikea cabinet here, or some kind of cabinet.
Felix: Yes, it's an Ikea one.
Jane: It does kind of worry me, especially when you see people getting Hoyas, cacti and Aroids. There's this collector's mentality of, like, "Okay, I've got to tick these off the list and the only way I can get hold of this is by importing it from Indonesia or somewhere" which isn't without its problems, right?
Felix: Exactly.
Jane: I'm concerned about how these are growing in the wild and the pressure to import or to take them out of the wild. Yet, as your collection shows, there are a lot of species and cultivars that you can get hold of in the UK. Where do you source most of your plants from?
Felix: I'm quite lucky that my local garden centre has got a much bigger collection of Hoyas than most other places. I don't know if I'm supposed to say...?
Jane: You can absolutely say specific places - it's cool!
Felix: My local garden centre is called Cowell's.
Jane: Oh the famous Cowell's! Wow!
Felix: Everybody says that when I mention it. They're family-run, they're really nice. I was really lucky. That's how I managed to get a good enough collection to start off my application at Plant Heritage, so I've been lucky with them. There are some online places that I get them from, but I wouldn't recommend them because they're all the ones that send me half-dead plants. It's like a really, really big problem with Hoyas in the UK. The garden centres and often the nurseries that supply plants to the UK don't know how to look after the plants, so you're often getting half-dead ones. I agree - I think it's super-important to get ones that are responsibly-sourced and that is really, really hard. From what I've heard of the Thai nurseries, they do a slightly better job because they breed a lot of their own plants. They're ones that are already named and described. In Plants of the World Online, for example, they can be really sketchy. I've got a Hoya wayetii and they're, correctly, endangered in their native habitat, but they're super-common as a houseplant now.
Jane: They're so common, aren't they?
Felix: I can't imagine there's not a causal link in that. Obviously, with Hoyas, once you've got them, you can take cuttings from them so easily that, as far as poaching goes, if you know what you're doing, you'd probably only have to do it once or twice, but that's still once or twice too many.
Jane: Exactly. If there's lots of individuals going out and doing it and the market is there for people who are doing it, it's scary. It's great to have these plants proliferating in your home and, as you say, hopefully people will be inspired to give some of these plants a try. If you were telling somebody who's starting out where to start with Hoyas, what would you recommend? Is it the old classic Carnosa that we go for?
Felix: Yes, absolutely! I think Hoya is one of those genera that is... you can't go wrong with it and all the super-boring, old ones are just as nice as all the fancy ones.
Jane: It's so true.
Felix: Yes, you don't have to do anything fancy with a Carnosa and a Pubicalyx -- they're bomb-proof and so beautiful. They'll grow all over the place, they'll flower so prolifically and the flowers smell amazing and you can get quite a lot of variety within those two species anyway. I think the thing that's difficult with Hoyas is that they're all named wrong.
Jane: Oh my gosh!
Felix: So you can think that you're going to go buy... I've got a M**emoria here, "I'll just go get one of those," well, that's also called a Gracilis and, depending on what name they've got in the garden centre, you could pay a tenner for that or you could pay £40!
Jane: With that one, I've never really got to the bottom of what it should be. Have taxonomists reached a decision on this?
Felix: That one's quite complicated because Gracilis was described first but everybody seems to default to Memoria and correct Gracilis and I don't know why it's that way around. I really want to dig into that. I want to see what the original publication for Gracilis was and if that was something that they decided, that the Memoria was more robust or something? I don't know.
Jane: I'm looking here and I can see some Hoyas here where I know there's confusion. Is it Latifolia outer-variegated, or is it... what's the other name?
Felix: I've got them as Macrophylla. I still haven't got to the bottom of that.
Jane: I think Macrophylla is the one that's in vogue at the minute, but I think that's the problem. If there are loads of Hoyascientists and taxonomists, there must be some, but there's not whole books that you can just go and look at for this information, are there?
Felix: There's a couple of scientists in Asia at the minute who are doing a really good job with reclassifying Hoyas. The thing that they've realised now, is using the flowers to classify them is much better than using the leaves because there's a lot of variation in leaves within just one species. But they've literally only just started doing that work, so, at the minute, a lot of names are getting changed but people already know them, they've been changed over the years, nurseries are making new ones up to sell very standard Hoyas at very high prices.
Jane: Yes.
Felix: The Latifolia/Macrophylla one, I think, from what I can tell, what happened is that two people described one of them around the same time, but with the same name but different descriptions. So one of them matches Latifolia, for example, and the other one doesn't. It's so confusing, I really don't know.
Jane: That is, though, what I would say is in my top three Hoyas. Then again, my top three Hoyas is always changing but I do really love that outer-variegated... whatever the cultivar name is! I think the leaves are absolutely beautiful on it. I've found, once it's got going, that one has been okay for me, but I don't know how you find that one and you've got it in the cabinet.
Felix: I wouldn't have that one if I didn't have to.
Jane: Oh, that's interesting!
Felix: I've got a bit of a pet peeve against all of the cream variegations because I think they're... I think, partly, if I could get an unvariegated one in this country, I'd probably just have that one.
Jane: That's the interesting thing, as you say, I've never seen a plain green one.
Felix: I think you can get them in the States, but you can't get them here. I know I'm a bit biased against them!
Jane: That's the thing, is that you're absolutely allowed to have your own preferences about these things. I guess that's what the National Collection does, is to force you to say, "Well, I've got to have this because it's part of the National Collection." What do you have to do, what are the processes that are involved? Presumably just get as many Hoyas as you can and keep records about them? Is that a very crude summary?
Felix: Yes, the hard thing with Hoyas is you have to become an expert on nomenclature really quickly, just to make sure that you've got what they've said that you've got, which helps with the National Collection because that's what you have to do for that, anyway. Basically, the job of a National Collection holder is to try and get a hold of all the cultivars of a specific genus and just keep them alive for posterity, or for scientific interest. Probably not so much for Hoyas, but for things like vegetables or other medicinal plants that can be really useful. Say, if a cultivar goes out of fashion, for somebody to still have it if they later find out that it has blight tolerance or can survive in different climates and stuff like that. Plant growing is like any other fashion, things go in and out of style and Hoyas are just coming back into style after 30 years of being your grandma's plant. So you usually have to get one of every one that you can find and then have another two copies of it in case anything happens. Your house fills up quite quickly, which I'm not complaining about!
Jane: No. These plants have a particular architecture, can I say? I don't know if all Hoyas are epiphytes, but I'm presuming that almost all of them are. Obviously, a lot of these are hanging. You've got them emulating that up-in-the-trees kind of environment, but how does that impact on the kind of substrates that you use and what do you find works? I've opened up a can of worms here!
Felix: I find it hard to make any general statement about Hoyas because it's such a huge genus, there are so many different plants. Hoyas stretch all the way from the Himalayas down to the very tip of Australia and so they're a really, really massive range. There's probably, like, six or seven major different ways that you can care for different Hoyas. So, substrate is another tough one.
Jane: Say you've got a bog standard Carnosa or Pubicalyx. Presumably they're so tough that you could just stick them in houseplant compost, just regular, from a bag, and they'll be fine.
Felix: You could put cuttings in a houseplant compost and they'd grow. You could put them in anything, I'm sure.
Jane: I think I have seen some big old Nana's Hoya kind of thing, where it's in garden soil in a pot! It's that, kind of, like, "We're not going to buy compost for this!"
Felix: Yes, I think, with those two, you can put them in pretty much anything you want. Once you get past them, I generally use bark compost. You can get that, usually, cheaper than normal compost, with a mix of orchid bark and perlite. I am starting to experiment with using cork instead of orchid bark and that, I find, generally, like, works for most of them. Often, when you get them from nurseries, they'll be in all sorts of different substrates. I've got one in here that you can see, it's really miserable, which came in a...
Jane: Yes, I've had them in that. It's stuck in something...
Felix: I don't even know how to describe that.
Jane: I know exactly what you're talking about. It's like it's in a stump of wood, or something. I don't know whether it's coconut, or whether it's...
Felix: Yes, that's what I've been trying to work out.
Jane: I had something exactly the same and it did really badly and I eventually just took cuttings of it and abandoned the whatever it was. It's really strange, isn't it?
Felix: I've really struggled with all of the ones that I've got that are in, that did well in their first year and then, as soon as they got out of that and into any kind of stage of maturity, they really struggle.
Jane: From what you were saying, I think that flags up for me that it is important, when you get a Hoya, to do a bit of research and find out whether it's one of those Himalaya, high altitude kind of Hoyas, or whether it's something growing in a much lower altitude and might need less water because that seems to be quite a key point. I'm trying to think of some of the ones that I can think of that are more high altitude. I'm thinking of things like Hoya polyneura, which I know I've seen somewhere.
Felix: I've got Polyneura, Retusa and Linearis in the kitchen because it's unheated in there. They're Himalayan ones, they like a big temperature variation between night and day and that's the thing that really gets them to flower and be super-happy.
Jane: I really like those three, particularly Polyneura and Linearis. I just think they're such good plants. You look at Polyneuraand Linearis, I think they call it the Fishtail Hoya, those amazing leaves of the Polyneura compared to... I always think the Linearis leaves look a bit like green beans or something! They're so different, such different plants. We haven't really talked about the flowers yet though, which are, for some people, the stars of the show.
Felix: You know what? I don't understand people who buy plants just for the one month of the year that they flower. I think it's a good bonus, obviously. I love all the flowers on my plants, but the foliage, if you're not going to enjoy it the rest of the year...
Jane: I guess maybe it goes back to when people had massive collections and they could bring the flowering things up to be enjoyed, I don't know, but who lives like that any more, right?
Felix: I wish I could!
Jane: I know, it would be so cool, wouldn't it? It would be so cool! The flowers are great and what I love about them, one of the first houseplants I had as an adult was Hoya carnosa and I remember when it flowered and just looking at these weird, pink, fuzzy flowers and going, "That is so cool! That's amazing!" I do think the flowers are otherworldly, of Hoyas.
Felix: They just look like little stars, don't they? Little shooting stars. They're so cute!
Jane: The other thing I must mention, when I'm talking about flowers, is I'm one of those weird people who licks Hoya flowers! I enjoy the nectar!
Felix: I do that too!
Jane: Do you do that too?
Felix: Yes!
Jane: Thank you! I feel relieved because sometimes people look at you, like, "Okay, that's really weird!" but it's just sugar, basically, isn't it?
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Jane: More from Felix shortly, but now it's time to hear from our sponsors.
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Jane: This week's show is supported by Cozy Earth, the premium bedding company that helps you get the deep, restorative sleep you need. Bedtime is literally my favourite time of day, so it's really important that my bed is the most comfortable place it can be. I got to try out a set of Cozy Earth sheets and they really are so comfortable! Cozy Earth's high quality bedding is responsibly-sourced and made from soft and sustainable viscose that comes from bamboo fabrics. Bundle up in Cozy Earth pyjamas made from ultra-soft viscose, from bamboo, this holiday season. Now available in holiday hues! Want to give the gift of a good night's rest with Cozy Earth? On The Ledge listeners can take up Cozy Earth's exclusive offer today - get 40% off site-wide at cozyearth.com using code LEDGE for 40% off now!
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Jane: Now back to my chat with Felix and I wanted to find out how many Hoyas there actually are, both in cultivation and in the wild?
Felix: When I started collecting, there were, like, ten that you could get. Then, in the two years since I've had my National Collection, now there's about 30 / 40. That's still less than a quarter of ones you can get in cultivation in the world and probably about one percent of all the Hoyas that are out there.
Jane: Really?
Felix: Yes. People speculate there's somewhere between two and four thousand different kinds of Hoya species.
Jane: Wow, that's amazing!
Felix: That's just in the wild. That's not even cultivars. That's why I always say I'm not an expert!
Jane: I think, in a way, one of these things that's great about National Collections is, you're not portraying yourself as an expert. You've got a lot of Hoyas here and you're obviously very good at looking after them. Like all of us, things go wrong, it doesn't always work, but that's inspirational. If everything worked and everything was going great guns, then we wouldn't be able to relate.
Felix: Only liars live in a perfect world!
Jane: Indeed! I think they are a fantastic genus. I just hope that we can enjoy them without wrecking the places that they've come from. That's my worry.
Felix: That's my worry too. I think the thing is, with the houseplant boom at the minute, Hoyas are a really, really easy one for people to, like, capitalise on because it's so hard to name them and a lot of them look really similar to each other. I did that when I first started collecting. I bought what I thought was a really rare Hoya and it just turned out to be a Pubicalyx and I spent probably 50x what I should have spent on it.
Jane: That's crazy, isn't it?
Felix: People do a lot of things, like, the big one at the minute is a Hoya Wilbur Graves, that people keep trying to sell for loads of money. A Hoya Wilbur Graves is descended from one specific plant, so if you can't prove that it's descended from that one specific plant, then it's not a Wilbur Graves, but that specific plant was a type of Carnosa.
Jane: Yes, it's a Carnosa cultivar, isn't it?
Felix: It's the easiest thing to fake.
Jane: That's the interesting thing, isn't it? One plant had a particular little spore and produced more. This whole 'splash' thing - people are mad for this kind of silver variegation.
Felix: It's because they don't understand that all Hoyas do that. My Polyneura through there is a bog standard Polyneura, but two of the branches on it have decided to put on some splash variegation. If I was so inclined, I could cut those off, root them and sell them for, like, £100 each. I spent less than half of that for that entire plant. It's so easy to fake things, it's so easy to scam people. I would generally recommend not buying cuttings until you're really, really confident that you can keep them alive, even if they're in the worst condition you can imagine, when you get them. A lot of people don't let them root for long enough before they sell them on. When I take cuttings, I'll leave them for six months to a year in Leca, or whatever. I use Leca but I know other people use Pon.
Jane: Yes, one of the reasons why I like Leca for all kinds of things, is just because it's really easy to clean it. Whereas with Pon, it's so fine, it's a pain, whereas that, it's much, much easier. Even if it's gone disastrously wrong and it's all covered in algae, you can just clean it up fairly easily and rinse it off and it's good to go and you can you reuse it over and over again, which I think is good for a sustainability point of view and Hoya seem to really enjoy it.
Felix: The thing is, with Hoyas, people spend so much money on them and I kind of have to because I've got to get the plant for the collection, but, in general, I would recommend not spending any more than £30 on a fully-grown plant, for Hoyas. Unless you're really, really into them, don't go for the rare cuttings. They're just really not worth it when the rest of the genus is so nice.
Jane: I wholeheartedly agree. It's fun... I brought you a cutting today and you've got a cutting for me, I love that kind of thing. If you tell me in two months' time, "That cutting didn't do anything, Jane. It's dead!" I'm just going to be, like, "Oh well, if you're not paying any money...!" That's part of the fun for me, but yes, it's high stakes when people are paying a lot of money for a two-leaf cutting.
Felix: I think the thing with any interest that a person has, you do it because you love it, but also, it's a really good way of getting to know people. Community is a thing that we're desperately trying to rehabilitate at the minute and, actually, something like this can really give you an opportunity to go and meet other people. Like you were saying, take each other cuttings, swap plants, that is just a really wonderful thing to be able to do with something that you're enjoying. I don't see the point... they're so easy to propagate. If they're so easy to propagate, why are all these people who are selling it online doing such a rubbish job of it?
Jane: One of the other things I wanted to ask you about, was hanging versus climbing. A lot of the ones here you've got hanging. Do you find any difference in growth when you trail them up something, or do you find that doesn't make any difference?
Felix: It's been a real plant-by-plant situation. With all the plants, I don't know if I said this before or after we started recording, but I really think that, with any plant, you can grow it the best way if you understand where it comes from in the wild and what its root system looks like.
Jane: I'm loving this attention on roots because it's so underrated, isn't it? When you have done your Hoya dissections, what are you looking at? When you're looking at the roots, what are you looking for and what is that telling you?
Felix: The most common problem that Hoyas have is over-watering and those roots are really easy to tell the problem because they become very stringy and the outer layer of the root comes off really easily. So then you can tell maybe you're being over-watered, or maybe you're in the wrong substrate and wrong substrate is such a common problem with Hoyas. Back to what you're asking about, whether they're trailing or climbing, that depends so much more on the root of that individual plant, how that individual plant is growing, than anything else, so I really do have to take it on a case-by-case basis. In here, I've got my Lacunosathere, which is super-happy. I have two Lacunosa cuttings in my cabinet which I have had for two years longer than I had the entire plant. I don't know if you can see the one down there? I've managed to get seven leaves on it now but because, when I bought those cuttings, the root system was in a really bad shape and it takes years to recover from that. So when you buy your Hoya from the garden centre, or the nursery, or whatever, there's several different soils that it could be in. We've seen, with that one, it could be inside a little bark, like an actual tree bark.
Jane: A bark tomb. It's very strange.
Felix: Or it could be, how did you pronounce it before?
Jane: Coir. That's just how I say it.
Felix: I'll just say coir. So you can buy it in coir and I've only recently started seeing Hoyas being put in coir and, so far, they look alright, but I don't know if I'll have a different opinion in a year's time.
Jane: When you say coir, are you talking about the big chunks as opposed to, like, the very fine... because I've had it before, it's in, like, chunky coconut pieces?
Felix: I've seen that before too, yes.
Jane: The Kerrii that I killed was in that.
Felix: My Sigillatis is in that and it's been alright.
Jane: I took it out. Maybe I've made a mistake by thinking, "I can't cope with this substrate because I don't understand it!" so I repotted it.
Felix: I repot probably about 60% of all Hoyas that I buy because they're either in the wrong substrate or in the wrong size pot. A lot of things that garden centres and nurseries - to be honest I think it's probably nurseries - do and to be able to charge more money for a plant, is put it in a bigger pot than it needs. So, I'll show you. My Densifolia is in this tiny, tiny little pot here and look at how much plant has grown out of that and it can stay in there for another year.
Jane: Densifolia; I wouldn't know that even as being a Hoya. I've not come across that one before.
Felix: Yes, I was lucky getting that one. Again, I'm totally prepared to look it up in a year's time and realise it's a completely different plant!
Jane: It's going to be something else.
Felix: So that's in a really small pot and Hoyas need to be pot-bound; they really enjoy it. So, because they're epiphytes, what they do, you find your place to root in the tree and if you can keep anchoring yourself in there, you're just going to keep doing it. You put out the leaves with your aerial roots when you haven't got a stronger hold on it. So, if you think about it like if something's quite root-bound, they'll put out those anchoring roots and that means more branches, it means more flowers growing off that because they've got more space for the peduncles to grow. If you want your Hoya to grow, let it be in a little pot. So often, when you get it back from a garden centre, take it out of the pot, look at where the roots actually go and then re-pot it in a pot that's the size for those roots because you'll often find, like, centimeters and centimeters of, just, empty soil around it. I understand why they do it because a bigger pot looks like a bigger plant. Again, you've got to make sure that you're getting the right humidity for your Hoya, if you're, like, letting it get nutrients out of aerial roots, which means misting. With Hoyas, mostly, you want to water them just when they need it, but mist them quite liberally.
Jane: Again, as epiphytes, I guess they're experiencing moist air? I don't know. I guess, if they're in the Himalayas, the higher altitudes... fog is probably not the right word, but do you know what I mean? It's a moist-air environment.
Felix: Most of them grow in rainforest conditions, whether that's tropical rainforest or mountain rainforests. The ones that do the best in this country are the ones that come from Australia. The Carnosa comes from Australia, Australis does, but we've got our own problems with Australis here.
Jane: Yes, the weirdness of Australis!
Felix: I guess my main message is Hoyas are fantastic but nobody knows how to grow them, so they're probably going to be crap! So just go with the really boring ones because at least everybody's selling them and you'll know how to grow them!
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Jane: Thanks so much to Felix for that Hoya realness, ending the interview, and if you're a Patreon subscriber you can hear an extra chunk of interview that'll be coming out in the next few days. As ever, do check the show notes for some photographs of the flowers on some of Felix's collection and also a fantastic PDF download of Felix's care guide for Hoyas, which is really required reading. Plus, details of how to find out more about the Hoya National Collection and National Collections more widely.
Now it's time for Question of the Week and you remember I mentioned, at the top of the show, we were dealing with a languishing lime? I just can't stop saying it! I want a languishing lime, or I want a lime, not a languishing one! Quite frankly, the talk of lime is putting me in need of a gin and tonic, but let's plough on! Ruth got in touch about a lime plant that was given to her by her son last Christmas but, unfortunately, it is languishing. "What does that actually mean in a horticultural context, Jane?" you may be asking! Well, in Ruth's case, it means that it's dropping leaves at an alarming rate. So Ruth was worried that it had been over-watered after being brought indoors for the winter. Ruth made the sensible choice of hoicking it out of its pot, cleaning it up and putting it back with new compost. Good choice Ruth! I'm hoping you used citrus compost but if not, don't worry too much, but ideally there is a good argument to use specialist citrus compost for things like lemons and limes, peat-free if you can. They do have quite specific nutrient needs and also, they need well-drained soil. So it's a good choice if you have a citrus plant that needs repotting. Anyway, back to Ruth's problem.
The leaves are still dropping, despite the changes that Ruth has made and Ruth wants to know what's going on? Well, I think that citrus are a bit of a problem in a house where all the rooms are centrally heated. Maybe not so much this winter, in our fuel crisis, where everyone's turning off the heating, but in a normal winter, where it might be anything around 18-20C / 63-65F, citrus will often be a little bit unhappy, particularly if the air is a bit on the dry side because they really desire a cooler temperature over the winter. Limes can get down to about 10C / 50F at night, so they do best in a really well-lit, bright room, but one that is that bit cooler. So, either the thermostat set, maybe, around nearer 12-14C / 56/57F. That tickles their sweet spot of the temperature they like and tends to mean that the plants don't go into this state of, "I'm stressed! I'm unhappy! I'm going to drop all my leaves!" Even if you're boosting humidity, as Ruth is doing, Ruth's saying the temperature generally is 16/19C when the heating's on. I think that's probably a little bit too high, Ruth, particularly if combined with not enough light because then you have the problem that the plant isn't actually ticking over very fast in terms of photosynthesis, it's not drawing up much water, therefore that water is sitting around and causing problems. The plant gets stressed and that means it's a magnet also for pests, things like a red spider mite absolutely love citrus, same with things like mealybugs. So I would also give your plants a really good check over for any pests and, if you can, move it to a cooler, lighter room, Ruth. I know maybe that's an impossibility. I don't know. I don't want to prematurely condemn your lime to death but I am worried that if you don't have a cooler room, it might not make it through the winter. I do respect you though, Ruth, because you did say that the two marble-sized limes that dropped have ended up in a G&T, which is really the only way to enjoy lime, or maybe on some jerk chicken.
Now, you did suggest that if you can't halt its decline, that you should uninvite your son for Christmas so he doesn't see it! Ooh, it's a tricky one! I don't know what to suggest! I don't wish to be at the centre of a domestic drama this Christmas! I no doubt have enough of that from my own family, but I would suggest that if you can find somewhere that might work with those lighter conditions and lower temperatures, maybe you can pull it back in time for the festive season, Ruth. As I say, check those leaves really carefully for pests, keep an eye on those roots and, hopefully, you'll find that it's all looking more positive for Christmas time and you'll get some new leaves and shoots. If you've got a question for On The Ledge drop me a line: ontheledgepodcast@gmail.com
[music]
Jane: That is all for this week's show. I will be back next Friday. Make sure your NPK balance is correct, which, of course, stands for 'Nature, Plants and Kindness'! 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 Whistle by Benjamin Banger. The ad music was Holiday Gift, by Kai Engel. All tracks are licensed under Creative Commons. Visit the show notes for details.
Subscribe to On The Ledge via Spotify, Apple Podcasts, Player FM, Stitcher, Overcast, RadioPublic and YouTube.
I travel to Newcastle in the UK to visit the National Collection of Hoyas, and chat with its holder, Felix Horne, and I answer a question about a languishing lime.
Felix is working on a website called hoyas.co.uk - it’s not live yet, but in the meantime, you can download his PDF cheat sheet for buying and caring for hoyas here.
Patreon subscribers at the Ledge End and Superfan level can hear an extra chunk of Hoya chat with Felix in An Extra Leaf 100.
Dates for your diary
On December 2 2022, I'm taking part in a panel discussion on houseplants at the British Library, along with James Wong, Carlos Magdalena and Mike Maunder. Indoor Jungles: The Story of the Houseplant starts at 7pm, and livestream and in person tickets can be booked here.
Check out the notes below as you listen…
The National Collection of Hoyas contains 30 species, 20 cultivars and 46 taxa.
Find out more about the National Collections on the Plant Heritage website
Felix mentions three favourite Hoyas -
Hoya ‘Sunrise’ - a hybrid of H. obscura and H. lacunosa
Hoya lacunosa
Hoya archboldiana
The Hoya Felix mentions that is extremely common in cultivation but threatened in its habitat is Hoya wayetii.
The local garden centre where Felix sources many Hoyas is Cowells in Woolsington.
If you are starting out with Hoyas, Hoya carnosa and H. pubicalyx are both bombproof and there are cultivars to choose from. These will grow in regular houseplant compost, but other Hoyas may have more specialist needs. Felix needs bark compost with a mix of orchid bark and perlite, although he is starting to experiment with cork rather than bark.
Hoyas bought from nurseries come in all kinds of substrates including coco husks.
There are many Hoyas where the correct name is a subject of debate - such as Hoya gracilis/memoria. Another example is H. latifolia/macrophylla.
Some hoyas come from higher altitudes of the Himalayas and like cool temperatures particularly at night - H. polyneura (fishtail hoya), H. linearis and H. retusa.
Hoya ‘Wilbur Graves’ is a carnosa cultivar that is hugely sought after.
When iti comes to propagation, Felix roots Hoya cuttings in damp leca (expanded clay pebbles).
Most Hoyas are epiphytes - plants that live in trees. This means they don’t like a huge root run: this might mean checking new plants and repotting them to fit the size of their roots.
Scroll down for a gallery of images (all copyright Felix Horne) showing Hoya flowers of various species.
QUESTION OF THE WEEK
Ruth wanted to know what to do with her languishing lime - this citrus was looking decidedly peaky and dropping leaves since she brought it inside for winter. Citrus are a bit of a headache for many houseplant owners - they love being outside in summer, but come winter in temperate climates, it’s too cold outdoors but often too warm indoors. Ideally they prefer to be cool but not cold - limes can take a minimum of 10-12C at night. That means centrally heated rooms will often cause problems, especially when combined with lower light levels than they’d ideally like. That’s because they often end up photosynthesising slower than they should, leaving water sitting around the roots and causing root rot.
If stressed by higher temperatures combined with dry air from central heating, citrus will respond by dropping leaves, and may fall prey to pests like red spider mites. There is no easy way round this - so if you can move limes and lemons to a cooler, unheated room with plenty of light - a conservatory is ideal.
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.
THIS WEEK’S SPONSOR
COZY EARTH
This week’s show is supported by Cozy Earth, the premium bedding company that helps you get the deep restorative sleep you need. Bedtime is literally my favourite time of day, so it’s really important that my bed is the most comfortable place it can be. I got to try out a set of Cozy Earth sheets and they really are so comfortable! Cozy Earth’s high quality bedding is responsibly sourced and made from soft and sustainable viscose that comes from bamboo fabrics. Bundle up in Cozy Earth pajamas made from ultra-soft viscose from bamboo this holiday season. Now available in holiday hues! Want to give the gift of a good night's rest with Cozy Earth? On The Ledge listeners can take up Cozy Earth’s exclusive offer today - get 40% off site wide at cozyearth.com using code LEDGE now.
HOW TO SUPPORT ON THE LEDGE
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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 Whistle by BenJamin Banger (@benjaminbanger on Insta; website benjaminbanger.com). The ad music is Holiday Gift by Kai Engel.