Episode 130: OTL sowalong part two - your questions

Episcia seedlings sown as part of last year’s sowalong, seen through a magnifying lens. Photograph: Jane Perrone.

Episcia seedlings sown as part of last year’s sowalong, seen through a magnifying lens. Photograph: Jane Perrone.

Transcript

Episode 130

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Jane: Hello and welcome to On The Ledge podcast! It's Sowalong time and I'm here to answer your questions. I'm your host Jane Perrone and this week is another On The Ledge Sowalong special, in which we'll find out about germination tests, where to get your seeds and how to tell a fake seller from a real one. Plus we meet listener Emily and Kevin from Epic Gardening answers a question about hydroponics.

Thank you to Anna and Monica who've both become Patreon subscribers this week, unlocking extra exclusive content. Find out how by visiting the show notes at JanePerrone.com where there's lots of other ideas about how to support the show. And a confession from me - it's been pointed out to me by a listener by the name of GargantuanSound, great name, that I made a mistake in the spider plant episode, number 101, and that was my Variegatum cultivar with my Vittatum. The audio was wrong, the show notes were right - not sure what was going on in my brain that day! - anyway, I've gone back and corrected that in the audio and the transcript, so that that is correct. If you spot an error in On The Ledge, do point it out! It may not be something I've spotted and I always appreciate your beady eyes and beady ears helping me out!

Talking about old episodes, I got a lovely message from Logan in the mid-west of the US about the plant swap episode, number 112, and Logan emailed to say: "Thank you for the plant swap podcast. I don't know why the idea of plant swapping hadn't crossed my mind before but after listening to that episode I decided to look into swaps in my area on a whim. Luckily for me, there was a swap happening in a few days. I'd never have thought to look if it wasn't for you!" How lovely! Glad to hear that Logan and that is the power of On The Ledge, spreading plant swap joy all over the world!

I also asked for those of you who have taken part in the On The Ledge Sowalong in previous years, to get in touch and tell me how your leafy charges grown from seed are doing. Thank you to Michelle who posted a wonderful picture of some Monstera deliciosa, the Swiss cheese plant, that she grew from seed - these plants are incredible, from 2018 to now, they've got enormous... I will post a picture on the Facbeook page for you to have a look at and if you've got some lovely plants that you raised for the Sowalong, then do let me know! So do share your successes and your failures from the Sowalongs of previous years in the Facebook group, or drop me a line to so I can feature them in an episode.

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Jane: Can you hear that? That is the sound of left-over seed. If you are a long-standing On The Ledge listener and you've taken part in previous Sowalongs, you may find, like me, your eyes are rather bigger than your seed trays! So you go out and buy a load of seed and then realise you can't possibly sow them all! As a result, you end up with leftover seed from previous years. So can you sow that seed? As with most things in life, there's a long answer and a short answer to this one. The short answer is yes, give it a go, because most seed will last a few years and still be viable, will still germinate quite well. There are a few seeds that really do need sown very fresh, for example Cliviaseed - which we will be talking about in an upcoming episode soon - definitely needs to be sown fresh. But the vast majority of seeds that you might be growing, for example cacti and succulents, these seeds will last a good few years, particularly if you've stored them carefully in a dry place at a reasonable temperature.

If you really want to get technical, you can do a germination test. This is just a way of taking a small sample of your seed and finding out if it's going to germinate. It's not difficult, you just need to get a piece of damp paper towel - kitchen roll, if you're a UK listener, that's what we call it here in the UK - and you can lay a number of seeds onto the towel. Obviously this won't work particularly well if you've got very dust-like seed - for example, Lithops seed is really, really small, so that might not work for this. But if you've got a slightly larger seed, lay them out on your damp kitchen roll, you probably need an absolute minimum of about five seeds, ideally about ten would be great. Space them out and lay them on the kitchen towel, check whether the seeds need light or darkness to germinate then fold over your piece of kitchen towel and then roll it up into a little tube and put it in a plastic bag or even in a propagating tray with a clear lid, so that you can see exactly what is going on, make sure you label it so you know what's what and then begins the old waiting game.

If you want to get really fancy, you can buy specialist germination paper online, which is designed for botanists to use for exactly this purpose, but to be honest kitchen towel will do just as well. You can also do this experiment on damp sand, particularly if you're planning to keep the seedlings and grow them on. So follow the normal instructions for your seeds, light or dark, whatever they need and you should have an idea from the seed packet how long germination will take. If germination has not happened in the slightest within a few weeks of the suggested germination period then it's likely your seed isn't going to make it. Say you get one out of five seeds germinating, that would be a 20% germination rate and so on. So if all your seeds germinate you're very much good to go, I would say anything above 60% germination rate definitely means that it's worth sowing those seeds. Germination tests are really worth it if you've got a lot of seed that's maybe a few years old and you just want to know what's worth sowing because that way you'll only be sowing the stuff that really is worth spending time on, therefore hopefully you won't have too many disappointments. Maybe you're raising a quizzical eyebrow right now because you haven't actually got round to buying any seeds yet. Don't panic, I have suggestions for you as well.

Lots of you are looking for reliable places to buy seeds, including Rachel and Yakwise on Instagram, it is definitely worth taking a look at my US and UK buying guides which are on my website. I will link to them in the show notes because there is a seed section on both of these, giving lists of great places to buy seed in the US and the UK. Do take a look at that, but here's a few suggestions for you to be getting along with.

If you're in the UK, Chiltern Seeds has quite a good range of house plants and are definitely worth a look, they've got quite a lot of Coleus, cacti and succulents like Ariocarpus and Aloe variegata, Aloe polyphylla, Clivias, Coffee plants and, of course, the Monstera deliciosa, so definitely check out Chiltern Seeds if you can. There's also Special Plants - if you use their menu on the left-hand side to pick out conservatory plants, you'll find quite a few different interesting species in there, including an amazing intergeneric hybrid called Hippeastrelia, which sounds amazing. The Baobab begonia, Begonia dregei, which is a dwarf wild begonia and apparently is good for bonsaiing, who'd have thought? Then there's Seedaholic, who have a nice range of Coleus, Agave, Aloes, The Umbrella Plant, Cyperus alternifolius and the sensitive plant, Mimosa pudica, which I know a lot of you have had success growing in the past. My final UK-based suggestion would be jungleseeds.co.uk from here you can get the wonderful Desert Rose, Adenium obesum, Dragon hybrids of Streptocarpus and Schlumbergera truncata, although they call it Zygocactus truncatus which is, I think, an old name.

There's a great Etsy shop owned by a grower in Serbia called UnusualSeeds and I think they ship all over the world. They've got a great range of cacti and succulents, Adeniums in particular. They are well worth a look. Seedman.comships to Canada, Germany, UK, Northern Ireland, Italy, Spain and the US and has a really good range of seeds. Lisa also recommended, on the On The Ledge Sowalong thread on the Facebook group, SunnyPlants.com who do indeed have a lovely selection of plants, including cacti and succulents and quite a few tropical plant seeds, a mix of palms for example, Strelitzia, both reginae and nicolai, the orange and white flowered species of the Bird of Paradise and you can even grow a Baobab an Adansonia digitate - wouldn't that be cool?

So I can recommend all of those companies, fairly confident that they are good sellers, but obviously there's a lot more options out there online when you're choosing seeds. So how do you know whether someone's genuine or not? Well, the first thing I would say is if it seems too good to be true then it probably is, so if you're seeing pictures of things you've never seen before, like a begonia with blue leaves, or a plant that seems to have three different types of fruits coming out of it, it's probably just been photoshopped. On places like eBay and Etsy there are sellers who are selling all kinds of stuff that just doesn't exist - you're just going to get a packet of cress seeds or similar, through the post. Often times these sellers are in China, but not always. You'll also find lots of fake seed on Amazon too. I've just been having a scroll through to find out what's there. Oftentimes, the descriptions will be a weird old mishmash of different names. So, for example, I just found a listing for something that was either a venus fly trap or a Heliamphora or maybe both, but the pictures of the venus fly trap had bright blue traps - yes, not so good. When you click through to look through to the seller in question and see what else they sell, often with these sellers you'll find they're selling all kinds of stuff - not just horticultural stuff - random gadgets and all sorts. Oftentimes, that's a good sign that they are not going to be supplying reliable seed.

I've just come across another one which is a Begonia listing and on this one the Begonia has been photoshopped. It's one of those big flowered, tuberous Begonias and it's been photoshopped to have bright blue flowers and dark blackish leaves. That's really not going to happen. So, again, be cautious. You'll find that a lot of these seeds that are listed ... this is a good one, I've just found Lily of the Valley seeds and everyone of the flowers on the Lily of the Valley is a different colour, so they're either yellow, orange, dark blue, light blue, purple, yellow! Yes, that's not happening! For £2.19 that is not going to bring you much of a reward, so buyer beware of the online seed purchases.

The reviewers on this listing have got the sense to point out that this is not real, somebody said: "There is no bargain, seeds are not good at all, none of the seed was live, all dead, no plants after a few months of waiting. Really disappointed." Then another one: "Another con job, this is just bits of dust, not a single seed could be found, after checking under a microscope not one single seed was found." Yes, this is so disappointing for people to have this happen but it's a very common thing. We need to be really aware of it and spread the word to other gardeners because not everyone is as web savvy as they should be and avoid these sellers who are just making a fast buck.

I would also emphasise that it's really great to get on board with plant societies because they often have seed schemes, for example, the Gesneriad Society, the British Petrological Society, which we talked about last week and their spore scheme, The British Cactus and Succulent Society and many more. They operate on the kindness of their members in swapping or providing seed and it's a great way of supporting these societies. So do check that out if you're struggling to find some special seed. If there's a society you can join they will probably be able to help you out.

Some people have also asked why certain housplants' seed seems to be just unavailable online. It's a good question. I guess, partly it's down to how much seed a plant produces. So if a plant is not particularly forthcoming in terms of flowering and producing seed, that makes the seed very expensive to buy and expensive to produce. Some plants just don't flower that often and are very easily propagated, vegetatively, from cuttings, so really people don't bother with seeds, or sometimes seed is only viable for a really short amount of time and that makes it impractical to sell.

So the next obvious question is 'What am I sowing this year?' Well, in front of me I've got a rag tag bunch of seed packets that I've gathered together. Some have dropped on the floor, hang on, just going to go and pick these up. It's a long way down. Okay, I'm back. Let's see what I'm sowing this year. I've got some things left over from last year, so I've got half a packet of the bargain basement lottery mixtures, greenhouse plants. I've never actually identified what any of these were, embarrassingly, some of them went into pots outside and some are bedding, because there was nothing that really looked houseplanty, as such, that germinated, but I'm going to give this another go, because that's a bit of fun.

I've also got some ... what's this? I've got some Lithops seeds. I've got Lithops Bromfieldii Embers which came from the BCSS and the seed on this is absolutely tiny. I can hardly see them in the packet, but I've got a few of those to sow. I've got another Lithops, which is Lithops Aucampiae Bella Ketty and I've probably got about ten seeds there to sow. I've also got a lovely bargain basement packet of Coleus. This is a rainbow mix, the classic combination, and this just provides cheap and cheerful bedding for my outside beds and any good plants can be kept inside over Winter for the following year. So, lovely cheap and cheerful stuff.

Okay, what else have I got here? I've got Aloe polyphylla, I think these came from the BCSS, I know that Chiltern Seeds have got them, but I think they may be out of stock there. That's the wonderful succulent Aloe, with the spiral patterned rosette which is absolutely gorgeous and it's a generous packet of about a dozen seeds there, so I'm hoping for some success with that. What's this? Oh, Dioscorea elephantipes which has got lovely seed actually, quite large, with a fan type extension on it. Love a Caudex as we know, so I'm going to try to sow those. If you're not familiar with the Latin, this is the elephant's foot plant that produces this incredibly wonderfully textured elephant's foot-resembling Caudex, a big swollen root at the bottom. I realise I'm not going to be getting a huge caudex very soon because this plant, of course, will require some time to bulk up, but I thought this one would be a fun thing to try.

What's under this? I've also got some random chilli seeds, self-saved chilli seeds which I will be sowing too. I'm not exactly sure what variety they are but some of those will no doubt end up on my windowsill so that's kind of fun. So that's what I've got to sow so far this year I think I've got some more seeds on their way. I may have done a bit of late-night ordering, so this may not be the end of it! For the moment, this is what I'm choosing from.

I'll probably get started on the Coleus first because it's really easy to sow and has a really good success rate. I might wait a couple more weeks to do the cacti and succulents. One more seed packet that I forgot, this is from Chiltern Seeds, Plectranthus, Mixed Species, so this'll be interesting because Plectranthus can make good house plants as well as being great summer bedding. Apologies, the tiny seed packets are appearing from everywhere. The other thing I've got are Cheiridopsis denticulata, also from the BCSS. I'm going to have to Google that one because I can't even remember what I've bought there. Ah, yes, this is a lovely succulent with lovely pale yellow, daisy-like flowers. I guess the denticulata is because the leaves do resemble little teeth, so that's another great plant that I'm looking forward to growing. It's a South African native, as are many of these plants.

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Now, to more of your questions, this one came in on Instagram - where I'm @j.l.perrone - from Benjafin: "How much difference does compost actually make?" As in, can you just use multipurpose and get similar results? Great question! So do you need to splash out on specialist seed-sowing mix, as opposed to just using any old multipurpose compost you've got hanging around? The main issue with using that regular compost is just the size of the bits within the compost. If you look at seed compost, it's usually very fine, it's more like, I'm going to use an analogy that probably won't work to Americans now, if you're making a crumble the consistency of the crumble mix before you put it on top of the fruit is generally about what seed compost looks like. So, more breadcrumby than big, massive chunks, whereas if you get something that is a multipurpose compost that can have quite large pieces in it. The problem for the seeds is that they can then just get stuck underneath a massive pile of something - to them it's massive, if it's a tiny dot of a seed - and it can hinder germination.

The other thing about seed compost is that it tends to be relatively low in nutrients because seeds as they germinate draw energy from their own selves to power that germination, so they don't need a lot of nutrients early on in the process. Can you use multipurpose if you've got massive seeds? Quite possibly, yes, if you've got something, I don't know what the equivalent would be in the houseplant world, maybe a palm seed, or a runner bean seed or something like that, that's really big, it probably won't do any harm to use larger-grained compost. What you might want to do is just pick out any really large bits or give it a bit of a sieve, that may help. The other thing to bear in mind though is that seed compost is generally quite well drained so that the seeds don't get waterlogged and have water hanging around that could rot them before they get a chance to germinate. That can also be a factor in the world of damping off, which is something that happens to seedlings now and again. It's a fungal condition where suddenly your seedling will collapse and fall over and sometimes a little bit of visible fungus around the base. You can combat that by providing good drainage and also really good hygiene, washing your seed trays with hot soapy water and rinsing before you begin and also to some extent using fresh seed compost. Don't use last year's supplies, buy in fresh. Don't waste last year's, you can obviously use that as a mulch in your garden, or mulch on top of your houseplant pots, but don't use old compost for seeds. So fresh compost, ideally seed compost is the best thing you can use, and for certain seeds, cacti and succulents particularly, you might want to be adding a layer of vermiculite on the soil's surface before you start sowing, so that the seeds are even more well drained.

As always check the seed packet, see what it recommends, maybe try doing a couple of different combinations of compost for your seeds and see what works best? But I hope that helps Benjafin and your seeds romp away this year.

Right, now it's time to meet our listener and her name is Emily. Remember if you want to feature on the Meet the Listener, then drop me a line It's ridiculously simple to take part. You just need a smartphone, which is something all of us have, I would say. So get involved, let's hear you on the show, hear the answers to your questions. I love this because every listener has got their own take, which is brilliant. So without further ado, let's hear from Emily.

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Emily: Hi, I'm Emily from Erfurt and I'm actually getting trained as a gardener in the oldest still existing cactus and succulent nursery in the world, Kakteen Haage, and I'm very excited about that because I also have a growing collection of succulents and cacti of my own. I also live together with all my other houseplants and they really bring me joy.

Jane: Question one - there's a fire and all your plants are about to burn. Which one do you grab as you escape?

Emily: This is a horrible scenario, especially when you have many, many plants, but I would probably grab myEcheveria laui because she's very close to my heart. She's a tender plant and not really easy to keep, but right now she seems super-happy, so I want to keep her that way and would take her with me.

Jane: Question two - what is your favourite episode of On The Ledge?

Emily: My favourite episode of On The Ledge must be the one about the Prick Cactus Shop with Gynelle Leon. I really loved it because she showed me that women can succeed in this business and she's super-positive and that's really my dream, she's living my dream and I hope to recreate that one day in Germany and now I really want to go out and meet her and talk about this.

Jane: Question three - which Latin name do you say to impress people?

Emily: I would love to use Latin names all the time but I don't really have people around me that get excited about them. They just get confused and don't know what I'm talking about! So the Latin name I'm actually using sometimes is Monstera deliciosa because everybody knows that plant by now and I can then go on to explain why it's called deliciosa and that's because of the supposedly very delicious fruit.

Jane: Question four - crassulacean acid metabolism or guttation?

Emily: For me, it's crassulacean acid metabolism all the way. I just loved it when I found out about it in the first place and it got me even more excited about the plants I already own because I thought it's just such a cool survival strategy to keep in your bath in the day and then start breathing at night when the temperature drops and gets liveable, really.

Jane: Question five - would you rather spend £200 on a variegated Monstera or £200 on 20 interesting cacti?

Emily: After hearing everything I've said before, you're now probably going to expect that I want those 20 cacti, but actually I don't! I would really love the variegated Monstera because I don't have any more space for 20 cacti! I'm just allowed to buy one or two sometimes, but I do have space for that Monstera and if anybody is interested in Germany to swap a cutting for a variegated Monstera against some nice cacti, hit me up!

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Jane: Now it's time for the Question of the Week which comes from Sonia, who has just discovered On The Ledge and is catching up on episodes. She's currently on episode 34, so she might have to skip forward a bit to get the answer to this particular question. She's using hydroponic seed starters and feeding them with liquid nutrients every couple of weeks and she's realized, after the fact, that she'd been feeding the seed starters double the amount of liquid nutrients recommended, oops! "I was wondering how to proceed with the feeding at this point? Should I give them less food but at the regularly scheduled time interval? Give them the normal amount of food but wait a bit longer in between the feedings? Or just act like nothing bad happened and give them the normal amount of food at their regularly scheduled time interval?"

Now, I am not a massive hydroponic expert, so it was time to call in someone who is. That man is Kevin Espiritu from Epic Gardening. You'll have heard Kevin in my hydroponics episode, so he was the ideal person to deal with Sonia's plight. Over to Kevin now to answer the question. Kevin, what do we do about these seed starters who've received a little bit too much in the way of nutrients?

Kevin: Well, hello there Jane, thanks so much for thinking of me. I'm glad to be back on the podcast to answer this question for Sonia. The thing to think about with hydroponics is that we control the entire environment and sometimes we do make these mistakes. Now, the question has multiple answers. Depending on the type of hydroponic system that you're using, one solution would be to change out the reservoir and correctly apply the right amount of nutrients. What that means is you're taking out all the water and nutrition, dumping it out and then replacing it with a fresh batch. Now, a lot of hydroponic growers are doing that on a weekly or bi-weekly basis anyway, so this could be a good opportunity to do that.

If you don't want to do that, then what you can do is get an EC, electrical connectivity, or a TDS metre, they are effectively the same thing. What this will do is tell you the concentration of nutrients in the water and what I might do, is I might continually top my reservoir up with water but not add nutrients until that level falls below a certain point. Like you said, you fed it twice as much nutrients, so what will happen is that the plant will drink water and nutrients but it's not going to decrease the concentration too much because the plants aren't large enough to be using it yet. Now, fortunately, it sounds like you've avoided what we call nutrient burn, when you put way too much nutrient in the solution and actually that damages the plants. As long as you've avoided that, I might say to just leave it in and continually top up with water that does not have additional nutrients until it's diluted to a point or the plants are at their normal feeding schedule. That's it from me! Thanks so much Jane - back to you.

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Jane: Thank you, Kevin and now I've got a couple more questions to answer before we close. The first one is: Matthew wanted to know how to get hold of Gesneriad seeds for Gesneriads that aren't for sale in the US. Well, one thing that is worth doing, is checking out the various Gesneriad Facebook groups because sometimes people do share seed and sell seed via those forums. There's one called African Violet and Gesneriad and there's a few examples of people offering seed there. There's also another Facebook group called Gesnerinerds, which is also worth checking out. Somebody on there suggests a website called Brazil Plants. I can't vouch for this one, but looking at it, it does look like it's got a great range of plants - I'll put a link in the show notes to the species list that they have for their seed service. It's a pretty basic site, so you need to email this chap, who I think is in Brazil, to get the details and obviously, you've got to make sure that you can get the seeds through whatever customs regulations you have in your country, but that's worth a look,BrazilPlants.com If anyone's used BrazilPlants.com successfully, I'd love to know, and then we can verify that as a good supplier. The top tip really on Gesneriad seed, is to join the Gesneriad Society and then you can take part in the seed fund which is wonderful. You'll get some really interesting seeds to sow. That really is the best way of getting hold of some cool Gesneriad seeds, so do take that top tip.

Finally, Rachel wanted to know about relatively fast-growing, flowering cacti. If you want something that's going to give you a quick win, by which I mean probably go from seed to a flowering cactus in about two years, then the best cacti are probably either Mammillarias or Rebutias, which are very easy, produce really beautiful flowers and one of my favourite types of cacti. A lot of the Columnar cacti will take an awful lot longer to be mature enough to flower, so, again, Mammillarias or Rebutias are the ones you want to go for.

If you get into cacti and succulents, as I've said many times before, the BCSS, The British Cactus and Succulent Society is brilliant. I've got in front of me their wonderful seed-raising information sheet, which is really good. It's just four pages but it gives you everything you need to know about raising cacti and succulents from seed. One thing I've just learned, which I didn't know, is if you're planning to grow Epiphyllums from seed, apparently these really don't like having a lot of lime in their compost. So you need to make sure that pH of your compost is more on the slightly acidic side, as opposed to the limey side, and that will hopefully ensure your success.

One other thing that's definitely worth watching out for when you have got young seedlings of any plant, is fungus gnats. Now, normally on mature plants fungus gnats are not going to cause too much of a problem, but for seedlings those little baby grubs can eat away at roots and cause significant damage and loss of seedlings. So go back and listen to the fungus gnat episode if you haven't done so already and the best solution for fungus gnats is a nematode drench, where you add some microscopic nematode worms to water and add that to your seed trays. That will kill off the fungus gnat lava in a very safe way and your plants will not be damaged.

Well, that just about wraps up this week's show, I hope you've enjoyed it. I will be back next Friday with a bit more On The Ledge Sowalong info. Oh and just to say, I'm sorry to say, this week I'm not bringing you the details of the Chelsea ticket giveaway. I'm just waiting on a bit more information from the RHS about how to word the terms and conditions, but it will be coming soon, so don't worry. That's on its way. Coronavirus notwithstanding, the RHS is saying at the moment that all its shows will go ahead, so I'm working on that basis with our fingers fully crossed. So I'll get the giveaway details to you as soon as possible, hopefully next week. In the meantime, plant people, enjoy sowing and tending your plants. I'm off to do a couple of interviews for upcoming episodes. Exciting, exciting, top secret stuff, but you're going to love it! So tune in again next week! Bye!

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Jane: The music you heard in this episode was Roll Jordan Roll by the Joy Drops, An Instrument the Boy Called Happy Day, Gokana by Samuel Corwin and Quasi Motion by Kevin Macleod. All licensed under Creative Commons, see my website JanePerrone.com for details.

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If you’re keen to get involved in the OTL Sowalong but aren’t sure what potting mix to use, where to find your seeds or what to do about those ancient packets of seeds you’ve been hoarding, this is the episode for you! Plus Kevin Espiritu of podcast Epic Gardening (and my guest in the hydroponics episode) answers a listener question about nutrients for hydroponic seed starters, and we meet listener Emily - the German cactus nursery she mentions is Kakteen Haage.

If you haven’t listened to any of the previous Sowalong episodes, you can find them all here. If you’d like to share what you’re sowing on social media, just use #OTLsowalong so I can spot it! I’d also love to hear how all the plants you’ve sown for previous sowalongs are doing.

Apologies that I made a mistake in the spider plant episode, mixing up ‘Vittatum’ and ‘Variegatum’ - I’ve now corrected it. If you spot a mistake, please let me know!

How to do a germination test

  • A germination test is a way of telling whether old packets of seed are still viable: useful if you have a lot of seeds and want to check what’s worth spending time on.

  • Take a minimum of 10 seeds - or five if it’s a small pack - and lay them out on damp paper towel (aka kitchen roll). Roll up the paper and place into a clear plastic bag, labelling so you know what’s what. You can also sow onto damp sand, and (for larger seeds anyway) there’s a chance of growing the seeds on so you don’t waste any.

  • Check the packet to see what temperature and light conditions the seeds like, and treat accordingly.

  • Count how many seeds germinate within a few weeks of the suggested germination time frame - one out of 10 means a 10% germination rate, and so on. Above 60% germination gives an indication that it’s worth sowing the whole packet.

  • If you want to get all fancy, you could use germination paper instead of kitchen paper.

  • If in doubt, though, just sow the seed and see what happens!

More seed sowing tips

Mammillarias and Rebutias produce beautiful flowers, as illustrated by the Southfields Cactus Nursery display at the Chelsea flower show.

Mammillarias and Rebutias produce beautiful flowers, as illustrated by the Southfields Cactus Nursery display at the Chelsea flower show.

  • If you are looking for hard-to-source gesneriad seed, check out Facebook groups for enthusiasts such as African Violet and Gesneriad and Gesneri-Nerds as sometimes members post seed for sale or swap - you may also want to check out Brazil Plants who sell a lot of Sinningia seed as well as other houseplants (lots of Begonias too!). But best of all, check out the Gesneriad Society Seed Fund.

  • If you are looking for fast-growing cacti, go for Mammillarias or Rebutias, which can go from seed to a mature flowering plant in two years.

  • Watch out for fungus gnats on seedlings - the larvae can cause a lot of damage to the fragile roots of seedlings as they grow! Check my fungus gnat episode for advice on how to deal with them.

  • Why not use plain old regular plant potting mix? Seed mix tends to be finer-grained and well-drained, which offers seeds the best chance of growth. It’s also low in nutrients which is great for seeds, as they don’t require a lot of nutrients in the very early stages of growth.

  • Regular potting mix can be used for really big seeds, but add some drainage material. For cactus and succulent seeds, a layer of vermiculite on the top of the potting mix can ensure seeds don’t get waterlogged.

  • Watch out for damping off, which is a fungal condition that can cause the sudden collapse of young seedlings. Avoid by washing trays and lids with hot soapy water before use, use fresh seed mix, and make sure the seed mix is well drained and there’s some air circulation around the seedlings.

    Where to buy seed

How to spot a fake seed seller

That multicoloured lily of the valley - just, no….

That multicoloured lily of the valley - just, no….

Unfortunately the internet is full of fake seeds for sale to unsuspecting growers - here’s what should set alarm bells ringing…

  • If it sounds too good to be true, it probably is! (Yes, that Begonia with bright blue flowers has been photoshopped, and lily of the valley does not really grow multicoloured flowers!)

  • Watch out for sellers who offer a whole range of other, unrelated goods as well as seeds - this can be a sign that they are just in for a fast buck.

  • Check feedback ratings and reviews, but don’t rely on them - people sometimes leave good feedback before they’ve actually sowed the seed, and reviews can, sadly, be ‘bought’.

  • Listings are often very wordy and consist of a mishmash of different plant species.

HOW TO SUPPORT ON THE LEDGE

Contributions from On The Ledge listeners help to pay for all the things that have made the show possible over the last few years: equipment, travel expenses, editing, admin support and transcription.

Want to make a one-off donation? You can do that through my ko-fi.com page, or via Paypal.

Want to make a regular donation? Join the On The Ledge community on Patreon! Whether you can only spare a dollar or a pound, or want to make a bigger commitment, there’s something for you: see all the tiers and sign up for Patreon here.

  • The Crazy Plant Person tier just gives you a warm fuzzy feeling of supporting the show you love.

  • The Ledge End tier gives you access to two extra episodes a month, known as An Extra Leaf, as well as ad-free versions of the main podcast on weeks where there’s a paid advertising spot, and access to occasional patron-only Zoom sessions.

  • My Superfan tier earns you a personal greeting from me in the mail including a limited edition postcard, as well as ad-free episodes.

If you like the idea of supporting On The Ledge on a regular basis but don't know what Patreon's all about, check out the FAQ here: if you still have questions, leave a comment or email me - ontheledgepodcast@gmail.com. If you're already supporting others via Patreon, just click here to set up your rewards!

If you prefer to support the show in other ways, please do go and rate and review On The Ledge on Apple Podcasts, Stitcher or wherever you listen. It's lovely to read your kind comments, and it really helps new listeners to find the show. You can also tweet or post about the show on social media - use #OnTheLedgePodcast so I’ll pick up on it!

CREDITS

This week's show featured the tracks Roll Jordan Roll by the Joy Drops, An Instrument the Boy Called Happy Day Gokana by Samuel Corwin and Quasi Motion by Kevin Macleod.

Logo design by Jacqueline Colley.

PropagationJane PerroneotlsowalongComment