Podcast Episode 10: How to Prevent Mold on Microgreens

Episode Description

Have you experienced mold problems on your microgreens, and are wondering what the solutions to these problems are? This episode will answer a lot of your questions on mold on microgreens.

In this episode you will learn:

  • How to identify mold.
  • What mold is, and what it’s actually for!
  • Why you’re getting mold.
  • How to best prevent ever getting mold in the first place.
  • What to do to treat mold, once you realise you have a problem.
  • What hydrogen peroxide is and how to use it.

Mentioned in this episode:
Microgreens seed density calculator:
https://microgreensentrepreneur.com/seedcalculator
Beginners guide to starting a microgreens business free ebook:
https://microgreensentrepreneur.com/ebook
True Leaf Market discount code: Enter “MGE5” at the checkout to receive a 5% discount on your order.
https://trueleafmarket.com
Ask a question:
https://microgreensentrepreneur.com/ask 

Episode Transcripts

Microgreens Entrepreneur Episode 10: How to Prevent Mold on Microgreens

You’re listening to The Microgreens Entrepreneur Podcast, where the aim is to help you start, grow, and improve any microgreens business. I’m your host, Brian, owner of a microgreens business that I operate out of my own home. Stay tuned and welcome along.

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[0:30] Hello, and welcome to another episode of the Microgreens Entrepreneur Podcast. I hope you’re having a good week, and all is good with you. In this week’s episode, we’re going to be talking about everything mold on your microgreens. I’m going to go through what mold is, how best to prevent getting it, why preventing it is much better than having to treat it. But none of us are perfect, so for when we do have to treat it, we’ll go through some remedies for mold too.

[0:54] Before we get started, I just want to let you in on some good news. After last week’s episode, when we had Parker Garlitz from True Leaf Market on the podcast, I’ve since been able to become an affiliate for True Leaf Market. The good people over at True Leaf Market offered a discount to all of the listeners of The Microgreens Entrepreneur Podcast.

[1:14] So, for any of you who are in the States, and you’re thinking about buying seeds or any growing equipment, or if you’re already buying from True Leaf Market, if you use the discount code ME5 when you’re at the checkout, you’ll receive a 5% discount on your total order. I’ll leave a link for True Leaf Market in the show notes and the details about that discount code. Again, it’s ME5

[1:39] All right. I want to tell you a story before we get into talking about mold. Thankfully, in Ireland, the restaurants are opening again next week, so I spent the whole weekend planting up for that and preparing for that. I hope wherever you are in the world, things are getting back to normal, as well, and your restaurant part of the business is getting back to normal too.

[2:00] The story is that I had a chef reach out to me from a restaurant that I hadn’t been doing business with, and because his restaurant was opening again soon, he was actually changing the whole menu. He had never used microgreens before, but he just wanted to start using them now.

[2:16] So, I offered to come in and meet him at his restaurant and bring him in some samples as you normally would, but he actually asked if he could come over and have a look at my operation and see how I grow the microgreens. He just wanted to see how things were doing here. It’s not a request that I’ve ever had before. I’m sure some of you have had that request before, but I haven’t. 

[2:36] It was funny when he did come over because he came into the house, and I don’t think he was really aware of urban farming or indoor farming because when he came into the house, he was looking for a greenhouse, and he got a bit of a surprise when I was bringing him into the spare bedroom. But he actually thought it was one of the coolest things he had ever seen, and he was really interested in it.

[3:00] We got to talking then, and he was talking about how he had never used microgreens before, and now he feels that he has to use them because they’ve become so popular. And what brought him to finally look into using microgreens was that when he was last out for a meal himself, he got a pea shoot on his dessert. I actually forgot to ask him what dessert it was. I must find out what it was, but I thought that was interesting.

[3:23] Hopefully, everybody starts using them on dessert, and we can sell more microgreens. Anyway, let’s get on to what we’re really here for, which is to talk about mold and microgreens. To prevent mold on your microgreens, just use hydrogen peroxide for everything. No, I’m just joking around – don’t do that, but that’s really the main advice that I see online on how to prevent mold.

[3:48] But, we’re not going to talk about hydrogen peroxide until the very end because, in my opinion, it’s your last resort. Let’s take a look at what mold actually is. Look, I can appreciate that this is new information for some of you, but I still think it’s really interesting. 

[4:06] So, as much as a nuance that mold is when we’re growing microgreens, it’s actually really good. Yeah, you heard me correctly. Mold is a good thing, and we actually need it here. The job of mold and all fungus, I suppose, is to return all living things or things that were once living, to return them back to the soil, and that’s us humans included, I’m afraid to say.

[4:29] So, it decomposes us and all dead things and returns nutrients to the soil. Then they’re available for new life. So, it’s a nice closed-loop system, I suppose you could call it, and that’s all made possible by mold.

[4:48] So, we’ve established that mold is great, and we need it, but we don’t need it on our microgreens, and we certainly don’t want it, but before I get into how to prevent getting mold on your microgreens, let’s go over first how you can actually identify whether or not you have mold.

[5:04] You’ll usually notice it on top of your seeds. For me, it’s normally grey, but it can be black or even blue. There are loads of different kinds of mold. So, it will usually grow on top of your seeds, and it can grow at the bases of your plants if they’re sown too densely, and there’s poor airflow there.

[5:23] Sunflower is prone to having mold issues. That’s the one that I probably have the most issues with, and it’s usually on the hulls of the seeds. You will also notice mold developing on dead things in your tray. 

[5:36] So, like we said, mold’s job is to break down dead things, so it will be attracted to things like little bits of sticks if they’re in your soil, or dead or nongeminated seeds that are in the tray. So, keep an eye out for that kind of thing. You’re looking for a spiderweb-like formation in your tray, or your seeds might look a bit furry. Usually, again, it’s grey. 

[5:59] I think one of the biggest mistakes that definitely new growers make, and I’ve certainly made it, is the mix-up between root hairs and mold. I actually just made a little video on Instagram this weekend that shows the difference between mold and root hairs. If you’re not familiar with that already, you can check out the Instagram, and it’s in the Top Tips. The Instagram handle, I suppose you’d call it is microgreens_entrepreneur.

[6:27] Now that we know what mold is going to look like in our trays, we’re going to take a look at why we get mold. I really learned all about growing plants by working on golf courses for 17 years, so I’m going to use the golf course as an example to explain it. 

[6:42] Now, stick with me. It’s the same concept. One is grass; one is microgreens. They’re all plants. Every golf course that I’ve ever worked on always had at least one putting green that was prone to getting diseases, and it was always just unhealthy. That was always down to the little microclimate that that specific green had that made it different than the rest of the greens and the rest of the course.

[7:07] So, if you picture a putting green that’s surrounded by trees on all sides except for the front of it, there’s a little microclimate there that’s just different to the rest of the golf course. The airflow is drastically reduced because the wind is just not as effective because it’s being blocked by the trees. That leaves the air stagnant.

[7:25] If you listen to last week’s episode, The Microgreen’s Seeds Masterclass with Parker Garlitz, you would have heard Parker Garlitz saying that mold is always in the air. It’s in every breath that we take, and he’s 100% right. Mold spores that are in the air are the reproductive particles of mold.

[7:39] So, back to our golf green where the wind is being blocked out by the trees, if there’s no wind to keep the mold spores moving, those mold spores are going to come to rest on the green.

[7:50] Then we’ve got the issue of the trees not only stopping the airflow, but it’s also blocking out the sun, as well. These two issues keep the plants wet and damp for a longer amount of time, and the humidity in that area would be higher, as well. Mold and other plant diseases love those conditions.

[8:11] The low airflow, too, could cause the temperature in those areas to be higher than on the rest of the golf course, so mold loves moisture and dampness and heat. It thrives in those conditions. That’s why those areas of a golf course always suffered. So look, that might have been a bit longwinded, but what have we learned here? Mold loves moist, damp conditions, low airflow, low sunlight, and heat. 

[8:37] Now, think about when you’ve got all your microgreens trays stacked on top of each other. What are the conditions that are in there? You’ve got low light. You’ve got dampness, a lot of moisture, low airflow; it’s hot because the plants that are germinating there are creating energy and creating heat. 

[8:56] Your trays are hotter when they’re germinating than it is in the rest of your grow room. So, that all being said, your microgreens are at their most vulnerable and probably most likely to get mold when the trays are stacked on top of each other in the germination stage.

[9:14] With all of that in mind, let’s see what we can do to help prevent getting any mold on our microgreens. The first thing relates to your seed. You want to buy seeds that have a high germination rate. 

[9:25] If you’ve got seeds in your tray that aren’t germinating, they’re dead basically. They’re just not going to germinate, and mold is going to be attracted to them. It’s going to want to break them down and return them to the earth because that’s mold’s job.

[9:40] If you’re in America, I do recommend that you buy your seeds from True Leaf Market. Parker Garlitz, one of the founders at True Leaf Market, was on the podcast last week, and he talked about all the testing that they do on their seeds before offering them for sale. 

[9:54] They make sure that there is at least an 85% germination rate on their seeds before being sold. Probably, much higher than 85% because they turn over their inventory four to five times a year. So, you can’t go wrong with their seed.

[10:10] The next thing you can do is sterilize your seed. You do that with hydrogen peroxide, but like I said, we’re not going to get into talking about that until the very end because, in my opinion, it’s your last resort. 

[10:25] Your farming practices, I suppose you could call them, and your environmental growing conditions are the most important things, so we’re going to talk about all of that first.

[10:34] Firstly, we’ll talk about the growing conditions in our grow room that we can control with the help of some automatic systems that we set up. They are the airflow, the humidity, and the temperature.

[10:48] My aim for heat in my grow room is a consistent enough temperature of around 20 degrees, but it ranges from between 18 to 23 degrees. That’s roughly around 65 to 74 Fahrenheit. Now, I’m not saying you can’t grow good microgreens over that heat, but your chance of having a mold issue is greater the hotter it is. 

[11:11] So, we can control our heat with a thermostatic heater or an air conditioning unit. The room that’s in my house, there’s no air conditioning, and there’s no need for it. Ireland is a cold enough place, so heating is all I have to worry about here.

[11:26] The next thing is humidity. When the air is too humid, your microgreens are going to stay wet, and that’s going to help to cause mold. So, get yourself a hydrometer that will show you the percentage of humidity that’s in your air. They’re very cheap. You can get one for 10 euros or $10 or whatever it is. Your humidity then can be controlled well with a dehumidifier. 

[11:52] When I first started growing microgreens, the advice that I was seeing online was telling me that the humidity needed to be around 40%. But, in my experience, it doesn’t need to be that low at all, really. Ireland is a humid enough country, and the average humidity outside every day here is about 75%, so it’s pretty hard to get the humidity that low.

[12:13] Before I had a dehumidifier, the humidity in the room could be up over 80%, and I would see a lot of mold problems. But, I have a really good dehumidifier for a long time now, and even running that all day, the humidity in my grow room is usually somewhere in the mid-50s, and I very rarely have any issue with mold now.

[12:35] In my opinion, if you can keep your humidity below 60, that’s great. I suppose you don’t want to go too low with it either if you’re in a less-humid part of the world because it can help dry out your trays a bit quicker, too. So, somewhere in the region of 50% and 60% is my recommendation.

[12:53] If you’ve got any view on that that you’d like to share, you can DM me on Instagram with your opinion on that. I’d be interested to hear what you say on that.

[13:03] The next thing we’re going to look at is our airflow, and it’s possibly the most important aspect, and it’s very easy to control. It’s important because we know that mold spores are in the air all the time, so by having a fan blow the air, acting as the wind, I suppose, it just helps keep those mold spores moving around the room. It doesn’t let them settle on your plants or on your germinating trays, and so easy to control on there. 

[13:31] So, keep a fan running all the time or fans depending on the size of your operation. I suppose they’re the environmental conditions that we need to get right, and we have a bit of help there from our equipment. 

[13:44] The next three points we’re going to go over, they’re completely on us. They’re our farming practices. The first one is our starting point, and that’s sanitization. First off, that relates to ourselves, so we’re going to make sure that we’re clean, our clothes are clean, our hands are washed, so that when we touch anything that we use, we’re not spreading anything around.

[14:06] Then the room itself that you’re growing in, you should keep that spotless. I think the grow room in my house is the cleanest room in the whole house. So, it’s really important to keep it clean and a tidy workspace and make sure everything is clean. 

[14:19] That includes the trays that we’re growing in. They need to be sanitized after every use. You can power wash them if you have a garden, and then sterilize them with food grade hydrogen peroxide or bleach. That will kill any of the mold or the fungal pathogens for you. To be honest, it’s the one microgreens job that I don’t like doing, but it’s a really important one that you need to put the work in and set yourself up for a successful grow at the start.

[14:55] The second one is getting your seed density right. You need to get the seed density as dense as possible and get the best yield that you can from the tray, but not so dense that it’s going to cause you problems.

[15:08] So, let’s go back to the golf course, just for a minute. Imagine you’ve hit your ball into the woods, but it’s just on the edge of the woods, on the outskirts. When you’re at your ball, you’re still going to feel the breeze or the wind coming through the edges of the woods. There’s still airflow there. It’s still going to get the sun, so the ground is relatively dry. It’s not a bad place to be.

[15:29] But then, unfortunately, you’re a bit of a crappy golfer, like me, and with your next shot, you hit it into the middle of the woods. So, you go in and get it, and when you get in there, it’s a different story. Things are damper. You can’t feel the wind anymore. You can just about see the tops of the trees swaying in the distance, and there’s no sun reaching you there at all. Do you see what I’m getting at here?

[15:53] Sorry about all the golf course analogies. That’s the last one, I promise. But if you compare your trays to the edges of the woods, and you think about the edges getting more airflow than the middle, there’s an opportunity there to sow more densely in the edges of the trays and don’t have the middle so dense.

[16:12] I think everybody has a natural tendency to fill up the middle of the trays with seeds. But in actual fact, if you focus on seeding the edges a little bit more densely, that’s the part of the tray that’s going to be able to withstand the higher seed density.

[16:26] Basically, don’t sow too dense that there’s no airflow around the bottoms of your microgreens. When you sow too densely, there’s more heat, there’s less airflow, more moisture, and that’s perfect for mold. And mold is just rubbing its hands at those conditions.

[16:42] If you’re unsure about the seed density right now, I have a free seed density calculator that you can download from my website, and you can get that at microgreensentrepreneur.com/seedcalculator, and that will give you the density that I use in my trays for the top-ten most popular microgreens that I grow.

[17:02] Basically, every seed needs its own space, and just like we all do right now, the seeds need to do a bit of social distancing, as well, I suppose you could say. So, never sow seeds too close to each other or on top of each other. You’re just really asking for problems that way.

[17:17] Then, the last one that’s completely on us is to water carefully. This is something that you’ll have to get better at, and you’ll get better at it with experience. Some things you can do straightaway are always water from the bottom once the germination period is over, and that’s going to keep the foliage dry and reduce the chances for mold.

[17:37] Then, you don’t want to overwater. You want your soil to be damp all the time so that your microgreens always have a bit of water to grow, but you don’t want them saturated and have all the pores in the soil drenched. You’re just asking for mold like this.

[17:52] What works for me is filling the bottom tray with no holes up, just enough that the plastic of the bottom of the tray is covered in water. Then you’ll also get to know the feeling of when your trays need or don’t need water just by feeling the weight of them. That is something that comes with experience.

[18:10] Those are all the ways that I know that we can prevent ourselves from ever getting mold on our microgreens. If you have any other ways or any other tips or tricks, I’d love to hear them. Again, you can DM me on Instagram with that.

[18:24] But, for now, we’ll get onto the remedies that we have available to us when we actually do get mold. So, none of us are perfect, and no matter what we do, if we do all of the right things, you just never know. There’s still a chance that we’re going to get the odd bit of mold here and there.

[18:39] So, when you do, first know it is mold in your trays. If it’s only in a small area, the best thing to do if it’s just a really small area is to put your hands in and take out that little small area of mold and remove it. You can just fill it up with some of your compost that you’re using. Also, keep an eye out for any ungerminated seeds that might have been getting a bit of mold on them and remove them too if you see them. 

[19:04] Then, watering from the top usually helps get rid of mold, for me, anyway, especially on sunflower. It’s the husks of the sunflower seeds that mold gets on sometimes. But what I’ve found, and it works for a lot of other people too, is that when you take your microgreens out of the germination phase, you unstack the trays, and there’s a bit of mold there. 

[19:27] When you water them, it breaks up the mold, and I think it kind of damages it or something, but it definitely stops it in its tracks most of the time, and by doing that and then putting it into the light, it generally goes away then.

[19:41] So now, it’s finally time to look at our last resort, and that’s hydrogen peroxide. Before we get into how to use hydrogen peroxide, I’m just going to explain what it is for anybody that doesn’t know what it is. When I first started growing microgreens, as far as I knew, hydrogen peroxide, for me, was associated with dyeing people’s hair. That’s pretty much all I knew about it. 

[20:04] But hydrogen peroxide is very close to being water. It’s a chemical symbol or chemical definition, or whatever you want to call it is H2O2. Obviously, water is H2O. So, it’s one extra part oxygen. As long as it’s food grade hydrogen peroxide, it is safe to use in microgreens growing, and it will kill any fungus or mold pathogens that are there in your soil or on your seeds.

[20:31] Just make sure you’re wearing gloves when you’re using it. Hydrogen peroxide is an oxidizer. Putting something like hydrogen peroxide onto your plants or into your soil might sound a bit funny, but because it’s only one molecule, I think is the word, different than water, and it’s an unstable substance when it gets exposed to heat and to light, it breaks down and turns back into water and oxygen. So, H2O2 becomes H2O and O2.

[21:00] I just want to mention again that it is important that you use a food grade hydrogen peroxide because as it is an unstable substance, stabilizers are added to normal hydrogen peroxide, but they’re not added to food grade hydrogen peroxide. 

[21:15] These stabilizers that are chemicals – I’m not exactly what they are, but I know that there is a chance that they may cause some kind of health issue. I’m not a chemist or a doctor. This is just what I know to be true for me, but always make sure that it’s food grade hydrogen peroxide.

[21:32] So, now that we know what it is, let’s talk about using it. The first point to use it is before you’ve even grown anything, and that’s sterilizing your seed in it. Whether that’s soaking your seed in a water solution that has hydrogen peroxide mixed in with it or doing your first watering of a tray that has seed and soil in it with the hydrogen peroxide and water mix, for that you want to dilute the hydrogen peroxide down to 3%.

[21:58] For example, if you were to make up 10 liters of it, you would mix it with roughly 10 liters of water and 300ml of hydrogen peroxide. Personally, though, I don’t do this. 

[22:07] I don’t know about America or the rest of the world, but in Ireland, hydrogen peroxide is not cheap. It’s an extra resource that you have to pay for, and it also takes time to mix it up. 

[22:19] Then, not to mention, it’s nasty enough stuff that could burn you if you got a concentrated amount of it on your skin. And it’s also an oxidizer, so it’s possibly bad for your respiratory system to be breathing that in as well.

[22:34] But it’s not just the cost or those reasons that I’ve just mentioned. We know that mold is in the air all the time and if you sterilized your seed and your soil, and your environmental conditions are still bad, and your farming practices are still bad as well, there’s still a really high chance and high potential there for you to get mold.

[22:55] I might be sounding like a broken record at this stage, but your growing conditions and your farming practices are your most important tools in preventing ever getting mold, so you won’t have to treat it then.

[23:08] Another way to use hydrogen peroxide is to spot treat. The way you do that is, you get a small water spray bottle, and you mix up that same solution, that same 3% hydrogen peroxide solution. If you happen to see a little bit of mold on your trays, you just spray it with that.

[23:26] I do this the very, very odd time, but I would always try the method I said before of top watering and trying to break up the mold first before doing it that way. 

[23:37] Another couple of things you can try is to diluting with baking soda, I think is one of them. A lot of people say vinegar does a good job on mold. To be honest, I’ve never tried these methods. 

[23:49] What I’ve talked about in this episode, that’s what works for me. But there probably are other remedies out there that you can look up and check out, but it really does all come down to your growing conditions and the practices that you do in your grow room.

[24:02] So, that brings us along to the end of the episode. It’s an interesting topic I find. I think this is going to end up being a bit of a longer episode than I’ve previously done. So, thanks for sticking with me all the way to the end. It’s also a topic that I’m sure people have different opinions on and different methods of treating and preventing the mold.

[24:21] If there’s something you think I should have mentioned, or there’s some kind of tip or trick that you know, I’d love to hear from you, and you can get me on the Instagram account or send me an email at brian@microgreensentrepreneur.com

[24:33] If you do have a question on any microgreens topic that you’d like me to answer, and you think I might be able to answer it for you, you can leave a voice note through the link that’s in the show notes, or you can go directly to microgreensentrepreneur.com/ask, and your question might be answered on a future episode of the podcast.

[24:53] If you’re just starting on your microgreens business journey, I’ve got a free ebook that you can download at microgreensentrepreneur.com/ebook, and that will go through all of the basic steps that you need to take in order to start a microgreens business, and it will help you from starting to grow microgreens to making your first sale. 

[25:11] One more thing. I want to remind you about that offer from TrueLeafMarket.com. If you need any seeds or equipment, all the listeners of the Microgreens Entrepreneur Podcast can get a 5% discount. To do that, enter the code ME5 at checkout.

[25:26] So, look, thanks again for listening. I hope you enjoyed the episode. If you have any feedback, please get in touch with me. Have a great week, and I’ll catch you on the next episode.

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