Watering Microgreens: When and How Much Episode 22 of the Microgreens Podcast

Watering Microgreens

Episode 022 of the Microgreens Podcast

In this episode of the Microgreens Podcast, we discuss watering microgreens.

  • We cover the following topics.
  • When to water microgreens
  • How to water microgreens
  • How much water to use for each size tray
  • Bulk watering microgreens
  • What are the exceptions to the rules?

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This watering microgreens podcast has an associated article titled: How to Water Microgreens – We Find This the Best Way.

The article contains other information, such as what type of water we use and all of the environmental factors that affect watering microgreens and how they grow. 

Below is a Transcript of the Watering Microgreens Podcast – Episode 022

Welcome to episode number 22 of The Microgreens Podcast.

Today, we’re going to talk about watering your microgreens.

When I wrote the related article to this, I thought it was going to be a really quick short article, but the more I got into it, I couldn’t believe how much goes into watering. But still that proverb, that Roman proverb that I stated in the beginning of the podcast, is more true than not.

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“Too Much Care does More Harm Than Good”

I receive so many photos of people having problems with microgreens.

And the majority of them are really caused from overwatering.

People care too much for the microgreens.

And I get it. It’s really simple to look at these plants and just leave them alone.

You want to care for them. You want them to be the best they can be. But sometimes, just leaving them alone is the best thing you can do for them, when we’re talking about watering microgreens.

So I’m going to break this up into several different categories.

I’m going to talk about first, watering during planting.

The watering after the blackout.

Followed by watering as the microgreens are growing on. 

And also just before harvest time, when you should water them before harvest.

If you want to see the show notes for this episode, go to homemicrogreens.com/022.

That’ll take you to all the show notes, if you want more information.

Anything else I talk about in here that I can think of linking will also be in the show notes. And again, that is homemicrogreens.com/022.

I also embed this podcast in the related watering article on homemicrogreens.com.

Watering Microgreens During Sowing

All right, when we first water microgreens, it’s actually during planting. I’ve seen a lot of videos and I’ve read a lot of blog post about how people plant their microgreens. And I don’t really like the word planting.

I think planting is when you take a start or a set and put it in the ground.

What we’re really doing is sowing the microgreen seeds.

Well, anyways, a lot of people will wet that whole soil surface. I have even seen people that have a tray, they pour water into it, then they put their soil into it.

They basically make a mud.

They add more soil until they get it to the consistency they want.

I don’t believe in that at all. It’s just, it’s unnecessary. Those seeds need so little water to get started.

They need to be wet and they just need a little bit of water to start growing.

So I don’t believe that watering the whole soil profile, from the top of the soil to the bottom of the tray, is necessary.

It’s just extra water.

And it’s sort of like the atmosphere.

What happens when we have a lot of moisture in the air?

We get thunderstorms, right? Storms brew up and it precipitates, there’s rain. There’s problems. There’s issues.

Same with all that water in the soil. We don’t need it all.

So just water the upper one third of your tray. And we do that before we put the seeds on it. I just use a mister bottle. When I’m planting 10, 20 trays, a lot of them, I do use a hose end sprayer and I’m really careful not to over water the tray.

So then we sow our seeds on top of the soil, and then we just need to wet the seeds.

We just mist them once or twice just to get the seeds wet.

That’s the first time we water our microgreens.

Watering Microgreens in the Blackout

And then when they’re in the blackout, we’re covering them. We’re either putting something, a dome over the top, or putting a piece of chloroplast or another tray and the blackout.

What that does is it basically holds the moisture. Any moisture that comes up and evaporates, hits that upper surface, condenses and goes back down. That’s why we don’t need a whole lot of water in there.

If we have a whole lot of water, more water’s moving up to the top, condensing, and basically drowning the seeds or drowning the germinating plants.

That’s why I only like to water the upper third.

I don’t water my microgreens at all in the blackout period. I leave them alone.

Exceptions to Watering Microgreens During Blackout

Now there are some exceptions.

If you have a area that’s really windy, like once a while I have the windows open, there’s a lot of breeze. Maybe you have that circumstance where it’s very hot out. Sometimes the edges of the trays, depending on what you’re using to cover them during the blackout, can dry out. Or in the cases of say celery or any microgreen that takes a long time to germinate, that upper soil surface, especially around the edges, can dry out and you may have to take the mister bottle ends and just mist it down again, just to wet the surface.

I don’t really like to disturb any of the seeds when they’re in the blackout period.

So I don’t really look at them. I just sort of go by the conditions.

If there’s a lot of breeze, if there’s a fan blowing in the room say in the summer, if it’s been really hot out, then I may check them. But generally I just leave them alone during the blackout period. I just don’t water them except for those minor little exceptions.

Watering Microgreens After the Blackout Period

So here’s where we really get into what most people would consider watering microgreens.

This is after the blackout.

When you take them out of the blackout, this is a good time to start watering.

Those plants have started to grow underneath the dome or underneath the blackout. And their roots are spreading down, right? The whole purpose of the way to blackout is to get those plants stronger, so those roots have to grow down into the soil to get an anchor to grow up.

So they are down in the area of the soil that is dry now. So this is the first time that we really water our microgreens.

How We Go About Watering Microgreens

And this is how I do it. I water from the bottom.

I never mist microgreens over the top. Never, ever. I want them dry.

You’re only going to have problems if you wet those microgreens. It’s could lead to salmonella. It could lead to listeria. It could have mold problems.

So I never water on the top, always from the bottom.

That’s why I always use a planting tray or a watering tray. Now watering this is going to really depend on how you’re growing your microgreens up. Are you using a tight fitted tray? In other words, a tray the same size as the planting tray? Or are you using what I call the bulk method where you’re putting several planting trays into one large watering tray.

Watering Microgreens in a Tight Planting & Watering Tray

Here are the types of trays we use to grow microgreens.

So how you water is going to depend on which method you are using to grow your microgreens up.

But let’s start with the tight fitting tray. In other words, the watering tray is the same size or basically the same size as the planting tray.

How Much Water We Use for Each Size Microgreens Tray

Home Microgreens Tray

These are the volumes that I use. For the home microgreens tray, which is five, it’s either five and a half by seven or seven and a half by five.

Whichever one it is, I use a half a cup of water. I basically lift the planting tray out of the watering tray. I put a half a cup of water into the watering tray and I gently put the planting tray back on. It will float. That water will be forced up into those holes by the pressure of the weight from the planting tray. The planting tray pushes the water up the sides of the watering tray causing a pressure.

The pressure is forced up into the holes in the bottom.

And then once that soil becomes wet, it starts wicking water up. So for the home microgreens tray, I use a half a cup.

1010 Microgreens Tray

For a 10 by 10 tray, I use one cup.

1020 Microgreens Tray

And for a 1020 tray, I use two cups.

Most Important Take-away from this Podcast

But first, before we even put water in there, this is the most important part about watering microgreens.

The most important part is to feel the weight of that tray as you’re taking it out of blackout.

For all intents and purposes, that tray is dry.

And that weight, whatever weight that tray is, is a dry weight.

Kind of set that weight in your memory, right? Just get a good feel for that. I’m using my hands like I’m lifting a tray here, you can’t see that. But anyways, lift that tray and remember that weight. Because when that tray becomes that weight again, when it becomes that light, then it’s time to water.

Not before.

Wait until it dries out like that.

No Watering Schedule

Don’t put your microgreens on a schedule like I’m going to water every two days. I’m going to water every day. I’m going to water every four days. No, the conditions change too much.

Just remember the weight of that tray. And that’s your best guide for when to water microgreens. So let me state that again, because it’s that important. When you take the microgreen trays out blackout, feel the weight of that tray. That is the weight. When that tray becomes that weight again, that light, that is when you water.

Recap of Watering Volumes

If you’re using a home microgreen tray, use a half a cup. If you’re using a 10 by 10 tray, use one cup. If you’re planting your microgreens in a 10 20 tray, use two cups. So that is with watering trays, the same size as the planting tray.

Watering Microgreens Using the Bulk Method

Now what about the bulk method? Well, this becomes a little bit more difficult because maybe you’re growing different varieties of microgreens. So they’re going to use different different amounts of water at different times.

So you have to be a little bit more careful. And again, the first thing you do is lift each tray up out of that larger watering tray and feel the weight.

If it’s heavy, don’t water it. Put it aside for a moment.

If it’s light, put it back in the watering tray.

And then depending on the size of your watering tray, you’re just going to have to pour water in there so it is up, I don’t know, an eighth, quarter of an inch. You can even go if you want a half inch, if you’re going to be around.

Let those trays, the dry trays, absorb the water. Wait 15, 20 minutes and then take those trays out and dump the water out of the watering tray and put your planting trays back into it and any excess water will drain out of them.

I don’t really like to water that way.

I mean, it makes a lot of sense.

And I do use that method, but you really have to be more careful and you could run into more problems because those trays will not dry out at the same rate.

You know, one tray to another. Even the same variety sometimes, they just don’t seem to dry out at the rate. So you have to be a little bit careful if you’re using the bulk watering method.

The best way is to water them, dump out the excess water, put the trays back in. It can make a little bit of a mess. The other thing to do would be to add a little bit of water, let it disappear, add a little bit more water and just keep going from there until the trays got some heft to it, you know that it has absorbed some water.

Watering Microgreens During the Growing Phase

All right, the next step is the growing on phase.

Now this is all really going to depend on how long the microgreens are growing and the conditions in your house. And in the article, I go through all the different conditions. This is what took so long in the article is all the different conditions that can cause your microgreens to use water at different rates. There’s tons of them. I’m not going to go over them here because we should just be relying on the weight of that tray. But when that tray is dry and light, that’s the time to water. I don’t set them like I’m going to water them every two days. I might check them every two days to see if they need water, but I’m not going to put them on a watering schedule, two, three, one, four, doesn’t matter.

I’m not doing that. It’s all individual. Lifting a tray, seeing if it needs water.

Generally I check them every other day, unless it’s been really hot, then I will check them every day. A lot of times microgreens can even wilt. And this goes back to that Roman proverb, right?

Like too much care. Like we all always want to help these microgreens grow, so we want to give them water.

But a lot of times we overwater them when we do that. So we have to be a little bit careful. Now you can look at them every day. And a lot of times, truthfully, I can start to see them wilt before I even water them again. Now, if you’re using peat moss, this can be a little bit of a problem because peat moss, once it gets dry, has a hard time absorbing water.

This is why I like coco coir, it doesn’t seem to have that wetting problem. But a lot of times my microgreens are starting to wilt a little bit before I water them. They’re fine. They’re using that water and now they’re telling you, hey, I need some water. So it’s time to give it to them. Now I will admit, for the microgreens I’m growing for my retail sales, I generally water them all when, and it’s just bad, I run into problems all the time where I over water trays. I have 15, 20 trays growing. I just go throwing water on them all unless it’s super heavy, and that’s just the wrong way to do it. But it’s just, I don’t know, it’s just the way I do it. And it’s wrong. Always lift your tray and feel the weight of it. When it’s light, water it. If it’s heavy, leave it alone.

Watering When You Will Be Gone

The only exception to that would be if you’re going away, if you’re not going to be there the next day, if you can’t care for them, then you have to use a little bit of judgment. Will this microgreen tray have enough water to get through the period of time I’m gone? And then just use your better judgment.

It’s better to maybe half water it.

If that’s the case, just give it half a dose of water to get it through that day that you’re going to be gone. That’s fine too.

Again, it’s a little bit better to underwater than overwatering. Most problems with microgreens, I’m going to say all problems with microgreens, unless you let them get crispy, is from overwatering not under watering.

Many times, I only water them when they come out blackout and then once before harvest. Especially in the cooler winter months. In the summer, then I might have to water them two or three times. But again, I don’t really rely on any watering schedule. I look at them, I check them, and when they’re dry, I water them. If they don’t need water, I don’t water them.

When to Water Microgreens When It’s Harvest Time

So what about harvest? Now a lot of the microgreens I grow for myself, I cut right off the tray as I’m using them. So you want to be careful when you water. Maybe this comes down to when you water in the day. It’s not a good idea to water your microgreens just before you harvest them, because that water’s going to drip onto whatever you’re cutting them on. Now you are washing your microgreens before you eat them, right? You are, right? You should be. I don’t necessarily do, but you should be.

So any of that water that drip off the tray on your microgreens, if you do see that you will have to water them just to make sure you rinse that off. But if I know I’m going to be using microgreens that evening a lot and they do need water, a lot of times I’ll water in the morning. That way all that extra water can be absorbed and it’s just easier to harvest. Also, I think the microgreens are a little bit more plump if you have a little bit of water before they harvest. And again, this is a situation where you might just want to give them a quarter or a half a dose of watering. In other words, half the volume that I generally use before you water them. I do think it makes a difference.

I think they cut and harvest easier.

They get a little bit tougher when they’re on the dry side. So adding a little bit of water, even if that’s a quarter or half a volume, is a good idea just before harvest.


All right. So I think that’s about it on watering. So let’s summarize. We don’t want to overwater. Just, overwatering always leads to problems. So we want to make sure that we are, if anything, underwatering more frequently than we are overwatering. We want to feel the weight of that tray as we take it out of the blackout period, and that dry weight is the weight that we’re going to water. When we feel like that tray is that weight again, that’s when we water. We don’t water on a schedule. We don’t water every day. We don’t water every other day. We don’t water every third day. We water when the microgreens need the water. And we make that judgment call based on the weight of the tray.

And as far as watering before we harvest, we try to water several hours before we harvest so that any excess water will go away and we’re not dripping any of the water that’s coming out of the soil onto whatever surface we’re harvesting the microgreens on. We want to keep those microgreens dry. We’re growing microgreens for the nutrition, the flavor too, but we’re growing mostly microgreens for the nutrition, the health benefits. So there’s no sense of adding anything nasty to our microgreens by dripping water out of the trays onto the microgreens that we’ve just harvested. So try to water earlier in the day than later in the day. Unless you’re using them for breakfast, then you can harvest them and then water for the day.

Thank the Sponsor, Home Microgreens Store

I’d like to thank the sponsor of this podcast, the Home Microgreens Store. I’ve actually added some new organic varieties, some cilantro.

I’ve added a couple other newer varieties maybe by the time you listen to this, the edible chrysanthemum and hopefully by then some chervil and maybe a couple other ones like brussel sprouts. But if not, they will be in the store soon. So again, go to the Home Microgreens store. I have very competitive pricing. I have some new updates coming up and I’ll whip that into another podcast I’m very excited about.

But please go to the Home Microgreens Store and check out my selection of seeds and the prices. I think you’ll be very happy with what I have in the store. And if you want the show notes, go to homemicrogreens.com/022, and this podcast will be on the web player. I’m also going to be embedding the podcast in the associated article on watering. So you can get a little bit more information, especially on what conditions will dry out the microgreens the most. I think it’s a pretty good article. I was really happy with it when I got done. And I hope you think so too. So in the meantime, keep growing.

Do not overwater your microgreens. Check the weight of those trays before you water. That’s the most important takeaway from this podcast.

I hope you have a great week.

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  • Todd

    Todd is the founder of Home Microgreens & the Home Microgreens store. He also writes for several other websites, including MyViewFromTheWoods.com. Todd worked at a large farm market, garden & nursery center for 20 years. Somehow he snuck off to become a geologist and professor before coming back to his senses to write & lecture about microgreens and gardening. When not at the computer, he can be found in the garden, trout stream, or mountain trail with his new Springer Spaniel Caden.

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