May 24, 2020

The Best Way to Water Microgreens

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There are plenty of opinions out there about the best way to water microgreens. Some argue you should always bottom-water microgreens while others say it works just fine to top-water them. So in the wake of this debate, I decided to set up an experiment to determine which method works best for my setup.

Pros and Cons of Each Method

Before we jump right into the experiment, I just want to outline a few of the potential pros and cons of each watering method.

Top-Watering

Pros

Requires less supplies

Helps maintain seed moisture during germination

Cons

May damage shoots

Increased risk of mold

Increased humidity after watering

Arguably more time-consuming

Bottom-Watering

Pros

Shoots remain dry and undisturbed

Less humidity increase

Decreased risk of mold

Somewhat quicker and easier

Cons

Requires more supplies (extra tray)

The Experiment

To set up my experiment, I used two round plastic takeout containers as my planters, and one lid.

Recycled takeout containers make excellent microgreens planters

For the top-watering side of the experiment, I left the takeout container intact. For the bottom-watering side, I drilled holes in the bottom of the container and used the lid as a watering tray.

Drilled holes in the bottom of one container

One container with holes, the other without holes

Eliminating variables

To ensure there were no other variables, I kept everything else about the experiment the exact same including how the seeds were planted and where the trays were stored, making sure they were on the same shelf of my grow rack.

Planting

I decided to use peas for this experiment so I soaked some seeds for about 8 hours prior to planting.

I filled each container with about an inch of peat-based seed starting mix, soaked the surface, and spread an even layer of peas across the surface of each.

Spread pea seeds evenly across the surface

Both containers are planted and ready to germinate

I then gave the seeds another quick soak and stacked them on my grow rack to germinate. (I placed an additional container on top with a can of stain to weigh it down. It actually worked perfect!)

I stacked the containers and weighed them down to allow them to germinate

Germination

I left the stacked containers undisturbed for about 3 days before checking their progress.

After unstacking them, I was actually really pleased with the germination of both trays. The can of stain provided excellent weight which seemed to create strong, even shoots.

Both trays germinated really well and looked strong when unstacked

Watering

Once I unstacked the trays, I placed them next to each other under my grow lights.

I used a spray bottle to water the top-watering tray, making sure the whole surface was evenly soaked.

I top-watered one tray with a spray bottle as needed

For the bottom-watering tray, I simply lifted the container up, poured about half an inch of water in the lid, and put the tray back down. (The water was almost instantly absorbed up into the soil.)

I bottom-watered the other tray using the lid

I repeated this process as needed over the next 4 days based on the weight of the trays. If they felt light I gave them water, if they felt heavy I left them alone.

(On a side note, I was amazed at how quickly the root systems developed in the bottom watering tray!)

Results

After a couple days under my grow lights, both trays seemed to be growing evenly. They both continued to grow strong shoots throughout the experiment.

At the conclusion of this experiment (after 8 days) I noticed absolutely no difference in the growth of the microgreens or the yield. I also didn’t have any mold issues on either tray.

Both microgreens trays grew extremely well

As you can see, both containers grew evenly and tremendously well.

Final Thoughts

I was actually a little disappointed that both trays grew so well. I was hoping there would be a noticeable difference between the top and bottom-watering methods where I could definitely say “this method is better” but I couldn’t.

As far as ease of watering though, I thought it was much easier to bottom-water as opposed to spraying from the top while trying to avoid the shoots. I know from experience that it can be especially cumbersome to try to evenly spray an entire 1020 flat.

Overall, I think either watering method could be effective. Historically, I’ve always top-watered my microgreens and it’s worked pretty well, but I have had some mold problems from time to time.

I’m going to start using the bottom-watering method moving forward so I’ll keep you updated with my thoughts and opinions about the best way to water microgreens!

Happy Gardening,

Cody

Thistle Downs Farm

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