Troubleshooting Top 10 Microgreens Growing Problems

Pretty alfalfa microgreens growing in a nice pot

Troubleshooting Top 10 Microgreens Growing Problems

You've decided to grow microgreens and we want you to get off to the best start possible. Microgreens are a great way to add fresh greens and herbs to your diet, but sometimes they can be difficult for people just starting out. To help you out, I’ve collected the Top 10 Problems when growing microgreens.

#1 - Mold Growth on Microgreens

Mold and mildew are one common problem with growing microgreens. If you're having this problem, you're not alone. Mold growth is the number one problem for microgreens growers - particularly when they first start growing.

What Causes Mold?

There are multiple reasons that could be causing mold on your microgreens.

Improper airflow
- Make sure your microgreens trays are getting good air circulation.
- Increase air circulation by using fans.
Soil-based fungi
- Not all growing medium is created equal. Many aren’t clean and already have issues with soil-based fungi.
- As a result, soil-based fungi spread from plant to plant and take over.
- Use the best growing medium like Burpee Organic Potting Mix that allows for drainage.
Microgreens Seeds Planted too Densely
- If you plant too many seeds, especially seeds like Chia that are mucilaginous, it could cause clumping, reduce air circulation between the plants and cause mold to begin growing.
Overwatering
- Overwatering is the most common reason microgreens develop mold.
- Water your microgreens every one to two days or when the growing pad feels dry or when the pad begins to feel dry.
- If water “pools” on top of your soil, you’ve overwatered.
- Also, empty the drainage tray. If you don’t, this will greatly increase the humidity around your microgreens increasing your chances of mold.
- Use growing trays with drainage holes.

Inadequate Light
- You need to give your microgreens light every day
- If your main source of light is natural, be sure they get a minimum of 6 hours
- When using artificial lighting, they’ll need light for twelve hours using a 20-watt bulb.

What Does Mold Look Like?

There are many different types of mold and they all have a different appearances. Some may look like spiderwebs or have a white, fuzzy appearance while others may appear as blue/gray or even yellow spots.

You should also be aware that microgreens have very fine root hairs, so be careful to not mistake the root hairs as mold and throw out your microgreens. Radish, sunflower and a lot of other microgreens have fine root hairs.

How do you remove the mold?

To clean the microgreens, gently take a cloth and wipe it across all the microgreens.

You should immediately remove all the mold you can see with a soft cloth.

You can also remove sections that have mold if it hasn’t spred to the entire tray.
Spray using hydrogen peroxide to kill the mold.

Disinfect or sanitize your growing trays before replanting.
- Remove any leftover soil.
- Spray the trays and wash with soapy water.
- Spray the trays with hydrogen peroxide and let them sit for at least 20 minutes.

#2 - Falling Over

One reason your microgreens are “leggy” and keep falling over is that they might not be getting enough light. Remember, you need to give your microgreens light every day and if your main source of light is natural, they need to get a minimum of 6 hours. When using artificial lighting, they’ll need light for twelve hours using a 20-watt bulb.

And once again, you’ve got to get that “blackout time” right. If they stay in blackout after they’ve germinated, they’ll continue to grow, but without sunlight. This creates weak, spindly microgreens that can’t stand up.

Another possibility is incorrect watering. You may be over or underwatering. If you’re underwatering, the roots won’t have enough water and start to dry out leading to wilting. If you’re overwatering, it can lead to seeds damping off, causing the roots to rot. This could cause your microgreens to fall over.

You could be waiting too long to harvest your microgreens. Waiting too long to harvest leads to “leggy” plants, causing them to fall over. Once the first set of true leaves has emerged, harvest your microgreens.

One more cause of microgreens falling over is overhead watering. Microgreens are delicate little plants. If you choose overhead watering, it’s best to use a mister. Your typical watering can (even smaller houseplant watering cans) won’t do.

A spray bottle as simple as this one will do:

Or choose a watering can with a small tip like this one:

#3 - Slow Germination

Too little water. Your seeds need the correct amount of water to begin the hydrolytic process. The water softens the seeds and prepares the stored food in the seed ready to be used. Without enough water, the seeds can begin this process.

But of course...

Too much water causes poor germination and could compact your growing medium. If you compact your growing medium, your plants may not get enough oxygen. So once again, pay attention to the instructions your seeds came with and carefully follow them. As important as the right amount of water is to germination, having a blackout period is equally important.

After you have prepared the growing medium, watered, and sown the seeds, it’s time to cover your growing trays so you can trick the seeds into thinking they are under the ground. Seeds require this period of darkness before they can germinate.

But don’t put your microgreens trays in the pantry or basement and forget them. This germination stage is crucial and they must be kept moist.

Another very important aspect of getting your microgreens to germinate properly is making sure you have the temperature correct. Are they in a cold basement? Are they sitting next to your radiator during the wintertime? A good rule of thumb is to keep the temperature around 70 degrees fahrenheit - not going below 60 degrees or above 72.

Once the seeds have germinated and it’s time to take them out from the dark, they need light to grow healthy. If you can’t provide natural sunlight or enough light in the space where you grow, there are alternatives such as using artificial growing lights. If you live where you have issues with controlling the temperature for your microgreens, you might need to consider getting a seedling heat mat. Check out “The Best Seedling Heat Mats of 2021” for complete reviews and affordable prices.

#4 - Uneven growth

Yes, we all want those perfect, pretty trays of microgreens. Well, at least I do anyway.

Two of the most common reasons trays of microgreens end up growing all wonky, is;

Uneven Light
- It all depends on your setup, but most likely, you’ll have to rotate your growing trays if you depend on natural light. Since they’ll need roughly 6 hours of light, chances are you might have to move the trays to different rooms.
- If you don’t rotate or move the trays, you’ll have microgreens that are different sizes and that lean toward the sunlight.
- If this is a problem or seems like a pain, you might want to try plant lights like these:

Too many Seeds
- It might not seem like sowing seeds too densely would cause them to grow unevenly, but it does. Some seeds get “chocked” out by others and their growth is stunted.
- You’ll also get uneven growth due to the fact that all seeds don’t germinate at the same speed. Yes, even if they are all the same type.

#5 - Clumped Microgreens

Yeah, you want microgreens that look like that! I feel you! When I first started out growing Microgreens, mine didn’t look like the picture you see above.

Nope...

Some of mine would be a weird clump “growth.” As the microgreens grew, they seemed to push some of the others up and I would have a strange-looking mass instead of nice pretty trays of microgreens.

Live and learn. This is caused by planting the seeds too densely. They’re sort of growing right on top of each other or fighting for space so to speak. This is an easy fix. Simply sow fewer seeds per tray. Concentrate on sowing the seeds more evenly. There are a couple of tricks to do this:

Put your microgreen seeds in a salt shaker.
Mix your microgreen seeds with sand. Pour a handful of dry sand in a cup, add the seeds and mix. Next, sprinkle the sand/seed mixture over your growing tray.
Make your own “seed tape.” Mist squares of toilet paper. Sprinkle seeds on the toilet paper and lay the toilet paper seed-side down in the tray.

#6 - Microgreens Invaded by Pests

Unfortunately, we’re not the only ones that love microgreens. Little irritating creatures love them too. If you have noticed some tiny bugs swooping around your microgreens, they’re probably fruit flies, aphids, whiteflies, or thrips.

Fortunately, having pests when you grow microgreens inside isn’t as big an issue as when you grow them in greenhouses.

The best way to approach pests in your indoor microgreens is by preventing them. To do this, always use a growing medium from a reputable nursery or garden store. Do not use dirt you brought in from outdoors. You could be bringing them in with the dirt.

#7 - Yellow Microgreens

First things first. Before you do anything, read the seed packets that came with your microgreens. The packets will have detailed growing instructions including how much light, water etc.

All seedlings will be yellow when they first come out of their “blackout time.” This is because photosynthesis hasn’t had a chance to take place. Once the seedlings get some light, they’ll start to “green up.”

Different seeds require different blackout times. So, what’s a “blackout” time or period? This is the time period immediately after planting. Microgreen seeds need anywhere from two to eight days of darkness.

Why?

This gives them a chance to germinate. Basically, it simulates covering the seeds

with dirt as you would do in an outdoor garden. When growing microgreens,

you don’t cover the seeds with soil and you sow the seeds compactly.

If you covered the plants with dirt, as they grew, they wouldn’t knock the dirt

off and when harvest time rolls around, you would end up with a dirty crop.

Because the blackout period is crucial for germination, you’ll need to improvise. We usually use trays that come with a blackout dome, simply because it is convenient. If your trays didn’t come with a blackout dome you can simply turn an empty grow tray upside down over the new crop. If the tray has drainage holes in it, cover the holes with cardboard or old towels so no light creeps in.

Unfortunately, the causes of microgreens turning yellow are many...and confusing. It could be too much light. Not enough light. Too much water. Not enough water. The blackout period is too long. The blackout period was too short.

You get the idea.

This takes trial and error. As you start growing microgreens, start with one or two types. See what works best with that particular microgreen before moving on to your next choice.

#8 - Leggy, Weak, and Pale Microgreens

When you grow microgreens, you want them to look like all the pretty, healthy, vibrant microgreens you see online.

Right?

So, it’s very disappointing when yours turn out looking sickly. The causes of leggy, weak, and pale microgreens are much the same as the “yellow microgreens” problem.

The most common causes are:

Your microgreens might have had too long a blackout period if they are stretching out and “leggy.” And keep in mind that some microgreens are supposed to look yellow (like popcorn shoots, and yellow beets).

They might not be getting enough light or they need brighter ligh.

Their roots may be under attack from mold or bugs.
The water pH may be off. The water needs to be neutral for proper nutrient uptake through their root system.
Seeds sown too densely may be blocking light.

#9 - Stinky Microgreens

It is normal for seeds to have a distinct scent. If your microgreens stink, they have most likely been overwatered, and have developed mold or stem rot resulting. Mold and stem rot can also come from planting your seeds too densely and overcrowding your plant. Another culprit is very high or very low temperatures, inadequate airflow, or high humidity.

Any of these issues can result in microorganisms that have taken over, giving your microgreens a bad smell. If you’re not sure, give them more time to grow. If the smell is still lingering when your plants are 1” to 3” go ahead and toss them.

#10 - Dirty Microgreens

Seeds grow traditionally in nature or in the garden if they are covered with a layer of soil. Being covered by a layer of soil gives the seeds a chance to germinate. Seeds need to have darkness created by soil to do this. But, it’s a little different for microgreens.

The best practice for germinating microgreens is to simply sow the seeds on top of the soil, then cover the growing trays with a “blackout dome” or an unused tray upside down over the seeds. This creates the darkness the seeds need to germinate.

If your microgreens are dirty or have a lot of soil on them at harvest time, you most likely covered the seeds with soil. And since microgreens seeds are sown very densely, as the seedlings grow, they are so close together, they carry the soil up with them as they grow.

You can also get some dirt and debris if seed hulls are still attached and dirt rides upon the seedlings this way.

Hang in There!

While growing microgreens at home can sometimes present challenges such as mold, legginess, pests, and slow germination, it's important to remember that these issues are surmountable. With a little patience, persistence, and the right knowledge, you can effectively address and overcome these common growing problems.

By paying close attention to your microgreens' environment, adjusting watering practices, ensuring proper lighting, and maintaining cleanliness, you'll create the ideal conditions for your microgreens to thrive. Remember, every problem encountered is an opportunity to learn and improve your growing techniques. So, stay positive and keep experimenting—success with your lush, nutritious microgreens is just around the corner.

Happy growing!