8 Common Microgreen Problems and How to Fix Them

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Growing microgreens is easy. You don’t need many resources and it’s fairly quickly. Nevertheless, you can always run into different problems which may cause your growth to not be as healthy as you had wished for. Common issues are slow germination, growing mold, yellow and wilting microgreens. All these problems can be overcome by preventive actions.

As you face a problem with your microgreens, the best solution is to understand what caused it, how you can rectify it, and what you can do to prevent it from happening again. We have been going through the most common problems, have done trial & error, and researched solutions for growing healthy microgreens.

Below you’ll find a list of 8 possible problems you may encounter and providing you the insight into what is causing these issues, how you can solve them, and prevent them from happening again.

My microgreens grow mold

When you see that you have a fine cobweb between the leaves and the stem you are suffering from mold. This is not to be confused with the fine hair which is growing on the stems of some microgreens. Mold is different as it shows itself in a way that it looks like a cobweb or silvery hair which extends from the leaves. 

What is causing mold?

Mold spores like moisture, warm and humid environments. Mold in your microgreens is mainly caused by too much humidity. This can happen when you are continuously giving them too much water or if they are placed in a humid environment where they are not getting the right temperature and enough light. 

How do you remove the mold?

You should immediately remove all the mold you can see with a soft cloth. Gentle take the cloth and wipe it across all the microgreens. This may be more challenging than what you are used to with larger plants and vegetables. Microgreens have many small leaves so you need to be careful to not break any while you clean the crop.

Continue by removing all dead and yellow leaves and clean out the tray so you only have the healthy microgreens left. It’s important to go through the entire tray, leave by leave, to ensure you remove any mold.

To remove mold you can as well use a mix of Hydrogen Peroxide (3%) and water and spray gently over the medium. Mix around half liter of room temperature water with a couple teaspoons of hydrogen peroxide and add to a spray bottle.

Once that is done, you have to ensure you are not overwatering the microgreens and that you reduce the humidity in the room. You can do this by using a room dehumidifier if you have a lot of damp in the room and open the windows to get good airflow. It’s very important to keep the space where you grow your microgreen in a dry condition and with good airflow.

If you find that the entire crop is affected by mold, you will have to get rid of it and start over. Next time you know what can cause mold and prevent it from being repeated.

If you’re interested to know even more on this topic, we have written a full article on why microgreens mold and how you can prevent it.

RELATED: Why Microgreens Mold and How to Prevent It

My microgreens germinate slowly

You believe you have done it all right and yet your microgreens don’t germinate as fast as they should. There may be different reasons why you don’t see the speed as expected. We have listed some commons causes which may slow down germination. 

Not enough darkness

Microgreen seeds need to be placed in darkness to germinate. This is referred to as the blackout period. If you simply prepare the growth but don’t put them in a dark space, and/or cover them with soil (depending on the type of seed) you’ll find that they may not germinate, or not as quick and not with the same quality. 

It is a fact of life that most plants need light to grow and keep them healthy, but not all plants need light to germinate, and, as we shall see, some seeds find light a hindrance. If we look at the matter from the gardener’s point of view, however, we can use the rule of thumb that most cultivated plants on sale in seed form prefer to germinate in the dark. 

SOURCE: The Effect of Light on Germination and Seedlings

You don’t need advanced equipment to prepare germination in darkness. Simply put your container or tray in a dark cupboard, cover it with another tray on top or use any other thing you have which allows the entire tray to be covered in darkness. 

If you have kept your microgreens in the dark and kept the medium moist, within a few days, you will see that the seeds have germinated.

Not enough light

Similar to not having enough darkness during germination, not having enough light after the blackout period is as well a factor that may cause slow growth. 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. 

Too many seeds

Microgreens are typically planted in small containers. This means that each seedling is competing for limited amounts of resources, such as sunlight, water, and soil nutrients. 

It can be tempting to use many seeds on one tray, with the hope to get a larger crop, but it will work against you. If you have planted too many seeds, you will find that they don’t germinate as quickly and as even as they should. When you place too many seeds they won’t get the proper amount of aeration and the seeds can block each other from growing healthy.

My microgreens are growing unevenly

Your microgreens are out in the light but you find yourself ending up with uneven growth. Some of the microgreens are tall, others short and some seeds have not even have germinated. Why is that? 

When not all of your seeds have germinated or grown at the same speed, it’s most likely because of overseeding or uneven distribution of light. 

Too many seeds

Same as for slow growth, overseeding can cause uneven growth. If you plant too many seeds on your tray they won’t allow themselves to grow but block each other from germination as there is not enough space. The seeds compete for aeration and getting the right amount of light. We faced this issue with larger seeds such as sunflower. Some of the seeds did not go through the germination phase but stayed as seedlings. We realized that the seeds had been clumped together and not giving enough space and those trapped never got to germinate.

This can easily be solved by using a dispensing bottle to spread the seeds evenly. You can make them yourself by using a spice bottle with big enough holes. Always pay careful attention to the recommendations for seed spacing when planting.

A good rule of thumb is to spread about 1 ounce of the smaller microgreens such as broccoli and basil in a 10×20 tray. 

Uneven sunlight

Once your microgreens are ready for the light they need to get an even share of the sunlight reaching them. The seedlings will naturally grow towards the light and if not the entire crop will get that, only those in the spotlight will grow. Depending on your setup and the ability to provide light, you need to ensure that you rotate the tray so they get an even amount of light. 

If you are not able to provide your microgreens with natural sunlight, you can work with the artificial growing light.

My microgreens are turning yellow

During the blackout period, your microgreens can look yellowish because the chlorophyll in the leaves hasn’t carried out photosynthesis yet. This is normal and the microgreens will turn green as you place them under light. 

Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a byproduct.

Source: Wikipedia

If your microgreens continue to look yellowish and not turning green it may be that you are overwatering or not providing enough sunlight. As you have read in this article, these issues are common causes for failing your microgreens.

Another thing to consider is the use of fertilizer. If you are using a fertilizer mixed in with your soil or water, you may use one which doesn’t fit the purpose. Microgreens normally don’t need fertilizer as the growing period is so short but some mediums which don’t naturally include any nutritions may benefit from it. It’s always important to ensure that the fertilizer you use is prepared for microgreens. 

My microgreens are wilting

If you find that your leaves are wilting it’s a sign that they are either getting to little water or over-crowded seedlings.

Not enough water

One of the most common reasons for wilting microgreens is simply that they aren’t receiving enough water. When you let them too dry they will start to wilt, same as growing the full-size vegetable. It’s important to keep the microgreens moist and not dried out.

How to prevent under watering

A great solution is to water your microgreens from underneath. This gives you a controlled way of keeping the medium moist rather than dry or soaked. 

To water your microgreens from underneath you need two trays placed on top of each other; one tray with holes and one without. You place your medium and seeds in the top tray with holes. Then you place this tray inside one without holes.

Start by filling the bottom tray with water which gives the roots access to constant water. You should not overfill the bottom tray but instead, keep it under control and add frequently more water. Check your bottom tray 24 hours after watering to see if it’s completely dry or if there’s still water. You will then find out how often you need to fill it up.

Overcrowded seeds

As mentioned, having too many seeds sprinkled over a tray will cause you problems. The competition that is created by over-seeding will usually result in some of the seedlings receiving an un-sufficient amount of space to grow and consequently, the entire crop may be malnourished and wilting.

There can be more reasons your microgreens are wilting and we have written a longer article around this topic. 

RELATED: 10 Reasons Your Microgreens Are Wilting

My microgreens smell foul

If you notice that your microgreens are starting to smell bad it may be that they are molding. Foul-smelling microgreens have most likely been overwatered, and the plants have developed mold or stem rot. 

It can also have been caused by other factors such as overcrowding, high or low temperatures, insufficient airflow, or high humidity. However, most likely it will be from the mold which can cause the stems to rot.

You need to monitor your microgreens to ensure they are being kept moist and not soaked and always in a dry environment. If there is high humidity it will contribute to the microgreens turning bad.

My microgreens are clumping

It may be tempting to add many seeds with the belief that you will get a larger harvest, but that won’t be the case. That will result in just the opposite. Microgreens need space to grow and they cannot be clumped together as it may cause them to not germinate.

The issue will be even greater if you are growing mucilaginous seeds such as chia. They will form a sticky gel-like coating when they are wet and you’ll have an issue if they clump together. So it’s important to keep the distance between the seeds and you will find yourself having a healthy crop.

My microgreens have been invaded by pests

It’s not very common to get pests when you grow microgreens indoors. However, depending on where you have placed them inside your home or if you are growing in a greenhouse, pests may find their way to your microgreens. That may be plant lice (also known as aphids), thrips, whiteflies, or other pests. You’ll notice that you have to deal with these small invaders when you see them on your crops causing the leaves to deform and/or turning yellow. 

What is causing pests?

Pests may invade your garden and microgreen setups for various reasons. It may be caused by all of the different reasons we have explained in this article; too much water, too little water, light and heat, use of fertilizer, and more. 

Pests don’t normally invade microgreen crops if you are growing them in trays separate from any other plants. Nonetheless, if you have your trays close to other plants and gardening projects, pests may expand their residence.

How to prevent pests?

It’s always easier to prevent pests than to eliminate them. When it comes to microgreens you rarely face pests. However, there are some precautions you can take to ensure you won’t have to deal with this issue.

Always provide your microgreens the growing conditions they need so that they can grow healthily. Don’t place your trays close to other household plants when growing indoors.

Ensure to not use soil that has been used before. In this context, it may be that there are pests. We don’t recommend to reuse medium for growing microgreens but rather reuse it for other gardening projects.

Always use mediums that are made for growing microgreens and when using the soil you need to buy commercially prepared potting soil and not one that you have taken from outdoors, which can be a source of pests.

To defeat the unwelcome pests

If it’s too late and you can see that you have already had unwelcomed pests you need to eliminate them. If you find that you have pests you need to evaluate if you can maintain the growth or get rid of it. Depending on how badly impacted it is, you may be able to get it cleaned out from the pests.

To defeat any unwelcoming pests you should first familiarize yourself with the insects and then learn how you can specifically eliminate them from your crops.

The most common approach is to use pesticides but you need to be cautious before you start to spray anything on your microgreens as it may be harmful to not only the greens but it may be toxic for eating them later on.

As mentioned for prevention, it may be that you have placed your microgreens too close to other plants that attract these pests. Then you should move them where they are in no close contact with other growths.

Final thoughts

We love growing microgreens as it’s such a rewarding way to provide our family with nutritious greens. It’s, in general, an easy, quick, and overall a very clean process. However, depending on how you grow your microgreens and the conditions you can offer, you may face problems to get healthy microgreens.

If you know what causes your microgreens to fail, then you are also better equipped to prevent that from happening. What is important is that you follow the instructions for the specific seeds you are growing as well as following the instructions for the different growing methods. Then you will be up for success!

Microgreens Corner
Microgreens Corner
We are Janette & Jesper, and we love microgreens.


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