Diseases and Pests for Microgreen & Common Growing Problems

by Lettuce Be | Last Updated: 05/15/2021

You will most definitely run into problems if you are a newbie to growing your microgreens or edible plants. Consequently, you either treat the plant diseases or discontinue your vegetable confetti journey.

You get better at it by practicing!

Growing microgreens and recognizing everything that could go wrong wasn’t clear when we first started growing microgreens indoors. Even without a clearly outlined list of possible problems and solutions, we could use the guide to identify where we stood.

A wide range of issues arose. Mold was one of the drawbacks we encountered. We had to figure out what went wrong and how to fix it, even though this was very frustrating and time-consuming. Having a moldy, infected host plant is therefore unattractive! To make finding answers quick and straightforward, we developed this guide to protect plant health.

All in all, know that you’re not alone when you’re starting. You’re in good hands! We will do our best to answer any questions you have.

The topics we will cover include:

Problems You May Face While Growing Microgreens

You will learn the six main obstacles and handle them to help you with the initial learning curve. As a result, you can resolve any issue quickly and easily.


The first thing to remember about mold is that it is not a huge problem. Therefore, you should not toss your crop away since you might be able to save it. It can be avoided or controlled if you follow a few guidelines. Firstly, it is essential to understand what is meant by root hair and mold.

Each plant has tiny hairs that shape part of the root. They emerge from the root system and enhance the surface area of your microgreens, allowing them to absorb all the water they need. Tiny hairs may seem like mold at first glance, but some main differences indicate root hair.

The microgreens on and around which mold grows are filled with bacteria, moisture, and little or no air circulation. Mold in any setting is no different than this. Providing your microgreens are growing in the right conditions will prevent mold growth.

So now you know how to distinguish mold from root hair, let’s check out why you might have mold:

Not Enough Ventilation

Mold thrives in dormant air, where it can develop and spread before becoming active. Mold growth occurs when a food source is available and warm, and moist air does not circulate. Baby greens require proper ventilation throughout their entire growing cycle. Germination of your microgreens is critical. Mold is more likely to breed in areas where they’re covered, and there is minimal airflow.

Keep the shallow trays cool with a fan running for at least 15 minutes every hour. you will keep mold at bay by keeping the air around the trays fresh. As part of our aeroponic system, we are continuously running our fans and using Biostrate Felt. So you might want to stick with 15 minutes per hour if you are using any soil surface.


Mold on your microgreens is often caused by too much water. The typical soil alternatives such as peat moss and coco coir hold moisture longer. Even so, you are at greater risk of developing mold problems.

It can be hard to check how much water is in either of the alternatives. On the other hand, it’s easier to deal with a layer of soil. You can always water more, but you cannot remove moisture. This means you need to learn how to determine if a plant needs to be watered.


Adequate light such as direct sunlight is unwelcome to mold. You can move plants into the sun as soon as they germinate until they reach the true leaf stage. You can use grow lights, fluorescent light, or indirect sunlight to grow microgreens for yourself.


You need to thoroughly clean all your equipment before you begin growing your microgreens. You can clean the trays with a 1500ml spray bottle filled with food-grade hydrogen peroxide, vinegar, and tap water. Before sterilizing the growing medium and sanitizing the microgreens seeds, wash your trays and other equipment with this solution.

Soak seeds before planting them in water so that you can sanitize them before planting. Add a teaspoon of hydrogen peroxide to a bowl of water. Plant them as usual after they have soaked for about two hours. By this method, you will kill the seeds from any infection, and you will not have to worry about getting sick from mold on microgreens.

Seed Density

Seeds sown too densely can stick together and lead to mold and uneven growth of your microgreens. As the microgreens grow, they block the airflow. A lack of airflow and a concentration of moisture can therefore lead to mold. You can use an old spice jar if you don’t have a dispensing container available.

When seeds are gelatinous (sticky), they create a sticky gel-like coating when wet, making it difficult to handle – particularly Chia seeds, Flaxseed, and Basil. In addition, when you can’t evenly spread the seeds on the tray, they can be challenging to handle. You should therefore use some seed dispenser!

Control of Humidity

Moisture is essential to mold’s survival, so it loves it. Your plants, however, also require water to grow. Therefore, growing media must have accurate humidity.

You can dry off microgreens without altering their characteristics. An inexpensive dehumidifier is all you need. Your growing medium will determine how often you can turn on your dehumidifier. If it’s on all day or anytime during the day, that will remove the humidity. In turn, this makes it nearly plausible for mold to survive.

Slow Growth

It usually takes 2-4 days for most seeds to embark on their short crop cycle, although some seeds might take a bit longer. There is something wrong if your seeds are taking longer to germinate.

Ensure that the microgreen tray has a blackout dome. If the seeds are too dry, you will have to spray them with water to moisten them. We spray water on the inside of the dome or tray used to maintain humidity during the blackout. A heating pad or heat mat may also help in faster germination. But, be wary of excess heat. In a vegetative state, do not spray water! Your microgreens can rot, dampen off, or fall over if this happens.

Other methods of accelerating seed germination include:

Irregular Growth

The rapid growth cycle of your microgreens can be uneven at times. This is because an end of the tray is taller than the other end, while the other end is shorter. When in a blackout, the first side of the window reaches for more light. Light will naturally attract the seedlings. This doesn’t just apply to sunlight, but any artificial light source nearby as well. It is also possible to prevent uneven growth by placing an inverted tray on top during germination, usually for 3-4 days, depending on the microgreen variety.

Collapsing Microgreens

Microgreens may fall over due to any of the following reasons:

Insufficient Water

Your microgreens may go dormant due to their thirst. It’s a good explanation. You will be able to restore them to normal if you water them and wait for the next day. You should make sure that your growing medium is moist but not soaked; otherwise, mold will grow. Mesh trays are recommended for draining excess water.

Seed Overload

Microgreen trays are small and confined spaces. Therefore, too much seed in the tray will result in the following things:

The seedlings will compete for limited resources, including:

There are microgreen growers who believe the more seeds you put in a tray, the more yields you’ll expect. But, unfortunately, this is not true at all. You may also experiment with various seed densities yourself and keep track of them. List the things that work and the things that don’t work for each microgreen variety.

Light Levels

Low light levels can also cause your microgreens to fall over. Plants require light to grow. It will help if you improve the lighting. When microgreens become too tall and leggy, they become thin and floppy so that they can fall over easily. Darkness makes them thinner. It would be best if you calculated blackout time appropriately. However, there are some exceptions. Basil and garlic chives, for example.

High Water Pressure

Microgreens are often watered from the top using watering cans and hosepipes. Seedlings can fall over when confronted with too much water force.

Using two trays, one mesh tray, and one corrugated tray will solve the problem.

Then, you need to:


Just like other plants, microgreens can be affected by bacteria and fungal disease. Bacteria and fungi can be caused by:

A microbe will compete for nutrients with the seedlings or destroy them (black stem rot). Therefore, make sure you grow your microgreens in a ventilated growth environment with hours of sunlight.

Yellow Stems

The true leaves (not the mature leaves) of your microgreens look yellow at a certain point because chlorophyll hasn’t had the chance to carry out photosynthesis yet. However, as soon as they are exposed to light, they will turn green. It’s not a big deal. It’s perfectly normal.

Microgreens become leggy and tall if you leave them in the dark for too long. Microgreens are always searching for sources of light. Consequently, they will become weaker the longer they stretch. Height is weakened by reducing nutrition. When the stored energy is exhausted, the fragile microgreens will collapse. For that reason, the blackout period is usually 3-5 days.

Pest and Disease Management

Transboundary plant pests and diseases spread more widely as the climate and precipitation change, according to experts. Most crop pest species thrive in warm, humid environments and need moisture to thrive, so increasing temperature and precipitation levels favor their proliferation and dispersal. Pythium and Phytophthora (root and stem rot) appear to be the most severe threat to microgreens. The problem of damping-off can be the result of two causes: excessive seeding and inadequate airflow.

You should pay close attention to the following cultural factors:

In addition to using mechanical control methods, such as light traps, sticky traps, introducing natural enemies and pheromone traps, you also need to manage farming practices such as crop rotation.


Our healthy microgreens are grown in aeroponics, not in a soil medium. Consequently, we are not affected by the same diseases in microgreens faced by the commercial grower. We have found that most varieties of microgreens are not exposed to diseases for a long time.

A variety of microgreens is more likely to suffer from the risk of disease and insect problems than others. Another disease factor to consider comes from the seed packets themselves. Mildew may develop on seeds, so sterilizing them may be worth the effort. In addition to preventing mildew, commercial treatments and kitchen-formulated solutions can prevent pathogens from affecting greens.

Our seeds are not sterilized since we have never encountered any problems; however, the “Poor Man’s Solution,” shown below, can be used to sterilize your good-quality microgreen seed. You can use a “poor man’s solution” by mixing white vinegar and hydrogen peroxide in equal amounts with clean water. You can use this solution to soak larger seeds for ten minutes.


Microgreens are popular today. That’s great, we think. However, most people do not count on the many things that might go wrong! Finding out where the problem began and how to fix it is even more complicated. It takes time to learn how to grow your fresh produce of healthy plants with plenty of vitamins.
It is sporadic for someone to get it right on the first try. But then, at some point, something will go wrong! This guide was written to aid you with that. We offer fast and easy solutions to your growing problems.