Microgreens are fun to grow and fun to eat. As I’ve previously written on FMC, sprouts and microgreens are a great first-time grow project for novice gardeners. Simple as microgreens are to cultivate, the urban farmer may encounter numerous hiccups as they grow — things like white mould, uneven growth, and even vermin. If you’ve experienced any of these issues, you’ve come to the right place. In this post, I will help you troubleshoot your microgreens and teach you how to deal with problems and, more importantly, prevent them from arising.
1. Web-like mould or fungus
This white fuzzy growth that resembles spider webs is a mould commonly seen in sunflower microgreens.
😢 Common causes
- Seeds are too close together. If you lay your seeds out and there isn’t enough space between them, you are creating the perfect circumstances for this type of mould to grow.
- Too much moisture. When you are stacking your seeds together, and they are too wet, this type of mould may appear. It’s better to water little and often.
- Seeds are not germinating around healthy seeds. This will cause them to decay while the other sprouts grow.
😄 2-step solution
- Hydrogen peroxide solution. Mix ½ tablespoon of 3% food-grade hydrogen peroxide with ½ tablespoon of white vinegar in 1 L of water. Fill this solution in a spray bottle and spritz onto the affected area.
- Remove affected area. After you have sprayed the area down with the above solution, and it has settled, remove the area that is affected with mould. This will stop the spread of the mould to the rest of your tray.
🚫 How to prevent mould
- Clean everything! Rinse the seeds well before soaking. Clean the container you will use to soak your seeds, clean the area that you are germinating in, and, finally, clean yourself — including your hands and clothes — before you start handling your seeds.
- Hydrogen peroxide. Add 1 tablespoon of 3% hydrogen peroxide to the water you soak your seeds in. This will clean and kill anything that might be on the hulas of the seeds.
- Remove seeds that are not germinating. These seeds will start to decay and infect the healthy seeds, preventing them from growing. The faster you remove these rotting seeds, the less likely they will develop mould.
- Plant seeds sparsely. Give your seeds space to breathe and allow air to circulate. Once you are growing without mould, you can place them closer together.
2. Uneven growth
When you are laying out your trays, sometimes there is an area that doesn’t grow.
😢 Common causes
- Not enough water. Most commonly, uneven watering will lead to uneven growth. As illustrated in the picture, a uniform area of unsprouted seeds fades to healthy growth.
- Too much water. Yes, it could be that the affected area got too much water and the seeds were not able to breathe. It’s important to have the appropriate amount of water for your seeds.
- Too much air flow. If you are seeing inadequate growth from one side, it could be that there is air flow just drying out one side of the tray.
😄 Solutions
- Water the affected area ASAP! Once you spot a dry patch, water it immediately. However, don’t over saturate it nor dump a lot of water on it, as it may drown the seeds. Spray a good amount of water into the area a couple of times during the day.
- Remove seeds that aren’t growing. After trying to water the area with the seeds that aren’t sprouting, remove the seeds to prevent mould and other problems from spreading to the healthy area of your trays.
- Remove tray from direct air. If possible, relocate your microgreens plant from any wind directly blowing at it during its germination stage.
🚫 How to prevent uneven growth
- Stay on top of your watering. Make sure that when you water, you get a consistent amount over all the whole tray.
- Check them a couple of times during the day. Inspect the trays before you leave or as soon as you come home. The sooner you catch an issue, the faster you will be able to correct the problem.
- Check the soil with your finger. After you water, clean your hand, and then stick your finger in the soil to gauge the moisture level. It should be moist but not damp.
- Add water underneath the tray during germination. The seeds don’t yet have the root system to drink water, but it will add some moisture to the bottom of the soil. You need only to add enough water to moisten the soil. Adding too much, however, could oversaturate the soil and suffocate the roots.
- Place the seeds in a space that doesn’t have direct air flow. Again, this will dry out one side of your seeds. You want the air to circulate in the room, but not directly at the base of the trays.
3. Stems falling over
If your microgreens stems are really thin and toppling over, there are many things that might cause this, so let’s go over them.
😢 Common causes
- Not enough light. The plant will try to reach for the sunlight and if there isn’t enough light the steam will overstretch and become long and thin.
- Too much time in the dark. It’s important to keep your microgreens in the dark for a little to have them stretch, but too much time will, again, make them reach too far for sunlight.
- Too much water. If you are using a hose or something with strong water pressure, it can damage the stems and have them fall over.
- Not enough water. With microgreens, there are a lot of plants growing all at once, and they need a lot of water. Make sure you are providing enough.
- Too hot. If the surrounding environment heats up too much, they might fall over.
- Exceeded harvest time. In some cases, you may have let the plants grow for too long, even when they are ready to harvest.
😄 Solutions
- Bring your plants closer to light. Put something under your tray or lower your grow lights.
- Add a fan. Have air flow blowing above your tray. Make sure it’s not on the soil because that might dry out the plants.
- Remove tray from the dark. And bring it to the light.
- Make sure there is enough water. But not too much! Again, we don’t want to drown our seeds.
🚫 How to prevent falling stems
- Install lights closer to the plants. With microgreens, having your lights 6″ to 10″ above the tray is ideal. Lights work on logarithmic scale, so every inch is exponentially less.
- Install more lights. If you notice your microgreens are not growing up evenly but towards the area of light, install more lights around your tray. Normally, having two T5 grow lights per tray will keep the sprouts uniform.
- Replace your bulbs. If you have been growing for a while with the same light, they will eventually lose intensity. Generally speaking, after one or two years, it’s time to replace florescent bulbs.
- Water underneath the trays once stems grow. Not only does this increase the root growth, you avoid damaging the stems, which often happens when watering above.
- Know when your microgreens are ready to harvest. If they grow too long in dense areas, they will not be able to support themselves.
4. Mice
If you are getting mice in your microgreens, or even where you store your seeds, it can be a major problem. Mice are known to destroy crops and, of course, they love seeds!
😢 Common causes
- Dirty environment. It might not even be your home. Remember, we are farming in the city, so these pests can be coming from anywhere around you.
- Seeds stored in vulnerable place. If your seed bags are placed on the ground, they are highly accessible to mice, and they won’t hesitate to ransack them.
😄 How to deal with it
- Clean! You want to remove all food from the area. Make sure all the nooks and crannies properly cleaned.
- Mousetraps. A key preventative strategy is stopping the mice from accessing your seeds or microgreens in the first place. Once the mice are there, they will love your area and want to stay around. There are many types of traps you can get, but the main thing you need to do is control the growth.
- Rat poison. Once mice infest your seeds, the issue can quickly escalate — and that’s speaking from experience. I once had over $5000 worth of seeds and crops lost to mice. Did everything, but I was in a dirty building and had to resort to stronger measures to deal with this issue.
🚫 How to prevent mice
- Store seeds in sealed containers. Mice will eat through the bags that seeds are shipped in, so repackage them in rubber totes or glass jars. If you are storing them for a while, I would also recommend silica packs to make sure moisture doesn’t accumulate.
- Consistent cleaning schedule. Make sure you clean up thoroughly and often. Ensuring isn’t food around is the best prevention against pests.
- Keep your waste away from grow area. After growing there is waste, so have a nice area for compost or your waste a good distance away from where you grow.
- Close holes to the space. Using steel wool and spray foam is an amazing way to block holes. The mice won’t be able to chew through the steel wool, and the spray foam will fill in the rest of the gaps. You can also mix poison into the steel wool to add another layer of defence.
- Set up traps. Check them regularly.
- Get your seeds off the floor. Move things up and make it hard for mice to get to your bags.
5. Fruit flies
Fruit flies are a very common issue in the urban farming world, but they don’t have to be. If you stay on top of things, they really should not be an issue at all.
😢 Common causes
- Eggs are in your seeds – They are everywhere and they could even be in your seeds.
- Dirty environment – Once a food source is found they will reproduce vary quickly.
- Bad growing habits – Once growing sprouts goes a stray from what you should be doing they start to show up
😄 Solutions
- Clean, clean, clean! As you see, this is an overarching theme with microgreens maintenance. Make sure you eliminate the food supply of the fruit flies as well as their eggs.
- Hydrogen peroxide solution. This one is a little different from the earlier solution used to eliminate mould. Mix 1 tablespoon of 3% hydrogen peroxide to 1 L of water and spray your microgreens. This will clean and kill anything that might be on the hulls of the seeds.
- Don’t stress. As long as the fruit flies are not out of control, you don’t really need to worry. They won’t harm you. Just wash your microgreens a little more before eating.
🚫 How to prevent fruit flies
- Wash your seeds. This goes for before and after soaking. Add 1 tablespoon of 3% hydrogen peroxide to the water you soak your seeds in. This will clean and kill anything that might be on the hulls.
- Make a trap for flies that is more enticing than sprouts. Here is a great post on some simple traps you can make from what you have at home.
- Don’t oversoak your seeds. If you soak too long, the seeds might go off and attract flies.
- Make sure your waste is not near your sprouts. Having compost or your garbage close to where you grow food will increase the likelihood of cross contamination.
Updated August 19, 2021. Originally published March 3, 2020.
