Have you harvested your microgreens and wonder if you can reuse your soil for another batch? Reusing microgreen soil is rewarding and beneficial if you do it right. Not only in regards to the cost savings it provides, but the nutrients it gains over time if done properly. The advantages are wide range, including that it is eco-friendly!
Should you reuse microgreen soil? Microgreen soil can be reused. However, it’s not as simple as storing away the soil for the next year. There is a process involved to reuse the soil for more than one growing season. It is essential to follow this process to maintain the overall health of the soil.
The roots and stems from the microgreen plants need to be broken down for the nutrients to be beneficial for future growth. The soil needs to be treated. If you reuse the soil too quickly after harvest, the microbes can cause harmful problems to the plants you will grow.
Reusing Microgreen Soil
Preparing the soil for use in the next season or your next crop is not difficult. Typically to break down the root structures, it takes anywhere from 10 to 12 days. Composting is a method to break down the remains of the microgreen’s roots.
Be sure to leave the roots and stems in the soil. Avoid removing these structures from the soil because they are part of the base of your soil nutrition.
After composting for several days, when the soil has darkened, that is when you know the soil is ready for the next planting. To enrich the soil, even more, you could add some topsoil or fertilizer. Continue reading and you will learn more about the different ways how you can prepare your soil to be reused.
Methods How to Reuse Microgreen Soil
There are two common methods when it comes to reusing microgreen soil. These include:
- Flipping the Soil
- Also known as the “flip-it method.”
- Convenience & quick
- Higher risk molding
- Vermicompost
- Uses worms
- Nutrient efficient
- More time involved
Flipping the Soil
The flip-it method is as simple as it sounds. Just flip the container you have the soil in upside down and use the backside for your new batch of seeds.
This method is convenient because it allows you to save time. The roots and stems from the previous plants degrade on the other side, adding nutrients to the soil, as the new seedlings begin to grow.
Although this method is time-efficient, it also causes more opportunities for mold to grow and your chances for microgreens to grow healthy may be less. If there are ungerminated seeds, they can cause mold so depending on the volume of soil you want to reuse it may be worth treating it using the Vermicompost method.
Vermicompost
Vermicompost is when worms are used to decompose vegetable or food waste, bedding materials, and organic matter. In this process, the worms break down the waste and, in turn, replace the soil with nutrient-rich organic matter. Worms for composting can be purchased inexpensively online or at a garden supplier.
This organic matter is essentially worm manure, also known as Vermicast. These castings are known to reduce levels of contaminants and produce higher levels of nutrients in the soil compared to vermicomposting without castings.
Vermicomposting is a great method to prepare and treat the soil before reusing microgreen soils. This process takes longer to break down the leftover root and stem vegetation, but in the end, it produces nutrient-rich soil. This is well worth the wait.
Both methods work for reusing microgreen soil. However, keep in mind the issues that can occur during the flip-it method, like having mold development. Vermicomposting is more ideal if you have the time to wait to grow your next batch of plants.
How to Properly Compost
If you decide to go for composting, you can do this indoors or outdoors. You can use a large or small bin or tray to compost the soil depending on the amount of soil you need to reuse.
If composting properly and long enough at the right temperature, the soils become pasteurized.
Pasteurization is like sterilizing the soil; however, it’s more involved than that. Over time with warm enough temperatures, microbes will decompose the waste in the compost bin. Temperature is important because if this is incorrect, microbes will not be able to kill off the fungus and bacteria that grow.
Aim for temperatures around 55C for at least three days. You can go up to 15 days if you prefer not to stir the soils during the 3 days. Either method will work efficiently. These temperatures are important for the killing of the potential pathogens in the soil if using manures.
It is suggested, especially when reusing soil to test the composting process for pathogens. If you prefer to avoid this step, you can purchase soils and compost from commercial compost suppliers.
Sterilizing Soil
Another advanced step in preparing reused soil is to sterilize the soil. A method to sterilize the soil is to put the soil in a metal tray and place it in the oven for two, two and a half, hours at a temperature of 320 degrees Fahrenheit.
To sterilize soil properly, remove the stems and roots that were leftover. Any remaining organic matter may create smoke and weird smells, but that is normal and just reassure you that your soil is sterilizing!
Some places sell sterilized soils, but that can become costly. If you have a small operation, this process is enough. When becoming a larger scale, you may need to invest in larger equipment or resort to industries that sell in bulk.
Issues with Reusing Microgreen Soils
If you do not properly follow the methods above, you can potentially run into issues with your soils and plant growth in the future season.
Some issues that will be expanded in this section include:
- Mold
- Confused with microgreen root hairs
- Preventative measures to fight mold
- Loss of production
- Soil quality
- Mold influence
Research suggests that if you don’t compost your soil it could cause mold. Mold has a spider-web like appearance. The root hairs of microgreens can sometimes be mistaken for mold. But mold is slimy to the touch, unlike the fuzzy root structures.
Mold does not disappear after rinsing with water, whereas root hair does. Mold can be located throughout the soil, not just the surface or root level.
Microbes can take over the soil as well, and temperature influences mold production or too much water saturation. Mold can kill the growth of microgreens, so you will want to be sure to look out for this when composting and reusing the soil.
Poor soil quality can influence poor growing conditions, which result in loss of production.
RELATED: Why Microgreens Mold and How To Prevent It
Avoid Reusing Growing Pads
Growing pads are more convenient than conventional soil plots; however, they are in general not reusable. Most pads cannot be reused because they are compostable, made of fibrous coconut or hemp fiber.
These pads are not feasible since they do not provide benefits of reuse. They are rich in nutrients, which promotes growth for microbes, which lies the reason they cannot be reused. These microbes cause problems in pads reused.
People have found ways around this in order to reuse these substrate pads. The solution is to bake the pad for a short time and soak them in diluted hydrogen peroxide. Then wash them with selective nutrients.
This process seems more time consuming than what it is worth. Not only that, but the expense of buying a new pad each time also adds up. It is better to reuse growing pads by composting them or mixing them into your garden, than trying to reuse them to grow another batch of microgreens.
Traditional soil plots are the way to go, especially when you can reuse the material and save the extra cost!
Reusing microgreen is not only rewarding for personal reasons, but it is environmentally friendly! You can reuse your soil for more than one or two growing seasons if you keep the soil healthy.
Reusing Microgreen Soil in a Nutshell
In summary, microgreen soils can be reused if it’s done correctly, and the process is simple. Overall, to maintain a nutrient soil, you should compost and treat your soil. Keep in mind the steps involved in preparing the soil for reuse, like composting and sterilizing. Remember that mold can grow under certain conditions, especially if the temperature is incorrect or if you do not properly use the flip-it method.
If you follow the instructions, you will be on your way to a healthy microgreen soil each year using less soil!
I’m new to microgreens.
I just grew a nice crop of mesclun greens. Delcious.
BUT….required lighting, heat mat and growing medium. All cost a few bucks.
I also grow sprouts.
Here’s the thing…no lights, no soil, little effort , small price with out of sight results.
So….why grow microgreens?
Hi Sue!
Growing microgreens and sprouts are different and the results are as well. So why do we grow microgreens? Microgreens offer a wider range of tastes and textures compared to sprouts, making them a great option for adding flavour and nutrients to your diet. They are visually different to sprouts and can be used with more variety, in salads, as garnish etc.
They can be grown in a wider range of containers and spaces than sprouts, and although they take slightly longer to grow, they are still quick to produce. They are also less susceptible to foodborne illness than sprouts.
We have written an article about the difference between sprouts and microgreens if you are interested to learn more.
Happy growing!