All about the Soil and Water
The type of soil and the air temperature make a big difference. For example sandy soil will heat up faster. Many Microgreen Growers mix their own soil. For example it might be 60% peat moss, 30% coco coir, and 10% Pertile or Vermiculate. Other Growers buy premixed soil. Experiment and find what works for you.
If growing outdoors, in the early spring the soil temperature is less than the air temperature and in the summer, the soil temperature is higher than the air temperature.
The amount of moisture in the soil also makes a difference. Wet soil is colder and warms up more slowly. Extra wet soil also encourages the growth of fungus and prevents the microgreens from getting enough access to the oxygen in the soil.
Should fertilizer be added to the soil when growing microgreens? Some choose to add some and others do not. The growth time (planting to harvest) for microgreens is so short, they are not as dependent on the nutrients in the soil as full grown plants. Here are a few easy fertilizer suggestions (if effective or not depends on the soil type you are using):
- Add 1/2 cup of bone meal per gallon of soil. Bone meal provides phosphorus which promotes healthy roots.
- Add 1/2 cup fishbone meal per gallon of soil.
- Add 1/4 cup of Dolomite lime per gallon (wear gloves). Dolomite lime contains equal amounts of magnesium and calcium which helps plant growth. This will also increase the soil's pH (make it more alkalined).
What pH should your soil and water be? Different Microgreens have different preferences but overall the pH of your soil and water should be in the neutral range which is a pH of 6.6 to 7.3. A pH of 7.4 or higher is Alkaline and a pH of 6.5 or lower is Acidic. To test the pH of your soil, add 1 Tablespoon of soil to one cup of Distilled water and test with litmus paper or a Meter tester. To test the pH of your water, test it directly with litmus paper.
A home test (no added equipment) for pH. In a glass mix 1 Tablespoon of soil, 1 cup of water and 1 Tablespoon of vinegar. In another glass mix 1 Tablespoon of soil, 1 cup of water and 1 Tablespoon of baking soda. If the vinegar glass bubbles first, the soil is alkalined. If the baking soda glass bubbles first, the soil is acidic.
To change the pH, to make it more acidic (to lower the pH), add 1 Tablespoon of vinegar or lemon juice per gallon of water. Vinegar has a pH of 3.3. To make it more alkalined (to raise the pH), add 1 Tablespoon of baking soda per gallon of water. Baking soda has a pH of 8.2. You may need to add more more than one Tablespoon of vinegar/baking soda to adjust your water to the correct pH. Everyone's water source is different.
If watering your Microgreens with chlorinated water, let the water sit at room temperature for a minimum of 24 hours before watering your microgreens. This will give time for the chlorine to decrease.
When mixing your soil, how much water is enough water? If you squeeze a handful of the dirt and two drops of water come out, that is enough water. If more than two drops come out, the soil is too wet.
Can soil be re-used? If you re-use the soil immediately for another crop (even if you try to pick out the roots) you will have mold and rot issues. It takes 20-40 days for the old roots to break down. You can add an enzyme to help speed up this process such as Hygrozyme Enzyme Formula or Cannazym by Canna. In the USA if you are selling the microgreens, you can not re-use the soil unless you have it professionally composted and records to prove so.