Success Is In The Details! This Microgreen 101 answers the most frequently asked questions about How to Grow Microgreens.
Begin with the lowest recommended seed density. Because microgreens are purposely grown in crowded conditions, your home environment will have an effect on how much seed you can grow per tray. Those with low humidity, bright light, and higher airflow (moving air from fans, etc.) will be able to grow more per tray than those who live in high-humidity areas, have filtered light, or in smaller spaces with little airflow.
Start with a smaller amount of seed and work up to the ideal amount for your conditions.
Water and Watering Microgreens
Microgreens are best watered from the bottom, pouring the water into the tray below instead of on top of the plants. Because microgreens are grown with high seed density, they can be prone to mold if they are watered from above.
Watering microgreens: Always use water from your clearest source. Avoid softened water or chlorinated tap water when possible. The most common problem with most plants, including microgreens, is underwatering or overwatering. Microgreens do not like to ‘swim’, but must be kept damp. The soil should be moist, but not dripping wet. When watering, allow the soil to soak up all it needs within 10-30 minutes. Then dump out any extra water to avoid standing water. The amount of water needed depends on the humidity of the air and the temperature. In most areas ¼ cup per tray is appropriate. Water once a day if it is dry and warm, and less if it is humid and cool.
What soil should you use for microgreens? The organic coco coir provided in your kit is an excellent microgreen grow medium. Besides being easy to use, it is the perfect combination of the nutrients that microgreens need to grow until harvest. The discs that we provide are sized exactly right for the grow trays. Add exactly 1/2 cup of water to each disc and it will grow to one cup of microgreen grow medium.
Use fresh soil for each tray
Never reuse soil for microgreens without complete composting, as reusing the used soil presents a possible build-up of pathogens in the soil. The used soil is full of nutrients, however, and should not be discarded in the trash. It can be recycled under trees or bushes, used in flower pots, or added to the soil in an outside garden. Adding coco coir to garden soil is an excellent way to improve the aeration of the soil and make it more productive. If you live in an urban environment, we encourage you to find an appropriate place to recycle the coir to preserve the nutrients and nourish other plants.
Other types of planting soil:
A good-quality potting mix will also work well for microgreens. Do not accidentally buy garden soil, however. Garden soil is too dense and does not allow the air to circulate to the roots in a container. Potting mixes are designed to be light and airy which reduces over-watering problems. Avoid mixes where the origin is unknown, or that states it is from a landfill as the green material from landfills often contains plant material that may have been sprayed with chemicals.
A Few Words About Hydroponics...
Although Hydroponics is a current trend that is based on ease of use, it is not necessarily the best alternative for microgreens. As we move toward the high-tech world of food production, we need to make sure that we are doing so with the proper scientific research to ensure that these advancements are also protecting the health and nutritional content of our food as well as our environment. Hydroponics can result in a healthy product, but it requires an intimate knowledge of the nutrient needs of each crop.
Microgreens do best in bright light once they have germinated and begun growing upwards. If you have a window that receives at least 6 hours of bright light each day, that will be an ideal spot. If you choose a window with full sun, check often that the trays have not dried out in the heat.
Using artificial lights
If you want to set up a more formal growing area, see our video for more information about choosing the right lights for microgreens. When using artificial lights, they should be placed within 6 inches of the tops of the growing microgreens. No lights? No problem. Just put them where they have the brightest available natural light.
Note that you do not need special grow lights for microgreens. The video goes into detail, but it is important to realize that the light spectrum in grow lights is needed for flower growth. Microgreens are harvested at about 10 days- long before the greens need the red spectrum of light.
Although the ‘ideal’ temperature in the growing area is 65-75F, microgreens are very adaptable and will grow in a much wider range. If it is cooler, the microgreens will take longer to grow. If it is warmer than 75F you may need to water the plants more often and uncover the germinating seeds earlier to prevent mold growth. The microgreen seeds that are included in your kits are among those that are the easiest to grow in a wide range of temperatures.
Microgreens can be grown in many different areas of the world, from deserts to tropical. While the ideal humidity is 35-45%, many homes fall outside that range- and microgreens will still grow. If you live in an area with high humidity and warm temperatures, such as some of the southern states, there are a few options to make your growing as successful as possible.
- Reduce the density of the trays. Begin with half of the seeds that are recommended so that the seeds get better airflow, and increase the amount gradually.
- Do not spray seeds after planting.
- Uncover your germinating seeds after 2 days of germination.
- Keep your microgreens out of rooms that tend to increase humidity such as laundry rooms and rooms adjacent to showers.
- Place a small fan near the microgreens. Have the fan pointed near, but not over the microgreens for best results. The idea is to increase airflow and dry out the top layer of soil.
- Water only when the soil is dry, not daily.
- Larger seeds, such as peas and buckwheat will do better in a very humid environment than small seeds such as broccoli and alfalfa.
Some of the larger seeds, such as peas and buckwheat, do best when given a soaking period before planting. This forces all the seeds to germinate at the same time and reduces the time to harvest. Use room temperature water. Some seeds, such as peas, double in size so be sure to use a large enough cup or jar that they will be able to absorb their weight in water. Soak for 6-8 hours. Drain the seeds into a sieve and rinse well under cool running water for 30 seconds. They are now ready to plant.
Small seeds, such as radish and broccoli, do not need soaking- they are small enough to absorb all the moisture they need quickly from the soil. Soaking the small seeds makes them difficult to handle. NOTE: Although sunflower seeds can be soaked, it is normally best to rinse them well in cool water before planting but not soaking.
Microgreen seeds are spread evenly across the top of the soil without covering them with soil. Rehydrating each coir disc with exactly 1/2 cup water assures that your seeds will have sufficient water to germinate. Cover the planted seeds with the black cover tray. The cover tray keeps the moisture in so that the seeds do not dry out before germinating. It also provides the dark environment that most seeds prefer. Adding the weight (below) forces the seeds into contact with the soil so that the roots can take hold immediately after they emerge.
The reason we use a cover tray instead of covering with soil is that we are harvesting our microgreens very close to the seed. This prevents soil from being 'harvested' along with the microgreens.
The microgreens must not be watered again until after the covers are taken off (2-4 days, depending on variety).
The black tray is put directly over the seeds and a weight is put inside the black tray. The weight can be a can of food such as green beans, a fist-sized rock, a jar with water in it, or anything that is clean and weighs about the same as 8 ounces of water.
The purpose of the weight is to press the seeds down into the soil, allow the roots to immediately burrow into the soil, and make the seeds struggle to grow upwards as if they were under the soil. It will also encourage all the seeds to germinate at the same time, making a nice, even crop.
On the second or third day from planting, you may take a peek at your microgreens and notice ‘white stuff’ growing in the tray.
Little tiny hairs, called root hairs, come directly off of the roots and are responsible for absorbing moisture and nutrients from the soil. If each patch of white comes off of a single seed or seedling, what you are seeing is root hair- a sign of healthy microgreens!
Read this article for more information about root hairs and microgreens.
Occasionally, mold grows in microgreen trays if the humidity is too high, the seed density is too thick for the growing conditions, or large seeds (especially sunflower) have not been properly rinsed.
Q. How do you tell the difference between root hairs and mold?
A. Root hairs-
• Come directly off of the root.
• Each patch of white comes from one root.
• Are fuzzy looking.
• Covers more than one microgreen seed or plant
• Is often on the top of the germinating plant, not on the soil.
• Is messy-looking and can look like a cotton ball that has been pulled apart.
If you are still not sure if what you are seeing is root hair or mold, use this simple watering trick: With your spray bottle, lightly spray the tray. If what you are seeing is root hairs, the fuzzy look will disappear. If it is mold, it will gather droplets of water and its shape will still be visible.
For further information about mold, See this article
Special instructions for sunflower microgreens
Sunflower seeds are a unique type of seed in that the way the seeds are grown and harvested in fields means they must be rinsed well before planting. Rinse well under cool, running water for at least 30 seconds.
Because sunflower seeds are prone to mold, remove the weight and cover-tray after 48 hours. Be sure they have good airflow to prevent mold issues. If you experience problems, reduce the density of the seed. If this does not alleviate the problem, spray the seeds with 3% H2O2 (hydrogen peroxide) before covering, and then when you uncover the tray after 48 hours.
For all your questions answered by experienced microgreen growers, inspiration, and ideas on using your crops, connect with us on one of these channels:
Youtube: The Mighty Microgreen
Volley: The Mighty Microgreen
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