If you’re familiar with microgreens you know how flavorful they are. You don’t have to buy them at a store. To save money and get fresher microgreens, you can grow them at home with a little bit of equipment and time. We’ll share 5 tips to make growing microgreens at home successful and as beautiful as they can be.
Microgreens are young, edible plants that are harvested just after the first leaves have developed. They are packed with flavor, making them a popular addition to salads, sandwiches, and other dishes.
To grow microgreens successfully, the first step is to have a great soil base for the seeds to germinate. The seeds then sprout and develop into young plants, which are harvested within 1-3 weeks (depending on the specific variety).
Successful microgreens growth requires these 5 components:
- Soil: Use a light, fine-textured seedling soil (not potting soil). Read our post on the best microgreens soil and get our pdf recipe.
- Temperature: Most microgreen seeds perform best when germinating at 75°F. This where a heat mat becomes very useful. After being transferred to a grow light, temperatures between 65-70 degrees Fahrenheit are ideal.
- Light: While germinating, the microgreens need to be in the dark (more on this below). After popping up, you should immediately move them to a grow light. Read our post about the right kind of light.
- Water: Seeds need water to germinate. They absorb water through their seed coat, which softens and swells, allowing the embryo to emerge. Once they are under a grow light, you will bottom water the tray. The water levels will vary depending on the specific variety, but you will need consistent moisture.
- Air Flow: After moving them under the light, keep good air flow in the overall growing space and cooler temperatures for best results.
Let’s explain all of this in more detail, starting with the germination of your microgreens.
Table of Contents
Understanding Microgreens Germination
When we’re talking about germination, it’s the simple way of describing the process by which a seed begins to grow into a plant. It is an essential step in the production of microgreens, as it is one of the factors determines the quality and quantity of the final product.
During germination, the seed absorbs water and nutrients from the soil, which activates enzymes that break down the food stored in the seed. This process produces energy that fuels the growth of the plant.
The length of the germination period depends on several factors, including the type of seed, temperature, humidity, and light. Some seeds, such as radish and broccoli along with other brassicas, germinate in as little as two days. Others, such as nasturtiums or shiso, take longer.
Use Soil to Grow Microgreens
As we mentioned in the introduction, the right type of soil is critical to the overall success of your microgreens. This blog article discusses that in more detail.
Hydroponically grown microgreens can never compare to the flavor or quality of soil-grown. This is because plants are designed to grow in soil, where the intricate web of life teeming with numerous things can work with the plant to reach its potential.
We are not discrediting the use of hydroponic methods. We simply feel that soil is what it’s all about, and you will never get a better taste or appearance than microgreens grown in soil. So for our purposes in this post, we are only referring to growing in soil.
Use a 1020 flat that is about 2″ tall if you’re growing microgreens longer than 10 days. For shorter growth cycles, you can use a shallow flat. Radishes and peas always perform better with deeper soil.
To keep it simple, you could simply use the deeper flat. This 1020 mesh tray by Bootstrap Farmer allows you to have a sturdy, reusable flat to fill. Use this secondary flat with no holes as your watering flat. That way you can lift the tray with the microgreens and water from the bottom, allowing the roots to absorb the moisture. This is much more important than moistening the top soil.
If you are buying pre-made soil mix, be sure to choose seedling soil with a pH of about 6.0. Something light and airy (rather than dense potting soil). Our own custom soil blend recipe allows us to make it in bulk amounts and save money, but if you’re only growing on a small scale for yourself a pre-made soil may be all you need.
Temperature for Germination & Growing
It’s important to note that a heat mat, especially one with a temperature-controlled thermostat, makes a difference in how well microgreens begin to sprout. If you’re a business or want to start a microgreens business, you’d be wise to invest in a quality heat mat.
Our heat mats are set to 75 degrees. If it’s very warm where you live or the humidity is high, you may only need to set the temperature to 72 degrees.
This one by Vivosun is very useful and easy to set up.
The higher heat is only necessary for germination. After the seeds are sprouting and showing their white root tails, you need to get them under the light as soon as possible. Allowing them to grow for too long while on a heat mat (especially with the dark cover) causes the plants to search for light.
That means they will grow taller too fast (leggy is the word used to describe it). The stems will be longer, but there’s little strength in the greens themselves because they weren’t exposed to light soon enough.
So don’t leave them in the dark longer than necessary for the sprouting to begin. Putting them under grow lights make the microgreens stronger faster and develop better color and appearance.
As they grow, try to keep the room less than 75 degrees. The closer to 65 degrees, the better. You may need to set up a small fan on a low speed to make sure there’s enough air flow. Don’t let the fan blow directly over the microgreens because that will dry them out too quickly.
Instead, aim the fan so that it will promote a steady air flow around the greens but not straight at them. For example, you may need to position the fan diagonally to make the air flow begin in the right place. It depends on how the growing shelf is positioned and where it’s placed.
Now that we have the temperature explained, let’s talk about light.
What Type of Grow Light Is Best?
For microgreens to grow well, you need a quality LED grow light. Don’t just choose any “grow light”. Make sure it is full-spectrum. This means that the wavelength of the light is designed for optimal growth of the plants.
We recommend full spectrum, 6500K LED grow lights from HTG Supply. This strip light is not heavy or hard to put up but will allow microgreens to have the bright light they need. It’s also energy efficient. Use at least 2 of these lights above your flat(s) at a height of 12-14″ away from the top of your greens.
You can also use this small fixture with the same type of LED lights.
For more details about light and why this is so important, read our post on LED grow lights.
Seed Quality for Growing Microgreens
We need to choose the right seeds for the best results in microgreens. By the right seeds, we mean selecting high-quality seeds. Our favorite companies for seed purchases are Johnny’s Seeds, High Mowing Seeds, and Mumm’s Sprouting Seeds.
Many growers also find good results with seeds from True Leaf Market.
Seed companies like these have a good reputation for quality. This is essential when growing microgreens and taking them to the finish.
Seeding the Tray (Density)
When you spread the seeds out over the flat, you don’t want to crowd them in so much that they end up competing for room as they grow. If they’re too close together, the plants will compete for nutrients and become stunted.
Keep in mind that microgreens are individual plants. Each of the seeds that sprout require nutrition from the soil and too many close together simply will not work. It’s a balancing act of just how many seeds you need in a flat. It also depends on the specific type of plant and size of the seeds.
Aim for an even distribution across the flat without the seeds touching each other. Over time, you’ll develop a feel for this. As you learn how much you need, a valuable tool is a little jewelry scale with precise measurements. You can weigh the seeds in a small paper cup or something similar so you know how much you need every time.
One of the most useful tools that saves us a lot of time and makes it easier to get the seeds even is this Vibro Hand Seeder from Johnny’s Seeds. The vibration level can be adjusted and allows the seeds to fall with a lot less work from you.
Watering & Covering the Flat
The moisture level of your soil should not be soggy when filling the flat. It should be moderately moist. After you spread the seeds, spray the whole flat evenly with a spray bottle or better yet, a pump hand sprayer.
Once you have sprayed the flat, cover it with a sheet of heavy duty parchment paper that extends over the edges of the flat. Tuck it under the flat to help retain moisture. Use an upside down empty 1020 flat over the top. Blocking out the light like this promotes germination, especially on the heat mat.
In the photo below, we have tucked the end of our parchment paper against the microgreen inserts we plant in. We use individual, 5×5″ tray inserts from Bootstrap Farmer so that we can mix different varieties into the same flat. They are available in shallow and deep heights.
After the parchment paper is secure, we place our upside down 1020 flat over the top. We tighten it over the edges of the tray inserts mentioned above. As shown, the end of the parchment can be tucked under the edge of your growing flat.
Troubleshooting Common Problems
If you notice poor germination in your microgreens, there may be a few things causing the issue. One common issue is using old or expired seeds. Use newer seeds if at all possible.
Another issue could be the temperature. Like we discussed, microgreens require warm temperatures to germinate, so make sure your growing area is at the proper temperature.
Under watering can also cause poor germination. Make sure to water your microgreens when the top layer of soil is dry. Be sure to pay attention to the corners and edges. Turn the flat to get an even distribution of water.
One common disease is damping off, which is caused by a fungus and can kill seedlings before they even reach maturity. The microgreen leaves can look soggy and crushed together. They wilt and fall over.
To prevent damping off, make sure to use clean containers and avoid overwatering. Especially be careful not to water from the top. A spray over the top is fine, but watering from above instead of at the roots makes it easy to give the plants too much water. The soil becomes bogged down and the roots (which start just under the soil) are drowning.
If you notice any signs of disease, remove the affected plants immediately to prevent further spread. You can also sprinkle a little bit of cinnamon over the top of your soil at the time of planting to stop unwanted fungal growth from happening. Just use enough to spread a thin layer of “dust” over them.
Harvesting and Usage of Microgreens
If you’ve watered the microgreens just right they will continue growing until they’re ready for harvest. The exact time to harvest depends on which microgreens you’re growing.
Cabbage family greens like arugula, kale, kohlrabi, etc. will be ready for use when they are still at the cotyledon (first leaves) stage, about 7-10 days. You can grow them to the true leaf stage if they are in deeper soil, but it will be 2-3 weeks before that occurs. They’re more tender at the cotyledon stage.
It’s best to stick with these easier microgreens until you feel comfortable with the process. If you decide you’re ready to to try other types of microgreens that are more complicated to grow, remember that many of them take at least 3 weeks to grow to their ideal harvest stage. Red veined sorrel is one of the slowest microgreens, taking about 6 weeks to reach maturity.
To harvest microgreens, simply use a pair of sharp scissors or a sharp knife to cut the stems just above the soil line. We recommend only harvesting what you need and using it right away. Leave the rest of the flat intact and keep cutting as you need.
That means fresher, tastier greens for you and it will last much longer being left in the soil than cut and stored in a refrigerator. Use them on salads, as a garnish for dishes, toppings on burgers and pizza, mixed into omelets or egg-bites, or even in smoothies.
In conclusion, the best microgreens you can grow at home are grown in soil, kept evenly moist from the bottom, have relatively steady temperatures to mature in, good air flow, and full-spectrum grow lights to give them optimal strength and appearance. Growing your own microgreens isn’t hard but requires some effort and practice.