Maybe you’ve tasted microgreens at a restaurant and got hooked. Or maybe you’ve seen friends grow flat trays of greens and wanted to give it a go yourself. Whatever your reasons for learning how to grow microgreens indoors, you’re in good company.
Microgreens are the young shoots of plants that are harvested when just a few inches tall. Not to be confused with sprouts which are germinated seeds that are eaten root, shoot, and stem, microgreens are plants that are cut from the stem-up and contain the cotyledons (seed leaves), stem, and maybe a few “true” leaves. Microgreens are smaller than baby lettuces.
Packed with nutrients and flavor, microgreens are easy to grow in a small amount of space. All you need are a few shallow containers, seeds, and potting soil to get started.
Why grow microgreens?
There are so many reasons to grow microgreens. Here’s just a few:
- Year-round fresh greens: Imagine having a fresh source of homegrown greens all year round, even during the bleak winter months. It’s possible with microgreens. Having the ability to grow microgreens indoors is a huge advantage—especially for those who live in colder climates.
- Health benefits of microgreens: While there are many different varieties of microgreens, most are a rich source of iron, potassium, copper, zinc, and magnesium. They also contain plenty of antioxidants.
- A study conducted by the USDA Agricultural Research Service (ARS) found that amongst 25 common varieties of microgreens, they contained about five times the amount of vitamins and carotenoids than the leaves of the same mature plant.
- Tasty: For such small greens, microgreens are packed with flavor. They generally taste similar to the mature version of their plant, but more highly concentrated. So add a splash of broccoli microgreens to get a taste of broccoli, or spice up your salad with arugula microgreens.
- High-yielding crop in small space: Unlike other crops that require a lot of space with a relatively small yield (pumpkins, I’m referring to you!), microgreens are sown densely and provide a big harvest in a small space.
- Fairly quick growing: One of the quickest growing types of plants, microgreens are rewarding for the impatient gardener. Most types of microgreens are ready to be harvested within one to two weeks, although some varieties are grown up to five weeks. If you want something that’s ready-to-eat in a matter of days, you’ll have to look into growing sprouts.
Good soil, good seeds
The taste of microgreens is greatly affected by its growing conditions such as amount of sunlight, type and quality of growing medium, and quality of seeds. You want to make sure you do everything possible to ensure microgreens are planted in a clean, nutrient-rich environment to produce the best young shoots.
This leads us to the importance of buying good quality seeds. While you don’t need any specific type of “microgreen” seeds, there are some seed packets that contain seed mixes specially designed to be planted together as microgreens. These are typically salad mixes. These are great if you’re starting out, or just want a variety of different microgreens in one container.
But really, you can plant any type of “normal” seed packets as microgreens grow just like regular plants, just more densely sown. Just make sure the seeds are good quality from a reputable seed company.
Good seeds produce higher, more uniform plants from good parent plants. And there’s nothing more disappointing than planting and caring for seeds and getting a lack-luster harvest.
Did you know that microgreens don’t need to grow in soil? There are other growing mediums as well. However, soil remains the popular choice as it’s fairly inexpensive, easy to buy, and produces great results. Let’s go over a few different growing mediums:
- Soil: Potting soil works well, or straight-up compost mix. Soil that’s rich in nutrients produces healthy, great tasting microgreens. It’s nice to not have any unnecessary chemicals or fertilizers in your growing medium. There are many organic options available nowadays. Keep in mind that some types of seeds require a thin layer of soil to cover them when planting.
- Hydroponic growing mats: You can grow microgreens without soil by using a type of growing mat made of coco coir (coconut husks), hemp, or jute/wood fibers. Growing mats are less messy than soil which is a main reason people who use them over soil. However, they are more expensive, and some like coco coir don’t hold water as well, nor provide enough nutrients. Mats also aren’t reusable.
- Soilless: Some people prefer to make a soil-free mixture of different growing mediums such as coco coir, or a mixture of vermiculite/perlite. Soilless methods are “cleaner” than soil, however, these soilless mixtures might not provide enough nutrients for your microgreens to grow.
So what are some of the easiest microgreens to grow?
- Bok choy
How to grow microgreens indoors step-by-step
Ready to start? Let’s gather a few supplies that you’ll need:
- Quality seeds
- Growing containers (You can buy grow trays, or any shallow container such as pie plates, or clear plastic produce containers work well. Just make sure to poke a few holes for drainage.)
- Potting mix (While there are other ways to grow microgreens without soil as mentioned above, we’re just sticking with soil here.)
- Spray bottle filled with water
- Hydrogen peroxide (for sanitizing trays)
- Clean, lintless cloth for cleaning
- Gloves (optional)
- Small piece of cardboard (optional)
Before planting, you’ll want to make sure your growing containers are clean. This is to reduce the chance of harmful bacteria proliferating in your food source. All you need to do is wash trays with warm, soapy water, and either spray or apply a bit of hydrogen peroxide all over the trays. Let sit for a few minutes then wipe off.
Before diving straight into planting, look into the growing times of each type of seed. You might want to grow each type of microgreen in a separate container. Or you can group together plants that have similar grow times.
Please also read the planting instructions on your seed packets as different types of microgreens require different planting methods. The following are only intended to be general guidelines.
Step 1: Fill with soil
Once your containers are all clean, fill containers with one to two inches (2.5 to 5.1 centimeters) of potting soil. You can use your piece of cardboard here to gently level the surface. Don’t press too hard—you don’t want the soil too compressed.
Step 2: Sprinkle seeds
Here’s the fun part—sprinkling seeds! To make the most of the growing tray space, you can sow seeds densely. Since microgreens stay in soil for a short time and grow to a small size, you don’t need to worry about overcrowding the way you would when planting normal vegetables.
Gently pat down the seeds. Refer to your seed instructions to check if yours require an extra thin layer of soil on top.
While different varieties of microgreens have different temperature requirements, a good temperature range to aim for is between 64-75 degrees Fahrenheit (18-24 degrees Celsius). Humidity should be between 40 to 60 percent.
Step 3: Water
Mist your seeds evenly with lukewarm water. You want to keep the soil moist (like a damp sponge), but not too wet. Typically, you want to mist once or twice a day.
When your tray gets too wet, you risk the chance of mold growing.
If you have a cover for your tray, you can place it on. This helps create a greenhouse effect, but this is optional.
Step 4: Harvest
If everything goes well, hopefully you’ll begin to see tiny greens shoot up in three to seven days.
Generally, microgreens are ready for harvesting when they are around two inches tall (5.1 centimeters). This often takes between one to two weeks. Some prefer to let their microgreens grow longer, depending on the variety, up to four or five weeks.
To harvest, you can use a pair of clean scissors, or a sharp knife. Trim just above the soil line and you’re done!
Step 5: Storing your microgreens
The best time to harvest microgreens is right before you plan to use them. Trim, give them a quick rinse in a colander, and you’re good to go!
If you plan on harvesting an entire tray or more, place microgreens in the fridge. First wet a clean paper towel with a bit of water and wrap around the microgreens. Then place the microgreens in a container in the fridge for three to five days.
Common questions about microgreens
Here are answers to some common FAQs about microgreens:
Do microgreens regrow after cutting?
Sadly, no. Microgreens do not regrow after they are harvested at the base of the stem. The good news however is that you don’t need to harvest all the microgreens in a growing tray all at once. Since they are densely sown, you can harvest microgreens over a period of several days so you can enjoy super-fresh greens each time.
Do microgreens need direct sunlight?
Yes, microgreens need a good source of light for at least four hours a day, preferably more (between four to eight hours). Sometimes when placed on a windowsill, microgreens tend to grow towards the sunlight leaving you with slightly bent stems. No biggie, really.
However if you prefer straight-growing stems you’ll need to get proper grow lights. You can experiment with different kinds of lights and lighting setups, but with standard size grow trays (10-inch by 20-inch) placed four-in-a-row, you’ll want to have a light source that equally covers all trays. If you have something smaller, such as a 17-inch grow light you’ll need to rotate the trays to ensure they all get enough light.
You’ll know if your microgreens aren’t getting enough light when they start to look leggy and slumped over.
Are there any types of microgreens that I shouldn’t grow?
Yes, not all seeds are suitable as microgreens. While fine to eat when mature, plants that belong to the nightshade family should not be eaten as young shoots (nor as sprouts) because they are poisonous. They contain solanine and tropanes which can cause digestive problems. This includes plants such as tomatoes, potatoes, peppers, eggplant, and goji.
Other microgreens such as alfalfa and buckwheat are safe to eat, but when eaten in larger quantities, may result in an upset stomach.
Don't grow seeds of plants that belong to the nightshade family as microgreens. Their young shoots and sprouts are NOT safe to eat.
Growing microgreens indoors for profit?
Interested in starting a side hustle? Growing microgreens indoors for profit is not as crazy as it sounds. If you think about it, microgreens are the perfect type of plant to grow—short grow times, high density, high yield all in a small amount of space.
Of course to turn your homegrown operation into a profitable one takes a bit of work, and a small investment in proper grow lights. But once that’s set up, you can test the waters by talking to local restaurants and farmer’s markets.