How to Grow Microgreens Without Soil

I love growing microgreens on a kitchen windowsill where I can check on them, water often, and marvel at the tiny seeds. But I also don’t want soil in my kitchen (at least as little as possible). Luckily, it is possible to grow microgreens without soil – in other words, hydroponically. This makes growing microgreens easy, fuss-free, and largely mess-free. 

Don’t let the phrase hydroponic scare you. There is nothing technical or complicated about the process, especially if you invest in the right equipment. Follow these steps to grow microgreens without soil at any time of the year.

Step 1: Choose Your Growing Material

When choosing your hydroponic growing medium, any non-soil materials that can hold moisture and small seeds will work. It’s more about convenience or what you have on hand. Some materials are easier to work with than others, so choose one that suits your needs best. 

Vermiculite and Perlite

Vermiculite and perlite are lightweight natural minerals often used to increase drainage in potting mixes and improve aeration. But, they can also be used on their own as a soil substitute. 

For growing microgreens, vermiculite and perlite hold some moisture and nutrients, acting like soil without the mess. 

Biodegradable Mats

Biodegradable mats – usually made from coconut coir, hemp, bamboo, wool, wood, or jute – are available in sheets. These can be cut to fit your tray or container exactly. 

They provide a clean and sustainable growing medium for microgreens. These materials hold water and nutrients, allowing the seeds to grow easily on their bumpy surface. They are made specifically for single use and will break down over time.

Fabric

Fabrics like quilt batting or felt can also be used as a growing mat. This is an unusual option, but trust me – it works. 

Fabric can be cut to size and, like biodegradable mats, is a clean way to grow microgreens. The fabric is absorbent, allowing water and nutrients to be stored and released to the seeds when needed.

Others

Alternative substances like paper towels, cotton wool, and sponges are all useful for growing microgreens without soil when you have nothing else to use as a growing medium.

Step 2: Choose a Container

Trays with about an inch of lip around the edge are ideal for growing microgreens without soil. However, they must include drainage holes to allow water to escape. Otherwise, you risk drowning your tiny plants.

If aesthetics are a concern when growing indoors, surround your tray with something decorative, like a wooden box or ceramic planter. Remember to remove the inner tray to water your microgreens before placing it back to manage drainage.

Step 3: Choose Your Seed

Each seed you choose has a different flavor from the mature versions of the plants. 

There is some resemblance, especially in strongly-flavored vegetables like beetroot, but not so much with subtle herbs like parsley and sage. They have a mild flavor as microgreens, as the stronger flavors develop later. Mix and match subtle flavors with stronger ones to cover all uses.

I like mixing different types of seed together before sowing. This provides a unique combination of flavors, much like crafting a new recipe in the kitchen.

You can also sow one type of seed for more of one flavor. Or, sow each variety in rows so you can pick and choose what to use on any given day. This is good for experimenting with combining flavors.

Any vegetable or herb seed can be made into microgreens. Some, like onions, have a strong flavor and must be used cautiously when mixed with other seeds, as they can overpower the flavor of other vegetables and herbs. 

Start with the flavors you would enjoy on a salad and choose seed from a reputable seed company for the best results. Here are some of our favorite blends to try:

Mild Mix Microgreen Seeds

A combination of veg and brassicas, such as beetroot, cabbage, kohlrabi, pak choi, and Swiss chard. Has a mild flavor and can be harvested five to ten days after sowing. This healthy vegetable confetti is packed with nutrients and color.

Mellow Blend Microgreen Seeds

Great for sandwiches and to get a green fix in the dead of winter. A mix of mustard, broccoli, kohlrabi, bok choy, and cabbage for a range of colors and textures. They have a 10-15-day maturity when the first leaves appear for harvesting.

Umami Asian Blend Microgreen Seeds

With savory and spicy notes, this blend has a special formula of seed ratios to get that tasty flavor we know as umami. 32% tatsoi bok choy, 32% pak choi, 16% ‘Red Giant’ mustard, 10% ‘Tokyo Bekana’ Chinese cabbage, and 10% ‘Red Streaked’ mizuna mustard make this unique blend a winner, ready in 10-15 days.

Ciao Bella Basil Blend Microgreens Seeds

This basil blend fits on any Italian menu. The basils chosen for this mix are ‘Genovese’ and ‘Dark Opal’, which contrast in color. This tasty combo is perfect for a tomato and mozzarella salad or a cheesy pizza. It is a traditional blend of subtle, fresh basil flavor and is ready for harvesting in 16-25 days.

Jazzy Mix Microgreens Seeds

This Jazzy mix has been carefully selected so the seed is ready to harvest at one to two inches simultaneously. It contains a mix of 30% mustard, 30% cress, 15% red cabbage, 15% ‘Red Giant’ mustard, and 10% radish. Together, they add a peppery bite to sandwiches, soups, and salads and are ready for harvest in 12-14 days.

Italian Amaro Blend Microgreens Seeds

For something different, try this blend of chicories: 60% Italian chicory, 20% curly endive, and 20% escarole. This bitter combo is perfect for balancing soft cheeses and is ready for harvesting in 15-25 days.

Step 4: Sowing the Seed

To sow the seed, sprinkle it evenly onto a dampened growing medium. In the case of vermiculite or perlite, press the seed into the mix lightly. Be careful when watering the first time, as the seed is not set into the substrate. It will be loose enough to bunch up with the force of the water, so it’s best to mist with a spray bottle instead.

You can add your seed to a powdered sugar shaker or duster with big enough holes for the seed to fit through to distribute the seed more evenly, or simply use your hands.

Germination times vary for each seed that you use. Some will be ready to harvest in 7 days, while others may take up to 21 days. Experiment with what works for you and play around with different seed types.

Step 5: Control the Environment

Choose a position with the best light exposure available indoors, or a sheltered position outdoors in part shade. When growing indoors, aim for at least 12-16 hours of bright light daily. 

This may be a challenge in winter. If so, invest in grow lights to grow the best microgreens, like the Small Epic Seed Starting Grow Light. This light has ultra-bright, full-spectrum LEDs engineered for perfect seedlings.

For the first week or so after sowing, cover with dark-colored material while the seeds germinate. After three to four days, remove the lid and move the container into the light.

The ideal temperature for germinating microgreens is between 65-75°F (18-24°C), close enough to the average temperature of most homes. Keep your seeds away from drafts, air conditioners, and radiators.

To keep humidity levels up, grow microgreens without soil in propagators or cover your seedlings to trap moisture. In dry climates, humidifiers are a better option.

Step 6: Keep Hydrated

How often you water will depend on the environment, medium, and container. Typically you’ll need to water around once per day, moistening the medium without drowning the microgreens  The watering will also transport any nutrients you add to keep the seedlings healthy.

Step 7: Feed

There is a surprising amount of life in the tiniest of seeds. But for strong growth early on, they benefit from a little help every one to two weeks. 

When you first dampen the growing mat or medium with water, include a diluted solution of all-purpose fertilizer or liquid plant food. Follow up when watering every couple of weeks or if they look like they need a perk up. 

They may need more as they grow up, as crowded microgreens fight for nutrients.

Step 8: Harvesting

Use a clean pair of scissors to cut the stems off microgreens when they are one to three inches tall or just before the first true leaves appear. Harvest as needed, but do not leave in the trays too long. They will start to get leggy and lose their fresh flavor.

To remove any seed shells, brush your hand over the top of them to loosen them before harvesting.

Once harvested, they can be kept in the refrigerator for a few days if necessary while you start a new batch. Do not wash the leaves initially as this will lessen their storage life. 

Step 9: Troubleshooting

There are a couple of important troubleshooting tips to know when it comes to growing microgreens without soil:

• Make sure there is enough air circulation around the trays. 
• Look for pests and diseases, especially at the bottom of the tray. If you see any signs of fungal diseases, often caused by bad air circulation, throw away the batch and start again.
• Keep up the watering. Microgreens are delicate and will wilt and die quickly at the first signs of stress. Keep a spray bottle on hand and water more than once a day if needed.

Final Thoughts

It takes so little effort to grow microgreens, but provides so much pleasure to see the little things growing. I encourage anyone to try it and make food more flavorful and nutrient-dense at the same time.