How to Grow Microgreens Without Soil

by Bethany Hayes

Microgreens are a new, popular gardening trend that quickly grows smaller baby plants, harvested in their second stage of growth. It’s easy to grow them; it’s possible to learn how to grow microgreens without soil. 

That’s right; growing microgreens without soil or hydroponically is possible using two methods. Both ways have pros and cons. Using hydroponic gardening allows you to grow plants, including microgreens, without soil. Instead, gardeners use growing mediums, such as Rockwool, coco peat, perlite, sand, and other options. 

Let’s look at how to grow microgreens without soil. 

4 Reasons Why You Should Grow Microgreens Hydroponically

Most people opt to grow microgreens with soil, so why would you use the hydroponic method instead? Here are some benefits to consider. 

1. Year-Round Growth

Hydroponic gardening works well indoors, allowing you to grow microgreens year-round instead of depending on warm weather. 

2. Maximizes Space

Using this route to grow microgreens requires less space so that you can grow more in less space. These types of setups grow anywhere – basements, garages, shelves, or wherever you want!

3. Uses Less Water

It might seem contradictory that hydroponics requires less water, but you can re-use the water in your system. So, on average, growing without soil means that you use 20% less water than growing in soil. 

4. Easier with Less Mess

Hydroponic gardening is, in general, easier with less mess. Some people use their countertops in the kitchen! Also, since you don’t need to dispose of your soil, there is no need to track dirt throughout your house, accidentally spilling it on your floor. 

What You Need to Grow Microgreens Without Soil 

Before you get started, you need to know what supplies are required to grow microgreens. Growing microgreens using hydroponics means that you’re growing them in an aquatic-based environment. The only nutrients and oxygen received come from the water instead of the soil. 

1. Seeds

One of the first things that you need to do is buy seeds to grow microgreens. There are many different sources for these seeds but look for seeds specifically for microgreens to ensure it hasn’t been treated with pesticides. 

2. Growing Medium

Even if you aren’t using soil, you need some sort of medium to hold the seeds in place as they sprout. Mediums are known as substrates, and they provide support for your roots in the hydroponic system. There are many different possibilities to consider. A few options include:

• Coconut Coir

Many people select coconut coir because it’s a cheap option. It has to be prepared ahead of time. Typically, that requires putting the coconut coir in a bucket and adding water to the bucket. Stir and mix it well, then wait for an hour before draining it out. 

• Vermiculite

Another option is vermiculite because it’s affordable, made from a natural mineral, lightweight, and sterile. It’s known for its water retention ability. Sometimes, it’s mixed with perlite to prevent the medium from becoming waterlogged.

• Clay Pebbles

These clay pellets are fired into a kiln, expanding and becoming porous when exposed to water. These retain moisture well and provide plenty of air circulation to the roots of the seeds. You also can clean and use them again and again. 

• Hemp Growing Mats

Another great option is hemp growing mats. These are easier to use and less messy, but they cost more money. 

3. Growing Trays

You need a tray or two for growing microgreens. You can use any sort of tray that you might have in your home, but it should be around 1.5 to 2 inches deep and about 20 inches long or more. 

If you buy a tray for growing microgreens without soil, make sure you find trays meant for hydroponic gardening because they don’t have any holes. 

4. Growing Lights

At first, the seeds need to germinate, and at that point, you don’t need lights. After 4-5 days, you need growing lights to start the photosynthesis process. Consider buying LED grow lights or direct sunlight if you have a south-facing window

5. pH Testing Kits 

When you grow microgreens hydroponically, your water’s pH range affects your plants’ growth and health. It’s best to keep your water around the pH range of six, but you need pH testing kits to be sure that it is in the appropriate range. 

6. Nutrients or Fertilizers

Remember, all of the nutrients come from the water rather than the soil. It’s recommended that you use nutrients designed for hydroponic gardening. If you can find nutrients or fertilizer for hydroponic microgreens, that’s even better. 

7. Spray Bottle

It’s best to buy a new spray bottle to use to water your plants. A used bottle might contain dangerous chemicals. 

How to Grow Microgreens Without Soil 

Now that you have the supplies needed for growing microgreens without soil, here are the next steps. 

1. Prepare Your Water

Since hydroponics revolves around water, the quality of the water that you use matters. Distilled water or rainwater is best; tap water is usable, but it’s recommended to let it sit for 24 hours or boiling it to remove chlorine. 

Test your water using the pH kit and adjust accordingly. Add wood ash or lime to raise the pH range, or use phosphoric acid to lower the pH. This is when you should add nutrients as well. Then, fill your spray bottle. 

2. Fill the Trays

The first thing we have to do is prepare the growing medium in the trays. Coconut coir needs to be prepared ahead of time, but no matter what you opt to use, spread it evenly throughout the tray. It should be one inch deep evenly across the entire tray. 

It only takes one mat per tray; do not double them up because they don’t look thick enough. 

3. Plant the Seeds

Now, look at the package of seeds and read the instructions. Typically, you take two to three tablespoons of seeds and spread them evenly across the tray and growing medium. Spreading evenly across the tray means that you make sure that there aren’t bare spots or large lumps of seeds in one place. 

These seeds don’t need too much space. It only takes a few weeks to harvest, so they don’t need tons of room to grow. You don’t need to space them as far apart as full-grown plants or even seedlings. 

4. Keep Them Moist 

After spreading the seeds across the growing medium, keep them moist with a spray bottle. Keep the tray covered, which keeps the medium moist, or keep them in the dark area. 

5. Germinate the Seeds 

It takes 3-4 days for the seeds to germinate if you keep them warm around 70℉. During those days, keep the tray dark and warm while ensuring there is air circulation because mold grows without airflow. 

Make sure you keep the soil tray moist, spraying it every 12 hours or so. It’s essential to use the pH water created in step one. Within a few days, germination begins, and the seeds sprout, which is when you move to the next step. 

6. Put Them Under Grow Lights 

Now it’s time to put the trays under the grow lights. You no longer need to mist and spray the seeds. Instead, don’t water the microgreens directly. Instead, pour a cup of water into the tray and then, after 10-20 minutes, remove the extra water from the tray. This method is called the dry and soak method. 

You must do this every day without fail until it’s time to harvest the microgreens. 

7. Wait and Harvest 

It takes up to two weeks after germination for microgreens to grow. Until that time, continue the dry and soak method. 

You know it’s time to harvest when the first set of true leaves appear. That’s the ideal time for harvesting microgreens. Use a pair of sharp scissors and cut the microgreens; you don’t want to cut the roots, just the stems. 

It’s best to use them the same day as harvesting. The nutritional value and freshness start to decrease each day after harvesting. 

Final Thoughts

Learning how to grow microgreens without soil is excellent for new gardeners and those new to growing microgreens. It requires a small investment compared to in-ground gardening or soil-based microgreen growing. Give it a try and see if you like growing microgreens hydroponically.