Due to their quick growth rate, bright flavor, and interesting colors, microgreens have become popular in both home kitchens and restaurants. If you want to try growing them, you’re not alone. However, these tiny greens can use a lot of soil, since growers should replace material after each harvest. To eliminate the mess and cost associated with using soil, another option is to grow microgreens hydroponically.
Plants in hydroponic systems are grown using a nutrient solution and inert medium, and this holds true with microgreens. Whether you’re looking to produce a handful of radish greens for salads or trays of broccoli greens for a chef, hydroponics can help you grow these beautiful, tiny greens.
What are Microgreens?
Microgreens aren’t one species of plant, but rather plants that are harvested at a specific stage. Some microgreens are ready when only their cotyledons are present, and other types are harvested after the plant’s first true leaves appear.
Microgreens are closer to baby greens, as they are considered nutritious, just their stems and leaves. However, they are much smaller and can be sold before harvest, as opposed to baby greens.
Some common types of microgreens include sunflower, broccoli, amaranth, buckwheat, cress, and arugula.
Growing Hydroponic Microgreens
Growing microgreens hydroponically is easy to do, even if you don’t have prior experience with hydroponics.
Just like with other hydroponic crops, microgreens rely on a nutrient solution and soilless growing medium. The main difference with microgreens is the short growth period and number of seeds. Rather than growing one head of lettuce or one tomato plant, you’ll be growing hundreds of tiny greens.
No matter what specific hydroponic method you use, you’ll need the following items to get started.
• Microgreen seeds
• Nutrient solution
• Growing medium
Balance the pH of the water
Since water is such an important part of growing hydroponic microgreens, it’s crucial that the water you’re using has the correct pH. Most microgreens perform best in water with a pH of 6.0, so you might need to lower the pH of your tap water before adding it to your hydroponic system.
Provide proper lighting
Proper lighting assures that your microgreens receive the energy they need to grow. Lighting can be natural or provided via grow lights. LED shop lights are an inexpensive way to get started, but you can also use LED bar lights designed for plants. If you notice your microgreens are spindly and reaching for light — aka they’re leggy — you need to supply more light.
Adjust room temperature
Most microgreens germinate and grow best at a temperature of 70°F. If you’re trying to grow microgreens in a room with a colder temperature, you can place your growing tray on a heating mat to raise the temperature around the microgreens.
Select a quality nutrient solution
Although hydroponic microgreens can germinate and grow with just water, they will perform better if you supply a proper nutrient solution. Plants don’t need much phosphorus in their early stages of growth, so look for a fertilizer with an NPK ratio close to 4-1-4 or 6-1-5.
Growing Hydroponic Microgreens with a Tray and Pad
One popular way to produce these hydroponic microgreens is by using a growing tray and growing pad. These pads, made from organic materials such as hemp and coco coir, are made to fit precisely in the trays. The pads absorb the supplied nutrient solution, providing the seeds with the moisture they need to germinate and the microgreens with the nutrients they need to grow.
To get started with growing hydroponic microgreens with a tray and pad, follow these steps.
- Place the pad into the tray, and pour the nutrient solution over the pad. The pad should be saturated, but remain uncovered by the solution.
- Sprinkle seeds over the pad. You want the seeds to be densely packed, but not touching. For small seeds including arugula, kale, and mustard, use 1 oz per tray. For larger seeds such as sunflowers and peas, you’ll be using closer to 10 oz per tray.
- Use a spray bottle to mist the seeds with water to encourage germination.
- Cover the seeding tray with a blackout tray. This will provide the darkness and humidity seeds need to germinate.
- Check the pad and seeds every 12 hours. It’s essential to keep the seeds and pad moist. The simplest way to provide more nutrient solution is to manually pour more solution into the tray. You can also mechanize and automate your irrigation using a nutrient film technique or flood and drain system. We’ll cover more about the different systems below.
- After the seeds germinate, remove the blackout tray.
- Continue monitoring your pad to make sure it stays moist.
Once the microgreens are the proper size, it’s time to harvest! The harvest time varies depending on the species and environmental conditions, but the seed to harvest time for most microgreens is 7-10 days. Using a knife or pair of scissors, cut the greens off near their base.
Systems for Hydroponic Microgreens
When it comes to maintaining adequate moisture in your hydroponic microgreen system, you have a variety of options, just as you do when growing larger plants hydroponically.
Here are three common methods of growing microgreens hydroponically.
If you want to try your hand at growing microgreens hydroponically without purchasing much equipment, you can water your trays manually. When you notice one of your growing pads is drying out, lift up the pad while being careful not to damage the growing greens.
Use a cup to add more nutrient solution to the tray and then replace the pad. It’s important to note that you should avoid watering the top of the pad since this can lead to mold issues with your plants.
Flood and Drain
If you choose a flood and drain system, you’ll repeat a cycle of filling and then draining your trays. This method requires a reservoir to hold the solution as well as a pump to fill trays.
Nutrient Film Technique
Nutrient Film Technique (commonly known as the NFT) is a growing process in which all of the ingredients needed are dissolved, and microgreens are rooted in a deep-sea stream of recircling enriched nutrient water. No strong root medium is available.
This system relies on a constantly flowing stream of nutrient solution. It can be used with the tray and pad system mentioned above or with larger troughs that can accommodate more microgreens. Like the flood and drain system, this method also requires a pump and a reservoir.
Get Started Growing Hydroponic Microgreens
Now that you know the basics of growing hydroponic microgreens, it’s time to get started. With a short seed to harvest period, you’ll see the results of your efforts in less than a month. And since hydroponic microgreens can be grown anywhere, everyone can try growing these baby greens.