Finding the best growing medium for microgreens goes beyond just regular soil. Many soilless mixes offer better benefits for these tiny vegetables during their short lives. Some of them are:
- Coconut Coir
Read our article to find out more!
What Is Growing Medium?
Growing medium, or substrate, is the material used in the container for growing a plant. It’s essential when you grow microgreens without regular potting soil.
The growing media often blend different materials to produce the desired balance of water and air holding capacity. Such materials can be organic (like bark or peat) or inorganic (vermiculite, rockwool).
Other roles of these substrates include holding sufficient nutrients and providing anchorage for the roots.
These are some of the different growing mediums for microgreens:
Growing Medium For Microgreens
Organic Potting Soil
Regular microgreens soil is a popular substrate for most container or indoor gardeners. But it’s somewhat pointless if you mix this growing media with your organic microgreen seeds, which usually already require additional costs.
Organic soil puts to rest the concerns about synthetic fibers, fertilizers, and other harmful chemicals. This soil medium doesn’t contain pesticides or chemicals made from natural matter like manure, compost, worm castings, or bat guano.
While this microgreen growing medium has rising demand, especially from eco-conscious consumers, keep in mind that not all “organic” potting soil products are the same.
Even the USDA has different organic labels for various organic categories. Look closely at the ingredients of the potting soil before making the purchase.
Coconut coir has gained enormous popularity among container gardeners, especially microgreens and herbs.
This affordable and lightweight material is the coconut fiber between the seed inside and outside the fruit.
The fiber of coconuts has a similar texture to peat moss and soil, allowing each coconut coir mat for microgreens to hold a huge amount of water.
It’s usually available as compressed and dehydrated blocks that you can store before layering on your microgreen trays.
Hemp Growing Mats
These hemp mats are loosely woven fibers designed to distribute water evenly throughout the entire medium.
The hemp fiber’s unique moisture-retention ability reduces the time and effort spent on watering, while the excellent aeration of the hemp mats promotes healthy growth.
Moving your hemp microgreens out of a tray could be tricky as they tend to rip when wet.
Hydroponic Growing Mats
Produced from wood fibers, hydroponic growing mats have excellent water retention capacity, so gardeners don’t have to babysit the water level constantly.
They are free from small, grainy particles usually found on coconut coir or potting soil for microgreens that can end up in the vegetables even after washing.
This hydroponic growing medium, however, needs additional fertilizer as they come with low nutrient content.
BioStrate is a brand of felt textile made for hydroponic systems. This bio-based and compostable growing media can soak in a great amount of water, thanks to its thick biopolymers and natural fibers.
But as BioStrate mats also dry out quickly, they require careful monitoring of watering.
Exfoliated vermiculite is a natural mineral that can be used alongside other materials composted pine bark or peat as a soilless growing medium for home gardeners and professional horticulturalists.
These mixtures do a great job retaining moisture, plant food, and air and releasing them when necessary. They promote quicker root growth for microgreens and provide young roots with anchorage.
Hydroponics grow medium is also a typical application of vermiculite.
Made of natural materials, rockwool consists of no toxic chemicals, making it a safe substrate for microgreens.
This fibrous material drains excess water quickly, but a tiny amount of extra water is left at the bottom. This variation in moistures levels between the top and the bottom makes rockwool an ideal growing medium for hydroponics.
That said, the tiny, sharp fibers of rockwool need extra attention from gardeners as they could cause severe irritation to the lungs, eyes, and skin.
Like other peat substrates, peat moss forms from decaying mosses and other organic materials in peat bogs.
This dark brown fibrous material makes a lightweight growing medium with a remarkable ability to drain water.
Another highlight of peat moss, which makes it always an excellent choice for growing microgreens, is its sterile nature.
It has no weed seeds, harmful chemicals, fungus, or any bacteria. But compared to other organic materials, peat moss is largely devoid of nutrients.
Burlap doesn’t just make excellent fabric for plant containers and hanging baskets, but this eco-friendly material can be a growing medium for microgreens.
It can maintain an acceptable level of pH and anchor the roots of microgreens. With proper watering and fertilizer, gardeners can yield decent results from burlap similar to soil mixes.
You can come across many ready-to-use jute growing pads and mats on the market.
Made from jute plants, they are fully compostable and possess excellent water retention properties.
This natural fiber produces humic acid, helping the roots absorb more nutrients and water, making it a good option for growing microgreens hydroponically.
Tips For Growing Better Microgreens
- For consistent growth, don’t let the soil or growing medium dry out. Monitor and replenish the water regularly.
- Remove any weeds that can compete with your tiny greens for extra nutrients and water.
- Thanks to the short growing period, pests and diseases are rarely a big problem for microgreens. But you still need to pay close attention to spacing, humidity, air circulation, and temperature to prevent those threats.
- Place your microgreens where they can get three or four hours of sunlight a day. A south-facing window will be the best spot for growing them indoors.
- Use a higher seeding rate in the winter than in summer to maximize production while preventing disease and plant stretching.
This choice might not sound exciting, but it matters greatly when it comes to successful container gardening with microgreens.
Which material is the best growing medium for microgreens depends mostly on the plant and what it needs from the potting mix. It could also be a personal preference as some media need more maintenance than others.