Coconut coir is a natural fiber derived from the husks of coconut. As a by-product of the coconut industry, coir is a sustainable, biodegradable alternative to peat moss. Coir has excellent water retention, and at the same time is well draining, making it the perfect medium on which to grow microgreens.
How to Prepare the Coir Bricks
Coconut coir is sold in compressed bricks, making it easier to store and transport. It needs to be re-hydrated and broken apart before using it.
- You’ll need a large container like a five gallon bucket, or I used an 8-quart stainless steel bowl, and place the brick in the container.
- Add warm to hot water. You can add boiling water if you want to sterilize it, but I don’t think it’s necessary. Slowly pour in about 4-5 times the bricks weight in water, which if you are using a 1.4 pound brick, it works out to about 3/4 of a gallon of water. But you don’t have to be super exact with this. Just slowly add the water while breaking up the coir with your hands ( It feels cool ). Then add water little by little until the coir clumps together, but is not drippy, soggy wet. If you do end up adding too much water, which I have definitely done, simply take some coir out of your container and squeeze out some of the water, and mix it back in until you get a nice consistency. It should clump together and stay together when you pack it with your hands.
- Coconut coir is devoid of nutrients, so it is beneficial to add some organic matter. I like to add earthworm castings to give the coir a boost of nitrogen, which helps plants grow green leaves. Add about 20% by volume of the earthworm castings to the Coconut coir. Just eyeball it, until you think it is about 20%. It doesn’t have to be exact. Then thoroughly mix it in with your hands until the coir is a nice rich black color.
Using Coconut Coir for Microgreens
Now the coir is prepared and ready to be used to grow delicious, healthy microgreens.
- Get a small container, like a 5 x 5 inch tray or a 10 x 10 inch tray, or reuse a plastic berry container or a greens cloche, and fill with the coir. I like the berry containers because they have a lid that can be snapped into place which will help hold in the moisture, and they have slots in the bottom which act as drainage holes.
- Grab whatever seed you’re using such as: Arugula, beet, cilantro, red clover etc, and sprinkle a generous amount of seed on top of the coir mixture. Lightly press the seeds onto the coir so that they make good contact.
- Now cover the seeds with another 5 x 5 or 10 x 10 tray to keep the moisture in and the light out. Or if you’re reusing a berry container, snap the lid in place and cover with a plate or a piece of aluminum foil to keep the light out until the seeds have sprouted.
- I have found it beneficial to have a heat mat and a grow light so I can control the light and temperature. I put the microgreens container in a seed starting tray on top of a heat mat and wait for germination.
- Once the seeds have sprouted it’s time to remove the cover and expose the seedlings to light. Using a grow light will help with providing the microgreens with consistent light. Now just sit back and watch the greens grow!
- Check for moisture, and lightly water as needed. A small spray bottle for misting can help to gently water.
- Microgreens are usually harvested once they reach about 1 to 3 inches tall. Simply grab the microgreens with one hand and cut with a serrated knife or kitchen scissors and enjoy immediately. Microgreens don’t last that long so it is best to consume right after harvest.
Coconut coir bricks are an excellent, sustainable choice for growing your own microgreens. With the right preparation: hydrating, mixing with earthworm castings, you can grow beautiful, delicious microgreens to keep you and your family happy and healthy.
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