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.
Uses for Coconut Coir
Coconut coir is processed in three forms, each with different uses.
- Coconut fiber: Course strands that can be used to improve aeration in potting mixes, or used as a mulch to help insulate plants.
- Coconut chips: Chunky pieces that provide good drainage, commonly used as an orchid growing medium
- Coconut peat: Fine textured, excellent for moisture retention. Usually compressed into bricks that need to be re-hydrated. Can be used as a seed starting mix, or to grow microgreens.
How to Prepare Coconut 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 wheelbarrow, tub or a five gallon bucket. Place the coir 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.
Using Coconut Coir as a Seed Starting Mix
Starting seeds indoors in trays requires a lightweight, well draining medium that retains moisture without becoming soggy. Coconut coir is light and fluffy with excellent moisture retention. It is sterile and free from pests, fungi, and harmful pathogens. Coconut coir has a neutral Ph, unlike peat moss which is acidic, making it suitable for most plants. The only drawback to using coir for seed starting is that it lacks nutrients. So it is essential to use a water soluble fertilizer when watering.
After hydrating the Coconut coir I like to mix in vermiculite to help retain moisture and improve aeration.
What is vermiculite? Vermiculite is a natural mineral that expands when heated, forming lightweight absorbent granules, which helps retain moisture and distribute water evenly. It also prevents the mix from becoming compacted, improving aeration.
How much vermiculite should be added? It is about a 2:1 ratio of Coconut coir to vermiculite, but I like to just eyeball it and add vermiculite until it looks like regular potting soil. Mix it in with your hands.
Now The Coconut coir is ready to be used as a seed starting mix. Check out my how to start seeds indoors post.
The Importance of Fertilization
Coconut coir is nearly devoid of nutrients, so seedlings will need feeding as soon as their first true leaves appear.
- Use a diluted water soluble fertilizer. Using a one gallon spray bottle mix the fertilizer, following the instructions on the label, with water. Shake it up and spray at the base of the plants.
- Start feeding after the first true leaves appear. The initial sprouting leaves contain stored nutrients, but once true leaves develop seedlings will need an external food source.
- Fertilize regularly. Monitor your plants, because every plant species is different and will have different needs, but fertilizing once a week should be sufficient for most plants.
Coconut Coir for Microgreens
Coconut coir is also great for growing microgreens. Since microgreens are harvested before any true leaves develop, there is no need to fertilize. Also there is no need to add vermiculite. Just hydrate the coir and fill a shallow 5 x 5 or 10 x 10 tray, sprinkle the seeds evenly and mist with water. Add a dome to the tray until the microgreens have sprouted. Remove the dome after the greens have sprouted and watch them grow until they reach one to two inches in height, and harvest.
Coconut coir bricks are an excellent sustainable choice for staring seeds. With the right prep, hydrating, mixing with vermiculite, and adding fertilizer, you can create a seed starting mix that encourages strong, healthy seedlings.
If you haven’t tried using Coconut coir for seed starting yet, give it a shot! It’s lightweight, retains moisture beautifully, and provides an excellent foundation for young plants. Remember, gardening is about experimenting and having fun!
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