Coir: Everything you need to know

Nick Moyle and Rich Hood 15 March 2021

Gardeners are rejecting the use of peat-based compost in ever greater numbers, concerned about the damage to the ecosystem caused by removing it from natural peat bogs that have built up over centuries, trapping carbon deep underground. Among the more environmentally friendly alternatives, coir is gaining popularity. But what exactly is it?

What is coir?

Coir, also known as coconut peat, is a sustainable growing medium made from the husks of coconuts. 

As coconuts are harvested for their milky, nutty flesh, these husks are a natural by-product put to good use through a process that’s much more sustainable than excavating peat.

 

How is it processed?

To prepare the husks they’re cured, washed and de-fibred before being dried and packaged for the gardener. When choosing a coir, it’s advisable to look for products that are salt-free—some producers soak their coir in local rivers and it’s best to avoid getting salt into your garden. 

For increased environmental benefits try to use coir that has been sun dried. The alternative, machine drying, not only uses more energy but can also produce dust which makes the coir less effective.

 

How does coir work in the garden?

Before using your coconut peat, you need to rehydrate it by adding water and letting it soak in. You’ll tend to find that you need around 5 litres of water for every 1kg of coir. Give it a mix to make sure all the water is distributed evenly, and the resulting compost is ready. It even has a similar look to garden compost. 

Much like peat, coir is great at retaining water (you’ll actually need to do less watering than peat), is good for aeration (those dust-laden coirs aren’t as successful in the aeration department) and can be mixed with another compost or used on its own. It doesn’t break down like other composts which means you’ll reap the benefits for a long time.

 

What about nutritional benefits?

Unlike traditional compost, coir doesn’t contain nutrients, so you need to add these using homemade or shop bought feeds. The advantage of this is that you can add nutrients that will be of specific benefit to the plants you want to grow.  

We have found that coir is brilliant in containers and raised beds (for the latter we mix it with our own compost). Its water-retaining abilities mean our watering can is less busy and, by targeting specific nutrients to the plants, we’ve had some great vegetable growing successes with it. We’ve also used it in a wildflower border, with plants that are less concerned about a constant supply of nutrients and have been rewarded with stunning displays of colour from spring to autumn with barely any effort on our part.

So, if you’re keen to ditch the peat for a more sustainable alternative then coconut coir is a growing medium that’s well worth consideration.

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