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Get Started With Coco Coir in Your Garden

Welcome to another entry in the soil and compost section of the DIY Gardening website!

Coconut coir, also known as coco coir or coco peat, is fast becoming one of the most popular growing mediums in the UK and for a good reason, but if you’re new to using coir in your garden, check out our guide to the seven things you need to know before you start.

What is Coco Coir?

Coco coir is a by-product of the coconut industry and is made from the husk, which traditionally was discarded as a waste product of little value.

The coir is a fibrous material which can be used by gardeners as a growing medium as it’s similar to peat but is far more environmentally friendly.

Coco coir and compost

How is Coconut Coir Made?

The process of turning coconut husks into coir is long and involves soaking the material in either fresh or saltwater for months to loosen it from the coconut shell.

Good quality manufacturers then wash the coir to remove any salt, treat it to kill off any bacteria, so it’s as inert as possible with a neutral pH.

The coir is then dried, packed and shipped.

Gardeners buy coir in dry, compressed bricks which are lightweight but they will need to hydrate it with water to reconstitute it before using it in the garden.

Once hydrated the coir is ready for use in gardens, pots and hydroponic setups.

7 Things Every Gardener Should Know Before They Start With Coco Coir

Here’s our guide to getting started with coco coir in your garden:

1) Coco Coir Has No Nutritional Value

Many gardeners seem surprised when they first realise that coco coir has no nutritional value whatsoever and that it won’t feed their plants.

Coco coir can still be an excellent product to grow plants in, and if used correctly, your plants will develop strong roots that will maximise the number of nutrients the plant can uptake from other sources.

Coco coir in hand

2) You’ll Need to Add Nutrients.

As coco coir has no nutrients in it, you’ll need to your own, and you have a few options:

  • Add compost – a simple and easy step that will provide nutrients for well over a month.
  • Add wormcasts, manure or similar.
  • Add slow-release fertiliser pellets.
  • Add quick-release fertiliser dissolved in water.

Think of coco coir has a base material where you can then customise the nutrients specifically for the plants you intend to grow. The coir retains nutrients very well, so once added, they won’t just flush out with every watering.

3) It Can be Very Forgiving to Over or Underwatering

Coir is well known for its water-retaining properties; it can hold moisture well without the material becoming clogged, it also remains very well aerated, even after heavy watering. That means the roots of your plants have access to moisture but are unlikely to rot due to overwatering.

You might be surprised to know that coir holds between 8 and 10 times its volume in water.

For less attentive or busy gardeners, coco coir is very forgiving to overwatering, underwatering and even irregular watering.

We try to think of coco coir as an excellent moisture regulator, while the surface may appear dry, it takes a long time for the coir in pots and baskets to fully dry out.

Coconut waste products can be used to make many dozens of different items, from hanging basket liners to doormats, rope and even animal bedding material.

However, as the coconuts are grown close to the sea and usually soaked in seawater as part of the manufacturing process, coco coir may have a high salt content. Salt can be detrimental to plant growth and can block plants from uptaking calcium, magnesium and iron.

Good quality manufacturers should thoroughly flush the coco coir. If gardeners wish to use it as a growing medium, it should also be treated with a calcium, magnesium and iron solution, so the salts don’t create nutrient deficiencies in the plants, this process is called buffering.

For plants sensitive to iron, magnesium and calcium deficiencies, we recommend Canna Coir, it’s more expensive than some other brands but is a professional grade product that’s also popular with commercial cannabis growers.

Our first experience of using coco coir was with a cheap brand and led to iron and calcium deficiencies in our long trailing petunia plants and also a high pH number which we discovered after testing the soil.

After correcting the coir with some additives, our plants went from strength to strength and have significantly outgrown the petunias we grew in regular compost.

If you want to flush and buffer the coir yourself, go with any brand but if you’re just starting out, try a trusted name like Canna:

canna coco coir

Canna coco coir is:

  • Treated for bacteria and viruses.
  • Fully buffered, eliminating the side effects of growing in coco coir.
  • Pure and organic, better for the environment than peat.
  • Professional grade.
  • Perfect as a base for mixes including compost and organic matter.

5) It Will Breakdown and Degrade – Eventually

Coco coir is 100% organic but is long-lasting and takes years to degrade and breakdown in the soil.

If you’re using coco coir on its own, you can reuse it the following year.

Mixing coir with composts and organic matter for pots, hanging baskets and containers? Just dig the waste material into your flower beds at the end of the season, it will help aerate the soil and won’t cause any issues whatsoever.

6) It Works Great With Perlite, Grit and Vermiculite

Perlite and vermiculite are minerals that absorb and slowly release moisture, they also create air pockets when added to a potting mix.

Used with coir, they improve moisture control and aeration even further.

The end result? With the correct nutrients, you can expect the roots to grow in near-perfect ground conditions; moist but never saturated media, plenty of aeration with no compaction or issues with lack of oxygen. Also, coir absorbs and holds onto the added nutrients.

Horticultural grit is often found in potting mixes for seeds, seedlings and cuttings as it helps to aerate the mix, making it easier for the young roots grow. 

You can add grit to coir, along with perlite, vermiculite and organic material, together they make a great potting mix for containers and baskets.

Perlite bag

Perlite is:

  • Perfect for adding aeration to soils and potting mixes.
  • Retains moisture so keeps the soil moist but not waterlogged.
  • Harmless and safe to use.
  • Can be used with coco coir, vermiculite, grit and fertilisers.
  • Often in potting mixes for seeds, seedlings and cuttings.

7) Coir is an Eco-Friendly Alternative to Peat

Gardeners have been using peat as a growing medium for years, but the process of digging up peat bogs produces considerable amounts of CO2.

Read more: The Guardian on peat and the environment.

Coco coir is an environmentally friendly alternative that growers can use in gardens and hydroponics. You do, however, need to be aware of potential issues with high salt/potassium content blocking the uptake of iron/calcium and magnesium in some plants.

Suggested Potting Mix

The following mix would be perfect for hanging baskets or window boxes and is a good starting point for anyone looking to use coco coir for the first time:

  • 50% coco coir.
  • 30% nutrient-rich material, ie compost, manure, worm castings or a mixture of these.
  • 20% perlite, vermiculite and horticultural grit.
  • Slow-release fertiliser pellets.
  • Quick-release water-soluble fertiliser to top up as required.
  • Sequestered iron with magnesium which cures leaf yellowing (interveinal chlorosis) in line-hating plants.

See more of our suggested potting mixes here.

EXPLORE MORE OF OUR CONTENT BELOW:

“Our Plants” Section

The “Our Plants” corner of our site contains everything you need to know about the plants the DIY Gardening team is currently growing in our gardens. Start here

Our Soil and Compost Guide

Discover why so many gardeners in the UK are now ditching peat and using coconut coir as an eco-friendly alternative instead. Start here

Inspiration and Ideas

From garden edging & fast-growing shrubs to hedges for privacy & garden plants that produce beautiful winter colour. Explore our ideas & inspiration corner. Start here

This guide to using coconut coir was created by the team here at DIY Gardening

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