A guide to managing coco coir nutrient and pH levels

In recent years, there has been increasing attention paid to the environment and climate change – and the need to reverse and slow down the damage being caused.

This is happening across all walks of life and the horticultural industry is no different. In fact, it is one of the industries making major changes to products that are used by customers, who range from large-scale growers to gardening enthusiasts at home.

The use of coco coir in soil mixes, instead of using peat, is one of these changes and is going to become more commonplace due to damage caused to peat landscapes around the world.

Defra calculated nearly three million cubic metres of peat are sold for horticultural use every year in the UK, one third of which comes from UK peatlands. The main users are amateur gardeners (66 percent), followed by industry (34 percent).

Nutrients
So, as coco coir and other substitutes are becoming more popular as sustainable and viable alternatives to peat-based composts, this article takes a look at the nutrients and PH levels in coco coir and how to get the best out of it for a grower's needs.

Does coco coir have nutrients?
The nutritional makeup of coco coir is likely to be quite different from products you have used before so there are a few things to take note of before you get to work in your glasshouses in order to get the most from your plants.

There is not an over-riding nutrient present in coco-coir and its pH level is generally quite stable. It does, however, err more to the acidic side of neutral but, on the plus side, is unlikely to change. The benefit of this is that deciding what nutrients to feed plants is easier and can be driven by what crop you are growing and what it best needs to thrive.

It is worth noting that coco coir can have higher than desired levels of sodium nitrate and chlorine, which, if not managed correctly are harmful to plant-life.

This can be counteracted with a buffering process. At Botanicoir, we provide pre-treated coco coir, which saves you having to regulate it on site. We wash the coir first and remove 30-35 per cent of salt in the substrate.

If needed, a further buffering process can take salt levels down to almost zero, but we can tailor the process to create the optimum environment for your crops and a product that is instantly ready to work with.

Coco coir also has higher amounts of natural phosphorus and potassium. These are good qualities to have as phosphorus is essential for the development of roots and flowering, while potassium regulates plant metabolism and water pressure surrounding the plant cells.

Adding nutrients to coco coir
It is likely that you will need to add some nutrients to coco-coir due to it having a more consistent pH level compared to other growing mixes.

However, as it is a stable product, the level of nutrients you are trying to counteract will be lower so a degree of "guesswork" has been removed and you can concentrate adding whatever is best for your particular crop.

Best nutrients for coco coir
If you were to add nutrients to coco-coir, calcium and magnesium products are a good starting point to avoid an imbalance.

Coco coir has a good cation exchange capacity, so is adept at holding onto nutrients with positively charged ions, such as potassium, but this is at the expense of others, like calcium and magnesium.

Iron is worth adding for similar reasons and nitrogen will need to be added depending upon the levels of natural light your crops are getting.

pH levels
It is not just nutrition in the soil that you need to think about when considering how to get the best out of your growing projects. The pH level of the substrate you are using, and the ground that you are working with, is also crucial to the results that you will get.

For growers, understanding the pH of the growing medium is critical and, if the information isn't available, it is worth investing in professional lab analysis to guarantee the accurate and precise results you need to optimize crop production.

What is the pH of coco coir?
A pH test measures soil acidity or alkalinity. A pH of 7.0 is considered neutral. An acid soil has a pH value below 7.0 and a pH result above 7.0 means the soil is alkaline.

When it comes to coco coir, the pH level ranges between 5.8 and 6.5 which puts it on the more acidic side and may mean you need to adjust the pH levels.

How to adjust pH levels in coco-coir?
One of the benefits of using coco coir is that it is a relatively stable product and maintains its pH level, even if it is on the more acidic side of the neutrality scale. However, several factors can influence a product's pH level.

Firstly, the quality of the water you use on coco coir can affect its pH level, so it is worth testing that before you use it. Secondly, the pH of coco coir will be affected by the type of fertilisers, so it is necessary to check that pH levels remain within the range required when using such products. And, thirdly, buffering agents, which help to regulate the pH balance, may become less effective over time due to watering and fertiliser use so it is worth bearing in mind products which can bring the pH level back within the desired range.

If you need to adjust the pH levels in coco coir you can do this by adding or removing its acid or alkaline qualities. To lower the pH you can add an acidic solution, such as sulphuric acid or phosphoric acid. Use a small amount at first and then re-test to avoid moving the pH pendulum too far. Likewise, if you need to raise pH levels, add an alkaline solution, usually found with potassium hydroxide or calcium carbonate rich products.

Best pH for coco-coir
There are varying recommendations as to the best pH for coco coir and we recommend you aim between 5.8 and 6.5. At that range, it has a score that lends itself to being suitable as a growing base for most types of plants.

Coco coir has higher levels of sodium nitrate and chlorine and higher amounts of natural phosphorus and potassium than other growing mediums, along with lower levels of nutrients such as carbon, magnesium and iron.

The product requires nutrients adding to ensure you get optimum results and also has a pH level that may need adjusting as it tends to sit on the acidic side of neutral.

However, in the UK alone, only around 20 per cent of peatlands remain in a near-natural state, and, world-wide it has been calculated that more than ten per cent of the 500m hectares of peatlands have been drained.

The awareness around the need to protect peat stocks is growing, as well as the need to source sustainable alternatives, making coco coir a commodity that is set to gain in popularity and demand over the coming years.