Peat-free compost: how does it compare?

Melody Rousseau

Peat is a popular ingredient in commercially produced compost, but British bogs are at an all time low, depleting far faster than they can replenish themselves. So what are the alternatives?

Saga caught up with TV gardener Chris Beardshaw at Notcutts in Surrey, where he was teaching gardeners how to use different types of compost effectively, as well as encouraging gardeners to start using peat-free and reduced peat compost containing recycled green material.

Chris, why shouldn't we use peat?

We don't need to use peat for 90 per cent of what we grow. Historically, we used peat because of its properties. When you're putting compost together, peat is very good at holding water and retaining nutrients. Peat blended together with fertiliser and mineral particles became what's known as 'potting compost'. In the past, we weren't aware of the issues surrounding peat extraction and use, so it wasn't necessary to look for alternatives.

I think the most important thing is that as gardeners, we recognise that not only are we trying to make beautiful gardens, but that also being more in tune with what's going on in the environment than a lot of other professions, we should be aware that if you extract huge quantities of a sensitive product it is going to have a knock-on effect.

Despite what some people may say, peat will only regenerate itself at a rate of five millimetres a year in a good peat bog, and the extraction rate is significantly higher than that.

The traditional argument is that horticulture uses a very small proportion of the peat that is extracted throughout the British Isles, with the vast proportion being used as a power source in power stations. That's not an excuse for using it in the garden. People will also claim that it's OK to use peat because there are plenty of resources in America and Russia. However, we can't just pretend that we can distance ourselves, just because it happens to be extracted from another country. We need to be sensible and sensitive in equal measure.

How do reduced-peat and peat-free products compare with peat-based ones?

I've tried peat-reduced compost and peat-replacement compost, and I've grown plants for show gardens with them.

The most important thing for people to recognise is that it does require a different approach by gardeners. If you use a peat-based product and a peat-free product side by side in exactly the same conditions, the peat-based one will outperform the peat-free one.

However, if you, as a sensitive gardener, are prepared to modify what you do, then you can get the same, or a better, performance out of them as a peat-based product. It just comes down to basic things like watering and feeding.

What is the best approach to working with peat-free products?

With a peat-free or peat-reduced product, you tend to find that they retain water better than a peat product. That can be great during the summer months but, of course, in the winter that can cause a lot of plants serious problems and they become very sensitive to the excess moisture. You have to reduce the amount of water that you put on and you may have to mix grit and sharp sand with the peat-free and peat-reduced product, to create ideal drainage and water retention properties in the product.

In the summer, when you're watering pots of bedding plants and pots of tomatoes and aubergines, what we found worked best was watering little and often. Apply the same total quantity of water but water over a longer period, so that instead of the 'drought and deluge' that you traditionally went for with peat, what you have is more of a trickle supply with a peat-free product. That does the job.

The same is true of nutrients. The peat-free product tends not to hold onto nutrients very well. So what we do is apply the same type and quantity of nutrient but over a longer period. Instead of feeding once a week, feed twice a week with 50 per cent of the quantity. That's how we managed to get the peat-free products to work for us. It's a change of mentality and a change of approach which is required.

That's why I'm working with The Know Your Compost Campaign, because there's a breed of gardener out there who says you can't use a peat-free product. What we're saying is, you can use a peat-free product. In most circumstances it performs just as well, it's just that as gardeners we have to get our heads around what it is, what properties a peat-free product has, and how can we make them work best.

Can our home composting help at all?

I think it's very important to distinguish between compost and composting. The two are completely different. The compost you buy in a garden centre is a formulated product and the reduced peat and peat-free composts that are becoming more and more available - and will become the norm over the next few years - are very carefully blended products with nutrients, mineral particles and organic matter in the right rate to provide the correct growing conditions for the majority of plants.

Composting at home is all about recycling the green waste from your garden. As gardeners we've been encouraged to be incredibly tidy. In recent decades, to sweep and clean and take away any debris, it used to be in bins. Now, instead of garden waste ending up in landfill, people are recycling it through local authority recycling schemes or they're home composting.

The product you end up with is almost 100 per cent organic matter; it is usually very high in nitrates. It's really to be thought of as a soil improver, so scatter it on the surface of the soil and you'll find that it breaks open soil particles, relieves compaction, increases drainage capacity, increases water holding capacity, increases nutrient retention and increases rooting.

Anything that comes out of your composting bin should be thought of as a soil improver. If you want to grow plants in it, you must mix it with another product to put the mineral particles and the nutrients back into it. This is why we always say that unless you have a huge garden and plenty of time on your hands, you're much better off buying a compost product for your potting and cutting and seeds, and using your home-produced compost as a soil improver.

The great thing about the soil improver that you produce from your home composting bin, is to think of it as almost 100 per cent organic matter. Take a bucket of your ordinary garden soil. If you add five per cent of your organic garden compost, it increases the water holding capacity of that garden soil by up to half. So you get a 50 per cent increase in water holding capacity from a five per cent increase in organic matter. That, of course, means you don't become as reliant on the hosepipe, because the rainwater is locked into your soil and made available for your plants for a longer period of time.

I think using organic matter in the garden, whether it's as a compost or as a soil improver, is something gardeners have forgotten to do. The golden rule in gardening is to put organic matter on, not fertiliser, but organic matter. Because it improves soil structure, it improves the water holding capacity, improves nutrient retention and feeds the micro organisms which are responsible for digesting the organic matter and also releasing enzymes that promote plant growth. It's a win win situation. Organic matter - bang it on.

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