Peat-based composts are disappearing from garden centres due to environmental concerns
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I was at the Royal Horticultural Society’s spring press conference this week to hear about the latest gardening trends. Whether or not you care about horticultural fashions, one development is in progress that will affect nearly all gardeners.
Most of us will have to make a few changes in how we care for our plants from now on, thanks to different types of compost taking over from traditional kinds in the shops.
This applies to those heavy bags of compost – strictly called “growing media” – that we buy from garden centres and what commercial growers use to nurture the plants we buy for our gardens.
For a long time, the dominant growing medium used was peat, taken from peat bogs in the UK and other north west European countries such as Ireland and Scandinavia.
Peat use is increasingly frowned upon and being phased out because peat bogs are seen as precious ecosystems. So, what exactly is peat made of, and how will the new types of compost make a difference in how we garden?
What is Peat?
Peat is an unusual kind of soil that forms in rainy areas with poor drainage, so the earth becomes waterlogged. In the UK, most of the remaining peatland is in Scotland, but there are also areas in Exmoor, the Peak District, and the North York Moors.
The water stops plants from decomposing normally, leading to a build up of spongy organic matter.
This peaty soil turned out to have a variety of uses – if the bogs were drained and dug up – including as a traditional fuel. But it also makes an excellent growing medium for young plants, being light, airy and free draining.
For decades, peat bogs were being destroyed at a rate far faster than they could form to feed the expanding horticultural industries in countries all over the world. But this has been increasingly recognised as environmental vandalism. Along with the diverse wildlife they support, peatlands prevent flooding by soaking up heavy rainfall and act as a store of carbon.
In the UK, bodies like the RHS have led the campaign for peat-free gardening. The last government said it would ban sales of peat-based growing media, and while the law wasn’t passed before last year’s election, many companies responded by switching to suppliers of peat-free growing media.
To consider two of my nearest garden centre stores, the chain Squires says it stopped selling peat-based compost last year, while Blue Diamond says its goal is to go completely peat-free this year.
Campaigners were disappointed the promised law hasn’t yet come in, but large firms seem unlikely to U-turn on this sensitive issue, so peat-based composts may be increasingly rare on the shelves.
Fortunately, several other kinds of growing media are available – they may be made from composted bark, wood fibre and coir or coconut fibre, for instance.
In the past, peat-free composts could be about 10 per cent more expensive than peat-based products, but these days, prices are similar, as UK peat extraction has been plummeting, so most peat composts are imported.
But gardeners may notice some differences when they use the new products, said Nikki Barker, the RHS’s peat-free transition coordinator, at the press conference.
Bearded man throwing vegetable scraps into a compost heap in the backyard
Kitchen scraps can be used to make your own compost (Photo: Os Tartarouchos/Getty Images/Moment RF)
The main one is that peat-free composts are less free-draining than peat and can be easier to overwater. The top layer of the soil typically gets drier, but that can be deceptive because moisture levels may be fine a few centimetres down.
So, to avoid drowning their plants, people need to ensure they don’t just water their pots whenever they look dry, but instead, stick a finger into the soil to check for moisture levels, said Ms Barker. “If you water just by look, you will tend to over water.”
Impact on your gardening
On the other hand, a drier surface has the advantage that weed seeds will be less likely to germinate.
Another issue is that plants grown in peat-free compost may need more feeding, as products such as wood fibre are not completely decomposed.
Therefore, The decomposition process continues while the material is used in pots, which use nitrogen. “As the microbial activity occurs, that tends to absorb a bit of the available nitrogen,” said Ms Barker.
The newer peat-free composts may be more variable than long-established peat-based versions as manufacturers experiment with different ‘recipes.” So, if you don’t like the first product you try, don’t give up, said Ms Barker. “If you try one and you don’t get on with it, try another, and it may be fine.”
Her last tip is that people should buy several different types of specialised growing media – for instance, seed compost and young-plant compost – rather than a multi-purpose compost. “We can’t underestimate the importance of using the right product for the job,” she said.
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