Peat laid out to dry in Ireland

Should we ban peat-based composts?

As a new petition calling for the banning of peat compost gets close to 10,000 signatures, Guy Barter, head horticulturist at the RHS, looks at the situation in this country with peat and the complexities on both sides of the arguments

My personal opinion, which is heavily influenced by the research we have done here at the RHS, is that every gardener should try and use exclusively peat-free compost. But there are several issues with banning it completely.

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Peat is ultimately very inexpensive, because it can be dug out of the ground. It is completely inert, it has no weeds, no diseases, no pests, no fertiliser, so it’s a blank canvas. Peat also has very good physical and chemical properties so you can use fine peat for seed sowing and coarse peat for growing trees and shrubs. It holds on to fertiliser and releases when plants need it and it is acidic, so you can add as much lime as you need to make it suitable for acid-loving plants or plants that prefer more alkaline soils. Peat is a wonderful substrate, which is why we’ve used it with gay abandon in the past.

Young seedlings appearing through dark compost soil

But since the 1990s it’s become apparent that the depletion of the peat bogs was proceeding rather fast. Contrary to what many people have said, peat is not replenished in a sensible time frame. It takes hundreds of years for a peat bog to reform. In this country we use both Irish and British peat but we also import it from countries, such as Finland, Estonia and Latvia and these places are increasingly concerned about their peat bogs. The Irish are stopping it being used for burning in their power stations. Ultimately, we will run out of peat, although, to be fair, it will take a very long time. However, bogs are rare and valuable ecosystems that should be preserved.

Peat bogs are thriving ecosystems which get destroyed and aren’t replaced in any sensible way

But there are other very good reasons to leave peat bogs untouched. They are thriving ecosystems which get destroyed and aren’t replaced in any sensible way. Then there’s the climate-change factor. The carbon content in peat is enormous. When you dig out peat and allow it to oxidise, all the carbon dioxide is released into the atmosphere, which contributes to global warming.

Surprisingly, it is gardeners, not commercial growers, that use most peat compost. The main reason is that there are millions of gardeners and they tend to use big pots and window boxes, so the volume of compost needed is very high, whereas commercial growers tend to raise young plants in small pots.

The peat bog in River Ferta Valley, County Kerry
The peat bog in River Ferta Valley, County Kerry, Ireland.
© Getty Images

Full statistics on peat usage haven’t been published since 2015, but those can still give an idea of the scale of use: in 2011 peat accounted for 62 per cent of the total market, which fell to 52 per cent in 2015. Commercial nursery consumption fell from 72 per cent in 2011 to 64 per cent in 2015. Around 58 percent of compost brought home by gardeners in 2011 was peat.

The Department for Environment, Food and Rural Affairs (Defra) gave out binding targets under the 2018 25-year environmental plan to phase out peat for garden use by 2020 and use by commercial nurseries by 2030. Despite this, it’s been clear for a while now that the 2020 deadline can’t be achieved and the targets will be revisited in December this year. It’s a cause of immense concern as to what the outcome of that will be, and it may include extra measures such as a ‘peat tax’ to encourage faster action on phasing out peat.

Peat extraction in bog showing piles of harvested peat drying to be used as traditional fuel
Peat extraction in bog showing piles of harvested peat drying to be used as traditional fuel
© Arterra/Universal Images Group via Getty Images

A peat tax could be a tricky thing, because it will make peat compost more expensive. It is unclear how this will affect the millions of plants coming in from the Netherlands, for example, are all grown in peat-based compost. But the peat media industry is doing something clever at the moment, which is making a tool that measures the sustainability of all the ingredients in a compost, so manufacturers can formulate more sustainable compost. It means people can buy composts based on mix bark, coir, wood fibre and municipal composts and reduce the amount of peat they use.

The RHS is almost entirely peat free. We’re about 99 per cent. There’s a tiny amount we need for growing carnivorous plants and many people have tried to find a peat-free alternative but they are not offered commercially, to the best of my knowledge. But my soil science colleagues at RHS Wisley are going to launch a research project into that, so we can finally replace that tiny but annoying fraction.

How to reduce peat in your garden

1

Check the label

All composts differ. Read the instructions on the back as they will give guidance on how much feeding and watering you need. My favourite composts are often based on wood fibre and you need a little more water and fertiliser than you might need for peat-based material.

2

Choose a compost that’s suitable for what you want

Peat-free composts are not quite as flexible as peat composts so it’s important to pick seedling compost if you are raising seeds, for example.

3

Take it step by step

It’s OK to half fill a pot with peat-free and then top it off with peat-based. At least then you’ve halved your peat use and it’s a step in the right direction and by reducing the topping off over time you get used to the peat-free compost and can make the full transition.

4

Watch out for seedlings

When I first started using peat free compost around 20 years ago, I found that when transplanting seedlings into pots, it was better to use larger seedlings when I wasn’t using peat compost. Instead of transplanting them when there are two seed leaves, wait until there are a few true leaves and then move them.

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5

Water seeds

I have found generously watering seedings well after transplanting them often really helps.