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14 Mar 2022

Best peat-free composts for your summer patio

Sustainable composts that will grow great pots of summer bedding plants and veg

Growing pots of summer bedding and veg gives months of pleasure, but can you do it without costing the earth? Yes with a low-cost, peat-free Best Buy compost.

Which? Gardening magazine has found five Best Buy composts, all of them peat-free, which are perfect for plants in containers. This year we only tested peat-free composts as we know plants grow just as well as in peat, and it's best to avoid using peat where you can.

Best Buy sustainable composts

We tested 25 composts, all peat-free, in summer 2021. Some have been reformulated since we tested, but we still found five excellent composts that were awarded a Best Buy. Two of them are from large DIY chains and so are low-cost and readily available. The other three can be found in garden centres.

There are many reasons for choosing peat-free compost, not least of all the fact that harvesting peat releases huge quantities of carbon dioxide. Figures from The Wildlife Trusts suggest that is 2020 alone, the peat harvested for use in UK composts could release up to 880,000 tonnes of CO2, the equivalent of driving to the moon and back 4,600 times.

Read our guide to peat-free composts to see the arguments for making the shift, and how to use them.

How to choose peat-free compost

Peat-free compost is usually made from a mix of several materials, including treated wood fibre, composted bark, coir and green compost, in other words compost made from the contents of green-bin collections. There are even composts made from composted bracken and sheep's wool.

Many composts are now scored for how sustainable they are and you can check how they rate. The score is calculated from how each material is sourced, taking into consideration: energy and water use; social compliance; habitat and biodiversity; pollution; renewability and resource use efficiency. There is no measure for greenhouse gas emission at the moment, but this should be included later this year.

The information should be shown in the garden centre, or on a QR code on the bag, but if not you can look at the Responsible Sourcing Scheme website.

How to use peat-free compost

The variety of ingredients in peat-free composts mean they behave differently to peat.

You will need to pay close attention to watering and feeding, making sure you don't get the compost too wet, or leave it to dry out, and be ready to give your plants a feed using a Best Buy liquid feed if growth stalls. Check your pots at least once a day

If you are planting up pots of summer bedding and veg, you might find it easiest to use a controlled-release fertiliser. This will feed your plants for most of the summer without you having to do anything.

Controlled-release feeds, as the name suggests, releases fertiliser slowly, when the compost is moist and the weather is warm, giving your plants all they need for months on end.

Find out which brands are Best Buy controlled-release feeds and how to use them.