Best compost to buy in 2021

The best compost will provide all the nutrients and support needed for seeds and veg to grow and thrive, while the worst will leave you with meagre crops and feeble plants.

But the only way to know if a compost is good or bad is to grow plants in it and compare them - something we've been doing for more than 30 years.

Many people no longer want to buy peat compost as it's believed to damage the environment and add considerably to global warming. However, peat composts are still the most widely-available composts in garden centres and are preferred by many gardeners. 

Find out more about peat vs peat-free compost and make up your own mind about where you stand. 

To make it easier to choose the right compost for you, we have separated our results in two sections. The first lists the peat-free composts we have tested, and you can find our recommendations for peat composts at the bottom of the page.

Keep scrolling for our comprehensive list of the best - and the worst - composts to buy in 2021. 

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Best peat-free compost for sowing seeds

Only logged-in Which? members can view our recommendations in the table below. Join Which? to get instant access.

Best peat-free compost for raising young plants

Only logged-in Which? members can view our recommendations in the table below. Join Which? to get instant access.

Best peat-free compost for containers

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We also test grow bags - see our round-up of the best grow bags.

Best peat composts for sowing seeds

Only logged-in Which? members can view our recommendations in the table below. Join Which? to get instant access.

Best peat composts for raising young plants

Only logged-in Which? members can view our recommendations in the table below. Join Which? to get instant access.

Best peat composts for containers

Only logged-in Which? members can view our recommendations in the table below. Join Which? to get instant access.

Getting the best from compost

It’s best to buy only the amount of compost you need, and use it up as soon as possible. If you need to store any compost for more than a month, put it in the shed where it will be cool and dry, or undercover, especially through wet weather. If you can’t use up peat-free compost within three months of buying it, use it as a mulch on your borders. Peat ideally should be used sparingly as it's bad for the environment. 

Find out more about why you should buy peat-free compost.

Why Which? compost reviews are better

We test compost for three different tasks; sowing seeds, raising young plants and for use in containers. 

• Sowing seeds - we use 17 different composts to grow basil 'Cinnamon' and Petunia 'Express Rose' seeds. 
• Raising young plants - we use 15 different composts to grow tomato and antirrhinum, sown as seed and transplanted when they have two non-seed leaves. 
• Containers - we use 25 different composts to grow pelargoniums and potatoes. 

All three tests are carried out by an expert at a horticultural institute, and the compost for seeds and young plants test takes place in a temperature and humidity-controlled greenhouse. The composts for containers are tested outside once the nights are frost-free. The results are compiled by an independent assessor who's an expert in compost and plant health. 

We also send secret shoppers to buy our composts, so we can be sure we're getting the same compost as you.

Find out more in our guide on how we test compost. Alternatively, jump straight to our round-up of the best controlled release fertilisers.