Best compost

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 discoloured crops and pest-ridden 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.

Last year alone, we completed over 70 different compost tests, growing various seeds, young plants, herbs and vegetables in temperature and humidity controlled greenhouses to bring you this comprehensive list of the best - and the worst - composts to buy in 2021.

Only logged-in Which? members can view our recommendations in the table below. If you're not yet a member, you can get instant access by joining Which?.

Compost for containers results will be updated in March 2021

Best compost for sowing seeds

For more information, head straight to our guide on the best composts for sowing seeds . 

Best compost for raising young plants

For more information, head straight to our guide on compost for raising young plants. 

Best compost for containers

For more information, head straight to our guide on compost for containers. 

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. This is particularly true of peat, which ideally should be used sparingly as it's bad for the environment. 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.

Why Which? compost reviews are better

Which? is independent and doesn't accept advertising or freebies, so you can trust our reviews to give you the full, honest and impartial truth about a product.

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 cabbage and antirrhinum bought as plug plants from a specialist nursery. 
• Containers - we use 25 different composts to grow pelargoniums and potatoes. 

All three tests are carried out by an expert at a horticultural institute in a temperature and humidity-controlled greenhouse and 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.