Best composts for containers
The best compost for containers will help you grow large, healthy vegetables and plants that are covered in flowers all through summer.
The worst we've tested will cost a fortune and only deliver slow growth, pale leaves and tiny harvests.
But the only way to tell the good from the bad is to grow plants in the compost and compare the plants - which is exactly what Which? Gardening has been doing for more than 30 years.
We've pulled out our top composts for containers from our tests in the table below.
New test results will be available in April 2021.
Best peat-based compost for containers
Best peat-free 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.
Before testing we send out secret shoppers to buy all our compost based in four locations around the UK, so we know we are getting the same product as you. We also buy two of each to see if there are any variation in the quality of each bag.
Here's a run through of how we test compost:
- We grow ‘Palladian Pink’ pelargoniums, ordered as plug plants and 'Charlotte' potatoes.
- This year, we decided to alter our feeding regime. The potatoes were fed with controlled-release fertiliser unless the compost bag stated that it contained enough feed to last for the length of the trial. However, we decided to grow the pelargoniums without feed to see how well the compost performed on its own.
- The pelargoniums were assessed for flowering impact and vigour, which means leaf colour, the size and bushiness of the plant and general health. We carried out these assessments throughout the summer up until early October.
- The potatoes were harvested in September, when they were weighed and assessed for size and quality. In our evaluation, we only included potatoes that were of a sensible size to use in the kitchen; that is larger than 30mm in diameter.
Our scores are based on how well both trial plants did, weighting the results of both trials equally.