A compost from a discount supermarket is the best compost for patio pots for the first time this year in the Which? Gardening trials. The peat-based compost costs just 5p per litre, but beat other composts costing as much as 60p per litre.
It also scored well in our tests for sowing seeds and raising young plants, so it’s a great all-round option for half the price of many other composts. Find out which other composts are excellent by looking at our Best Buy composts for containers.
Best peat-free compost
For those that prefer to use peat-free composts, there is plenty of good news. Not only is there a peat-free Best Buy but seven other peat-free composts scored well.
Unfortunately not all the peat-free composts were excellent. One was a Don’t Buy compost and another was one of the lowest-scoring composts. Find out if the peat-free composts from Lidl, B&Q, Waitrose, Miracle-Gro, New Horizon and Wyevale Garden Centres are worth buying by reading our full compost test results.
What makes a great compost?
Only Which? carries out independent tests of composts every year. We grow bedding plants and potatoes for four months every summer to find the best composts for containers, and test poorly performing composts to find out exactly why they have failed to grow great plants. The bedding plants should grow into large plants and flower prolifically. We also look at the overall health of the plant.
We weigh the potatoes and count how many small, medium and large potatoes we have harvested. Ideally we will have plenty of medium and large potatoes, rather than lots of small ones. We also look for smooth skins and take marks away for scabby potatoes. We buy compost from four areas around the country to make sure the quality is consistent. Find out how we test compost.
Compost for seeds and plug plants
There’s still time to sow your seeds for veg crops and to fill the gaps in your flower borders. Every year Which? Gardening tests composts to find the best composts for sowing seeds. We look at peat-based and peat-free composts as well as both multi-purpose and seed composts. This year we found five that were Best Buy composts for sowing seeds, including two peat-free composts.
If you’re potting on your seedlings or small plug plants, you’ll need a compost that can give the growing plants all the nutrients it needs, while being well-drained. We recommend four Best Buy composts for raising young plants which will give your plants the best start in life.