Which? Gardening can reveal that green fingers has nothing to do with luck, it’s down to using a decent compost to sow your seeds in.
Every year Which? Gardening magazine trials compost from well-known brands and own-brands and we’re always amazed at the differences in quality we find. The professional gardeners at our trial site try to raise seeds and young plants in each brand of compost, giving them all the light, warmth and water they need, but even then these are the sort of staggering differences they get!
You don’t even need to pay more to get a decent compost. Our tests revealed a Best Buy compost for sowing seeds that only costs 8p a litre, compared to a Don’t Buy compost for sowing seeds that costs 27p a litre.
Buying well-known brands is also not an assurance of quality as one of our Best Buy composts for raising young plants is a supermarket own-brand compost.
How Which? tests composts
In March 2018, we picked 25 composts to test for raising young plants and 22 to test for sowing seeds. We also grew our seeds in a peat compost made for professional growers to see how our garden-centre composts compare. Most of the composts were suitable for both sowing seed and raising young plants and so were included in both tests, as we know many people prefer to buy just one bag for both uses. A few were specialist composts for either seeds or young plants.
We send secret shoppers to buy our composts, so we can be sure we’re getting the same compost as you. Our shoppers live in four different parts of the UK, so we’re able to see whether there is any variation between composts sold in these areas. We bought the composts for garden centres, DIY stores and, this year, several supermarkets and discount retailers.
We carry out our tests at a well-respected horticultural institute, which runs trials for scientists and horticultural industry bodies. The experts there have the knowledge and expertise to ensure our trials are conducted using the best growing techniques, so we know that any differences in performance are down to the compost itself. Our independent assessor is an expert in compost and plant health.
Read more about how we test compost.