But for great plants you need a great compost. Which? Gardening has been testing compost for almost 40 years,, so we know how variable they can be and the difference a Best Buy can make.
We tested 25 peat-free composts that are meant to be used in pots. Peat-free compost is the most sustainable option, so you can do your bit to reduce the release of CO2 by making the switch.
Peat composts will be banned in the UK by the end of 2024, and in our past trials we've found there's little to be gained from peat when growing in containers. Large pots hold a lot of compost, so filling them with peat is particularly wasteful.
Best Buy composts for containers
Several of our Best Buys also scored very well in our trial of composts for young plants – that's seedlings and plug plants. This means that by choosing carefully you can buy a compost that can be used to pot up your plug plants and then plant them out into large containers. It will, in short, help to nurture your plants from when you first get them at the garden centre to the first frosts.
Peat-free composts are made from a wide variety of different materials and so aren't as uniform as peat composts. The composts in our trials are made from wood fibre, composted bark, coir, wool, bracken, green compost created from green bin collections, and anaerobic digestate (the left-over material from green energy production).
Getting started with summer pots
You might already see plants for sale in the garden centre, but unless you have a greenhouse or a lot of window sills, it's worth delaying your shopping for a few weeks. There is a huge choice of plants you can grow and a vast number of varieties. Garden centres have a good choice, but if you want to pick from a wider selection, it's worth taking a look at online retailers.
Looking after your plants
Plant up your pots outside from mid-May onwards, depending on where you live. Some parts of the country are prone to late frosts that might kill your tender plants.
Finally, remember to deadhead your plants for the best results. Some, such as the modern varieties of petunias, will keep flowering without this, but others give a better show if you remove spent flowers. Our recent trials have shown that cosmos, marigolds and bidens all benefit from regular deadheading.
source https://www.which.co.uk/news/article/best-peat-free-composts-for-pots-of-summer-bedding-in-2023-a3VEt5z8KHr6