How to buy the best compost Compost for different uses
You can buy composts for different stages of plant growth – from seed and cutting compost with low levels of nutrients, to potting compost with increased nutrients – or opt for a multipurpose compost that can be used for both seed-sowing and potting on.
Composts promoted for summer containers, such as hanging baskets and patio pots, tend to be expensive and often have slow-release fertilisers (and sometimes water-retaining gels) included, to promote flowering over the summer.
At the other end of the spectrum, the cheapest compost is in growing bags (these are long, thin bags of compost, into which you directly plant your plants). First used by commercial growers for tomatoes and now for strawberries, growing bags are cheap and handy for some crops, but tricky to water and not very attractive on a patio. Grow-your-own crops for containers, such as potatoes, strawberries and tomatoes, can be grown in sacks, pots or other planters, filled with the compost from growing bags.
Hanging baskets, summer containers and grow-your-own crops only require compost that lasts for one growing season, but for shrubs grown in pots year after year you need a compost with more ‘body’, with a physical structure that will not break down over time or in winter rains. For shrubs or small trees in pots, either repot regularly or use a loam-based compost; the latter is heavier and good for trees in pots, which tend to be top-heavy. Acid-loving plants, such as azaleas, camellias, blueberries and some heathers, are best in ericaceous composts (ie lime-free) and watered with rainwater rather than tap water.