Compost on test

[KG magazine]

The right compost can make the difference between struggling seedlings and a glowing garden, says Gardening Which? today.

In a trial testing 17 multi-purpose and 15 specific-use composts, Gardening Which? sowed 13,200 seeds, potted on 880 seedlings and planted up 276 pots with 828 plants.

The results show that there is huge disparity between the quality of different composts. Crucially, gardeners need to think carefully about which compost to buy, whether it’s for young plants, container plants or raising seedlings.

Successful for the sixth consecutive year, New Horizon Multi-Purpose Peat-free Compost (8p per litre) was awarded Best Buy in the peat-free multi-purpose compost category - both pricked-out seedlings and plants in containers grew nicely with this compost.

Best Buy J Arthur Bower’s Multi-Purpose Compost (6p per litre) received top marks in the peat-based multi-purpose compost category, for raising seedlings and growing on young plants. With less need for watering than the other peat-based compost, this was a clear all-round winner.

But Gardening Which? advises staying away from Homebase Peat Free Multi-Purpose compost: it performed poorly at both raising seedlings and growing on young plants.

Julia Boulton, Editor, Gardening Which?, said:

"If gardeners are worried that their green-fingers are no longer doing the trick, the results of our compost test show that they should not be downhearted: it may be that they are not using the right compost."

"Picking the right compost makes all the difference, turning struggling seedlings into precious plants."

Gardening Which? has been trialling compost for over 20 years. Last spring, its researchers bought 29 widely available composts and used an independent horticultural research institute to carry out a series of growth trials to assess their performance. As composts vary from bag to bag, as well as from brand to brand, all 29 were bought from four different parts of the UK.

On test were multi-purpose and designated seed, potting and container composts, including peat-based and peat-free brands. Using plant species known to be good indicators of compost quality, GW? tested each compost at regular intervals for growth, health and flowering. In addition, the amount of watering that each compost required was recorded.