RHS Journals

The Garden
September 2000

Low-peat performers

Alternatives to peat-based composts for seed-sowing and potting were recently assessed at Wisley. Jon Pickering summarises the results

Since gardeners’ use of peat first came under serious scrutiny in the late 1980s, it has become widely accepted that sound alternatives already exist for most outdoor uses such as mulching and soil conditioning. Bulky materials such as straw, manure, leaf-mould or home-made compost can be used for such purposes; even grit or gravel may be employed where no nutrient content is required.

1   2
Above: 1 Good results were produced by Fuchsia ‘Dollar Princess’ grown in Great Mills Multipurpose Compost, a ‘reduced-peat’ product. 2 In Levington Peat-Free Universal Compost, Fuchsia ‘Dollar Princess’ produced weaker growth and came into flower later. Photographs copyright Tim Sandall

For seed and potting composts, where nutrient levels are critical and uniformity from batch to batch is essential, the development of effective alternatives to peat has proved much more difficult. Many gardeners who had tried the early, poorly developed peat-free composts and obtained correspondingly poor results from them were reluctant to try again. As research into peat alternatives has progressed, however, their quality has improved. Sustainably produced, locally available materials (composted wood wastes and plant residues, for example) also show great promise. ‘Reduced-peat’ compost, a recent compromise, is gaining popularity. Made up of peat ‘diluted’ up to 50 percent with other materials, these products can help to reduce peat usage, while still maintaining many of the characteristics of peat-based products.This year, as part of a commitment to provide up-to-date information on peat alternatives, staff at RHS Garden Wisley produced a glasshouse display of plants raised in the latest generation of ‘peat-free’ and ‘reduced-peat’ growing media. Seeds and plants were grown to assess how peat alternatives perform compared with peat-based compost. Seed was sown in early spring and the pot plants have been on display throughout summer so that visitors have been able to see the results for themselves.

Page 1 | Page 2 | Page 3 | Page 4Further informationJon Pickering, a former horticultural scientist at Wisley, works for a composting consultancy in Berkshire

back to The Garden contents page