Peat Free Composts

A report by Rosie Hall for Hollin Lane Allotment Association

Background

Peat only started to be used in garden composts in the 1950s with the rise of popular gardening. Humans have used peat for centuries as a fuel, a building material, for animal bedding and, more recently, for horticulture. In the UK, gardeners and commercial growers get through 3.5 million cubic metres of peat a year. To meet this demand, areas of lowland bog are being stripped of their peat, destroying valuable habitats both here and abroad (65% of our peat is now imported). Because peat bogs take so long to form they are an unsustainable resource. If we continue to destroy these peat habitats we will ruin a vital part of our natural heritage, lose many rare plants and animals, and valuable information about our planet’s past.

While some of our remaining peatlands are protected, there are many in other European countries that aren’t, and it is these which now supply most of our garden peat.

Peat in the garden

Peat has three uses in the garden: as mulch, as a soil improver and as a growing medium.

Mulches
A mulch is a layer of material spread on top of the soil to keep down weeds, conserve moisture and insulate the earth. Peat-based mulches do a relatively poor job as they break down quickly in dry conditions and often just blow away. Better mulches are based on bark, leaf mould, recycled wood waste, spent mushroom compost or garden compost.
Soil improvers
Peat adds no nutrition to the soil. Better products for this are manure, compost, spent mushroom compost (though this is of variable nutritive value)
Growing media
All growing media should be peat free by 2020 according to Government targets.  Growing media do not have to be based on Peat. They can have the following as a basis: composted bark, coir, leaf mould, garden compost, screened green waste and screened composted manure

Peat-free Products

Clearly we need different grades of media for different jobs in the garden; the differences in water retention are also very important.

In researching the available peat free products it is clear that one product will not fit all. Multipurpose works all right up to a point, but often the products are far too coarse for seed sowing.  In looking at available products I have tried to take the following into account, but there are sure to be other factors- it is a huge task!

  1. Have the products been tested by reputable trials?
  2. Are products available locally? How much do they cost?
  3. Do we know what the products contain?
  4. Are the companies involved in production of peat-containing products? I added this as something we might like to consider.
  1. Have the products been tested by reputable trials? The Royal Horticultural Society has some useful pages on peat free gardening. The main points for my purposes were:
    • In their trials they found that there was very little information on the main components of the composts.
    • They found considerable variations in quality between batches.
    • The more expensive composts tended to perform better.
    • Water management is critical.
    • How best to feed was a subject for further research.

    Other trials:
    Which? Test scores for 2010 as a percentage of germination in the following peat free composts:

    • New Horizon Multi-Purpose: 80% (also top in 2011)
    • Westland Multi-Purpose: 80%
    • J Arthur Bowers Multi: 74%
    • Levington Multi: 74%
    • Vital Earth Multi: 74%
    • Murphy Multi: 73%
    • Vital Earth Tub/Basket: 70%
    • New Horizon Growbag: 65%
    • Shamrock Multi: 63%
    • B&Q Tub/Basket: 53%
    • J Arthur Bowers JI no. 3: 50%
    • B&Q Multi: 49%
    • Westland Earth Matters: 48%
    • B&Q Peat-Free Multi: 46%
    • Westland Multi: 43%
    • Westland Container/Basket: 39%
    • Miracle Gro Peat-Free: 28%

    The previous Which? Score put B&Q multipurpose and New Horizon organic and peat free growbag along with B&Q sowing and cutting compost as top 3 for sowing composts. They suggested that Homebase multipurpose and Vital Earth were not worth buying as the germination was< 40%. (Compare with results above)
    A report in The Ecologist suggested that Petersfield and New Horizon both scored 90% germination.
    The trials are difficult to interpret. They do seem to illustrate that there is sufficient variation between batches to lead to variable germination rates, all else being equal.

  2. Are products available locally? How much do they cost?
    • New Horizon Multipurpose Peat Free is widely available; High Trees would deliver any amount for £18; a bag costs £5.99. Garden Goodies (Bingley) would deliver eg 30 x 60 litre bags for £186+VAT including delivery.
    • Moorland Gold (see below) from West Riding Organics priced as follows: 20-64 x 40 litre sacks £5.34 each (individual price £7.99), full pallet £4.79 each (max 65 sacks) delivery £42 + VAT
    • Knotford Nook (Lancashire) bulk loads up to 5 tons (£40/ton -£60/ton depending on whether screen size and whether manure based)equivalent to a builder’s 1 cubic metre sack) £40 delivery + VAT
    • Petersfield which received good reviews, is based in Leicester so is not considered further here.
    • These are the ones I enquired about as a ‘taster’. Most on the Which? list are available locally.
  3. Do we know what the products contain?
    • New Horizon Peat Free: bark, timber residues, green waste, limestone, hoof and horn, rock potash, Vinasse (?) bone meal. Will need more watering then peat, and extra feeding after 4-6 weeks.
    • Moorland Gold: This is not peat free, being made of a mixture of entrapped peat from water purification + sharp sand. It is therefore a by product using a waste material, so not reliant on peat extraction. It is Soil Association Certified.
    • Knotford Nook: There are various types based on either green waste, mature compost or farmyard manure. They are screened to 40/30/20/8 mm, so suitable for different purposes.
  4. Are the companies involved in the production of peat containing composts?
    • New Horizon makes peat-containing composts. Since all compost will have to be peat free by 2020, this is going to change the picture considerably.

Conclusions

  • It would be good to encourage the use of peat free composts on the allotment site.
  • We should invite comments on this report from the plot holders.
  • We should consider buying a bulk load of compost or a couple of bags of several types to do our own trial.
  • Making our own means allocating an area , collecting leaf mould etc
  • We should make sure that every plot holder is helped to produce garden compost for use in mulching, soil improving and as a growing medium.
  • We should try to make Hollin Lane Peat Free as soon as possible