The Scottish Government has a commitment to restore Scotland’s peatlands. An element of this is to phase out the use of peat in horticulture. This Rapid Evidence Assessment looks at the current state of knowledge on the role of peat in UK growing media, and the potential for alternative growing media constituents.
There are significant gaps in Scotland-specific data. Our review of published literature (both grey and academic) has therefore been supplemented by information from industry experts.
- Peat extraction in Scotland occurs mainly on lowland raised bogs in the south and east of the country. Estimation of extraction volumes is hampered by information gaps, but is of the order of 0.5 million m3 per year. This represents perhaps 60% of the estimated 0.8 million m3 of UK production.
- Estimated carbon emissions arising from extraction in Scotland are of the order of 100k t CO2e per year, which could be avoided if all extraction ceased. However, alternative media also emit carbon so the net saving would be lower, at around 50k t CO2e per year, if they were used instead.
- Scotland-level estimates of peat consumption are not available, but UK-level estimates show that overall demand for horticultural growing media is approximately 3.8million m3, of which 2.1million m3 (55%) are peat-based. The shortfall relative to domestic production is met by imports, principally from the Republic of Ireland.
- Within overall demand for horticultural growing media, professional users (e.g. landscape gardeners, commercial growers) account for about 1.1 million m3, of which 65% is peat-based, whilst amateur users (i.e. households) account for about 2.7 million m3, of which 51% is peat-based.
- A variety of alternatives to peat are available, including coir, pine bark, wood fibre and composted organic waste. Most need to be mixed with other ingredients and are more expensive and not as readily available as peat. For example, wood fibre is also in demand for renewable energy.
- Peat-free alternatives have gained market share since the 1990s, but peat-based media remain commonplace. This reflects advantages offered by peat in terms of availability, price and consistency which are hard to replicate with alternatives and hence have to be traded-off against other criteria, such as environmental impact. The weight attached to different criteria will vary across different users, but those not already switched to alternatives may be harder to convert.