The Crown Estate's Savill Garden in Windsor is planning a peat-free policy after beginning compost trials.
Both Savill and Great Dixter (HW, 16 August) are switching to bark-based mixes from specialist supplier Melcourt.
Savill Garden head gardener Harvey Stephens said trials of different peat-free growing media are going well and they are "having good results" with Melcourt products. "The reduction in peat is an important national subject," he added.
Savill Garden intends to have a policy similar to that of the National Trust since members voted to ban peat use in 1999. The trust's Nostell Priory head gardener Paul Dibb said he makes 30 tonnes of leaf mould compost a year and uses 10 tonnes of horse manure.
But other head gardeners have doubts about the quality of replacements. Chelsea Physic Garden uses a range of compost mixes for its collection with materials such as fertile fibre coir for bulking and John Innes No 3, though head gardener Nick Bailey said they have reduced JI3 use by 20-30 per cent over three years in attempts to reduce their peat use.
If there was a suitable alternative "I'd jump in a flash but I'm not entirely convinced at this stage", Bailey added. The garden has been using ethically sourced peat-based compost Moorland Gold, sieved from moorland streams, for its carnivorous plants. He uses green waste from the London garden as a mulch and soil improver.
Syon Park's Topher Martyn said he suspects the reduction of peat in some leading brands to be the reason his gardeners have to sieve more compost before use this year.
Wakehurst Place's Chris Clennett uses Melcourt and Petersfield peat-free. Penshurst Place head gardener Cory Furness uses a 50/50 mix of John Innes and Sinclair potting compost.
The Government plans to end professional use of peat by 2030.
Great Dixter New mix
Fergus Garrett, head gardener at Great Dixter, also plans to go peat free. Garrett makes 20 tonnes of his own compost mix each year, comprised of a peat base, Dixter's green waste and Melcourt chipped bark.
"We're now going to cut peat completely, having spoken to Melcourt," said Garrett. "I think this will give us the final push."