As the horticulture industry moves towards becoming peat-free what does this mean for the ericaceous plants and the specialist growers who have yet to discover a viable alternative? Ericaceous plants will, as usual, be at the core of the Burncoose Nurseries’ exhibit at Chelsea Flower Show 2022.
Included in this group are the Rhododendrons and Azaleas, Styrax and Stewartias, Fothergilla, Chimonanthus, Nyssa, Kalmia, Pieris and Acers. These plants are the cornerstone of our nursery and, for the past forty years, we have propagated and grown them.
Traditionally ericaceous plants have been propagated in peat because it has a low pH of 5-6 and an excellent capacity to hold water and air in the perfect ratio to ensure that the plant’s roots will develop and thrive. Exactly the growing conditions ericaceous plants experience in the wild in the mountains of Asia and elsewhere. More and more peat alternatives are now becoming available, but they usually have too high a pH for ericaceous plants to thrive or grow well in.
Our exhibit will attempt to demonstrate the principles of why ericaceous plants thrive in acidic soil. We want to show the intriguing nature of the soil and root environment so that the issues and problems involved for nurserymen in switching to peat-free can be understood.
At the nursery we are making a huge effort to scale-back our use of peat. After running trials, we have now reached the point where we will be potting all our herbaceous plants in a peat-free mixture this year. The ambition is shortly to pot all our lime tolerant (i.e. non ericaceous) plants in a peat-free compost.
The sticking point is when it comes to plants that grow in acidic soil. So far the horticultural industry has yet to find an alternative compost that can support the growing of ericaceous plants, particularly rhododendrons. We, like many ericaceous growers, have been testing and using reduced compost with only 40-50% peat mixed with bark and wood, conifer needles, leaf mould and other products.
The move to peat-free has come to a head recently since the Government published its Peat Action Plan in May 2021 that outlines a road map to return the UK’s peatland back to their natural state.
The plan states this is to help protect and restore valuable habitats, help carbon sequestration, prevent flooding, improve water quality, and help the country reach its targeted net zero. It reported:
‘We want our peatland to meet the needs of wildlife, people and the planet. All uses of peatland should keep the peat wet and in the ground.’
Burncoose Nurseries wholeheartedly support and welcome the change to move from peat to peat-free in the growing of plants that grow properly and thrive in alternatives. We are also committed to raising awareness about the peat alternatives that can be used in everyday gardening.
The Department for Environment, Food and Rural Affairs (DEFRA) has published the remarkable statistic that 70% of the peat sold in the UK currently is in the form of bagged growing media that is often mis-used as a soil improver.
While it is easy to accept that bagged peat should not be sold by garden centres as a soil improver it is far less easy to find an alternative to peat for nurserymen and growers producing ericaceous plants.
Neil Williams from Petersfield Growing Media has said:
‘The blends of raw material used in peat-free composts inevitably end up at pH 6 – 6.5 it is hard to call them ericaceous. Reducing the pH of growing medium is practically impossible without including a raw material that has a lower pH.
‘Having worked very hard with commercial growers, The National Trust and RHS, I have concluded that the only way to get a reliable compost for Rhododendrons is to have a reliably low pH by using peat based 50% Peat, 50% Peat free.’.
In a consultation published in December 2021, DEFRA recognises that it will consider ‘narrowly defined exemptions to the proposed measures to end the use of peat and peat containing products in the retail sector.’ Will this extend to growers of ericaceous plants?
Reducing the amount of peat used in UK horticulture by 70 – 80% will be a huge achievement and will drastically help to turn things around for our peatlands. Ericaceous growers call for an exemption to the ban while further research and development takes places into ericaceous alternatives to peat.