Growing media

With a scheme promoting responsible sourcing nearing completion, growers need to take a fresh look at what they are using, says Sally Drury

Peat: growers now informed on environmental and social impacts of growing media - image: ICL
Peat: growers now informed on environmental and social impacts of growing media - image: ICL

Peat-reduced and peat-free growing media are used by some growers while others continue to use peat. A few use products from both categories, depending on the client or customer requirements. But it is a busy time of the year and a lot of growers simply opt for whatever can be delivered quickest, whatever comes with the lowest quote or simply use what they used last year, the year before and probably the year before that.

"Growers are very active this year but the growing media mixes they grow crops in seem to have stabilised," says ICL technical manager Dr Jim Smith. "There is a demand from some customers for peat-free growing media but the majority are happy to use peat." If that is you, it is time to take a look at what you are using and perhaps to review your thinking.

Variable quality

Quality of alternative is often stated as the main concern by many peat users. Indeed, Dr Smith has noticed less coir being used in the ornamental sector due to variability in quality. It has, he says, in general been replaced by pine bark. But environmental sustainability has reached new heights in many industries and, with its use of peat, horticulture is no exception.

Only last month Friends of the Earth, Plantlife, the RSPB and Wildlife Trusts hit out at retail peat suppliers, claiming that products are "poorly labelled". Pressure groups have called on the industry to phase out peat from amateur use by 2020. On the agenda now is landscaping, particularly urban planting.

At Horticulture Week we have covered the topic of peat use for more than a quarter of a century, starting with the "debate" in the 1980s, through the 2011 environmental white paper's peat-reduction targets proposing the phasing out of peat as professional growing media by 2030 and the setting up of the Government-backed Sustainable Growing Media Task Force.

There can be no doubting that sustainable growing media is the future. Right now growers need to take a fresh look at what they are using, especially as the Responsible Sourcing & Manufacturing of Growing Media scheme nears completion. It has been designed by the Growing Media Initiative, which in turn was established by the HTA in conjunction with Defra, the Growing Media Association and other interested parties.

"One of the aims of the cross-industry scheme is to ensure that users - be they growers, specifiers, landscapers or gardeners - are aware of the environmental and social impacts of the growing media they are using," explains Melcourt Industries technical director Catherine Dawson.

The scheme seeks to score growing media across a range of criteria and as such all materials are given equal scrutiny, unlike in the past when peat was singled out for what was not always favourable attention. One of the many strengths of the scheme lies in the make-up of the working groups that have created it. All sides of the industry have taken part, including manufacturers, growers, retailers such as B&Q and Homebase, non-governmental organisations such as the RSPB and the RHS, the HTA and Defra.

The existence of the scheme will make it easier for anyone purchasing growing media or containerised plants to specify that the growing medium has been responsibly sourced. For the first time it will be possible for a purchaser to have access to evidence-based information about the ingredients, their provenance and both their environmental and social impacts.

More responsible products are differentiated from less responsible ones, enabling comparisons of the same material from different sources, based on seven criteria:

- Energy use.

- Water use.

- Social compliance.

- Habitat and biodiversity.

- Pollution.

- Renewability.

- Resource use efficiency.

Work in progress

The scheme is still a work in progress. Two things will now happen. Firstly, an auditor will be appointed to help lead product benchmarking and, importantly, informing all concerned about the new scheme's relevance to all users of growing media.

"To this end, members of the working groups have been speakers at various industry events over the last year," Dawson notes. "One such opportunity is taking place at Hillier Nurseries, where several 'supplier days' have been organised in order to link various landscape groups with the nursery."

Melcourt is growing media supplier to Hillier, and Dawson has been a speaker at two events for local authorities and garden designers. "It is very useful to be able to address a group of landscape professionals in the nursery environment," she says. "The more they understand about plant production, including the part played by growing media, the more likely they are to create successful plantings in the landscape."

As well as the responsible sourcing scheme and the use of its Sylvamix growing media at Hillier, Melcourt has taken the opportunity to update delegates on the basics of mulching and soil improvement - two areas where Dawson believes methods in the field are far from ideally practiced. Melcourt has a long history in the supply of mulches and soil improvers so is well-placed to advise on their applications.

ICL, which supplies Levington-branded growing media, is also fully committed to the scheme. UK and Ireland marketing manager Dave Steward says: "This initiative is good news for growers, helping them use more responsibly sourced growing media manufactured from fully assessed materials."

Latest research

Research and development work is bringing us new products, both in terms of growing media and associated consumables such as wetters, fertilisers and crop-protection products for use with reduced and peat-free media.

A benefit to those using or looking to use peat-free growing media is the fact that ICL's Exemptor (active: thiachloprid) can now be added to media to control vine weevil and sciarids. This is the only contact and systemic pesticide for the control of black vine weevil in container-grown ornamentals. Previously it was authorised for use only in growing media containing 50% peat, but now it has an EAMU to include all commonly used organic growing-media constituents, including peat-free.

ICL technical manager Andrew Wilson says: "It is particularly good news for growers of fleshy rooted perennials susceptible to vine weevil such as primula and heucheras as well as vulnerable hardy nursery stock genera including rhododendrons and azaleas. It is particularly timely as, following a mild winter, vine weevil pressure is likely to be high this season and the adult beetles are starting to emerge from protected structures."

Large volumes

One nursery using large volumes of peat-reduced growing media is James Coles & Sons. As the UK's largest amenity grower, James Coles produces more than 1,600 lines on four sites, totalling 550 acres, within a 10-mile radius of Leicester. The nursery is respected for delivering high-quality hardy nursery stock and containerand field-grown trees to landscapers, local authorities and wholesale nurseries nationwide.

At any one time the nursery has in excess of two-million trees in the ground, with 200,000 planted annually. Each year two-million shrubs are produced along with 80,000 container-grown trees, but just six tailor-made Levington Advance Solutions mixes are used.

Each mix features up to 25% peat reduction by using ICL's wood fibre product Fibagro and each one is designed to suit particular crops' needs, using colour-coded Osmocote Exact to give programmed controlled release over various longevities. Supplementary feeding is provided by Peters, Universol and Osmocote. Mixes for vine weevil-susceptible plants also contain Exemptor.

At James Coles' 21-acre Syston site, production manager James Moffatt works closely with ICL technical area sales manager John Clarke and plant nutrition expert Andrew Wilson. "Every autumn we meet to review the mixes and where necessary tweak the recipes," says Moffatt.

"If any issues arise, ICL is quick to identify and resolve them. Last season, for instance, tissue analysis showed a lack of trace elements in the 10-litre Pinus, but it was promptly resolved with water-soluble Micromax."

A business the size of James Coles needs a complete and robust service. The nursery is passionate about staff development and has its own in-house three-tier training programme, but ICL also provides staff training covering its products and their use.

Substrate stabilises in plug tray - image: HW

New products: FORMiT (Jiffy), West+ (Sinclair Pro) and SylvaGrow Organic (Melcourt Industries)

A loose-fill substrate that stabilises in the plug tray when water is added joins the range of products from Jiffy. FORMiT provides plug integrity to allow mechanical transplanting without root disturbance.

Growers looking for peat-replacement ingredients should note that Sinclair Pro has introduced West+. Produced from softwood spruce, it has an organic colourant that works as a wick to absorb moisture and acts as a filter to protect plants from phytotoxins and as a biocide to slow down decomposition. According to the company, West+ can be used at rates of up to 50% in pot, bedding and nursery stock mixes.

For the retail industry, Melcourt Industries has introduced SylvaGrow Organic. Like all its retail mixes, it is the same formula as the equivalent professional product, Sylvamix Natural. Both are Soil Association-approved, giving them organic credibility. "With our retail range, first introduced in 2014, we have decided to produce to a professional standard rather than to a price," says technical director Catherine Dawson. SylvaGrow Organic is available in 15 and 50 litres and is RHS-endorsed.

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