Championing peat-reduction in plant propagation | Kernock Park Plants

With plant propagation identified as one of the more testing areas for peat-free growing media, Kernock Park Plants is tackling these challenges head on.  While its liner production has been peat-free for five years, the production team is making good headway transitioning other areas of its operations – reducing peat element in all peat mixes and eliminating all peat from 30% of its plug production.

Based at Pillaton, near Saltash in Cornwall, Kernock is an independent wholesale producer of high-quality, young ornamental plants. With 4ha of cover, predominantly glass, the company propagates more than 1,200 varieties, producing over 12 million plants annually.  Propagated from seed, cuttings and tissue culture, the young plants are supplied in various formats and specifications to customers throughout the UK, Ireland and mainland Europe.

Kernock was founded in the early 1980’s by Richard and Jan Harnett.  Richard, then an ADAS consultant, spotted a gap in the market and the couple began propagating plants in a polytunnel in the back garden. Forty years on and this go-ahead business has a burgeoning award’s cabinet – testament to its many innovations and achievements. Winner of the 2018 Horticulture Week Grower of the Year award for Wholesale Protected Ornamental, the following year Kernock scooped the silver prize in the AIPH International Grower of the Year – Young Plants category.

“We’re always keen to bring to market new and hard to find varieties that keep growers and their customers interested – as well as classic garden favourites,” says Julian Cooper – operations and senior ICT manager.  “Part of the European Proven Winners brand and linked to hundreds of independent breeders and agents, we have access to interesting new varieties from around the world.”

Peat-free liners

Kernock began reducing its reliance on peat over ten years ago.  Since 2019 its nursery stock liners have been exclusively grown in a peat-free Levington Advance Sustain mix comprising buffered coir, Fibagro Advance Standard woodfibre and pine bark.

Within the mix, the nutrition programme features Micromax Premium – containing a well-balanced combination of trace elements; Osmocote 5 – our latest generation, controlled release fertiliser developed specifically for sustainable growing media; and Osmoform High N – our new base fertiliser promoting higher nutrient efficiency in the early stages of plant growth, while being better for the environment – due to reduced leaching.

Eliminating peat from plugs  

“Up till now, demand for peat-free plugs has been relatively isolated,” says Julian. “The plug is a relatively small part of the overall finished product that it has not been a major issue. However, more recently we see expectation for peat free from some larger retailers.”

Kernock employs the environmentally friendly Ellepot growing system for its plug production.

“We wanted a system that eliminated transplant shock,” explains Julian. “Having trialled other systems, we settled on Ellepot and have invested in our own Ellepot machines – to manufacture plugs on site.  Made from paper, they are root, air and water permeable and degrade naturally – encouraging fast root development.

30% of Kernock’s Ellepot plugs production is already peat-free – with the remainder grown in a bespoke 35% peat-reduced Levington Advance mix.

“Switching to peat-free for our liner nursery stock was relatively straight forward,” says Julian.   “For plug production it is proving slightly more challenging – not due to the growing media consistency, but the buffering of nutrients and water in small cells.

“The key issue to overcome in small plugs is nutrition deficiency early on, particularly in winter when water isn’t needed. In summer there is the option to supplementary feed with water soluble fertilisers – applied via the irrigation. We’re really pleased with the progress we’re making. Working with ICL we’ve developed a bespoke mix and have been tweaking the nutritional content – in particular, the base fertilizer.”

“This peat-free Levington Advance Sustain mix contains buffered coir, perlite and pine bark,” explains Andy Hodges – ICL technical area sales manager for the South.  “The nutrition package includes Micromax Premium, Osmocote Exact mini (3-4 month) and 50% of the base fertiliser is Osmoform High N – which has an 8-10week release pattern.  To address the water management issues, we include H2Gro liquid and granules.”

“We aim to be ahead of the peat ban deadline,” says Julian. “Although the deadline for professional horticulture is yet to be finalised, most likely beyond 2030, we expect this transition to be driven more by the consumer, so we are aiming for peat free status as early as 2025.

“The varieties grown in peat-free plugs tend to be slightly more compact, which can be beneficial.  However, some plug plants clearly are not happy in peat-free.  We’re doing more trials this year to overcome these challenges with tweaks to the mix and watering methods, but ultimately, we could lose some varieties if the viability and/or the costs of production become unsustainable.”

Stock plants

Kernock’s mother plants are an extremely valuable asset.  While they never leave the nursery, the team is still working to eliminate peat from this area of its operations.

“For stock plants we currently rely on two 35% peat reduced Levington Advance mixes containing buffered coir and pine bark – one more free draining that the other,” says Julian.  “Working with Andy, we’ve recently developed a peat-free mix tailored to the specific needs of our mother plants. It consists of buffered coir, two different sized pine barks and Fibagro Advance Standard.”

“All three mother plant mixes include Micromax Premium and Osmocote 5 (8-9 month) as well as Osmoform High N base fertiliser,” explains Andy. “H2Gro liquid has been added to aid water management, while the peat-free Levington Advance Sustain mix also contains H2Gro granules – to help compensate for the hydrophobicity of the higher wood product content.”

Julian and Andy meet regularly to review all the Kernock mixes and tweak them as required. “Depending on the season, we might increase Osmocote and H2Gro levels,” says Julian. “It gives us an opportunity to review any shortfalls – identify areas we could do better – nothing is ever perfect.”

Once a year Andy, together with his colleague Andrew Wilson (ICL technical manager), hold training sessions to deliver basic nutrient deficiency recognition training to the 60-strong production team.  “It’s important not to ignore any signs of deficiency, but to flag up any issues early,” says Julian.

“Our ethos at Kernock is to lead, we don’t generally look to follow.  Working with ICL we get access to the latest growing media, nutrition and plant protection technologies – helping us keep one step ahead of new legislation and industry developments.”