Nursery stock - Bracing for winter

Nurseries are taking steps to avoid repeating the costly mistakes of previous severe winters, Hannah Jordan reports.

Johnsons of Whixley suffered huge losses of Phormium - image: GAP Photos/Kit Young
Johnsons of Whixley suffered huge losses of Phormium - image: GAP Photos/Kit Young

With the first frosts of 2011 already upon us and various reports predicting another severe winter, nurseries across the UK are stepping up stock protection. What they certainly are not doing is drawing a collective breath and hoping for the best, as some admit to doing last winter.

Many thought the tough winter of 2009, which broke a decade-long run of mild winters, was simply a one-off. But the dark months of 2010-11 brought one of the coldest UK winters on record and saw growers lose hundreds of thousands of plants.

With temperatures dropping from 10 degsC to nudging -20 degsC in some areas during the last days of November 2010, growers were caught with their pants down. In the worst hit regions such as the West Midlands, the north and the North East, crop losses of more than 20 per cent were not uncommon.

The fallout even prompted the RHS to issue a list of the worst hit plants over the two winters and to begin developing a new hardiness rating system for plants to help gardeners choose the right ones for their areas and to help garden centres give informed advice to their customers.

Problems compounded

The situation was compounded by the fact that last year many of their retail clients asked the nurseries to keep hold of their orders over the winter instead of risking having them under their own roofs. Yorkshire-based Johnsons of Whixley lost more than 10,000 phormiums for one client alone, which contributed to the nursery's decision to invest £500,000 in more protected space this year.

Director Andrew Richardson says they are taking no chances. "We've all been growing things fairly unprotected for 10 years and last year we got caught out. It may be that we don't have such a severe winter this year but we simply can't take that risk."

He sought advice from European consultants on how to maximise his investment. "What we experienced last year was a standard winter on the continent so we wanted to find out how they cope." Polythene cover was selected over glass due to the added space that could be achieved for the same money. "We've put up some really hi-tech polythene structures with heating systems and laid tarmac inside them. The plants will go onto trolleys and sit in there for the whole winter. We've also changed the compost we are using. We really can't have done more to try to protect ourselves."

In the West Midlands, too, nurseries have been reviewing strategies and increasing protected space. Wyevale in Herefordshire has erected more glass structures while Worcester-based Bransford Webbs has invested in both glass and polythene after suffering stock losses last winter.

Managing director Geoff Caesar says the nursery has changed its protocols and accepts that more work will go into moving crops to protected spaces. "Before we were leaving the plants out for longer because under protection they grow too much and then we have to trim them, which makes them unsaleable come spring. We'll move them earlier this year but not just yet because we want some cold on them first to stop them growing," he explains.

Caesar hopes the firm's £20,000 investment in around 1,000m of polytunnels with facilities to heat or ventilate the crops depending on the climate will help to alleviate the problem. "If it stays mild the heating won't activate and we'll open the doors and leave the adjustable sides up. But if it's colder we'll close it all up and the heat will come on," he says.

Plant management strategies

As well as installing more polythene-protected space, Rochfords Nursery in Hertford is also employing new plant management strategies. Orders on less hardy plants from Europe such as olives and Cordyline have been delayed while more home-grown plants will be brought inside. "We are using a lot more fleece as well," says sales manager Andy Moreham. "We are already starting to fleece plants that we didn't have damage on last time but we are taking extra precautions this year."

Fleecing is something that should never be disregarded, according to Dove Associates founder John Adlam, but he feels that plant cover products made of soft textured plastic offer a more effective "blanket" by creating pockets of trapped air. "Twin skinning" of polytunnels and lining glasshouses with bubble poly are also highly effective ways of increasing insulation while potentially saving on heating costs, he says.

"In an ideal world, growers should also increase the potash levels of plants prior to winter with a high potash liquid feed because higher potash in the plant tissue produces a sort of antifreeze effect," he explains. Products such as Cropaid Antifrost, which is marketed as a "natural plant antifreeze", are also worth investigating, Adlam suggests.

Nurseries should also improve environmental conditions by tightening up on housekeeping protocols, he continues. "Make sure that there is no standing water lying around, plants aren't too wet and windbreaks are operational. Ditches must be clear so that water can escape easily and careful consideration should be given to where salt is put down. If water runs off salted paths into the crops it can cause serious damage."

Adlam also advises using antitranspirant spray on evergreens to stop them suffering damage when their growing media is frozen. Treating plants prior to laying down salt on pathways will also help to protect leaves from potential salt damage, he adds.

Bare root strategy

While nurseries around the country are implementing many new precautions, there are a few that are not. Among them is Hillier Nurseries in Hampshire, which suffered no losses last winter and whose strategy will remain unchanged, according to managing director Andy McIndoe.

Similarly, Weasdale Nurseries will do nothing differently despite having seen losses last winter. Unlike Hillier, the Cumbria-based tree grower is situated at an elevation of 850ft and grows only in the open ground. "There is nothing we can do really - that is the way of a bare roots nursery," says director Andrew Forsyth. "We'll get as many plants as we can out before the bad weather, but most are very well protected in the ground."

Forsyth strongly believes that the industry should resist the move away from bare root nurseries. "There are so many advantages to it and last winter really underlined that. If we had been a container nursery we probably would have lost about 70 per cent," he points out.

Whatever measures nurseries are putting in place, ADAS senior consultant Andrew Hewson thinks the sector as a whole is responding in the right way. "Having had their fingers burnt for two successive winters, they are taking a cautious approach and I don't think that is an over-reaction because if we do have another hard winter and they don't do these things they are going to have more losses," he says.

Hewson adds that if nurseries were to suffer the same losses this winter they may lose buyers who could be hard to win back in the current climate. "At a time when we are building confidence in British-grown container plants, we don't want to risk eroding it, so it's even more important to take the right precautions now," he insists.

But he feels that UK growers are taking a well balanced approach. "We just have to hope that we don't have a winter like the last one," he says. "But if we assume the worst, we will come through in better shape than last time."

Andrew Hewson's key tips for winter preparation

- If protected space is short, identify and prioritise stock requiring protection.

- Do not bring outdoor stock inside too soon because it needs to acclimatise gradually to bolster its natural resistance to winter injury.

- Ease back watering and feeding regimes as autumn unfolds and winter arrives.

- Keep crops well vented as conditions allow to harden them up.

- Ensure that they are healthy and free of pests and diseases.

- Gap up container stock for extra root protection - double stacking can be considered for extra short-term protection.

- Ensure that you have plenty of protective fleece available - order it now if not already - and use twin layers over plants if it is extra cold.

- Use straw bales around blocks of plants to keep cold winds at bay and use space heaters during very cold spells.

- If protected space is short, stack certain plants on trolleys, taking care not to cause damage, and wheel inside to utilise pathways. Do not leave them inside for too long come springtime, otherwise they will quickly deteriorate.

- Ensure that glasshouses and tunnels are well sealed to keep frost out and heat in.

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