Cutting down on chemicals in plant production

Can chemical use be reduced without sacrificing quality? Darby Nursery Stock thinks so. Gavin McEwan reports.

BCP Certis' Sampson and Darby's technican manager Myuzelefov inspect crops in the nursery for pests and diseases - photo: HW
BCP Certis' Sampson and Darby's technican manager Myuzelefov inspect crops in the nursery for pests and diseases - photo: HW

Norfolk-based hardy ornamentals grower Darby Nursery Stock has set itself the challenge of growing more sustainably. But in a competitive market with high customer expectations, that poses considerable challenges.

"We have had an environmental policy and audits for over 12 years," says sales manager Jane Darby. "In the first stage we were pushed towards an environmental policy by our customers. A seminar then told us that at worst it would be cash-neutral, but more probably you will make a saving, and that's been true. Once you start, opportunities arise."

The family-run nursery has always been set up to service garden centres. Jane's father started the business in the 1960s as a way of diversifying from arable farming, just as the garden centre format and plant containerisation were taking off.

It now has 85 permanent employees, including office staff, rising to 150 in season, the difference being made up equally by eastern European and local staff. Its two sites cover 12ha in all.

Reducing chemical use while maintaining quality is complicated by the wide range of plant lines grown in the nursery, currently numbering over 500.

According to managing director Anthony Darby: "If you have a monoculture, it's easier to manage the culture - you are more likely to get closer to optimal conditions. But that's difficult to do in the UK market - you need a range. And we are at the premium end of the spectrum, so there's less tolerance of the odd minor blemish."

Integrated pest management

The nursery has been using integrated pest management (IPM) for the past 10 years - originally under glass, but now in outdoor areas too.

"It's been a gradual move out of doors," says Jane Darby. "You are more in control under glass - the insects don't just fly off and feast on a neighbouring crop. But most of our stock is outside - that's where our reputation is."

The nursery works closely with specialist supplier BCP Certis, which provides the beneficial insects and ongoing on-site support.

BCP development manager Clare Sampson says: "There are fewer and fewer pesticides you can use and the pests are increasingly resistant to these. Customers also want fewer pesticides used and workers prefer it too.

"IPM has come a long way and is improving all the time. There are a few key species that we have used for decades, and we are also developing new products and ways of applying them. But outdoors, the economics are more difficult - pests breed much faster in glasshouses."

Darby operations manager Alastair Hazell has more than 20 years' experience of IPM. "We use the full range," he says. "We have to treat for each pest, which means 'walking' the crops a lot - it has to be time-consuming to get it right. But there is no shortage of volunteers for the work."

Hazell admits, though, that chemicals will continue to play a role. "Plants have to look their best," he says. "We could grow organically today, but the plants would be variable and blemished, and without control-release fertiliser after 12 to 14 months they would potentially be only half the size.

"We try to avoid pyrethroids, for example. But you may need to spray a hotspot of aphids or two-spotted spider mites - their numbers can grow very quickly so you need early control, but it's very targeted. Some pesticides work alongside IPM."

Hazell, a member of the HDC's hardy nursery stock panel, says the incentives to find alternatives to spraying will only increase. "In the next five to 10 years we will lose chemicals that we used to rely on, and the cost of getting Specific Off-Label Approval (SOLA) has gone from hundreds to thousands of pounds," he says. "If the HDC uses the business levy to pursue this, that's money that can't be used for research."

The nursery has also benefited from training and support from the HDC as well as ADAS and the International Plant Propagators' Society.

Technical manager Selchuk "Simo" Myuzelefov says: "It's a big challenge and it depends on the guys on the ground to spot the pests. But we have a very knowledgeable group of colleagues."

Weed management

Alongside reduced pesticides comes the threat of a possible restriction - or even withdrawal - of weed-control chemicals. "I have lost key herbicides recently," says Hazell. "No single herbicide will control all weeds." The changes will affect the nursery's neighbours too, Anthony Darby points out. "If agriculture gets 'dirtier', more weed seeds will blow in," he says, adding that several Australian nurseries have had to close recently because of weed infestation.

"It's relatively easy to keep a propagation nursery clean," he says. "But for liners you have six to 12 months to keep them clean and for finished plants it's two to three years. So it's vital that you only buy from clean nurseries."

This entails a close working relationship between the nursery and its suppliers, says Jane Darby. "We don't chop and change, even if we get a good offer. Some plugs are from Euroland, but more are from the UK. This is deliberate as we like to visit our suppliers.

"We are interested in their environmental credentials and are quite fussy about what they are doing to their plants. For example, do they use heavy chemical treatments? Are weed seeds likely to be a problem?"

Hazell adds: "We check over deliveries and if there are any problems, we notify the supplier and ask them what they've been using. If they've sprayed with pyrethroids for example, there's not much point in using IPM as the residue would deter them. But most of our suppliers are similar to us in their approach."


The nursery invested early in sand beds, which are more efficient than overhead sprinklers and also reduce the spread of disease, says Hazell.

Jane Darby adds: "Water is becoming much more of an issue, from both the environmental and cost point of view. There's no need to recycle water, but there is the risk of Phytophthora and water-borne root diseases. You need good plant husbandry and a clean nursery."

But Anthony Darby is concerned about their long-term viability. "Sand beds will be very questionable in a non-herbicide culture," he says. "You can keep a sand bed clean by using Mypex, but that reduces the capillary action."

The nursery harvests rainwater from the glasshouse roof, but this has to be topped up from the borehole during dry periods.

The glasshouse is heated only to prevent frost, so maintaining plant quality through winter. Otherwise, heaters are used simply to circulate air, reducing the risk of Botrytis.

All this is slowly registering with customers, says Jane Darby. "We have about two requests a year for environmental information," she explains.

"Soon all of them will have environmental policies, and that will probably happen in the next 18-24 months. The big retailers have expanded and are now integrating their stores. Then they will concentrate on the sustainability side."


Darby Nursery Stock was among those piloting an environmental management system (EMS) eight years ago, attaining BS8555 for the phased implementation of an EMS. It has since become the first UK nursery to be awarded ISO 14001 for such systems.

Anthony Darby says that these "have given structure to what we were already doing". And horticultural adviser Jeremy Darby explains: "Everyone is now working towards the same end. EMS draws in existing elements, including the regulation of pesticides and our move towards IPM." This has involved extensive training, including in the management software, he says. "It imposes a discipline. There's a list of responsibilities for each member of staff, so everyone knows where the buck stops. But on paper it would fill a filing cabinet."

The nursery has found waste segregation among the most important issues that the system has thrown up. Careful management has reduced waste volumes going to landfill by 75 per cent, bringing considerable savings.

"You also get into the habit of switching things off, saving energy," says Jeremy Darby. "All the green waste is shredded, composted and re-used in the nursery." He adds that the system encompasses peat use. "You identify it as an issue, then look at alternatives," he says. "We are down to 60-65 per cent peat, and that is advancing."

Environmental consultancy WYG, which helped bring in the EMS, is now involved in measuring the nursery's carbon footprint. According to Jane Darby: "WYG understands the nursery sector and they know what data we keep for the EMS.

"It's difficult though - the supermarkets, for example, have their own way of measuring it. You need something like that that's tailored to nurseries."

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