We all fall for the occasional impulse buy when visiting the garden centre, but do we know anything about the plants we’re buying? Flowers, enticingly displayed near the tills, may have been drenched by insecticides and others might even be genetically modified cultivars.

It is widely believed that the EU ban on GM flowering crops had neutralised the perceived dangers of GM plants, but this isn't true. In April, the Finnish Food Safety Authority identified orange petunias that had been bred using GM methods. The plant material originated in the Netherlands and Germany.

Eight orange petunia cultivars were immediately withdrawn in the UK and thousands of plants destroyed. The mail order firm Mr Fothergill was horrified on discovering that African Sunset, which it had been selling since 2013, was a GM cultivar. The existence of other examples cannot be discounted.

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What a carry-on. All sense of proportion flies out the window when GM is mentioned. Yes, as an organic gardener, I’m an unashamed heretic. I’ve been arguing for many years that GM is a naturally occurring process and I’m delighted that scientists are now able to use it in plant breeding.

Of course I deplore many of the ways GM has been used by multinationals, but it’s a method, a way of doing things, not a principle. When properly controlled and monitored, genetic modification can achieve excellent results much more quickly than conventional breeding methods ever could.

It's my view that the use of systemic pesticides should be much more worrisome for anyone with an ethical approach to gardening. There’s overwhelming evidence that neonicotinoids, a group of systemic pesticides, damage insects. This includes foraging bees because the chemicals persist in pollen and nectar.

Last year, Richard Gill, of Imperial College, London, reported on a long-term field study conducted at Silwood Park, near Reading. He found that bees exposed to the neonicotinoid clothianidin were not actually killed, but after five weeks they started foraging less effectively and the hives produced fewer young queens. As a result, the overall bee population declined significantly.

For some years, Professor David Goulson of Sussex University has been concerned about the damaging effects of neonicotinoids and the risk gardeners could run when buying plants treated with these pesticides. In June, he blogged: “If I’m buying plants to encourage wildlife, I don’t want the lingering worry that I might be accidentally poisoning my bees, hoverflies and butterflies. I don’t use any pesticides in my garden – I simply don’t need them. I don’t want to bring them in accidentally.”

Goulson was especially worried about the label "perfect for pollinators" that you see in garden centres. The Royal Horticultural Society authorises retailers to use the term for plant species that attract and are useful for bees and other pollinating insects. He recognises that the term is only correct if a plant is grown without the use of systemic pesticides.

His researchers tested how many plants labelled "perfect for pollinators" were for sale in a number of garden centres, supermarkets and DIY outlets contained neonicotinoids. They found that only two of the 29 plant specimens were pesticide-free. Seventy percent of them contained neonicotinoids, 76% had at least one chemical, 38% had two or more and one heather boasted an impressive cocktail of five insecticides and five fungicides. The report prompted responses from two of the outlets: B&Q said it will cease selling pollinator-friendly plants containing systemic pesticides from next February, while Aldi had stopped selling them a month after the samples had been taken.

If you’re concerned about introducing neonicotinoids to your garden – and you should be – ask staff at the garden centre if they have a policy on the use of such pesticides in plants they sell labelled perfect for pollinator.