Why you have to dig deep to grow your own

For the army of grow-your-own devotees, it is a moment of triumph that makes months of labour worthwhile – the harvest of a clutch of muddy carrots. That sense of green-fingered pride may fade rapidly, however, with the knowledge that it has been achieved at 15 times the cost of buying the same vegetables in a supermarket.

Consumer watchdogs today warn that thousands of novice gardeners are paying through the nose for the satisfying crunch of a homegrown carrot and other easily-grown crops by using expensive seedlings from nurseries which result in vegetables that cost more than £1 each.

A study by Which? found that inexperienced growers are buying plug carrot plants resulting in just one vegetable for up to £1.09 each. In supermarkets, the same outlay would buy a bag of about 15 organic carrots while a packet containing hundreds of seeds can be bought for as little as £1.

The resurgence of interest in amateur horticulture – which has seen waiting lists for allotments grow to 100,000 and august institutions from the National Trust to the House of Windsor setting aside land for growing fruit and veg – has been a boom time for garden centres and seed companies. Seed sales have grown by up to 7 per cent a year and the market for nursery plants and seeds stands at more than £41m. Seeds for edible plants now outsell flowers by about three to one.

But the stampede for a slice of the "good life" is also exposing gaps in the knowledge of many would-be disciples of the self-sufficiency trend. The Which? Gardening report found that some suppliers were offering novice gardeners "really poor value for money" with their pricing of plug plants – single seedlings which can be transplanted direct into the soil.

One company, Gardening Direct, was found to be selling carrot and beetroot seedlings for £1.09 per plant. Another supplier, Thompson and Morgan, was selling carrot plug plants for 14p and beetroot plants for 47p – prices that still represented poor value compared to seeds, according to the consumer body.

Ceri Thomas, editor of Which? Gardening, said: "£1.09 for a carrot is definitely not value for money. Carrot seed is really cheap to buy and very easy to grow – even for novice gardeners. Plug plants for carrots and beetroot are a complete waste of money."

Gardening Direct confirmed it had been selling a variety of carrot seedlings, Autumn King, at £6.99 for 10, but said it was withdrawing all its carrot and beetroot plug plants. The marketing manager, Mark Sherwood, said: "Whilst we believe that our premium quality plug plants normally represent outstanding value for money, we do not wish to mislead gardeners in any way nor be perceived as being poor value for money."