Ann Deacon has a weakness for onions. Dozens and dozens of them line her allotment in neat rows, waiting to become ingredients in her curries. Ann’s passion for the staple ingredient of savoury cooking has become a running joke among her fellow allotmenteers since she grew 400 of them last year. But, as she says proudly: “I haven’t had to buy a single onion since then.”

Ann and her friend Sue Constance regularly reap the rewards of their green-fingered toil. Their quarter-of-an-acre plot on the Worthing Road allotments in Littlehampton, West Sussex, yields a bountiful supply of produce. So bountiful that Ann and Sue have bought a giant freezer in which to hoard their harvest. Nine pounds of broad beans have just gone into storage, and there’s plenty more where they came from: leeks, shallots, sprouts, sweetcorn, French beans, runner beans, cabbages and cauliflowers, courgettes and carrots, and a forest of potato plants.

With careful planning, a lot of spade work and plenty of manure, Ann, headteacher of a small primary school in West Wittering near Chichester, and Sue, secretary at Ann’s previous school in Littlehampton, have transformed the allotment they took over four years ago from a derelict patch of ground into a veritable organic vegetable production line.

With a peppercorn rent of just Pounds 7 a year, an extra Pounds 2 in subscriptions and annual expenditure of less than Pounds 50 on seeds and supplies, the allotment pays for itself many times over. Grocery bills are a thing of the past, and Ann enjoys being able to swan through the vegetable section of her local supermarket, stopping only to wonder at the inflated prices people pay for their veg.

But the economic benefits of growing your own are only part of the joy of allotmenteering. The simple pleasure of sowing, tending and harvesting the crops is another, and one Ann inherited from her father, a keen vegetable grower and shower himself. Ann was chuffed to pick up several first and second prizes at local shows - especially when her onions won - but she insists she is “not a fanatic”.

In among the edibles she grows chrysanthemums, a favourite of her father, and the beans wending their way up eight-foot poles have been in the family for years.

Throughout the year, the allotments provide a peaceful weekend refuge from Ann’s working life. “I’ve never heard a portable radio up here or a mobile phone. It’s good to be away from all that. It gives you lots of thinking time. You can run through the school budget or development plan.”

Despite the new housing estate next door, the allotments still attract wildlife. Goldfinches and wrens are more welcome than the occasional mole, but Ann doesn’t mind any of them. “We’re not trying to beat nature but to work alongside it. It doesn’t bother me if we end up sharing some things with the pigeons.”

The allotment also provides a ready source of material for morning assemblies. “If you want to keep 80 little children riveted tell them the saga of the burned-down shed,” Ann says. Vandals torched their shed one night, destroying a herb garden and fruit plants. Ann was devastated, but turned the experience into a cautionary tale for her young charges about the value of respecting other people’s property.

Now Ann is hoping some of her enthusiasm for gardening will rub off on the children at her school. She has persuaded the allotment association to give the school a plot rent free and started an after-school gardening club for Year 6 children.

“One thing I have learned is that there’s not a book written yet that can tell you what to do and when,” she says. “It’s a sort of instinct.”

The other allotment-holders, sceptical old-timers who turned their noses up at Ann and Sue’s first efforts, are now casting admiring glances over their plot, swapping advice and, in the case of Walter, their 80-something neighbour, coveting their giant cabbages. “They were the size of footballs,” Ann says. “He used to hover round saying, ‘They’re beautiful’, so in the end we let him have one.”

Sharing the fruits and vegetables of their labours is one of the most satisfying aspects of having an allotment. And Ann reckons there’s nothing more rewarding after a year’s hard graft than sitting down to Christmas dinner having grown everything on the plate except the turkey.