When did you last see your parsnips?: Garden raiders are moving on from mowers and statues - now they steal the plants as well. Someone should invent a booby-trapped carrot, says Duff Hart-Davis

On farmland round the boundaries of tiger reserves in India, cultivators sleep out all summer in little shacks to protect their crops from nocturnal raiders. Now on allotments in the middle of Oxford gardeners are doing the same - the only difference being that in India the thieves are wild boar, deer and the occasional elephant, whereas in this country they are humans.

Does this mean that the law of the jungle prevails in rural England? The short answer seems to be: 'Unfortunately, yes', such has been the spate of garden thefts in recent weeks. You name it, it has been nicked: mowers, diggers, power-saws, strimmers, hand-tools, whole sheds, gates, benches, tables, building stone, paving slabs, roof slates, statues, urns, and - increasingly - growing plants, vegetables, shrubs and trees.

One of the most startling thefts was that of 20 two-year-old conifers - an entire hedge - from outside a house belonging to Bill and June Williams in the Oxfordshire hamlet of Cray's Pond. The trees were five feet high: the labour of digging them out with roots intact and loading them into a lorry must have been enormous - and they cannot have been easy to replant, especially with the ground as dry as it has been.

Clearly the thieves had a buyer ready and waiting; and as other, similar raids have been carried out in the same area, it looks as though a gang of cowboy gardeners is operating there: whenever they have a contract for a new hedge, they supply one - and if the trees or shrubs keel over and die a couple of weeks later, that's too bad, because by then the cowboys have vanished.

Opposite the Williamses lives Jack Hatt, veteran farmer, demolition expert, builder of dams and lakes, and fanatical fisherman. His professional motto is 'Dam and Blast', and his recommendation for dealing with intruders is equally robust. 'Shoot the buggers]' he cries enthusiastically - and he would, for he sleeps with a loaded rifle beside his bed. He merrily recalls the time during the Second World War when gypsies started pinching his kerosene. 'I let go half a dozen .22 bullets up the yard. That shifted 'em, I can tell you. They never came back.' The only proviso, says Jack, 'is that they must be coming towards you. Otherwise, if you shoot them in the backside, they can claim they were running away.'

It is easy to see the attraction of stealing some object as valuable as a mower, worth several hundred pounds. When it surfaces at a second-hand dealer's in another county, or at a car boot sale 100 miles up the motorway, the chances of it being traced are minimal.

Garden ornaments offer similarly good value for size, since antiques are often worth several thousand pounds apiece. Here, though, thieves can come unstuck through mistaking replicas for originals. I shall never forget the day when friends invited us to lunch at their medieval manor house, which stands near the head of an isolated valley: all went well until, after the meal, our hostess looked out of the sitting-room window and exclaimed: 'My god - the urns have gone]'

Arriving from London in the dark the night before, the couple had not really looked round outside, and now they suddenly realised that four lead urns were missing from the terrace. But the thieves had almost certainly failed to realise that they were only modern replicas, worth very little, and not the 18th-century Venetian originals they resembled.

Reprehensible as it is to steal such objects, the theft of plants is harder to excuse. Plants and vegetables, raised, weeded, watered and defended from pests with loving care, become extremely personal. As every gardener knows, the alleged new potato that you buy in a shop bears no relation to the one you have grown. The cash value of the crop under one Home Guard plant is scarcely relevant: what matters is that you have produced it yourself - and I do not blame anyone who has been robbed for seeing red.

It is difficult enough to maintain security in a private garden. How vegetables survive in wide-open allotments, I have never understood - and now that garden-raiding seems all the rage, it is hardly surprising that more than 200 thefts have been reported from Oxford allotments alone.

People have a strangely possessive attitude towards plants, especially in gardens belonging to large organisations like the National Trust. The trust loses prodigious amounts of growing material, and in some gardens now deliberately does not name plants until they have reached a certain size, in the hope that uncertainty will deter potential lifters. Most feared of all are busloads of middle-aged or elderly ladies who, by taking cuttings as if they owned the place, produce the devastating effect of a swarm of locusts.

For those not prepared to open fire in the middle of the night, the question arises of how to protect property. The police and insurance companies offer all sorts of sensible advice. Lock garden sheds securely. Fasten hinges with bolts that go right through the doors and cannot easily be unscrewed. Anchor statues and urns with stainless steel pins let into heavy concrete bases. Plant prickly shrubs like berberis or cotoneaster. Etch a personal code into the metal of machinery.

All this will help - but it will not save your vegetables. You cannot etch your runner beans or rivet your carrots into their sockets. If the soil is good, without too many stones, a villain can dig up a couple of potato plants without making a sound, and even a guard sleeping in a hut will not be disturbed.

More drastic counter-measures are needed. The most effective deterrent is undoubtedly a large dog loose at night: it is not easy to quarter an alsatian in a vegetable patch, but even an empty kennel and notices warning of the presence of a dangerous hound will probably help. Infra-red beams that set off security lights are obviously a boon, provided electricity is laid on. A television camera on a pole may also have a usefully inhibiting effect, even if it is only a dummy, and an oil lamp left glowing may give prowlers pause.

I myself favour trip-wires fitted to simple alarm guns that fire blank 12-bore cartridges and make bangs loud enough to awaken the dead. In the small hours of the night one's mind reaches out for more original devices: explosive parsnips or thunderflash carrots, which would detonate when touched; a pressure pad which, when trodden on, would release anaesthetising gas, so that in the morning you would find your visitor stretched out on the garden path, as comfortable and harmless as Beatrix Potter's Flopsy Bunnies, stupefied by their excessive intake of lettuce.

But horticultural theft is no joke: and it is intolerable that gardens should have to be so heavily defended. The proliferation of rural crime suggests not merely that law and order are breaking down, but that the nation is suffering from a collapse of common decency. In showing casual contempt for the feelings of fellow humans, more and more of us are losing all notion of how to live in harmony with each other.

(Photograph omitted)