There are two kinds of acquisitor. Those with expanses of garden to fill seek a few well-weathered urns, fountains and statues to adorn their acres, and are prepared to pay lavishly for them. Others, in the spirit of true collectors, prize more modest items such as tools and pots. Like those who snap up more conventional "bygones" such as toys, kitchenware, photographs and books, people who collect garden antiques are mainly motivated by their fascination with the development of technology and taste.
Alistair Morris is managing director of Sotheby's in Sussex and a collector of garden bygones in his own right. His book Antiques from the Garden (Garden Art Press, pounds 25) covers the whole range of collecting, from the rustic - summer houses or elaborate stone seats whose prices reach five figures - to the rusting: elegant trowels or plant labels worth only a few pounds.
"Some people think of garden tools as mundane objects," he said as he showed me round his collection. "But they're fascinating. There are lots of different approaches to collecting them. I know people who just go for watering cans: they love the different shapes of their handles and spouts.
"Then there are some who may be more interested in the agricultural type of antiques. Other people collect old lawn mowers and have their own museums and rallies."
Billingshurst is the sole branch of Sotheby's to hold regular sales of garden items. There are two a year, in May and September. Only the one in May includes collectable tools, generally in the upper range of the market. Alternative sources for collectors are house sales, antique and bric-a-brac shops, even car-boot sales. Londoners can browse in the shops that line Columbia Road in the East End, site of the regular Sunday morning plant market. They often have old watering cans and other tools. The Chelsea Gardener in Sydney Street, off the King's Road in west London, stocks cans.
One of the most unusual cans in Alistair Morris's book comes from his own collection. Small but ornate, possibly Austrian and for indoor use, it is made of tinned copper with an imitation horn handle. He paid pounds 80 for it some years ago but it would fetch substantially more today.
The earliest watering cans, made of pottery, had no spouts. Instead, small holes were pierced in the bottom and the gardener controlled the flow by covering the filler hole at the top with his thumb. A few have survived from the 16th century and fetch up to pounds 1,000 at auction today. By the 17th century the shape had developed to something more familiar. Squat glazed earthenware pots had a rose attached to the front on a short spout. Excavations at Bamber Castle in Sussex suggest that many were made there. In the past few years replicas have been produced, but originals sell for up to pounds 4,000.
Long spouts, the prototype of today's, were developed in the 18th century when the cans began to be made of copper and brass. A century later, copper was generally replaced by painted tin, which in turn gave way to zinc and finally plastic.
Metal cans with curved or exceptionally long spouts, needing a minimal tilt of the wrist to start pouring, are favourites with collectors. Prices range from around pounds 100 for ordinary cans, to pounds 1,000 for older and more unusual ones in brass or copper.
The essential processes of distributing water, insecticides and liquid fertilisers gave rise to other ingenious inventions. Early sprinkler systems were powered by hand pumps and some look like giant catherine wheels. Later came hand-held pneumatic syringes in copper or brass.
Although devices such as glass cucumber straighteners and crook-necked grape bottles have fallen into disuse, basic garden implements have developed little over the years in terms of function, only their designs have been modified.
The Victorians indulged their fondness for decoration, even in something as basic as a garden line, that long piece of string used for getting the rows straight - 19th-century lines, wound on to delicately crafted iron spools, are much sought after, and again modern reproductions are being made.
Anything with a distinctive Victorian look will sell well. Reproductions can confuse the market but a scrupulous dealer will always tell you whether you are buying the real thing. Among 19th-century designs being replicated today are bell-shaped glass cloches and iron - or lead-framed - handlights, miniature greenhouses to protect single plants. Originals sell for pounds 250 plus.
Tools for pruning, cutting and picking can also be fun. To gather flowers and fruit, scissor-type blades mounted on a long wooden handle were opened and closed by a ring-pull. The blades were designed to grip the stem to prevent the fruit or flower from falling to the ground. Mostly made in the first 30 years of this century, they can fetch pounds 100 to pounds 150, older and rarer models up to pounds 600.
There are intriguing devices for uprooting or decapitating weeds. Best known is the niblick, a sharp knife shaped like a golf club, allowing sporty types to practice their swing while demolishing the dandelions. It comes with a cover for the blade, so it can also be used as a walking stick. Dating from the 1920s, niblicks sell today for about pounds 100.
Before batteries and mains electricity came into garden use, hand tools required considerable muscle to make them effective. To prune a hedge with an 18-inch hand trimmer with sliding blades would have taken many hours, at the cost of severely aching wrists. A lawn trimmer, along the same lines, would have been no easier to handle.
At Sotheby's sales the emphasis is on artefacts to be looked at or sat upon rather than used. In auction-speak they are called architectural items - statues, gates, filials, columns, pergolas, gazebos and anything else not too bulky to be heaved on to a lorry and transported to Sussex. Some of the buyers for these large pieces come from as far afield as Japan, where an exquisitely furnished garden plays an important part in the culture. Others are local householders making a one-off purchase as a focal point for their plot. A well-preserved antique summerhouse is a rarity because most of them were built of flimsy material, not designed to last, and scarcely worth repairing when ravaged by weather. That is why a rustic summerhouse from the early years of this century, made from wooden logs with intricately designed panels, fetched pounds 13,225 at Sotheby's September sale. For pounds 5,300 you could have acquired a plainer 1930s house, looking a little like a beach hut but on a turntable, so that it can revolve to catch the sun. Good garden seats are also in demand, even when not very old. A reproduction of a classic Lutyens design made pounds 2,415 at the September sale: an original in good condition would have cost much more.
Items for the May sale are collected over the winter and kept in the walled garden alongside the splendid Victorian mansion where the Sussex branch is based. Already a fine collection of urns, planters, jardinieres, gateposts, statues and fountains is being assembled there.
Fantasy is an integral part of designing and making a garden. The Victorians understood that well, and that is why their flamboyant but well-made implements and outdoor adornments are making a comeback. So search your toolshed: that rusty can that the mice nest in, or the mysterious pole with a hook on the end, both ignored for decades, might polish up into something worth its weight in mulch.
! Sotheby's Billingshurst can be contacted on 01403 833500; the next sale is 19-20 MayReuse content