GARDENING / Oranges are not a lonely fruit: Citrus plants are colonising British conservatories with a vengeance. Michael Leapman gleans tips for growers

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NOT LONG before I arrived at Terence Read's remote nursery at Loddon, Norfolk, he had taken a phone call from the developer of a block of London apartments. 'He wanted six large citrus trees to grow in his foyer,' said Mr Read, as we pushed through rows of scented bushes in his greenhouse, some heavy with ripe fruit. 'I suggested he got something else; otherwise he would only come to me in six months saying the leaves had dropped off.

'Delighted as we'd be to sell him six big ones for pounds 1,000 or so, it's unfair on him and it isn't going to do us any good. We aren't in the business of providing people with plants that are going to die rather quickly.'

For Britain's leading grower of citrus trees and the holder of the national citrus collection, Read's nursery has a peculiar location. In the grounds of the 15th-century Hales Hall, next to the largest medieval brick barn in Britain, it is a mile or so off the road between Norwich and Beccles, reached by a rough, barely signposted gravel track. It is on the colder, flatter side of the country, exposed to strong winds.

Yet since citrus fruits have to be kept indoors in Britain for much of the year, the temperature and the wind do not matter much. What is important is that East Anglia has more light and sun than most places. Light is what citrus needs above all - and that is the main reason why Terence Read would not oblige the London developer. 'Not a lot of fruit will put up with low light and dry conditions,' he explains. 'Even the orangeries that were built on to big houses in the 18th and 19th centuries didn't have enough light.'

The fad for growing citrus trees and bushes in our unsuitable climate began during the 18th century, when no stately home was complete without its fruiting oranges and lemons for house guests to admire. With the introduction of more advanced structural materials, orangeries were transformed into modern, lighter conservatories.

In the Eighties, near the height of the property boom, conservatories came back into fashion and sales of citrus consequently soared. 'That was when the mass demand started,' says Read. 'People think it's fun to have a lemon in a pot.' He warns, though, that many modern conservatories are not ideal. 'Not enough ventilation,' he declares. 'They're more like garden rooms - built for sitting in rather than growing plants in. They need vents in the roof, even in winter; or an extractor fan.

'It is like you and me: in a stuffy room we get drowsy and tired and not very good company. Plants are the same. They mustn't have draughts but they need plenty of air.'

That is why attempts to grow citrus as house plants are invariably doomed. 'A few people grow the dwarf calamondin orange (Citrus mitis) in the house, but they don't live very long - not just because there's not enough light, but because the atmosphere's too dry.'

One hardy species of orange can be grown outdoors in Britain - the Japanese bitter orange. It produces fruits that resemble tangerines but are inedible, although you can make a bitter jelly with them to go with roast meat.

'We have one growing on the wall of the house,' Terence Read says. 'It has vicious spikes. We use it as a root stock to graft other varieties on to.'

For the most part, though, citrus must be kept indoors in winter and outdoors in summer. That is why most citrus are grown in pots, for ease of moving in and out. The minimum temperature they will survive at is 40 degrees Fahrenheit, although they prefer 45. Above 55 they will continue growing - and in some cases fruiting - throughout the year.

Easily the most popular single variety is Meyer's lemon, named after an American botanist who brought it back from China in 1902. It is semi-dwarf, growing to about four feet, and fruits prolifically through most of the year.

Popular oranges are Washington navel and Valencia late, both varieties that can be bought from greengrocers but taste a lot nicer fresh. Read is fond of blood oranges - Malta blood and Moro blood are the best - although they are less popular than they were.

Less often grown are limes: Tahiti is the best for gin drinkers and the pinky Rangpur the most unusual. Grapefruit, although delicious fresh-picked, are less prolific than oranges or lemons and the fruits have to be picked as soon as they are ripe, rather than being kept on as decoration. The small-fruited kumquats are pretty and fun, but are not well suited to the British climate.

Citrus are not difficult to grow, either as bushes or as standards, at the top of a slender trunk. Most can be kept to whatever height suits you best, anything between four and 10 feet. They should be pruned fairly hard in March to keep them in shape, and trimmed lightly in summer if they are getting too bushy.

'One of the problems I find is that people won't prune things enough,' Read says. 'They let them go mad. Remember that a conservatory is not a natural place for plants - you have to treat them unnaturally. You can't just let them grow to your heart's content.

'Putting them in the right size of pot helps. Citrus in particular don't like being over-

potted.' They grow best in terracotta pots or wooden tubs, in a soil-based compost - John Innes Number 2 or Number 3.

One of their attractions is the fragrant blossom. When this is finished, several fruits will develop in a cluster. These should be reduced to one per branch when they are about 3/4 -inch in diameter - large enough to judge which are likely to produce the best fruit.

Many people grow citrus from pips but these are unlikely to produce flowers or fruit: even if they do it could take 15 or even 30 years. Terence Read was recently sent a lemon bush grown from a pip more than 10 tears ago and asked to make it flower. He grafted a Meyer's lemon on to it and it ought now to start producing blossom and fruit next year.

The Read family have been active in Norfolk horticulture and market gardening since the last century. 'My great-grandfather was the first person to send cucumbers and tomatoes from Norwich railway station when it was built in the 1860s,' Read says proudly.

The nursery has been on its present site since 1970. It started dealing seriously in citrus fruit about 15 years ago, when Read was told that Rivers of Sawbridgeworth, once the country's leading fruit nursery, was likely to close. When it did close in 1983, Read's took over most of its stock. Now it caters to gardeners' perennial delight in growing things under conditions that nature never intended.

Read's Nursery is at Hales Hall, Loddon, Norfolk NR14 6QW. Telephone and fax 050 846 395. Open Tue-Sat, 10-1pm and 2-5pm.