Ever thought of growing your own citrus tree? Many are surprisingly hardy, and their evergreen aromatic leaves, edible fruits and scented flowers, often produced in these gloomy days of winter, make them a more useful prospect than you'd think. A sunny windowsill suits compact varieties, while larger trees will grow in frost-free greenhouses or in some cases outside in the garden.
Oranges require year-round warmth, so if you are without a heated glasshouse, other citrus trees are a more productive choice. Meyer lemons (Citrus x meyeri) are cold tolerant to -8C, so can be grown indoors or outdoors in a sheltered spot. Their fragrant, slightly sweet fruits are thin-skinned and do not travel well, so your best chance of getting your hands on Meyer lemons is to grow them yourself. The most useful variety of lime for home growers is the kaffir lime (Citrus x hystrix). The leaves, rind and juice can be used for flavouring food and adding an aromatic note to spirits. I can't get excited about kumquats (Fortunella species) but some people like eating them. They fruit readily and are a robust plant that tolerates beginners' mistakes. Some kumquats are considered cold tolerant to -10C, though I have not seen one grown outdoors in the UK.
My favourite citrus tree to grow indoors is calamondin (x Citrofortunella mitis) which is always flowering or fruiting and makes fiery-coloured, tasty marmalade. Japanese bitter oranges (Poncirus trifoliata) may be inedible but are cold tolerant to -20C. Scented flowers emerge in late spring and early summer, and long thorns make them an unusual addition to boundary hedges.
If you have a sheltered spot that gets full sun, a few other citrus trees may grow outdoors for you. Yuzu (C. ichangensis x C. reticulata var. austera) are tolerant of temperatures down to -15C. They produce sour fruits valued in Japanese and Korean cooking for their rind and juice. Grapefruits (Citrus x paradisi) will survive down to -8C. Even plants home sown from pips can fruit when grown outdoors, but will take 12 to 15 years to start producing a harvest.
Trees should be planted out after the risk of frost so they have a full growing season to become established before winter. When cold nights are expected, wrap trees in fleece, or bring pot-grown specimens under cover. Mature trees will survive cold temperatures, but if they are flowering or bearing fruit, covering them on a cold night will prevent flower and fruit drop.
Many citrus pips will readily germinate and develop into trees, but the fruits produced by mature plants may not be the same as the fruit you got the pips from, as citrus are often hybrids. Investing in mature trees means that plants will rapidly fruit, or already be fruiting, and they will be hardier as young citrus trees are much more tender.
The keys to success
• Citrus trees require full sun, neutral or slightly acidic soil. Water with rain water if your tap water is alkaline.
• Hardiness varies between varieties, so check the cold tolerance of your variety. Trees grafted on to P. trifoliata rootstock have increased cold tolerance.
• In the growing season (late March-October) they need high-nitrogen fertiliser.
• Citrus benefit from high humidity but falter in waterlogged soil, so stand pot-grown plants on gravel in trays of water.
• Prune only to remove dead branches and shoots growing from below the graft level, or to keep the plant at a desired size.
• The scourge of citrus trees is sap-sucking scale insects and mealy bugs. Watch out for a sticky black coating on leaves and use a cotton bud dipped in methylated spirits to get rid of outbreaks.
• Pests can also be controlled with sprays based on plant oils or soft soap, or biological controls.
Where to buy
Buy one Meyer lemon or one calamondin for £11.99, or buy both plants (one of each variety) for £16.99, including free p&p. Call 0330 333 6856, quoting ref GUA626. Supplied as 9cm potted plants. Parts of plant may be edible. Full details supplied with your order.