It’s not just oranges and lemons, you can also grow limes, grapefruit, kumquats and other citrus varieties in the UK. They are generally not too difficult to grow if, and it’s a big if, you have the right growing conditions. This is the difficult bit.
While citrus plants will sit out in the garden during the summer, our cold wet winters will kill them off in no time. To get good crops you also need to make the growing season as long as possible.
Trying to over winter citrus fruits in the house is generally not successful. The humidity and light levels tend to be too low and the temperature too hot. A frost free green house or conservatory is ideal. For most citrus fruits you’ll need a minimum temperature of 5C, lemons prefer it warmer with a minimum of about 10C. A thermostatic greenhouse heater will keep the temperature in the correct range.
Citrus plants can be grown from seed, but you would have to be very patient if you want fruit, so most people buy plants that are ready to crop. Think carefully about how much room you have before buying a plant. Choose a healthy single stemmed plant.
There are more and more dwarf citrus varieties becoming available. Choose a variety that suits the space and conditions you have to offer. If you want to eat the fruit rather than just have a decorative plant, then do some homework, search the internet to see if other UK gardeners have had good crops from that variety. If you want edible fruit then some of the best varieties are Satsuma ‘Owari’ and Clementine ‘Nules’.
Aphids, spider mite and mealybugs can all attack citrus plants. Scale insects can be a major problem especially under glass. If you notice the foliage has sticky patches then treat it with an organic scale insect treatment. Several applications may be needed. Be sure to spray liberally on the underside of the leaves.
Citrus fruits prefer acidic conditions, so water them with rain water in hard water areas. Avoid pouring cold water onto the roots on hot days, they don’t appreciate the shock.
Standing the pot on a tray of wet gravel or misting the foliage will help keep the humidity up. Citrus fruits like fairly humid conditions, it also helps deter red spider mite..
In the summer you can stand your citrus plant in a sunny, sheltered location outside. Water regularly, letting the surface of the soil just start to dry before watering again. Avoid water-logging and apply a citrus fertilizer weekly. Thin out the young fruits to get a better chance of properly ripe fruits. It takes about 9 months from flower to harvest.
In the autumn bring plants indoors. Stop applying fertilizer and reduce the watering so the compost dries out a little between waterings. Over watering and temperatures that are too high or too low can cause excessive leaf drop. Prune if necessary in late winter.
If the roots are congested, re-pot in the spring using a gritty compost. If re-potting isn’t necessary, just replace the top few centimetres of compost in the pot.