How to grow Citrus Fruit
Citrus Fruits Growing Guide
Citrus crops are more often associated with the warm climates of California, Florida and Mediterranean countries than the cool British Isles, but thanks to new varieties and cultural techniques, these sun-loving fruits are becoming a regular fixture on our shores.
The citrus family is a large one and it has grown as a result of hybridisation and selection over many centuries. Originally derived from just three species, today’s line-up includes familiar favourites such as lemon, orange, lime and grapefruit, along with the many fruits that have risen from these, including mandarins, satsumas and clementines. Citrus fans have developed ever-more exotic combinations by crossing the different varieties to give a whole raft of fruits with characteristics of more than one type. It makes for wonderfully diverse and exciting growing experiences – there’s always something else to try. To grow citrus, you will need a sheltered and sunny position outdoors, such as a sun-trap patio, and a frost-free greenhouse or conservatory to keep your plants safe over the coldest months. They are normally placed outdoors for the summer and then moved in for winter, which makes them the perfect container crop.
Growing Citrus Fruits month-by-month
Keep your plants frost-free and tidy, removing any dead or yellowing leaves to minimise the risk of them contracting a disease.
Re-pot plants using fresh citrus compost before the growing season begins and replace the top layer for established plants.
Begin formative pruning of trees to encourage a good, even globe or cone-shape. Start watering more regularly as the light levels and temperatures increase.
Your plants should be producing their fragrant white flowers by now. Give them a boost with regular top-ups of a citrus feed.
Move citrus outside by the end of the month as soon as the risk of frost has gone. Harden the plants off first, by leaving them outside for progressively longer spells.
Keep trees well-watered and regularly fed as they reach their fastest pace of growth. Those kept under cover should also be well-ventilated.
Check that greenhouse and conservatory plants are not drying out, and provide shading from scorching, concentrated sun rays.
Continue feeding and watering. Complete any necessary pruning before plants begin to slow down for the autumn.
Citrus plants should be fine outside throughout September, but if young fruits are swelling, consider moving plants indoors to maintain a higher night-time temperature.
Bring plants under the cover of a frost-free greenhouse or conservatory. Stand pots on trays of pebbles filled with water to generate humidity.
As cold nights appear check that your greenhouse or conservatory is maintaining a minimum temperature of 5°C. Use a thermometer to be sure.
Don't over-irrigate citrus plants during the winter months. Wait until the compost is dustdry on the surface before watering.
Caring for your Citrus Fruits plants + problems
Watering with consideration is essential and different times of the year will dictate different approaches. The trick is to keep plants moist in the summer, but never wet. In the winter, when temperatures are low and plants are growing very slowly, watering sessions should be dropped back to just once or twice a fortnight so that the compost almost dries out entirely in-between.
Container plants will need regular feeding if they are to flower and set fruit successfully. Special citrus feed is available, but during the growing season it is also possible to use a liquid tomato feed or liquid seaweed solution. Apply this every week or two, according to the instructions. Established plants will need to be potted on into the next size of tub as soon as the roots reach the base of their existing pot. Do this in winter and use fresh compost around the sides. Once the container size reaches 60cm in width and depth, it will be tricky to pot your citrus on much further. To give such plants an additional boost, scrape back the surface layer of compost from the pots each year in late winter and top-up with fresh compost mixed with a little general purpose organic fertiliser that is rich in trace elements.
Pests can become a nuisance under cover where the air is still. To counteract this, provide optimum ventilation – even during the winter (so long as it isn’t too cold outside). Aphids, scale insects and whitefly may be suppressed under cover using ‘biological controls’ – these are predatory insects that can be introduced to feed on the pests. Alternatively, you could spray the plants with a homemade soapy solution. These problems usually disappear when the plants are moved outside for the summer. If you want to keep them under cover all year, regularly damp down the floor and provide some shading during the sunniest, hottest months.
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How to harvest Citrus Fruits
Citrus fruits take up to 12 months to mature, the exception being grapefruits which take even longer! For this reason, it is quite normal to have both flowers and fruits at different stages of growth on one plant. Young plants should only be allowed to set four fruits, but older ones can be left to produce as many as they can – any excess will naturally drop off. The heaviest crops are achieved when average night-time temperatures are above 16°C for the six months following flowering in spring. If you want maximum fruit production then you may need to supply additional heat in early autumn when plants are brought back in under cover.
Consider supporting heavily-laden branches and pick your crops as soon as they are the right size and colour. Ripe fruit may be left on the plant for up to two months without deteriorating, and this is the best option to maintain their juiciness. Cut them away using a sharp knife or a pair of scissors, taking care not to pierce the branches.