RHS Growing Guides
How to grow citrus fruit
Our detailed growing guide will help you with each step in successfully growing Citrus.
Getting Started
What better way to add a Mediterranean feel to a sunny patio, doorstep or balcony than with a citrus tree? There’s a wide range of tempting options to choose from, including lemons, limes, calamondin oranges and kumquats.
Calamondins make attractive plants and the fruit is great in preserves
While citrus may not be the easiest plants to grow, if you can give them the right conditions they’ll reward you with fragrant white flowers, glossy evergreen leaves and juicy, tangy fruits. With some varieties, the citrus-scented flowers appear all year round, while others flower in late winter. The resulting fruit ripen slowly, for up to a year, so plants often carry flowers and fruit at the same time, for double the visual appeal.
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Choosing
There is a huge range of citrus plants to choose from, including lemons, oranges, mandarins, limes, grapefruits, kumquats, limequats, calamondin oranges, tangelos, citrons, kaffir limes and more. Some varieties produce fruits that can be eaten straight off the tree, while others are only for cooking or juicing.
Most citrus form attractive small trees or shrubs less than 1.5m (5ft) tall, so are ideal for growing in containers. Some are trickier to grow than others, so check their needs carefully to ensure you can keep them happy. If you’re new to growing citrus fruit, it’s best to start with one of the easier types, such as lemons. Certain varieties of kumquats, limes and calamondin oranges can also be fairly straightforward.
Look for varieties with an RHS Award of Garden Merit (AGM), which shows they performed well in trials. You'll also find citrus plants growing at many of the RHS gardens, so do visit to compare types and pick up growing tips.
What and where to buy
You might spot citrus plants for sale in your local garden centre
Most commercially sold citrus plants are grafted to ensure they fruit at an early age. Ungrafted plants may take up to ten years to fruit, so make sure the plant you’re buying is mature enough to crop. The easiest way to be certain is to buy a plant that is in flower and has started fruiting.
Recommended Varieties
Seville orange Red-tinted fruits traditionally used for marmalade. Image © Shutterstock
Kumquat Oval orange fruits with sour flesh and sweet rind, can be cooked or eaten raw.
Calamondin orange Small round fruits with sharp taste. Scented flowers in spring and summer.
Plant Care
Citrus plants need regular care all year round, including watering with rainwater, feeding with citrus fertiliser and protection from cold temperatures.
Watering and humidity
In summer, water citrus plants regularly, ideally with rainwater, aiming to keep the compost just moist. The compost can dry out quickly, especially in hot weather, so check it daily.
In winter, when plants are indoors, allow the surface of the compost to partially dry out before watering, then water thoroughly with tepid rainwater, allowing the excess to drain away. Overwatering in winter is one of the commonest problems, so err on the dry side, and never leave pots standing in water, as this can cause the roots to rot. Yellowing of the leaves or shedding leaves can be signs of overwatering.
Humidity is important too, especially if plants are kept in a heated environment. To raise humidity, stand the pot in a tray filled with gravel or clay pellets. Keep the water level just below the surface of the gravel, so the compost doesn’t get waterlogged. Misting plants is beneficial too – in summer, do it early in the morning to avoid scorching the leaves.
Misting citrus plants helps create the humid environment they enjoy
Feeding
Citrus are hungry plants and benefit from feeding all year round. Lack of nutrients can cause leaves to turn yellow or drop off, and prevent flowers or fruit forming. Use fertiliser specifically formulated for citrus fruit.
From Iate March to October, apply summer citrus feed, which is high in nitrogen. Then from November to mid-March, switch to a more balanced winter citrus feed.
Repotting
Most newly bought citrus plants can be kept in their original pot for several years. But if you wish to transfer a plant into a more attractive container, choose one that is a similar size and try to disturb the roots as little as possible. The container should be only slightly larger than the rootball – overpotting into a much bigger pot can cause problems.
Once roots start to appear through the holes in the base, it’s time to move the plant into a slightly larger pot. Do this in spring, and use either a specially formulated peat-free citrus compost or a nutrient-rich soil-based compost, such as John Innes No 2, and mix in about 20 per cent sharp sand or grit to improve drainage.
In the years between repotting, topdress by removing the top layer of compost and replacing with fresh.
Pollinating
Citrus plants are self-fertile, meaning you only need one plant to produce fruit. While the flowers don't need to be pollinated by hand, you can improve pollination by raising the humidity (see Watering and humidity above). This is particularly important over winter, when plants are indoors.
Fruit thinning
Citrus trees have a tendency to produce more fruit than they can successfully support, so it’s usually best to reduce the number of young fruits, to help the rest reach a good size and ripen well. As a general guide, most citrus trees about 1m (3ft) tall should be allowed to carry no more than 20 fruits at one time.
Only kumquats, with their much smaller fruits and bushy style of growth, can successfully carry a heavy crop without any need for thinning.
Winter protection
As citrus plants aren’t hardy, they must be brought indoors as soon as night temperatures start to dip in autumn. However, they don't tend to make happy houseplants – the main rooms of centrally-heated homes are usually too warm in winter and the air tends to be too dry.
Different types of citrus have different levels of tolerance to cold, so check your plant’s requirements when deciding where to keep it over winter. A frost-free greenhouse may be suitable for some, but others need warmer conditions, such as a conservatory. Some lemons, for example, will be fine as low as 5°C (42°F), kumquats often need 7°C (45°F) or more, limes and grapefruits should be kept above 10°C (50°F) and calamondin oranges need at least 13°C (55°F).
Citrus plants should keep their leaves all winter, which means they require plenty of light, humidity and some watering and feeding. Many also flower in late winter. Cool or fluctuating temperatures, dry air and cold draughts can cause them to drop their leaves, fail to flower or not produce fruit.
When preparing to move citrus plants outdoors for the summer, monitor overnight temperatures carefully – you may have to wait until mid-June before conditions are warm enough, depending on your local climate and the cold-tolerance of your specific plant. Also, take care to introduce citrus plants to outdoor conditions gradually by hardening off, so they don’t suffer damage or a check in growth.
Many citrus plants flower over winter, so ensure conditions indoors are suitable
Propagating
If you want to propagate your citrus plant, the easiest method is to take semi-ripe cuttings. This ensures the new plants are clones of their parent and will produce equally good quality fruits, usually within a few years.
Citrus plants grown from seed take several years to begin fruiting and the fruit may be inferior to the parent plant, so it is not usually worth doing. There are also biosecurity risks (such as introducing plant diseases) associated with growing from the seed of supermarket-bought fruits, so this should be avoided.
Pruning and Training
Citrus plants are generally compact and slow growing, and most need only minimal pruning to keep them in good shape:
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In February – thin out any overcrowded branches and remove wayward shoots that spoil the shape of the plant. Sparse or leggy stems can be cut back by up to two-thirds and the leading (tallest) shoot can be reduced, to stimulate bushier growth
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Over summer – prune back any strongly growing new shoots to within the crown to encourage branching, and remove any shoots arising from the main stem below the crown
Citrus plants flower on the tips of new sideshoots, so take care not to overprune, as plants will become very bushy and bear little fruit. If your plant develops an unproductive or very leggy branch, you can hard prune it to encourage new growth – but only attempt this on plants that are healthy and otherwise growing well, and don't hard prune more than one branch per year.
Wear thick gloves when pruning citrus as they are often armed with sharp thorns.
Harvesting
Pulling ripe fruit off can damage it, so always harvest using secateurs
Problems
Citrus plants need plenty of warmth, sun and humidity to thrive, along with careful watering and regular feeding. If conditions aren’t to their liking, they may fail to flower or fruit successfully, or lose their leaves. Specific requirements vary depending on the type of fruit.
Citrus plants are usually disease-free, but do check them regularly for sap-feeding insects (see Common problems, below), especially when indoors.
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