How To Grow Citrus Fruit / RHS Gardening

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 Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own. 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.

The concentration of water vapour in the atmosphere. This affects the rate at which plants transpire (lose water from their leaf pores), which in turn affects how much water their roots absorb from the soil. If air humidity is low, plants transpire quickly and become at risk of wilting if water is lost from the leaves faster than it can be absorbed by the roots. Different plants require different levels of humidity to thrive. Many tropical houseplants need high humidity and are best grown in a steamy bathroom, misted regularly or placed on a saucer of damp pebbles. In a greenhouse, humidity can be raised in hot weather by damping down (wetting) the floor or overhead misting. 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 Describes soil or potting compost that is saturated with water. The water displaces air from the spaces between soil particles and plant roots can literally drown, unless they are adapted to growing in waterlogged conditions. Waterlogging is common on poorly drained soil or when heavy soil is compacted. . Misting plants is beneficial too – in summer, do it early in the morning to avoid scorching the leaves.

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Feeding

Citrus are hungry plants and benefit from feeding all year round. Lack of nutrients To grow well, plants need a wide range of nutrients in various amounts, depending on the individual plant and its stage of growth. The three key nutrients usually taken up from the soil are nitrogen, phosphorus and potassium. Plants also need carbon, oxygen and hydrogen to make carbohydrates — their main energy source. Carbon and oxygen come from the air as carbon dioxide, while hydrogen is drawn from water absorbed by the roots. Other important soil nutrients include magnesium, calcium and sulphur. Most garden soils contain enough of these nutrients to support healthy plant growth. 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.

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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 The roots and accompanying soil when a plant is removed from a container or lifted from the ground. – 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 Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own. or a nutrient-rich soil-based compost Soil-based compost is a potting compost that includes sterilised soil/loam in the mix. As loam contains sand, silt and clay, it does not rot down like organic materials, so adding soil/loam to compost ensures it is longer lasting – it is often used for shrubs in pots and will last 3–4 years without the need to be replaced. , such as John Innes No 2, and mix in about 20 per cent sharp sand Sharp sand is washed, gritty sand used in potting compost mixes, This is sold for gardening and is not the same as builders sharp sand. or grit to improve drainage.

In the years between repotting, topdress by removing the top layer of compost and replacing with fresh.

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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 The concentration of water vapour in the atmosphere. This affects the rate at which plants transpire (lose water from their leaf pores), which in turn affects how much water their roots absorb from the soil. If air humidity is low, plants transpire quickly and become at risk of wilting if water is lost from the leaves faster than it can be absorbed by the roots. Different plants require different levels of humidity to thrive. Many tropical houseplants need high humidity and are best grown in a steamy bathroom, misted regularly or placed on a saucer of damp pebbles. In a greenhouse, humidity can be raised in hot weather by damping down (wetting) the floor or overhead misting. (see Watering and humidity above). This is particularly important over winter, when plants are indoors.

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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.

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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 The concentration of water vapour in the atmosphere. This affects the rate at which plants transpire (lose water from their leaf pores), which in turn affects how much water their roots absorb from the soil. If air humidity is low, plants transpire quickly and become at risk of wilting if water is lost from the leaves faster than it can be absorbed by the roots. Different plants require different levels of humidity to thrive. Many tropical houseplants need high humidity and are best grown in a steamy bathroom, misted regularly or placed on a saucer of damp pebbles. In a greenhouse, humidity can be raised in hot weather by damping down (wetting) the floor or overhead misting. 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.

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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 A clone is a genetically identical copy of a plant, produced by asexual or vegetative reproduction. Clones have the same genetic makeup as the parent plant. 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 Measures aimed at preventing the spread of potentially harmful organisms (pests, diseases or invasive species) into the environment. These include sourcing plants responsibly, quarantining new plants and practising good garden hygiene. risks (such as introducing plant diseases) associated with growing from the seed of supermarket-bought fruits, so this should be avoided.