How to care for citrus trees and plants
- Hardiness: Not hardy. Will need protection when temperatures drop below 10°C for most varieties.
- Pollination: Self-fertile.
- Height: Approx 6ft maximum.
- Flowering: Year-round.
- Harvesting: Year-round.
- Suitable for: Pot growing.
- Difficulty: Hard.
Citrus trees aren't native to the UK; they originate from much hotter regions like Australia and South Asia, and grow naturally in tropical and subtropical areas of the world. While it's possible to keep citrus in the UK, the grower will need to keep in mind that citrus cannot tolerate frost or low temperatures. For most varieties, temperatures below 10°C will result in damage to the plant.
With this in mind, the best way to for novice gardeners to grow citrus trees in the UK is to keep them in pots. They can be kept outside in a sheltered location with lots of sun from June to September, and moved into a frost-free greenhouse or unheated conservatory for the rest of the year. Even in summer you should keep an eye on the temperature and have some horticultural fleece on hand in case of sudden chills or frosts.
If you've never attempted to grow citrus before, a brilliant variety to start with is the Kumquat, which is more tolerant to cold and usually boasts good yields of fruit. Lemon and grapefruit are the most popular varieties to grow, but lime and orange trees will require year-round warmth, so can be a little trickier. Calamondin in particular will only tolerate winter temperatures of 13°C.
Your citrus tree will need to be repotted into a larger container in the first 12 months, and Spring is usually the best time to do it. Remember to always choose deep pots with drainage holes. There's no specific rule for how much larger the new pot should be, as long as it's big enough to allow the roots to grow for another year or two.
Some tips for repotting:
- We advise that you withhold water for a couple of days in advance to allow the soil to dry out slightly.
- Loosen the soil around the edge of the pot and pull the citrus tree out by the base of the main stem.
- Add some extra soil into the bottom of the new pot before you insert the plant. We recommend John Innes number 2 or 3.
- Fill in with a mix of soil and compost.
- Water the plant thoroughly and keep it well watered for several weeks.
After this first repotting, your tree will need to be repotted every few years as it continues to grow and deplete the nutrients in the potting soil. Look out for the following signs that your citrus tree is ready for a new home:
- Does your citrus plant look less healthy than it used to?
- Does it seem to dry out quicker?
- Are there roots growing out of the holes in the bottom of the pots or the top of the soil?
- Has the citrus tree been in the same pot for two years or more?
Citrus plants are heavy feeders that require a constant source of nutrients throughout the year. We advise that you use Vitax citrus feed, which is available on our website. Use the winter feed from October to March, and summer feed throughout the warmer months to ensure your citrus plant is getting the correct nutrients at the right times.
Ideal conditions for a citrus tree are free draining soil that doesn't become waterlogged, and a high humidity environment with good air circulation.
The best ways to achieve these conditions at home are to choose quality potting soil and a pot with large drainage holes to ensure the soil can drain freely. Stand the pot in a large tray filled with a good layer of gravel or perlite, and fill the tray with water just below the level of the gravel.
Mist the leaves of the citrus tree with water on early summer mornings and water the soil regularly, always ensuring that the base of the pot is not standing in liquid.
In winter when the weather is colder, citrus trees slow down their growing so will require much less water. As a rule of thumb, stick your finger into the first inch of topsoil and if it feels medium dry, water immediately. Always use rainwater where possible.
Grafted citrus trees will grow slowly and require minimal pruning, but when you are giving them a trim, beware the sharp thorns!
In late winter, remove any branches that are crossing, broken or unhealthy. In summer, pinch back the tips of any stems that have grown too long to limit vertical growth and encourage fruiting side shoots.
Fruit and Flowers
Citrus are highly ornamental evergreen trees, which can fruit and flower up to 4 times a year. Although the citrus trees we stock are self-fertile, it's a good idea to help the pollination along to ensure a higher yield of fruit. Simply take a cotton bud or soft paintbrush and lightly brush the inside of each flower, transferring pollen between the blooms.
After the fruit has set, it's completely normal for some to drop from the tree when it's very small, if the yield is too much for the tree to maintain. The fruit which is left can take up to 12 months to grow and ripen, meaning that citrus trees can often have fruit and flowers on them at the same time.
As soon as night time temperatures drop close to 10°C, move your citrus tree into an unheated greenhouse or conservatory (basically somewhere sheltered) to protect it from extreme temperatures and frosts. If you don't have a greenhouse or conservatory, citrus can also be grown on a very sunny windowsill, with good air circulation and constant temperatures, well away from central heating.