Growing citrus plants
Whether you grow luscious lemons or ornate oranges, and Steve Val Bradley explain how to keep your potted citrus plants in tip-top condition throughout the year
WITH their glossy leaves and highly fragrant flowers, citrus are popular indoor plants. Even the foliage is scented and they are ideal plants as natural air fresheners, especially if you are allergic to artificial ones.
Citrus come in many sizes and prices, from under £10 to hundreds for an older plant. Varieties include kumquat, orange, lemon, calamondin and lime. Some have full-sized edible fruit, while others are small and bitter, although they can be added to marmalade for extra tang.
Growing outside
The large range of cultivars means some types have vastly different requirements regarding temperature and hardiness to others. Japanese yuzu can tolerate temperatures of -10°C for short periods, while the red lime (Citrus limetta rossa) can only tolerate temperatures down to 5°C for short periods and much prefers a warm room. Almost all benefit from a period growing outside in the summer and they need plenty of natural light all year – the more, the better.
A lot of the plants on sale have been grafted onto a rootstock 1-1½ft (30-45cm) above the compost and many come from southern Europe where they are grown in soil or soil-based compost, which is why the containers are heavy.
Such plants may already have several sizes of fruit developing at the same time as they are producing flowers. This is because citrus flower constantly, even while fruits are developing. If you want fruits you can use, limit the number of fruits that are forming, but ensure you have a succession that will ripen one after another. They store on the plant, so you can pick them as needed.
Flower production
Where citrus plants are being grown indoors, a winter temperature below 10°C helps to encourage flower production the following spring. The most important aspect is good light at all times and you can stand plants outdoors on very mild winter days.
However, large fluctuations of temperature can cause rapid leaf drop, not just in winter, but at any time of year.
This does not have to be fatal, as the plants should start to produce new shoots in spring and the green bark of the stems is capable of limited photosynthesis, providing the light levels are good. If leaf shedding does happen, do not cut back the bare shoots. Citrus do not store large amounts of food in their tissue and severe pruning can weaken or even kill them.
The most common cause for citrus plants dying is incorrect watering, usually overwatering. The best approach is to allow the compost to dry out before flooding the container and allowing the excess to drain away, often at about twoweek intervals, depending on the time of year. If in doubt, do not water. They also benefit from regular misting over the leaves to create a higher humidity.
Troublesome pests include red spider mites and mealybugs, both of which can be treated with biological controls that are safe to use if you want to eat the fruit.