Citrus sp. (numerous species)
Plant of the month: December
Also Known As: orange, lemon, lime, grapefruit, satsuma, etc
Native To: South-East Asia
Blooms: small, white, highly fragrant flowers
Habitat: subtropical and tropical South-East Asia
Where Found At Birmingham Botanical Gardens: Mediterranean House
Citrus fruits have been cultivated since ancient times, first domesticated in south east Asia where they are found in the wild. Through time, mankind has spread these around the warmer parts of the world for useful crops. Citron (Citrus medica) was the first citrus to be introduced to Europe and was so by the Romans. This fruit can be the size of a rugby ball and can be found growing in our Mediterranean House. Citrus are evergreen trees and shrubs with highly fragrant, white flowers. These flowers can appear all year round, but are especially abundant from late winter to spring. After pollination, the ovary at the base of the flower swells and slowly grows into the fruit. It can take up to 12 months for the fruits to mature to its full size. The fruits only change colour when grown in cool climates; temperatures of around 10C. If grown in tropical countries, even mature orange or lemon fruits can stay green! Citrus like an acidic compost with excellent drainage and lots of fertiliser. We grow ours in ericaceous compost and perlite in clay pots for excellent drainage. Watering can be liberal during the summer, but should be greatly reduced during the winter. Citrus are gross feeders and quickly show signs of hunger (yellow leaves) if not well fed! We feed ours with a good citrus feed all year round. A specially formulated balanced citrus winter feed (N.P.K 20:20:20) is applied weekly from when the clocks go back until the clocks go forward. Thereafter, a high nitrogen citrus feed (25:15:15) is applied weekly. A foliage spray with water is done daily by hose, as they love humidity. Humidity helps to prevent leaf drop.