Citrofortunella microcarpa

x Citrofortunella microcarpa, or calamondin, is thought to be an intergenetic hybrid between a mandarin orange and a kumquat. In the UK it's grown as a small, ornamental tree, although the small fruits are edible. The flesh is sour, but the fruit is sweet. Citrus trees are self-fertile, so you only need one tree to produce fruit; you will need to hand-pollinate the flowers indoors. You may see the pretty, scented, star-shaped flowers and fruits on the tree at the same time.

In the UK, a calamondin is best grown in a pot so that you can move it to a sheltered spot outdoors in the warmer months (June to September), then indoors to a cool, bright and frost-free location, such as a conservatory or heated greenhouse, in the cooler months. It needs a night temperature of at least 13°C.

Plant in ericaceous compost, John Innes or citrus compost, and water with tepid rainwater if possible. In winter, keep the compost just moist - do not overwater. Feed regularly with a citrus feed from spring to autumn. You could raise the humidity by placing the pot on a saucer or tray filled with gravel and topped up with water.