It's very difficult to grow coconuts in the UK. There are no commercial sources of supply, so they would need to be bought from overseas. It is possible to grow coconuts bought from greengrocers and grow them indoors for a few years.
If sourcing seed from abroad, a cultivar called the nyiur-gadang is a small dwarf variety from Malaysia. In the tropics, it can produce coconuts when only about 4m high.
Coconuts require well-drained soil and need regular watering. They also require good light and a minimum temperature of 27°C, give or take 5°C. Organic or inorganic fertiliser is beneficial.
In nurseries, young coconuts with their husk still intact are laid sideways in a shady place and covered with coconut or banana leaves, then watered regularly until a sprout appears, usually after about 6 weeks. In a pot at home, coconuts should be just set in the soil, leaving the skin slightly exposed. It is important that the light source is good. Water it regularly until a sprout emerges. Two leaves should develop. In nurseries, the sprouted coconuts are planted out so that the best plants can be selected for final transplanting, which takes place about 5 months later in a permanent position during the beginning of the rainy season.
A tree may reach 30m in height, and a particularly good tree can yield 100 nuts or more in a season. Remove dead leaves as they drop and mulch around the base of the trees annually with compost, manure or seaweed.
Harvesting can either be when the ripe nuts fall from the tree or by climbing up and cutting fruits off.
Coconuts are prone to pests and diseases. Rhinocerous beetles can damage young trees, and they may be overgrown or smothered by weeds.
There are no sources in the UK. You can buy both mature and green coconuts from shops which may germinate if kept in a pot indoors. The nuts dry out after having been stripped of their husk and this inhibits germination.
Concussions can be caused by falling coconuts hitting plantation harvesters on the head, but it is unlikely to be a problem with UK grown plants!