Rice grows only in hot climates, although some strains are cultivated at high altitudes, and cannot be grown outside in the British Isles.
Rice grows tall for a grass, about 1 metre high, and has hairy leaves with a prominent midrib. The flowers are carried in loose tufts and are yellowish or brownish in colour. Rice which grows in cooler places has seeds with long awns or pointed hairs on, but rice from the lowland tropics has smooth seed.
If you can find seeds, you can grow mountain rice in a greenhouse in summer in the UK. Plants will die in the winter as the northern climate has insufficient light to keep them alive, even if they have not flowered. Minimum temperature 10°C.
In a 9 cm pot, just cover the grains with compost, then keep warm and damp at 20°C. Be patient, as germination may take from 2 weeks to several months.
As the seedlings germinate, first pot up into a 15cm pot, and then move to a 30cm pot. Transplants should be placed slightly deeper in the compost than they were previously growing, as this will help them produce sideshoots.
Plants should be put in full sun and kept well watered. They will need support such as canes or twigs to stop them falling over. Feed with a liquid fertiliser every fortnight. If flowers are produced, run your fingers through those on each plant in turn to help fertilise the flowers (pollen would normally be transferred by the wind when grown outside.)
As the grains develop, continue frequent waterings until they are fully formed, when you should begin to keep the plants drier, to hasten ripening.