Washingtonia filifera

Only borderline. Washingtonia filifera carries an RHS H1C rating, so it is much more tender than a hardy palm like the Trachycarpus fortunei. Desert plants tolerate brief cold to around -11C, but cold, wet British winters are the real risk. It is reliably happy outdoors year-round only in the very mildest coastal and city gardens. Elsewhere, grow it in a pot to overwinter under glass, or plant it in a warm sun-trap and fleece it in hard frost. For fully hardy options, see our hardy palms.

Keep it warm, sheltered and above all dry at the roots. In colder gardens the simplest approach is to grow it in a large container so it can move into a frost-free greenhouse, porch or conservatory for winter. If it is planted out, wrap the trunk and crown in horticultural fleece during hard frost and make sure the soil drains sharply, as cold wet roots cause more damage than the cold itself. It makes an excellent statement among our plants for pots for exactly this reason.

Washingtonia filifera, the California or desert fan palm, is the stouter, shorter and slightly hardier of the two, with a thick trunk and broad grey-green fans. Washingtonia robusta, the Mexican fan palm, is taller, faster and more slender but even more tender. For UK growers, filifera is the better bet, though both need a warm, sheltered spot and winter protection. Either way, treat it as one to protect rather than a fully garden-hardy palm.

It is best known as the California fan palm or desert fan palm, and sometimes the cotton palm for the fine white threads that trail from young leaves. It is the only palm native to the western United States, growing wild around desert springs in California, Arizona and northern Mexico, which is why it brings such a distinctive oasis look to a warm patio.

No. It can naturalise in hot, arid regions of the world, but there is no risk of that in the UK, where our cool, damp climate keeps it firmly in check. Here it is a tender ornamental that needs looking after rather than a plant that will spread. It stays exactly where you plant it and grows slowly, so it is well suited to architectural foliage schemes and large containers.

Yes, and in most of the UK a pot is the ideal way to grow it. A large, deep container of gritty, loam-based compost lets you stand the palm in the hottest spot through summer and move it somewhere frost-free for winter. Water freely in the growing season, keep it drier and sheltered in the cold months, and pot on every couple of years. It is one of our most striking plants for pots and hardy exotics.