Persea americana, the Avocado needs little introduction. A neo-tropical tree it has been cultivated throughout Mesoamerica for millennia. The 'Hass' cultivar originated from a Guatemalan form and is frost tender in the UK and is best grown as a houseplant, pruning it for shape. It will appreciate being placed outside in a warm sheltered spot after the frosts have past and it benefits from the increased light levels, avoiding the leggy etiolated look they can get when grown indoors year after year. In the sun, new growth takes on a coppery colour. Bring it back inside in early October and reduce the watering to a winter minimum.

I have left a few outdoors over some winters just to see what happens. It will go down to about 0C or perhaps -1C for brief periods of time but not the long periods of sub-zero temperatures that are common in the UK. Typically the top growth gets cut down by the frost but it is not uncommon for them to start growing again from the roots rather like a perennial. At the nursery we grow them in an unheated glasshouse and fleece them over the winter. They really don't like it much but it toughens them up and they start growing again once the weather warms up in Spring. The Mexican cultivars are hardier.