Weather wise

OLIVE TREES provide a nice way of defining a climate zone. A Mediterranean climate may be defined precisely using rainfall, sunshine and temperature statistics, graphs and so on. But it may be more easily defined by saying "olives will grow there''. They can be grown without difficulty all around the shores of the Mediterranean. However, a fairly sharp cut-off line marks the boundary of the Mediterranean - Central European climate zones. This is seen clearly in places like northern Greece; olives grow profusely along the north Aegean coastline, but are virtually unknown in Bulgaria, only a hundred miles to the north.

So can olives be grown in Britain - several hundred miles north of the Med? The answer seems to be yes. In west Wales, May's high temperatures are giving a flying start to a commercial olive-grower. Garden nursery owners Hilary and David Pritchard have planted olive trees from Italy on the sunny south-facing slopes of their 14 acres at Llangranog, Ceredigion. Brick walls surrounding the grove trap the heat and will help the crop ripen in a Mediterranean-style climate. "It will be a challenge, because there is no guarantee of success,'' Mrs Pritchard said.

Indeed. Olives need not so much year-round heat - though hot, sunny weather is necessary for ripening, as long periods of dry weather. Clearly it is possible to grow Mediterranean plants in Britain - in carefully constructed environments that create their own microclimates.

Those who believe our climate is changing could do worse than buy shares in ventures such as the Pritchards'. If Britain really is moving south, climatically, olives, grapes and who knows, even coconuts, may be gracing the shorelines of Pembrokeshire and Cardigan Bay before long.