Global Warming and Fruit Growing in the UK

A contribution from Howard Stringer, who gardens in Surrey in the south of England

There are many scares in the press about the apple growing no longer being commercially possible in the south of England in years to come and we have all heard of the foresighted man who has planted an olive grove. But is it necessarily so?

The problem arises because of the need for a period of winter chilling, defined as the sum of the number of hours the apple tree receives below 7°C in winter. If less than a number of hours specific to each variety, the tree fails to crop satisfactorily, which makes it commercially unreliable.

Blackcurrants and raspberries can also be affected by an unduly warm winter – for example, several varieties of blackcurrant raised in Scotland (the Ben varieties) and at least one raspberry raised by East Malling in Kent. So unduly warm winters will affect commercial fruit growers to a greater or less extent.

But when one thinks of the apple Pink Lady, which in Europe grows satisfactorily only in warmer climates than the UK, we can see that whilst Cox’s Orange Pippin, which needs the cool UK climate to crop satisfactorily, will be on its way out, or be planted further north, others from warmer climes, and one thinks of Australia, will find a home in the south and new varieties will certainly be bred to fit to the new climate.

An experiment that I undertook eight years ago, without any thought of global warming, was to plant an apple tree on a sunny south wall. Amateur growers usually reserve such a position for peaches, nectarines or the late winter ripening pears. It is sometimes said that a hot dry position encourages mildew on apples, but I wanted to try it out on a very late ripening apple, because I like eating home grown apples in Spring.

I selected the variety Lady Williams, because it emanates from Western Australia; it is one of the parents of Pink Lady, the other being Golden Delicious. Lady Williams is of a bright scarlet colouration in its homeland, making it easy for me to determine its ripeness. Over those years it has had warm winters and cool summers and in 2006 we had the golden opportunity of record temperatures in July and August. Scab or mildew infection has been consistently absent. Its skin colour varied from sun facing side only in a cool summer to an overall bright red in a hot one. Picking date is early December, which has necessitated bird netting. The flesh is white, extremely firm, rather too firm for my ancient teeth, juicy, with the best flavour developing over March to May. By June the flavour starts to deteriorate. After the the warmest year ever recorded my 2006 harvest was brightly coloured all over and although rather tough quite tasty.

Now I am thinking of trying Sturmer Pippin in such a situation, as I fondly remember the Southern hemisphere imports we used to have and the variety does not ripen satisfactorily as a free standing tree with me.

Howard Stringer