I missed it. Dahlias frazzled and a thick layer of ice in the water butts were the only clues as I wrenched myself out of the house and hurried to the allotment into the watery light of a hazy November Sunday afternoon. Jack Frost had well and truly paid a visit.
Despite the devastation, I was glad. Why? Well, frost is very useful to us gardeners, for a number of reasons. First and foremost, it keeps a lot of pests at bay. Think of all the problems that build up on old houseplants kept in their eternal indoor summer. Scale insects, mealy bugs and whitefly can breed away indefinitely, untroubled by even a whiff of frost. Winter’s cold may be tough for us, but it’s lethal to a lot of these nasty little critters.
Ever wondered why farmers in some areas will plough their fields in autumn, even if they’re not going to sow anything until spring? It’s because on a clay soil, the frost works to break down the enormous clods of earth into a fine tilth, ready for spring sowing. And what about the work frost does to sweeten our sprouts, parsnips and kale?
Some plants relish the cold. Apples and blackcurrants in particular, have what’s called a ‘chilling requirement’ (mind you I can think of several people who have that, although their chilling requirement tends to involve red wine rather than cold weather). They need a certain number of hours below a certain temperature in order to break their dormancy and grow properly next spring. It’s a kind of fail-safe mechanism against accidentally coming into full growth during a warm spell in January. Clever, eh?