Get ready for frost

When tem­per­a­tures dip, our gardens are trans­formed by frost. Here’s a run­down of what’s go­ing on

Garden Answers (UK) - - Contents -

When tem­per­a­tures dip our gardens are trans­formed by frost. Here’s a run­down of what’s go­ing on

Many gar­den­ers greet frost with a heavy heart. It’s a sign that win­ter has fi­nally taken hold of our gardens and that any ten­der plants left out­side will have suc­cumbed to its icy grip. While we can pro­tect prized spec­i­mens with sheets of fleece, mulches of straw or or­ganic mat­ter, cloches and heated green­houses, with­out such shel­ter or in­su­la­tion, a heavy frost spells dis­as­ter for all sorts of plants – from ten­der peren­ni­als to newly es­tab­lished plants, ex­otics, suc­cu­lents and those valiant lit­tle half-hardy an­nu­als that are still in bloom. Frost can strike at any time from au­tumn un­til late spring. It nor­mally forms on still, clear, cold nights, when the cool air makes wa­ter vapour con­dense and form droplets as dew. When the tem­per­a­ture falls be­low 0C (32F) the dew freezes into ice crys­tals.

There are five main types of frost: Air frost oc­curs when the air tem­per­a­ture falls be­low freez­ing point at least 1m (3ft 3in) above the ground Ground frost oc­curs when the sur­face of the ground, ob­jects or trees, has fallen be­low freez­ing point Grass frost can oc­cur when grass freezes but man­made con­crete or Tar­mac sur­faces don’t, be­cause they can hold onto warmth Hoar frost is a par­tic­u­larly feath­ery type of frost. Here the ice crys­tals form when the ground or sur­face tem­per­a­ture reaches freez­ing point be­fore dew be­gins to form. Fog tends to pre­vent the for­ma­tion of hoar frost, be­cause it re­duces sur­face cool­ing White frost is more glob­u­lar than feath­ery. This oc­curs when dew forms first, then sub­se­quently freezes. Frost causes dam­age be­cause plant cells con­tain wa­ter. As tem­per­a­tures drop, so the wa­ter freezes into ice crys­tals that can rup­ture cell walls and con­tents, and stop plant pro­teins from work­ing. Symp­toms in­clude stems col­laps­ing and fo­liage be­com­ing scorched, browned or black­ened. Some­times plants can die. Not ev­ery frost is hard enough to kill plants, how­ever. Con­di­tions such as a morn­ing fog can slow down the thaw­ing process, giv­ing plants a chance to thaw out slowly, re­sult­ing in less dam­age. Hardier species con­tain a type of anti-freeze made from com­plex sug­ars and amino acids, which can lower the freez­ing point of their cell con­tents, while many shrubs and trees rely on bark to act as an in­su­la­tion layer. What’s more, those plants grow­ing in shel­tered po­si­tions, out of frost pock­ets, next to the house or shaded from morn­ing sun­shine can of­ten es­cape with­out any dam­age at all. The good news is that a frost-dam­aged plant isn’t nec­es­sar­ily a write off. Af­ter the risk of frost has passed in late spring, the plant may start to show signs of life again. Trim off scorched growth back to an un­dam­aged bud and the plant should re­spond by pro­duc­ing new shoots.

Hardier species con­tain a type of anti-freeze made from com­plex sug­ars

The feath­ery flower plumes of Cor­tade­ria sel­l­oana (pam­pas grass) slump un­der the weight of thou­sands of tiny ice crys­tals

From etched spider-webs to crys­tallised um­bel­lif­ers, the ef­fects of frost can be daz­zling

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.