PLANTS EXPOSED TO FROSTS.

Waimate Daily Advertiser, Volume IV, Issue 179, 18 March 1902, Page 4

PLANTS EXPOSED TO FROSTS.

It is well known that plants and tree* situated at the bottom of a valley «uiTer much more from cold and frost iftan those in a higher situation. This is due to the fact that the valley, if surrounded by hills and high grounds, not only retains its own cold of radiation, but also serves as a reservoir for the cold heavy air which pours down into it from the neighbouring heights. It is also found that plants and shrubs which survive the severity of winter on ground raised above the level of a valley, perish where grown in the valley itself. As to the immediate effect of temperature upon plants, it is not a particular degree of cold that kills a plant, but the amount of quick thawing. This was illustrated in one case by the curious fact that one end of the same bush—a species of box—was killed in its foliage on one side, while on the other the foliage remained green. The sudden change of temperature produced by quick thawing is considered to be some degrees less for the plants in a high situation and for the shady sides of the half-killed shrubs. The higher situations are in this respect also favourable to plant-life ; because, while the frost is not so severe as in the valley, the effect of thawing winds is found to be the same for both. The plants on the higher grounds are therefore subjected to less strain by sudden variations from a low to a high temperature, and the reverse, than their congeners in the valley.