INTRODUCTION

In preparation for the most unfavorable weather, a plant may need special protection against the climate. These periods of recurring poor growing conditions must be anticipated well in advance. It would be no use for the plant to begin preparing for winter, for example, the morning of the first frost or for a long, dry, hot season in a desert when water was no longer available.

What a plant does in preparation for long periods of poor weather is often quite elaborate, requiring a long period of good weather after the signal is received that an unfavorable season is approaching. The signal received by the plant cannot be linked directly to future poor conditions. For example, it is not low temperature which triggers the processes inside a plant leading to preparations for winter. Preparations might begin in mid to late summer when the temperature is still high. Shortening day length is a more reliable signal than temperature for plants to use to anticipate winter.

SURVIVAL STRATEGIES

Winter buds

When forming winter buds a plant stops producing new leaves. Instead, small, tough scales are formed which tightly enclose the soft, delicate growing points in terminal buds on branches. They can withstand freezing and thawing many times over without disintegrating and they repel water while keeping the tender tissues inside moist and alive. Only in the spring, when their task is complete, are they shed as the growing points begin once more to grow.