Pliny Natural History, Vol. V (Loeb Latin-English)

...vegetation for the very reason that it does not deluge it. In this way, the earth also is made to ferment and is filled with her own substance, not exhausted by seeds sown in her attempting to suck her milk; and when the passage of time has removed her covering, she greets the mild hours with a smile. This is the method to make corn crops fatten most abundantly—except in countries where the atmosphere is always warm, for instance, Egypt. For there, the unvarying temperature and the mere force of habit produce the same effect that management produces elsewhere; and in any place, it is of the greatest benefit for there to be nothing to cause harm.

In the greater part of the world, when at the summons of heaven’s indulgence the buds have hurried out too early, if cold weather follows, they are shriveled up. This is why late winters are injurious, even to forest trees, which actually suffer worse because they are weighed down by their own shade and because remedial measures cannot help them, as it is not possible to clothe the tender plants with wisps of straw in the case of forest trees.

Effects of rain.

Consequently, rain is favorable first at the period of the winter storms, and next with the wet weather coming before the budding period; and a third season is when the trees are forming their fruit, though not at the first stage, but when the growth has become strong and healthy. Trees that hold back their fruit later and need more prolonged nourishment also receive benefit from late rains, for instance, the vine, the olive, and the pomegranate. These rains, however, are required in a different manner for each kind of tree, as they come to maturity at different times; consequently, you may see the same storm of rain causing damage to some trees and benefiting others, even...