Even well-adapted plants need protection from climatic extremes
Summer Heat and Winter Cold
Even if you're careful to choose plants well adapted to your climate, there are times when they may require protection from heat, cold, or wind. Seedlings and newly set-out transplants, for example, are vulnerable to both heat and cold. In mild-winter areas, tropical and subtropical plants (such as citrus trees) may need occasional protection from frost; where winters are very cold, certain shrubs and young trees may need protection all winter long. And some shade-loving plants must have sun protection and high humidity throughout the growing season.