Fertilizing of trees and shrubs during the winter in the high desert should not be done. Fertilizer could stimulate plants to come out of dormancy and start to grow and winter damage could occur. These plants are "resting" above the ground but do have activity in the roots if soil temperatures are warm. Normally trees and shrubs that go into winter with adequate soil moisture do not need watering during the winter. Usually winter rains or snow provide enough water. Deciduous plants do not need much water because the leaves, where transpiration occurs, are gone and nutrients needed for growth are not required because there is no shoot growth. The same holds true for most evergreen plants such as pines, junipers, and native oak trees. When the soil and air temperatures are cold and sunlight is reduced, why grow? That is what spring, summer, and fall are for!

Houseplants are generally tropical in origin and survive best in warm humid environments. Houseplants need to be watered because of the limited soil volume they are confined to. House temperatures are warm and allow plants to continue to grow. The best way to determine soil moisture is to stick a finger in the soil one to two inches. If the soil feels dry, water; if soil feels moist, don't water. Fertilizing houseplants during the winter months is not encouraged because of reduced light from the sun.