Anita Morton - Growing Gardens
Spring is often hard on gardens in our area, because of both our usual dry weather and sudden onset of warmer temperatures. Extra watering is necessary in most gardens, so perhaps this is a good time to go through the basics.
Water is drawn through plants from the roots up through the stem, branches, twigs and leaves, purely by the suction created by evaporation. Water evaporates through small pores on the underside of the leaves called stomata. These stomata open in response to increasing light levels and close as the light diminishes. As water is lost through the stomata during the day, the suction force created moves down through the plant to the roots, where fine root hairs draw in water and nutrients from the surrounding soil.
Therefore, it makes sense to water your garden in the very early morning. Thats when the stomata are opening, creating the suction which will draw that applied water into the plant. If you water in the evenings, the stomata are closing, so the plant cant absorb moisture. Of course, if you water in the heat of the day, most of it will evaporate before it gets down to the plants roots.
Wilting happens when water is evaporating too rapidly to be replaced from the roots, or when the soil is too dry to provide enough moisture. Always check soil moisture before you water. Drooping plants in moist soil are just suffering a temporary evaporation crisis they will recover in the evening. If the soil is really dry, you need to water deeply. Dont bother with brief sprinkles, but get a weeping hose, soaker hose or drip system and leave it on until you see (by digging holes with a trowel), that the soil is evenly moist. Then keep it damp with mulch and regular, light watering restrictions permitting!