Watering in the fall can be particularly problematic. Conditions continue to be dry and trees, shrubs, and lawns need water to avoid stress. Too little water during the fall and winter months can cause root die-off, something that may not be noticeable until well into the next growing season. Water stress during fall and winter can also mean that weakened plants will be more susceptible to insects and disease come summer. Too much water during these seasons can be a bad thing. In areas where there are water restrictions, autumn may require you to do more with even less.
Here’s an excellent article on watering trees and shrubs in the fall from the Colorado State University Extension Service. Some takeaways: shrubs and perennials with shallow root systems are most in need of water during these seasons to avoid root die-off. Mulch is important, not just in keeping moisture in the soil but to prevent soil from cracking (cracks allow cold to invade to greater depths, risking tender roots). Don’t water when temperatures are below 40 degrees; there’s a good chance soil moisture will freeze and damage roots. Water at mid-day so moisture will have a chance to soak into the ground before night-time freezes. (more…)