With drought conditions prevailing in nearly half the country this year, it's been a tough time for gardeners. There is some relief in sight for the southern half of the U.S. as the El Niño weather system moves in this fall and winter. El Niño - an above-average warming of water in the eastern Pacific that occurs every four to five years - is expected to unleash welcome rain in the south, from California to the Carolinas. But it may not be enough to save plants, and there is little rain or snow predicted to help parched areas of the mid-Atlantic, Midwest, and northern regions of the country. The upshot: Don't put the hose away yet!
During droughts, shrubs and trees are more vulnerable than usual to winter injury caused by drying winds and fluctuating temperatures. They also enter the next growing season with reduced resistance to pests and diseases. Conifers and trees and shrubs planted within the last three years are the most susceptible, so water them well this fall. Provide 5 gallons of water for every year a tree has been planted, but no more than 20 gallons. A 5-gallon bucket with small holes drilled in the bottom or a dribbling hose provide water slowly so it soaks into the soil without running off.
Make sure there are 2 to 3 inches of organic mulch (e.g., bark, leaves, peat moss) around trees, but not up against the bark. This layer will insulate the soil and help keep it moist, which in turn will reduce the depth of frost penetration. If the soil doesn't freeze during winter, continue watering. To determine frequency, check soil moisture with a long screwdriver or other metal rod. If you can easily insert the rod to a depth of 8 inches, you shouldn't need to water. If it takes effort to push the rod in, pull out the hose.