Home landscapes may need watering this winter
Winter isn't usually the time for homeowners to be thinking about outdoor landscapes.
But since fall 2012 has been another abnormally dry, warm season, homeowners ought to evaluate the condition of lawns, shrubs and trees, according to a pair of University of Nebraska experts.
This means going out at least monthly, brushing aside some of the mulch around trees and shrubs, and checking soil moisture. Where soil is dry, water should be applied to avoid some drought-related problems that showed following last winter.
A main concern is evergreen trees, according to Extension Educator Jim Schild of Scotts Bluff County and Community Forestry Specialist Amy Seiler of the Nebraska Forest Service. First, make sure evergreens are mulched, ideally out to the tree's drip line. Pine needle mulch is best for pine trees, but if those have been raked up, wood or wood chip mulch is fine, according to Schild and Seiler.
Mulch not only helps keep soil moist, but also helps keep the ground from freezing as deeply so the roots can continue to take up water and nutrients.
Evergreens should be watered at least monthly, according to Schild and Seiler. If there is little or no snowfall this winter, trees will need about one-fourth of an inch per month or 10 gallons per inch of trunk diameter. For example, a 2-inch trunk diameter requires 20 gallons. They should be watered only on days when the air temperature is over 40 degrees Farenheit.
Also, they say, frozen ground (usually on the north side of trees) should not be watered. The hose should be set on the south side, where the sun will warm the soil and the ground is less likely to be frozen. The target area for watering should extend 10 feet outside the drip line on evergreens.
Newly planted trees require additional watering, since their root system was damaged in the moving and planting process. They also probably need to be watered more frequently. If they're large evergreens that were moved with a tree spade, Schild and Seiler say it might help to spray them with an anti-transpirant to reduce evaporation from the needles. Healthy, mature trees don't need to be sprayed.
Deciduous trees and shrubs that are well mulched and went into the winter with good moisture should need no attention. But if in doubt about whether any tree or shrub needs water, play it on the safe side and check soil moisture, Schild and Seiler recommend.
As far as grass, Schild noted that bluegrass turf on southern-facing slopes or wind-blown knobs tends to dry out, and probably will need supplemental water during the winter, assuming little or no precipitation.
Again, turf should be watered only when the ground is not frozen and when air temperatures are above 40 degrees. Use a flat-head screwdriver to check whether the ground is frozen; the screwdriver cannot be pushed into frozen soil, even a little bit. North sides of houses and other shady areas are most likely to be frozen.
Frozen areas are not likely to be the problem spots next spring, Schild said; the fact they are frozen indicates they have moisture already. Areas with warmer micro-climates will cause problems: next to sidewalks, south-facing slopes, the south and west sides of homes, especially brick homes.
Turf needs only about one-fourth inch of water a month, enough water to keep the crowns hydrated so they don't dry out. Turf that went stressed into the winter will more than likely come out stressed into the spring.
Fall-planted lawns and newly sodded areas will need more attention this winter.
Evergreen shrubs, newly planted perennials, and existing non-native perennials also may need additional water. Check these areas monthly and determine water needs, Schild and Seiler said.
Roses should be mulched, he said. Crowns should be covered with mulch to protect the graft, and they should not be pruned until spring to determine how much winter damage there was to the plant.
When watering in winter, it's best to bring out hoses and attach sprinklers, Schild said, rather than start up underground sprinkler systems, which are prone to freezing up. Hoses should be disconnected in the evening when temperatures dip below freezing, to keep outdoor faucets from freezing.