Winter watering when a chinook clears the snow

Cheyenne's dry wind can clear a yard in a day. A chinook, the warm downslope wind off the mountains west of town, is the one that lifts or melts the snow and leaves the soil open. Roots and evergreen needles keep losing water in that air. CSU Extension says trees, shrubs, lawns, and perennials can be damaged through a long dry fall or winter when snow is not there to wet the ground.

Water only when the air and the soil are above 40°F, and only when snow is not covering the ground. CSU likes midday so the water soaks in before a night freeze. Cheyenne is stricter about the clock. BOPU prohibits outdoor watering from 10 a.m. to 6 p.m., lawns and trees included. Use the morning, before 10, on a day that will climb above 40°F. Skip it while the wind is still up. Watering in high wind is water waste on the BOPU rules. A sheet of ice that sits on the grass for more than a month can smother it.

BOPU allows lawn watering through November 30, no more than three days a week, and never from 10 a.m. to 6 p.m. From December 1 through March 31, lawn irrigation is not allowed. Trees and gardens may still be watered. Their winter note for December, January, and February is about once a month, whether the tree is established or newly planted.

That fits CSU's dry-spell rule: about once or twice a month when the ground is bare and a calm day gets above 40°F. Newly planted trees need it most. A tree takes about a year to establish for each inch of trunk diameter. South and west exposures, and anything getting reflected heat off a wall, dry faster. New sod and seed are the lawns that suffer in a dry November, and November is the last month the city still allows that lawn watering.

Leave the irrigation system off. If it was blown out, one warm weekend is not a reason to refill the lines. Use a hose, a soaker, or a soft spray wand, then disconnect the hose from the spigot so the bib does not freeze full.