January 2000 - Volume VII, Issue 1

Cold Weather Lawn Tips

David M. Kopec, Extension Turfgrass Specialist

Fertilizing winter lawns in the desert calls for nitrate nitrogen in the cold months of late December, January, and February. This is because the cold soil temperatures do not allow the conversion of other forms of nitrogen (organic, or ammonium) into plant available nitrates. The soil bacteria that allow this conversion are "sleeping" and are too cold to "wake-up."

So for overseeded lawns, apply 1/4 lb -N-/1000 sq. feet of lawn every two to three weeks. You can use potassium nitrate (KNo3), calcium nitrate (Ca2No3), or ammonium nitrate (NH4No3).

Color can be enhanced by spraying iron onto the leaves. One tablespoon in 1 gallon of water will cover a 10' by 10' area of the lawn. After spraying, let the solution dry all day on the leaf.

On mid-elevation turfs (3500-5000 feet), the cool season grasses are semi to fully dormant. Extremely windy and dry conditions may dessicate the lawn. Usually, one or two winter rains do the trick.

At high elevations (6000 feet and above), the grass is fully dormant at this time. Just remember that when shoveling snow off your driveway, excess piles of snow may cause dead spots in the spring. This can be due to a form of fungus (or several kinds of fungi) that causes snow mold.

PINK SNOW MOLD results in dead patches of grass which can occur whether there is snow cover, or not. The grass will look like straw, with a pink cast to it. This occurs when the ground alternates in freezing and thawing cycles- with standing water available. The patches can appear anytime from late January to March.

GRAY SNOW MOLD can occur from February to April (after the last snow melt). Gray snow mold requires a snow cover, and wet ground under the snow. Alternate cycles of rain and snow cover are the most conducive to snow mold. The patches that occur here are straw colored (dead) turf. When you carefully lift up the dead matted leaves, you will find small gray-black volcanic like stones, about the size of a match-head. These are the fungal bodies- all wound up into a resting crust. They will sit until next winter, hoping you had a nice labor day vacation!

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