After a very long winter, as soon as the snow melts on the ground, we all want the instant gratification of spring growth. One of the first places we look for spring is our grass lawn, only to be disappointed with the unsightly views of winter kill. We next ask ourselves why our lawn looks like this. Does the snow cause it? Does the cold cause it? Cool-season grasses are very resilient, but even the healthiest of lawns can experience winter kill. Let’s dig a little deeper into the “why” regarding winter kill on our lawns.

First off, what is Winter Kill? According to Merriam-Webster, to kill (a plant or part of a plant) by exposure to winter conditions. Our winter conditions vary year to year in Colorado, experiencing below average, average and above average snowfall months depending on the winter. Another unpredictable factor during Colorado winters is temperature.

So with unpredictable winters, how do we predict winter kill? It isn’t necessarily a very cold winter or a very warm winter that causes it, but extreme temperature changes can be the biggest factor. If we are having an abnormally warm fall and then experience a quick, severe temperature drop, our lawns may be left more susceptible to winter kill. Extreme thawing and refreezing cycles throughout the winter can lead to a higher probability of winter kill. If you need assistance with your lawn after a harsh winter give our local lawn care service business a call and we would love to help you with reviving your lawn in the spring.

Possible issues with your lawn after winter

The major contributors to winter kill are winter desiccation, crown hydration, direct low-temperature kill, ice sheets, snow mold, and winter desiccation. Let’s highlight a few of them;

Winter Desiccation: In Colorado’s arid climate, we usually have a pretty consistent snow cover, but as we know from previous years, we can go through extended dry spells with no of snow cover at all. One stressor that accompanies the absence of snow cover is winter desiccation; extreme dryness that occurs when water in the plant is lost at a faster rate than water is replaced. Winter Grasses can survive through just about any temperature if they are blanketed with snow, but uncovered grasses in very cold conditions will continue to transpire (lose moisture and oxygen) long after the ground is frozen solid. Frozen roots cannot replace the lost moisture sucked away by cold, dry winds, and the plants usually suffer cell death and perhaps even death of the plant crowns.

-Treatment: Patiently wait to see if the grasses return back to health. If the damage is only minor, individual grass plants usually can recover, and surrounding grass plants may fill in. With drastic widespread damage, you likely will need to re-seed or re-sod problem areas with extensive winter kill.

Low-Temperature Kill: Extreme cold like what we usually experience in Colorado winters, by its self, can produce winter kill. Low temperature happens below the grass in the soils root surface and on the turf plants themselves through ice crystal formations. Like other contributing factors to winter kill, extreme freeze and thaw cycles are significant contributors to low-temperature kill.

– Treatment: When spring arrives and you notice damage from winter kill, sodding or seeding may be imperative to help with turf grass recovery.

Crown Hydration: The crowns of turf grass can be suddenly killed if warmer, moist weather is followed by a sudden quick freeze. It is a problem usually associated with turf growing in wet soils. The saturated cells of the plant rupture and die off following extreme fluctuations in freezing and thawing temperatures. Cool-season grasses are especially susceptible to crown hydration damage, because they are more likely to awaken from winter dormancy at the first transition to warmer temperatures.

– Treatment: Widespread damage requires re-seeding or re-sodding. Typically there’s not much you can do to prevent the crown freeze.

Ice Sheets: Extended accumulation of ice sheets on the turf grass can result in plant death. Like many of the other contributing factors to winter kill, at the root of this problem is dramatic temperature swings, such as a late Fall ice storm instead of a gradual transition to winter and slowly establishing a snow blanketing cover on the turf grass.

– Treatment: Monitor your turf grass in the early in the spring and visually check if there is significant damage, it may require reseeding or re-sodding the damaged areas.

Snow Mold: A fungal disease that shows itself in the spring as the snow melts. Two kinds of mold become active under the snow, gray and pink mold. Signs appear as round patches on your lawn with a smashed down appearance and continue to grow if the lawn remains cold and wet. Unlike Winter Desiccation and Crown Freeze, usually Snow Mold is most common when an early, deep snow blankets the ground and prevents the ground from freezing.

– Treatment: The treatments used to repair the damage from these two types of mold are very different. For Pink Snow mold, it’s important to treat the area with a fungicide. Fertilome F-Stop or Bonide Infuse (granular formula), both work wonders. To prevent Gray Snow Mold from spreading gently rake the inoculated patches of the lawn to encourage drying and prevent further growth. Fungicides are not typically recommended on this type of mold.

Voles: These pesky rodents are the culprits to dead tunnels of grass that reveal themselves in the spring. Most voles prefer to reside in areas with heavy plant cover that shelters them from natural predators. During the summer months in Colorado, vole damage is primarily contained in gardens, but most lawn and turf damage occurs during winter beneath the snow. Winters with extended snow cover like in Colorado, can lead to extensive damage because the voles feed on the turf as they burrow tunnels. During the winter months Voles track scarce nutritional resources, such as bushes and plants.

– Treatment: Although an eye sore to look at, if the vole damage isn’t too extreme, the damaged turf areas will most likely grow back and retain their density over time. For severely damaged areas of the lawn, new sod or the need to reseed will be the plan of action.

Now that we have highlighted the causes of winter kill in your lawn, here are a few imperative actions you can take to help minimize winter kill. Unfortunately, there isn’t a solution to avoid the problem altogether.

How to Revive your Lawn in the Spring

Tips that help minimize winter kill

• Consistent lawn mowing from the beginning to the end of the growing season.
• Yearly Aeration at least once preferably twice a year to prevent soil compaction, allowing more water, oxygen, and nutrients deeper into the root system.
• A thorough Fall Cleanup every year to ensure yard debris on the lawn doesn’t retain moisture and become inoculated with mold spores.
• Hedge Trimming & Pruning back ornamental plants, shrubs, hedges, and bushes that could be possible nutrient sources for voles to damage.

The ideal winter for turf grass would be a slow and steady cool down in the fall, which helps to gradually prepare grasses for winter by hardening them off. This is know as winter (acclimation), followed by a good insulating snow cover on top of frozen soils, and a slow and steady warm up in the spring that causes a de-hardening or know as (de-acclimation) of our turf grasses. Since we live in Colorado, predictable weather just doesn’t exist, the best that we can do every year is pray for good weather and hope for the best when spring arrives!

If you need assistance reviving your lawn after a harsh winter give our professional and local lawn care service a call to handle all your maintenance needs to minimize the damaging effects of winter kill.