Your grass may look dead in the late fall, but don’t let it fool you. It’s only gone dormant and is hibernating for the winter. You still need to maintain it so it can re-emerge strong and healthy in the spring.
Dormant lawns usually only need irrigation once or twice a month in combination with supplemental rainfall. Each application should reach the grass roots level of 6 inches, which requires one inch of water. Water supplied to the root cells keeps them hydrated and insulates them from freezing temperatures. The moist soil adds even more protection, being warmer than dry soil.
There are a number of methods to determine soil dryness during the winter:
- Insert an 8-inch screwdriver into the ground. No need to water if you can push it in more than 3 inches.
- Use a hand trowel or shovel to dig down into the soil 6-8 inches. Roll a handful of soil in your palm. If it rolls easily into a ball, no watering is necessary.
- Attach a soil moisture sensor to your controller.
- Test different areas of your lawn with a soil moisture meter. Insert the metallic probe 6-8 inches into the soil. Check the dial reading for wet, moist, or dry.
- Wait until the temperature is above 40°F to water.
- Even if the temperature is above 40°F, don’t water if there’s snow or ice on the ground. The water can turn to ice and harm the grass.
- Don’t water when there’s frost. Ice can form, and damage or kill the grass.
- Watch the weather, and water a day or two before a predicted freeze. The roots need time to absorb the water for protection from the cold.
- Water earlier in the day, around 9 a.m., so the grass can absorb it before nightfall. The moisture on the blades also needs time to evaporate to prevent fungal disease.
- Avoid runoff on sidewalks, driveways, and roads, where it can freeze and become a safety hazard.
Dormant grass will grow if the temperature stays above 40°F for a number of days. During a moderate winter you will have to mow your lawn periodically. To avoid damaging the crowns, never mow when the grass is frozen, wet, or covered in frost.
If you mow during the winter, keep your grass at the maximum height for its type. Here are the low and high optimum mowing heights for common warm-season grasses, as recommended by the Texas A&M AgriLife Extension Service:
Bermuda (common) — 1.5 to 3 inches
Bermuda (hybrid) — 1 to 2.5 inches
Buffalo — 2 to 4 inches
St. Augustine — 2.5 to 4 inches
Zoysia (fine-textured) — 1 to 2 inches
Zoysia (coarse-textured) — 1 to 2.5 inches
Follow the one-third rule of only cutting off the top one-third of your grass blades. For example, if you want to maintain your lawn height at 2 inches, mow it before it grows over 3 inches high. The one-third rule prevents stressing the grass and ensures a healthy and resilient lawn.
The most common winter broadleaf weeds found in dormant lawns include burweed, henbit, chickweed and clover. A pre-emergent herbicide should be applied in September for prevention. You can split the application and apply the second half around December or January.
If winter weeds do spring up, you’ll have to apply a post-emergent herbicide. Only use a herbicide that attacks the weeds and is safe for your grass. Some weeds, such as chickweed and henbit, are easy to hand pull if there aren’t too many.
Regular lawn mowing will prevent winter weeds from flowering and producing seeds. Eventually this will reduce their numbers. Capture the grass clippings and weed seed heads in a bag attachment so you’re not spreading the weeds.
Apply a bio-stimulant with micronutrients to your dormant lawn in December or January. It helps build healthy soil by increasing the lawn’s microbial activity. If you use a top dressing with compost you run the risk of damaging or killing the grass. Instead, use the top dressing in the spring when the grass is growing.
Don’t fertilize too early in the spring. This helps cool season weeds rather than dormant grass, which can’t take advantage of the fertilizer’s macronutrients until it’s growing in the spring. Fertilizing too early also promotes shoot growth over the root growth needed for a healthy lawn.
Rake and remove the leaves that settled on the lawn during the fall, as well as any fallen branches. A build-up of leaves will suffocate the grass by blocking the nutrients it needs to survive.
Another reason to remove piles of leaves is that they provide a home for unwelcome guests, such as fungus, small rodents, and insects. Bacteria and fungus growing in this moist, warmer environment can cause extensive, long-term damage to your lawn. The insects and rodents will burrow into the ground and create even further problems for the grass in the spring.
An alternative to raking is adding a mulching blade to your mower or using a dedicated mulching mower. Both options will shred the leaves into dime-sized pieces that add nutrients to the soil as they decompose. A regular mower will accomplish the same task but will take several more passes over the leaves.
Removing Lawn Objects
Remove all objects such as logs, toys, lawn furniture, and landscape equipment from your lawn. They’ll damage it and compact the soil, with the affected areas being sparse, thin or dead in the spring. As well, never park vehicles on dormant grass for extended periods. The grass beneath the tires will be killed, and the soil compacted.
Minimize foot traffic as much as possible, especially in the same area. Dormant grass damages more easily and takes longer to recover. A stressed and weakened lawn is more prone to weeds and disease in the spring.
Don’t walk on frozen grass. Ice crystals form inside the blades during a freeze to protect them. Any weight on the frozen blades causes these ice crystals to puncture the cell walls. In the spring, these damaged blades won’t green up.
Many homeowners overseed their lawns with a cool-season ryegrass to keep it green throughout the winter. Overseeded winter lawns need the same maintenance as permanent lawns:
- Irrigate regularly.
- Mow the ryegrass once it’s established to the lowest recommended height for the dormant permanent grass.
- Apply a high-nitrogen fertilizer midwinter for ryegrass growth and color.
- Apply post-emergent herbicides to established ryegrass after it’s had several mowings.
Call the licensed irrigators at Smart Earth Sprinklers at 512-694-1147 or contact us online for your sprinkler system inspection, repair, and maintenance needs.