Many homeowners wonder how much they should be watering their landscapes during the winter. There’s no perfect answer, but there are some guidelines to help you irrigate your lawn, trees, and plants in the colder weather.
Lawns
Grass needs water year-round, even when it’s dormant. Winter watering prevents the roots from drying out and keeps them healthy for a strong re-emergence in the spring. Water in the root cells also helps insulate them from freezing temperatures and moist soil offers them further protection from the cold.
During the cold weather most dormant lawns only need watering once or twice a month. Make sure your irrigation program is set to water deeply to the grass root level (e.g. 6 inches). The amount of rainfall will determine how often you need to supplement with your irrigation system. A soil moisture sensor connected to your controller can monitor soil dryness, or alternatively, you can check by digging down a few inches with a spade. If you’ve overseeded your warm-season lawn with rye grass for the winter, it will require more water (e.g. 1 inch a week).
Mowing
Keep your grass at the maximum height for its type during the winter to help insulate the root system. The following heights are recommended for warm-season grasses (a range indicates varietal differences):
Bermuda (common) — 1.5 to 3 inches
Bermuda (hybrid) — 1 to 2.5 inches
Buffalo — 2 inches
St. Augustine — 2.5 to 4 inches
Zoysia (fine-textured) — 1 to 2 inches
Zoysia (coarse-textured) — 1 to 2.5 inches
Your grass may be dormant, but it will continue to grow when the temperature goes above 40°F. You may have to mow it a few times, especially if the winter is moderate. Just don’t mow when the grass is frosted or frozen. This crushes the crowns and prevents growth in the spring. Walking on grass that’s frozen or brittle also causes the same damage.
Mowing will also kill most common winter weeds. Use a mower bag attachment to prevent the seeds from re-rooting. You can help increase the density of your lawn when mowing by occasionally changing the direction and pattern of mowing (45- 90-degree angles).
Trees
Trees that are dormant in the winter don’t need as much water — once or twice a month should be sufficient if there’s no significant rainfall. Evergreen trees require more frequent watering, as do newly planted trees. The soil should be well-drained but moist to 4-8 inches deep. You can quickly check if the soil around your tree is too dry by pushing a long screwdriver into the ground. If it won’t easily sink 6-8 inches, it’s time to water.
Generally, trees need 5-10 gallons of water per inch of diameter. The lower end of the range is for healthy trees, and the higher end for stressed ones. Trees should be watered slowly and deeply. If possible, use a soaker hose, drip emitters, or bubblers, and don’t get water on the foliage of evergreens, as it can freeze and cause damage. Make sure to water all the way out to the edge of the tree’s root spread which, for most established trees, is equal to their height.
Garden Plants
Perennial garden plants that are dormant still need deep watering a few times a month. Flowering winter plants will need more regular watering. You won’t need to irrigate as much if there’s enough rainfall. Always check the soil first with a moisture meter, soil probe, or your fingers to see if it’s dry a few inches down before watering (don’t let it get too dry).
Drip irrigation and soaker hoses are ideal for garden irrigation. Water is distributed right at the root zone, and soaks into the soil. This method keeps stems and leaves drier, so water doesn’t freeze on them and harm the plants.
Winter Watering Tips
- Water when the temperature is above 40°F.
- Water when there’s no snow or ice on the ground.
- Water earlier in the day so the grass can absorb it before the temperature drops at night. Moisture also needs time to evaporate off the blades to prevent fungal disease.
- Mulch your plants to help them retain water and hold in warmth.
- Water a day or two before a forecast freeze so the water can penetrate the roots for protection.
- Water only your lawn, and avoid runoff on sidewalk, driveways, and roads. The runoff can freeze, creating a safety hazard.
Irrigation System
Make sure you’ve winterized your irrigation system so it’s protected from freezing temperatures, and ready for winter irrigation. Smart controllers have a “seasonal adjust” feature that adjusts the zone run times for winter. Weather-based controllers also adjust irrigation schedules based on local weather conditions gathered from either hourly data feeds and an on-site rain sensor, or from programmed historical climate data.
Be sure to water your lawn using the cycle and soak method. It improves soil water infiltration and reduces runoff by “pulsing” water onto the lawn in small amounts over several hours.
Call the experts at South Austin Irrigation at (512) 534-7449 or submit our online service request form for professional maintenance and repair to your sprinkler system.
