During the fall, you should decrease how much you water your lawn as the days shorten. Stop watering cool-season grasses completely once the ground freezes or nighttime temperatures drop below 30℉ for consecutive days.
When it’s blazing hot during the summer, your grass needs adequate water to keep it green and soft. As temperatures fade into the cooler autumn months, you’ll want to modify your watering habits, but your grass still needs plenty of moisture. You should only stop watering entirely in the fall once it goes dormant—if you live in warmer climates—or the ground freezes.
Understanding Why Grass Needs Fall Watering
Yes, the temperatures are cooling down, the leaves are changing, and you may wake up with frost on the ground here and there (this is, of course, if you live in a northern climate), but your grass still needs water. It’s vital that you keep watering your lawn through the fall.
There are two important reasons for this:
First, your grass just survived summer. Hot temperatures and scorching sun take their toll on your lawn; it needs this time to recover and repair itself for the next season. It needs plenty of water to fix the damage incurred.
Second, many lawns go dormant during the winter. To survive this dormancy, the blades of grass store water and resources to draw from as needed and to use first thing in the spring when they start growing again. So, they also need moisture to tuck away for the winter months.
However! Cooler temperatures mean less water is being lost from the blades due to evaporation or transpiration, so your grass doesn’t need as much water as it does during the summer.
Should You Stop Watering All Grasses in Fall?
This is a pretty straightforward question to answer if you live in a northern region. Homeowners in colder climates where there is snow and the ground freezes should stop watering completely. Your grass will go dormant once temperatures drop below about 40°F, so there isn’t any need for water.
At the earliest, stop watering cool-season grasses when the average nighttime temperatures drop into the low 30s. At the latest, you’ll want to stop watering them once the ground freezes solid. Water won’t seep into the soil if the ground is frozen.
If you live in a more temperate area and grow warm-season grasses, you should significantly reduce your water use, but you might want to continue.
First, determine what type of grass you’re growing and if it actively grows through the winter months. If it does grow all year, it may need some water during the winter to keep it green. But if you live in a climate with regular or even occasional winter rain, it may get enough moisture from precipitation.
In this case, ask your local garden center or the country extension office whether you should keep watering or let your grass go dry until spring.
The Importance of Winterizing Sprinklers in Fall and Winter
Wintering your lawn’s sprinkler system is crucial if you live in a climate where you stop watering because of below-freezing temperatures. This process protects above and below-ground components from irreparable damage incurred from freezing and saves your wallet from the cost of extensive repairs.
But why is water and winter a dangerous combination for a sprinkler system?
We learn early on in school that water expands and gets slightly larger when it gets cold and freezes. Most of us have probably accidentally frozen soda cans or water bottles and had them burst open as the contents expanded. The same happens inside your sprinklers when it gets cold.
When winter temperatures drop below freezing, any water in the soil and your sprinklers freezes and can expand by about 10%. While this might not seem like a considerable amount, when dealing with "1-2" water lines or sprinkler heads, it doesn’t need much expansion to put tremendous pressure on these parts.
This excess pressure can completely pop the heads off your system or cause plastic pieces to split or burst. Especially since the cold temperatures make plastic more brittle, increasing its susceptibility to splitting or cracking.
Winterizing gets all of the water out of a sprinkler system, so there isn’t a chance the water can freeze and cause damage.
When To Winterize A Smart Sprinkler System
Timing when to winterize your sprinklers also depends on your local climate. The goal is to keep your sprinklers running as long as possible, ensuring the grass gets water if it’s still growing. Once the grass growth slows for the season because of dropping temperatures and you stop watering, you should winterize your system as soon as possible.
The exact timing depends on the type of sprinkler system and local climate. You can generally expect to winterize your sprinklers between October 1 to Thanksgiving.
If your system is all underground or protected from the elements, you can wait a little later to winterize. If the system includes above-ground parts like exposed water lines or a back flow preventer pipe, err on the side of caution and winterize earlier in that time frame.