Winter Watering, Frost and Overseeding in Surprise
Winter watering in Surprise means longer gaps, frost nights and overseeded lawns. Use the city's seasonal table and Extension frost advice to set the timer.
Irrigation Guides5 min read
From December to March the City of Surprise watering table stretches most desert plants to their longest intervals, 30 to 60 days for desert-adapted trees. Overseeded winter grass is the exception and still needs water every 7 to 14 days. On frost nights, well-watered plants under cloth fare best, according to University of Arizona Cooperative Extension.
How often should I water in winter in Surprise?
Far less than in summer. The City of Surprise Landscape Watering Guidelines list December to March intervals of 30 to 60 days for desert-adapted trees, 30 to 45 days for desert shrubs, 21 to 45 days for desert groundcovers, and watering cacti only if needed. Warm-season grass goes 15 to 30 days.
Those are the city's guidelines for established plants, not a rule, and the city notes that cool or rainy weather calls for less water. The depth targets do not change in winter: about 24 to 36 inches for trees and 18 to 24 for shrubs. Water less often, not more shallowly.
| Plant group | Dec to Mar | Oct to Dec |
|---|---|---|
| Desert-adapted trees | 30 to 60 days | 14 to 30 days |
| Desert-adapted shrubs | 30 to 45 days | 14 to 30 days |
| Warm-season grass | 15 to 30 days | 6 to 21 days |
| Cool-season grass | 7 to 14 days | 3 to 10 days |
Source: City of Surprise, Landscape Watering Guidelines
Overseeded lawns need their own program
Some Surprise lawns are overseeded with winter grass on top of dormant Bermuda. The city's ordinance even defines lawn overseeding as planting winter grass on established turf. In the city's table, cool-season grass is the one group that needs regular winter water, every 7 to 14 days from December to March and every 3 to 10 days from October to December, and it gets no water from May to October once the warm-season grass takes over.
That means an overseeded lawn and the shrubs beside it need very different programs in winter. If they share a station, one of them is being watered wrong. Separate stations, or drip for the beds, solve it. The Surprise landscape watering guidelines guide walks through the full table.
How cold does it get in Surprise?
Cold enough to matter some winters. University of Arizona Cooperative Extension notes that first frost dates in Maricopa County range from November 21 in Buckeye to December 12 in central Phoenix, because elevation and the amount of pavement change how cold a place gets. Outlying areas run colder than downtown.
Source: University of Arizona Cooperative Extension, AZ1002 Frost Protection
Extension suggests reading a thermometer in your own yard and comparing it with the reported temperature, since a yard can run several degrees colder than the airport. Cold air flows downhill and settles in low spots, so a sunken backyard or a bed below a wall can frost when the front yard does not.
Watering before a frost
Extension's advice is to keep plants well watered and keep soil moisture as even as possible, because frost damage is worse on a plant that is already drought-stressed. Firm, moist, bare soil absorbs and releases more heat than dry or mulched soil. Extension also describes trickling water at the base of a tree late at night and early in the morning, for no more than three nights in a row.
That does not mean leaving the controller on its summer program. It means making sure the last scheduled watering before a cold night actually reached the root zone.
Covering plants
Extension recommends cloth or paper rather than plastic, draped all the way to the ground and at least out to the drip line, so it traps heat rising from the soil. Sheets and blankets should come off each morning once it warms; many frost cloths can stay on longer. A properly applied frost cloth protects to around 30 degrees F, and some fabrics lower. Keep drip emitters under the cloth running on their normal schedule.
Don't forget the monsoon damage
Winter is a good time to fix what summer storms broke. The National Weather Service Phoenix office marks the monsoon from June 15 to September 30, with downbursts of 50 mph or more. Heads knocked crooked, drip tubing washed out of place and debris in valve boxes are easier to find when the controller runs less. A seasonal irrigation tune-up in Surprise covers both.
Next step in Surprise
Set the winter program by plant group, or let a weather-based controller adjust it; see smart and Wi-Fi irrigation controllers. If the controller will not hold its settings, book irrigation controller repair in Surprise. For plants that went in this fall, read watering new desert plants in Surprise.
FAQ
How often should I water desert plants in winter in Surprise?
- The city's guidelines suggest every 30 to 60 days for established desert-adapted trees and 30 to 45 days for desert shrubs from December to March, with cacti watered only if needed. Water to the same depth as in summer. New plantings need more frequent water until established.
Do I need to water an overseeded lawn in winter?
- Yes. In the City of Surprise table, cool-season grass needs water every 7 to 14 days from December to March and every 3 to 10 days from October to December. It is the only group in the table that needs regular winter water, so keep it on its own station.
Should I water before a freeze?
- Keep plants watered so they are not drought-stressed going into a cold night. University of Arizona Cooperative Extension says frost injury is less severe on plants that are not already dry, and that even soil moisture helps. Do not switch to frequent shallow watering; make sure the last cycle reached the roots.
Is plastic okay for covering plants from frost?
- Extension recommends cloth or paper instead of plastic. Drape the cover all the way to the ground and out to the drip line to trap heat from the soil. Remove sheets or blankets in the morning when it warms, though many frost cloths can stay on longer.
Does Surprise get frost?
- Some winters, yes. Extension reports that first frost dates in Maricopa County range from late November in outlying areas such as Buckeye to mid-December in central Phoenix. Check a thermometer in your own yard, because low spots and open areas can run colder than the reported temperature.
Sources
- City of Surprise Landscape Watering Guidelines surpriseaz.gov