Lawns Are Off-Limits, Trees Aren't: A Two-Week Fall Watering and Shutdown Plan |
Lawn watering is banned in Denver Water's service area, but trees and shrubs still need winter moisture. Here's how to shut down sprinklers and water by hand over the next two weeks. |
Denver Water's ban on lawn watering took effect Oct. 1, and it puts fall yard work in an odd spot. Spray zones need to be shut down before hard freezes, but trees and shrubs still shouldn't head into winter dry. Here's a plan for the next two weeks.
First, check who supplies your water
The rules below are Denver Water's. Check your water bill to see who supplies your home. If it isn't Denver Water, look up your provider's own rules before you plan winter watering.
What's allowed
On Aug. 26, Denver Water's board amended its Stage 1 drought resolution to prohibit lawn watering as of Oct. 1. The ban covers lawn watering and all spray irrigation. It stays in effect until the board decides how and when lawn watering can resume. Denver Water says sprinklers need to stay off in spring 2027, pending an official board resolution, and it isn't issuing watering exemptions for new turf.
Trees, shrubs, perennials, annuals and vegetables can still be watered any day with a hand-held hose fitted with a shut-off nozzle, or with non-spray irrigation such as drip. What they can't get is water from spray heads.
This week: Shut down the system
For the blowout, CSU Extension advises:
Blow out each zone twice, using two short cycles instead of one long one.
Don't blow out a zone again once it's dry. Air moving through dry pipe creates friction and heat.
Never push compressed air through a pressure vacuum breaker (PVB) or reduced pressure (RP) backflow device. Its rubber seals can melt.
Work the ball valves and test cocks back and forth, then leave them half-open for winter. Valves left fully open or fully closed can trap water that expands and causes damage.
Next week: Start the hose routine
Water only when air and soil are above 40°F with no snow cover. Water at midday so the water soaks in before night freezes, per CSU Extension.
How much
Trees: 10 gallons per inch of trunk diameter, measured 6 inches above ground. A 2-inch tree needs 20 gallons (CSU Fact Sheet 7.211).
New shrubs: 5 gallons twice a month.
Small established shrubs (under 3 feet): 5 gallons monthly.
For established large trees, focus on the root zone within the dripline. Their roots spread at least as wide as the tree is tall.
How often: Water once or twice a month during dry spells with no snow cover. CSU GardenNotes #657 suggests monthly watering when precipitation from October through April totals less than an inch a month. Denver Water's trigger is about three weeks without significant precipitation. It also suggests mulching under the branches and leaving a few inches clear around the trunk.
When you're done, disconnect the hose and shake the water out so it doesn't freeze.
Why it matters now
The numbers behind the ban are stark. Denver Water's reservoirs were 66% full as of Oct. 19, compared with an average of 89% for this time of year, and streamflow forecasts called for 2026 runoff at 10% to 40% of normal. That makes every gallon you aim at a root zone count.
It pays off for the plants, too. Moist soil holds more heat than dry soil, CSU notes, which gives roots more time to establish and improves winter hardiness. Drought-stressed trees can suffer needle and branch dieback and are more vulnerable to insects and disease. New plantings are most at risk, since trees take roughly a year per trunk-inch to establish.
Which tree or shrub is first on your winter watering list? Tell us what you're keeping an eye on. |
27 Comments
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Just blew out my sprinklers this morning, but forgot about shaking the hose dry at the end. Good catch. Will go do that after lunch.
Anyone else feel like October is too soon for a total ban? Some falls have a lot more rain than this one did. Wish they'd allow more flexibility.
Jacki FeldmanI get what you mean. Some years my yard still needs a little water in October. Wish they'd make exceptions when it's extra dry. It feels like a one-size-fits-all solution.
Denver weather is a guessing game. Will try the midday watering, maybe I'll have fewer crispy shrubs come March.
Thanks for reading, and good luck with your shrubs, midday watering really can help minimize freeze damage!
Spray bans make sense but not being able to get an exemption for new sod is rough. Timing was just bad for us this year.
It’s definitely tough timing for new lawns, Denver Water has been clear that no spray exemptions will be issued for new turf this season.
I always mulch too close to the trunk, apparently. That might explain why my evergreens keep getting sad midwinter. Fixing my rings this weekend.
Anyone know a good way to estimate trunk diameter if your trees have low branches all around? Mine is a mess up close.
My HOA just sent an email panicking about brown grass as if Denver Water isn't in a drought. There are bigger issues than curb appeal right now.
Does anyone else just keep a log of how often it snows or rains from October on? I swear the memory is not enough anymore.
It’s weird that you can’t use spray but you can use drip irrigation for veggies. Guess I’ll be investing in more drip lines next spring.
Are apple trees considered 'new' for the 5 gal rule if they were just planted last year? Or does it only count the month they're planted?
Thanks for spelling out the blowout stuff! Nearly ruined my PVB one winter, expensive mistake. Now I triple check everything.
Watering with a hose in gloves is no fun but I'd rather do that than lose my maples. Sucks we got so little rain this fall.
My lilac really struggled last year after January never got snow. Going to be better about the midday watering window this time. Hoping it perks back up by spring.
20 gallons for my little crabapple?? That sounds like a ton but I guess it's what it needs. I'll trust the experts, but I might pace myself.
Does this mean we need to get rid of all lawns eventually? My neighborhood is starting to look very brown.
I appreciate the CSU links in here. Helped a ton with figuring out when to water last winter. The mulch tip really does make a difference too.
Glad the resources were helpful to you! Mulching can make a noticeable difference in protecting roots over the winter.
I feel like I'm always playing detective trying to figure out if it's my water district or Denver Water who makes the rules. Just wish it was standard all over the city.
Anyone recommend a brand of shut-off nozzles that doesn't break after one season? Last year mine cracked right away in November.
I never know how much is 10 gallons for my trees, honestly. I just count to 60 with the hose running and cross my fingers. Probably not the best method but it's worked so far.
Kind of wild that reservoirs are that low. Makes sense to hold off on lawns but this winter watering chore is no joke with a big yard.
It is a big ask, especially with acreage, but every bit of targeted root watering helps both your plants and our overall water supply right now.
Major thanks for the tip about valves being half-open. I always left them fully off after the blowout. Guess I'll be making another trip to the basement tonight.
Never realized Denver Water wouldn't allow exemptions even for new grass. Glad I stuck with the native plants this summer. Will be dragging out the hose for my lilacs though.