Generally — Most Areas
weeping willow (zones 4-9) suits most of Colorado (3b-7b) — zones 4-7 are in range, and the rest of the state is the exception.
Your yard isn't the whole zone.
Colorado spans zones 3b-7b, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score weeping willow against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Weeping Willow Needs
- USDA Zones: 4-9
- Frost-Free Days: 300+
- Sun: Full Sun
- Mature size: 45 ft tall
- Drought tolerance: Low
Colorado Has
- USDA Zones: 3b-7b
- Last Hard Freeze (28°F): Apr 25 - May 19
- First Hard Freeze (28°F): Sep 29 - Oct 16
- Annual Rainfall: 7-20 inches
- Common Soils: Sandy loam, Clay loam, Alkaline caliche
Plant Zone Range (zones 4-9)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Weeping Willow in Colorado
The frost window
Across Colorado, the last spring hard freeze (28°F) clears between Apr 25 and May 19, and the first fall hard freeze lands between Sep 29 and Oct 16 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 133-day window you can count on — up to 174 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
Winter standing
Colorado runs as cold as USDA zone 3, and no sourced winter-hardiness floor is on record for weeping willow, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether weeping willow is a permanent planting or a replant-every-spring crop for you turns on your own zone within Colorado; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Chaffee County, not the statewide average.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says weeping willow survives winter in part of Colorado, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Weeping Willow wants 300+ frost-free days; a typical Colorado site sees ~155 (NOAA Regional Climate Centers ACIS, 1991-2020) — 145 days short of what it needs. A typical Colorado season does not carry this crop to harvest outdoors, and a gap that size is not one an earlier sowing date or a faster cultivar closes; growing it here means growing it under cover.
Chill hours
Weeping Willow requires ~400 chill hours (32-45°F dormancy window). Colorado typically banks ~2500 chill hours per winter (from PRISM 1991-2020 climate normals), which keeps this plant on track.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Weeping Willow likes near-neutral soil (pH 6-8). That's the common-ground band across Colorado's sandy loam and clay loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6.5 and 7.5 — worth knowing before you decide whether a Colorado soil test result is a problem or just a number. Drainage matters: this plant wants poorly (saturated >50% of year), well (dry spells). If your Colorado site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Colorado's soils run mostly loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Weeping Willow needs about 19 inches of workable depth, so it is that horizon — not the surface — you are testing for. That map unit, not the state average, decides how weeping willow performs.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. Colorado soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Weeping Willow in Colorado — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 4-9 (USDA PLANTS Database)
- State Zones: 3b-7b (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Apr 25 - May 19 to Sep 29 - Oct 16 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Weeping Willow in Colorado
Zone compatibility tells you about winter cold survival — but Colorado growers also need to think about:
Low annual rainfall (7-20 inches) means irrigation is essential nearly everywhere
High altitude UV and temperature swings stress plants
Very short growing season at elevation (60-90 frost-free days above 8,000 ft)
Alkaline soils (pH 7.5-8.5) limit acid-loving plants without amendment
Growing weeping willow here specifically
Weeping Willow wants pH 6.0–8.0 and rates to USDA zones 4–9, but Colorado's soils are dominantly loam — the fit is decided by your parcel's own map unit, not the state average.
Match weeping willow to your parcel's SSURGO map unit — test pH and texture, and amend toward its 6.0–8.0 range. How to handle it →
What to actually do about these — and the constraints that apply to every Colorado grower, not just weeping willow — is covered on the Colorado growing guide.
Timing shifts within Colorado
Colorado isn't one climate. In Chaffee County, the last hard freeze (28°F) holds until about Jun 12 — roughly 38 days later than the recorded state median — so plant weeping willow to your county's window, not the statewide date.
Weeping Willow needs about 300 days of frost-free season to complete its cycle. No Colorado county gives it that outdoors: even Mesa County, the state’s longest season at 209 frost-free days, falls 91 days short — so it needs transplants, a short-season variety, or covered growing.
Across Colorado’s 64 counties the frost-free season runs from 85 days in Chaffee County to 209 days in Mesa County — a spread of 124 days, which is why a single statewide planting date misleads. The median Colorado county sees 155 frost-free days, which is 145 days short of what weeping willow needs — so on a typical Colorado parcel this is a transplant-or-protect crop, not a direct-sow one.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Weeping Willow's 300-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Where in Colorado Fits Best
Even within Colorado's zones 3b-7b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for weeping willow (USDA PHZM 2023):
Pollinator + Wildlife Value
Weeping Willow draws honeybees and native bees (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, weeping willow can only work that bloom inside Colorado's frost window — roughly 155 days, opening after the last 28°F freeze (Apr 25 - May 19) and closing at the first (Sep 29 - Oct 16), per NOAA Regional Climate Centers ACIS, 1991-2020.
Good to Know Before You Plant Weeping Willow
Weeping Willow is listed as toxic to dogs, cats (bark, leaves) at a mild level (Pet Poison Helpline). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
Colorado Cooperative Extension
For Colorado-specific cultivar recommendations, planting calendars, and pest pressure for weeping willow, the canonical source is Colorado State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Weeping Willow native to Colorado?
No — the USDA PLANTS Database lists Weeping Willow as introduced rather than native in the Lower 48, so it is not part of Colorado's native flora. It grows here as a garden plant; pairing it with a few Colorado natives keeps local pollinators fed too.
Looking for plants that belong here? The Colorado growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Weeping Willow in Colorado
When can I plant Weeping Willow in Colorado?
Colorado's last spring hard freeze (28°F) clears between Apr 25 and May 19, and the first fall hard freeze lands between Sep 29 and Oct 16 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Weeping Willow, so this page does not state whether it overwinters in Colorado and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Weeping Willow grown in across Colorado?
Colorado spans USDA hardiness zones 3b-7b (USDA ARS PHZM 2023). Weeping Willow carries a range of zones 4-9, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Colorado site have?
A typical Colorado site sees ~155 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Weeping Willow needs 300+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Chaffee, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Weeping Willow native to Colorado?
No — the USDA PLANTS Database lists Weeping Willow as introduced rather than native in the Lower 48, so it is not part of Colorado's native flora. It grows here as a garden plant; pairing it with a few Colorado natives keeps local pollinators fed too.
How should I amend the soil for Weeping Willow in Colorado?
Weeping Willow prefers pH 6-8 and poorly (saturated >50% of year), well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Colorado soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Weeping Willow actually grow on my specific land in Colorado?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores weeping willow against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Colorado
State-level data is a sketch. Your Growable Ground report scores weeping willow against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Colorado weeping willow averages can't show:
We read public map data around Colorado — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Colorado weeping willow average
Explore More
Growing guides for weeping willow
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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