Can I Grow Hollyhock in Colorado?

Hollyhock in Colorado — the short answer

Colorado is not one climate

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 hollyhock (USDA PHZM 2023):

Zone Comparison

Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.

When to Plant Hollyhock in Colorado

Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.

Soil + Drainage Fit

Drainage matters: this plant wants well (dry spells). If your Colorado site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.

Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Colorado soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.

What Else to Consider for Hollyhock in Colorado

Zone compatibility tells you about winter cold survival — but Colorado growers also need to think about:

What to actually do about these — and the constraints that apply to every Colorado grower, not just hollyhock — is covered on the Colorado growing guide.

Where in Colorado Hollyhock Is Zone-Hardy

Hollyhock is rated for USDA zones 5–9. 59 of Colorado’s 64 counties fall inside that band. The coldest that does is Chaffee County at zone 5a. 5 counties sit below the plant’s zone 5 floor, where an unprotected plant is relying on snow cover and a mild year. Where you are in Colorado decides this one.

Across those 64 counties Colorado’s winter-low ladder runs from zone 4b in Alamosa County to zone 7a in Mesa County — 2.5 USDA zones of spread, which is 25°F between the two counties’ average coldest night of the year. That is why a statewide hardiness answer is where you start and not where you finish.

The planting window moves with it. Chaffee County holds its last hard freeze (28°F) until about Jun 12, while Mesa County is clear by Apr 5 — 68 days apart. Set hollyhock out on your county’s date, not the state’s.

County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F killing freeze — earlier than the folk 32°F "last frost". Hollyhock’s zone 5–9 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.

Pollinator + Wildlife Value

Hollyhock draws honeybees, native bees, butterflies, and hummingbirds (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, hollyhock 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.

Colorado Cooperative Extension

For Colorado-specific cultivar recommendations, planting calendars, and pest pressure for hollyhock, the canonical source is Colorado State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.

Is Hollyhock native to Colorado?

No — the USDA PLANTS Database lists Hollyhock 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.

What pests threaten hollyhock in Colorado?

Japanese beetle is documented in Colorado and will find hollyhock, but it is manageable here. What an experienced grower watches for, and does:

Japanese beetle

Worth watchingdocumented in part of this state

This is on the University of Minnesota's list of Japanese beetle preferred plants — but their read is that fruits, vegetables and herbs tolerate limited leaf feeding, and that in most cases the damage is cosmetic and will not kill the plant.

What to do: Protect it only through the few peak weeks: handpick into soapy water in the cool of morning, harvest regularly through July and August to take the feeding pressure off the edible parts, and keep the plant well watered — a vigorous plant outgrows feeding that looks worse than it is. Do not hang a beetle trap.

Documented range: states listed as Japanese-beetle infested · University of Minnesota Extension, National Plant Board

The full japanese beetle playbook

Only pests whose documented range and host relationship both trace to a primary source appear here — so a quiet section means we have nothing sourced to tell you, not that your garden is pest-free.

Common Questions About Growing Hollyhock in Colorado