Generally — Most Areas
watermelon (zones 3-11) suits most of Alaska (1a-9a) — zones 3-9 are in range, and the rest of the state is the exception.
Watermelon in Alaska — the short answer
Watermelon in Alaska: hardy in zones 3–11, full sun, against a state median of ~147 frost-free days.
- Plant zones
- 3-11
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Alaska zones
- 1a-9a
- USDA PHZM 2023
- Frost window
- Apr 16 - May 15 – Sep 24 - Oct 29
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 85 days
- NOAA Regional Climate Centers ACIS station record, 1991-2020, county 28°F killing freeze
- Days to maturity
- 85 days
- Growable Ground Plant Database
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.
Your yard isn't the whole zone.
Alaska spans zones 1a-9a, but your yard has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score watermelon against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Alaska is not one climate
A single Alaska answer averages 28 counties whose growing seasons are 155 days apart — from 85 frost-free days in Southeast Fairbanks County to 240 in Sitka County. Which end of that your land sits nearer changes what watermelon can finish before the first hard freeze.
The middle half of 28 counties runs 118–196 days, with a median of 145 days — a 155-day span end to end.
Measured across 28 Alaska counties. NOAA Regional Climate Centers ACIS station record, 1991-2020, county 28°F killing freeze. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where in Alaska Fits Best
Even within Alaska's zones 1a-9a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for watermelon (USDA PHZM 2023):
Zone Comparison
Watermelon Needs
- USDA Zones: 3-11
- Sun: Full Sun
- Mature size: 1 ft tall
- Picking window: ~21 days of harvest
- Drought tolerance: High
Alaska Has
- USDA Zones: 1a-9a
- Last Hard Freeze (28°F): Apr 16 - May 15
- First Hard Freeze (28°F): Sep 24 - Oct 29
- Annual Rainfall: 10-160 inches
- Common Soils: Permafrost, Glacial silt, Volcanic ash
Plant Zone Range (zones 3-11)
Preferred Soil pH
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 Watermelon in Alaska
The frost window
Across Alaska, the last spring hard freeze (28°F) clears between Apr 16 and May 15, and the first fall hard freeze lands between Sep 24 and Oct 29 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 132-day window you can count on — up to 196 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.
When to start the seed
Those dates are when watermelon goes out, not when it starts. It is sown under cover about 3 weeks ahead, so counting back from Alaska's late-side last freeze of May 15 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Days to maturity vs. the window
At 85 days to maturity (Growable Ground Plant Database), counting from the last hard freeze it ripens with 47 days to spare even in Alaska's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — North Slope County, not the statewide average.
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.
Growing Season Fit
The zone check says watermelon survives winter in part of Alaska, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Days to maturity
Watermelon matures in ~85 days (Growable Ground Plant Database). A typical Alaska site has ~147 frost-free days, so plenty of room for a second succession.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS station record, 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
Watermelon likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across Alaska's permafrost and glacial silt — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6 and 7 — worth knowing before you decide whether a Alaska soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Alaska site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
SSURGO maps about 16.6% of Alaska as poorly or somewhat-poorly drained, and the class flips parcel to parcel. Watermelon tolerates drought well, so wet feet — not dry spells — is its real risk here — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
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. Alaska soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Before you plant watermelon for food
Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before watermelon goes in. What follows is Alaska’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.
Safe to Grow Here?
What the federal record shows across Alaska — and how to grow with it.
We checked the federal record across Alaska — 15,895 documented sites across 7 of the 9 source types we track.
The most significant on record: 281 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Alaska carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Severity Distribution
across Alaska
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Alaska, two things run higher than the national average across Alaska — Mining (5,812 sites) and Superfund (281 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What Else to Consider for Watermelon in Alaska
Zone compatibility tells you about winter cold survival — but Alaska growers also need to think about:
Extremely short growing season (70-110 frost-free days)
Permafrost prevents deep root growth in many areas
Limited soil development in glacial terrain
Growing watermelon here specifically
Watermelon roots run deep and prefer pH 5.5–7.5, but drainage comes first here: SSURGO maps about 16.6% of Alaska as poorly or somewhat-poorly drained, and wet ground rots its roots before pH ever matters.
Plant watermelon on a raised, gravel-amended berm so water drains fast and the roots stays dry. How to handle it →
What to actually do about these — and the constraints that apply to every Alaska grower, not just watermelon — is covered on the Alaska growing guide.
Timing shifts within Alaska
Alaska isn't one climate. In North Slope County, the last hard freeze (28°F) holds until about Jun 7 — roughly 33 days later than the recorded state median — so plant watermelon to your county's window, not the statewide date.
Watermelon needs about 85 days of frost-free season from planting to harvest. Even Southeast Fairbanks County — Alaska’s shortest season at 85 frost-free days — clears that by 0 days, so season length isn’t the constraint anywhere in Alaska. What varies is your own parcel.
Across Alaska’s 28 counties the frost-free season runs from 85 days in Southeast Fairbanks County to 240 days in Sitka County — a spread of 155 days, which is why a single statewide planting date misleads. The median Alaska county sees 147 frost-free days, leaving watermelon about 62 days of slack on a typical parcel — room for a second sowing where the season runs long.
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"). Watermelon's 85-day requirement: USDA PLANTS / Growable Ground plant database (days to maturity). A parcel report resolves your address's own frost dates.
Alaska Cooperative Extension
For Alaska-specific cultivar recommendations, planting calendars, and pest pressure for watermelon, the canonical source is UAF Cooperative Extension Service. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Watermelon native to Alaska?
No — the USDA PLANTS Database lists Watermelon as introduced rather than native in the Lower 48, so it is not part of Alaska's native flora. It grows here as a garden plant; pairing it with a few Alaska natives keeps local pollinators fed too.
Looking for plants that belong here? The Alaska 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 watermelon in Alaska?
Squash bug is documented in Alaska and will find watermelon, but it is manageable here. What an experienced grower watches for, and does:
Squash bug
Worth watchingSquash bugs will feed on any cucurbit — the University of Illinois says all members of the family — but they prefer squash and pumpkins, so a cucumber or melon planting is usually the second thing they find, not the first.
What to do: Let the squash rows do the scouting: check them first, and when egg clusters show up there, start checking leaf undersides here too. Crush eggs on sight and keep debris cleared.
Here: In Alaska that second clean-up lands around Sep 24 - Oct 29, when the first 28°F freeze typically ends the watermelon — pulling the vines then is what strips the overwintering shelter, and leaving them is what stocks next season.
Documented range: the United States · University of Illinois IPM, University of Minnesota Extension
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 Watermelon in Alaska
When can I plant Watermelon in Alaska?
Alaska's last spring hard freeze (28°F) clears between Apr 16 and May 15, and the first fall hard freeze lands between Sep 24 and Oct 29 (NOAA Regional Climate Centers ACIS, 1991-2020). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
Can Watermelon mature before first frost in Alaska?
Yes — Watermelon matures in 85 days (Growable Ground Plant Database), and Alaska's dependable hard-freeze-free window runs 132 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 47 days of margin. Plant once the last hard freeze has passed — two to three weeks later for anything tender — and it ripens ahead of the first fall freeze.
What hardiness zone is Watermelon grown in across Alaska?
Alaska spans USDA hardiness zones 1a-9a (USDA ARS PHZM 2023). Watermelon carries a range of zones 3-11, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Alaska site have?
A typical Alaska site sees ~147 frost-free days per year (derived from NOAA Regional Climate Centers ACIS station record, 1991-2020). Watermelon should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like North Slope, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Watermelon native to Alaska?
No — the USDA PLANTS Database lists Watermelon as introduced rather than native in the Lower 48, so it is not part of Alaska's native flora. It grows here as a garden plant; pairing it with a few Alaska natives keeps local pollinators fed too.
How should I amend the soil for Watermelon in Alaska?
Watermelon prefers pH 5.5-7.5 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Alaska soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Watermelon actually grow on my specific land in Alaska?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores watermelon 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 Alaska
State-level data is a sketch. Your Growable Ground report scores watermelon against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Alaska watermelon averages can't show:
We read public map data around Alaska — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Alaska watermelon average
Explore More
Growing guides for watermelon
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
Last updated: