Unlikely — Zone Mismatch
sourwood (zones 6-12) does not overlap with North Dakota's zone range (3b-4b). Growing outdoors is unlikely without significant protection.
One zone short — what would close it
Sourwood is hardy to zone 6, and the warmest ground in North Dakota is zone 5 — 1 zone short. Planted in open ground it will not survive a North Dakota winter. To grow it here, grow sourwood in a container and move it under cover for the coldest weeks, or give it a greenhouse.
Season extension and overwintering under cover both work at this margin. How to buy the weeks →
Zone math from 6-12 (plant) against 3-5 (North Dakota). Lift modeled by crop_engine Sprint 20B effective_zone_modifier (+2 zones) via api/fast_sections.py Unlock Engine v2.
Your yard isn't the whole zone.
North Dakota spans zones 3b-4b, 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 sourwood against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Zone Comparison
Sourwood Needs
- USDA Zones: 6-12
- Frost-Free Days: 150+
- Sun: Shade
- Mature size: 35 ft tall
- Drought tolerance: Medium
North Dakota Has
- USDA Zones: 3b-4b
- Last Hard Freeze (28°F): Apr 30 - May 6
- First Hard Freeze (28°F): Oct 4 - Oct 9
- Annual Rainfall: 14-22 inches
- Common Soils: Prairie loam, Clay (Red River Valley), Sandy loam
Plant Zone Range (zones 6-12)
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 Sourwood in North Dakota
The frost window
Across North Dakota, the last spring hard freeze (28°F) clears between Apr 30 and May 6, and the first fall hard freeze lands between Oct 4 and Oct 9 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 151-day window you can count on — up to 162 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
North Dakota runs as cold as USDA zone 3, and no sourced winter-hardiness floor is on record for sourwood, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether sourwood is a permanent planting or a replant-every-spring crop for you turns on your own zone within North Dakota; check its hardiness range against that before treating it as long-lived ground.
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 sourwood does not survive a North Dakota winter in the ground. The season figures below measure a different question — whether it could finish a season here at all — and they only bear on North Dakota under protection.
Frost-free days
Sourwood wants 150+ frost-free days; a typical North Dakota site sees ~157 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a tight window — use transplants and pick early-maturing cultivars.
Chill hours
Sourwood requires ~600 chill hours (32-45°F dormancy window). North Dakota 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
Sourwood likes near-neutral soil (pH 4-6.5). That's the common-ground band across North Dakota's prairie loam and clay (red river valley) — a soil test confirms it for your site.
Your land, not the state average
North Dakota soil pH runs about 7.0–7.5, and that sits above sourwood's tolerated 4–6.5, so the typical North Dakota parcel needs sulfur to bring it down. SSURGO maps it swinging by full points parcel to parcel, so your map unit, not the state number, decides whether sourwood needs lime or sulfur.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. North Dakota soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Sourwood in North Dakota — Quick Answer
- Verdict: Unlikely — Zone Mismatch
- Plant Zones: 6-12 (USDA PLANTS Database)
- State Zones: 3b-4b (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Apr 30 - May 6 to Oct 4 - Oct 9 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Sourwood in North Dakota
Zone compatibility tells you about winter cold survival — but North Dakota growers also need to think about:
Extreme cold (-40F) and short growing season
Persistent wind desiccates plants
Low rainfall in western ND
Growing sourwood here specifically
Sourwood does best acidic (pH 4.0–6.5); North Dakota soils average near pH 7.2, alkaline enough to yellow its leaves as micronutrients lock away.
Work in elemental sulfur or acidic organic matter to pull your parcel toward pH 4.0–6.5, then retest. How to handle it →
What to actually do about these — and the constraints that apply to every North Dakota grower, not just sourwood — is covered on the North Dakota growing guide.
Timing shifts within North Dakota
Sourwood needs about 150 days of frost-free season to complete its cycle. 44 of North Dakota’s 53 counties give it that outright. The tightest that does is Dunn County at 150 frost-free days — 0 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
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"). Sourwood's 150-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Sourwood draws honeybees and native bees (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, sourwood can only work that bloom inside North Dakota's frost window — roughly 157 days, opening after the last 28°F freeze (Apr 30 - May 6) and closing at the first (Oct 4 - Oct 9), per NOAA Regional Climate Centers ACIS, 1991-2020.
North Dakota Cooperative Extension
For North Dakota-specific cultivar recommendations, planting calendars, and pest pressure for sourwood, the canonical source is NDSU Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Sourwood native to North Dakota?
Sourwood is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in North Dakota. It can still earn a place in a North Dakota garden — the zone comparison above tells you whether it will thrive.
Looking for plants that belong here? The North Dakota 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 Sourwood in North Dakota
When can I plant Sourwood in North Dakota?
North Dakota's last spring hard freeze (28°F) clears between Apr 30 and May 6, and the first fall hard freeze lands between Oct 4 and Oct 9 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Sourwood, so this page does not state whether it overwinters in North Dakota 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 Sourwood grown in across North Dakota?
North Dakota spans USDA hardiness zones 3b-4b (USDA ARS PHZM 2023). Sourwood carries a range of zones 6-12, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical North Dakota site have?
A typical North Dakota site sees ~157 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Sourwood needs 150+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Sourwood native to North Dakota?
Sourwood is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in North Dakota. It can still earn a place in a North Dakota garden — the zone comparison above tells you whether it will thrive.
How should I amend the soil for Sourwood in North Dakota?
Sourwood prefers pH 4-6.5 (USDA PLANTS). That sits in the common-ground band across North Dakota soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Sourwood actually grow on my specific land in North Dakota?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores sourwood 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 North Dakota
State-level data is a sketch. Your Growable Ground report scores sourwood against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that North Dakota sourwood averages can't show:
We read public map data around North Dakota — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the North Dakota sourwood average
Explore More
Growing guides for sourwood
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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