Unlikely — Zone Mismatch
sweetspire (zones 5-11) does not overlap with North Dakota's zone range (3b-4b). Growing outdoors is unlikely without significant protection.
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 sweetspire against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Sweetspire Needs
- USDA Zones: 5-11
- Frost-Free Days: 180+
- Sun: Shade
- Mature size: 6 ft tall
- Drought tolerance: Low
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 5-11)
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 Sweetspire 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 sweetspire, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether sweetspire 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 sweetspire 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
Sweetspire wants 180+ frost-free days; a typical North Dakota site sees ~157 (NOAA Regional Climate Centers ACIS, 1991-2020) — 23 days short of what it needs. A typical North Dakota 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
Sweetspire requires ~400 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
Sweetspire tolerates a wide pH range (pH 4-7.5) — 3.5 units, acid ground through alkaline — so soil acidity is rarely what limits it in North Dakota. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant.
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.
Sweetspire in North Dakota — Quick Answer
- Verdict: Unlikely — Zone Mismatch
- Plant Zones: 5-11 (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 Sweetspire 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
What to actually do about these — and the constraints that apply to every North Dakota grower, not just sweetspire — is covered on the North Dakota growing guide.
Timing shifts within North Dakota
Sweetspire needs about 180 days of frost-free season to complete its cycle. No North Dakota county gives it that outdoors: even Richland County, the state’s longest season at 170 frost-free days, falls 10 days short — so it needs transplants, a short-season variety, or covered growing.
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"). Sweetspire's 180-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
Sweetspire draws honeybees, native bees, and butterflies (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, sweetspire 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 sweetspire, the canonical source is NDSU Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Sweetspire native to North Dakota?
Sweetspire 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 Sweetspire in North Dakota
When can I plant Sweetspire 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 Sweetspire, 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 Sweetspire grown in across North Dakota?
North Dakota spans USDA hardiness zones 3b-4b (USDA ARS PHZM 2023). Sweetspire carries a range of zones 5-11, 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). Sweetspire needs 180+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Sweetspire native to North Dakota?
Sweetspire 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 Sweetspire in North Dakota?
Sweetspire tolerates pH 4-7.5 (USDA PLANTS). That is a 3.5-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a North Dakota site — amend for drainage and organic matter first.
Will Sweetspire actually grow on my specific land in North Dakota?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores sweetspire 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 sweetspire against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that North Dakota sweetspire averages can't show:
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