Yes — Strong Match
delphinium (zones 3-7) covers every zone North Dakota contains (3b-4b), so hardiness is not what limits it anywhere in the state.
Your yard isn't the whole zone.
North Dakota spans zones 3b-4b, 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 delphinium against your land's actual soil, sun, and frost.
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Zone Comparison
Delphinium Needs
- USDA Zones: 3-7
- Mature size: 5 ft tall
- Picking window: ~30 days of harvest
- 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 3-7)
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Delphinium 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.
When to start the seed
Those dates are when delphinium goes out, not when it starts. It is sown under cover about 8 weeks ahead, so counting back from North Dakota's late-side last freeze of May 6 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
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.
Delphinium in North Dakota — Quick Answer
- Verdict: Yes — Strong Match
- Plant Zones: 3-7 (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 Delphinium 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 delphinium — is covered on the North Dakota growing guide.
Where in North Dakota Delphinium Is Zone-Hardy
Delphinium is rated for USDA zones 3–7. Every one of North Dakota’s 53 counties sits inside that band — from Bottineau County at zone 3b to Stutsman County at zone 4b — so winter cold is not what decides this plant anywhere in the state. What is left to vary is your own parcel: slope, shelter and cold-air drainage routinely move a site half a zone either way from the county figure.
Across those 53 counties North Dakota’s winter-low ladder runs from zone 3b in Bottineau County to zone 4b in Stutsman County — 1 USDA zone of spread, which is 10°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. Bottineau County holds its last hard freeze (28°F) until about May 9, while Richland County is clear by Apr 23 — 16 days apart. Set delphinium 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". Delphinium’s zone 3–7 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Where in North Dakota Fits Best
Even within North Dakota's zones 3b-4b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for delphinium (USDA PHZM 2023):
Pollinator + Wildlife Value
Delphinium draws native bees, butterflies, and hummingbirds (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, delphinium 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 delphinium, the canonical source is NDSU Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Delphinium native to North Dakota?
No — the USDA PLANTS Database lists Delphinium as introduced rather than native in the Lower 48, so it is not part of North Dakota's native flora. It grows here as a garden plant; pairing it with a few North Dakota natives keeps local pollinators fed too.
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 Delphinium in North Dakota
When can I plant Delphinium 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). 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.
What hardiness zone is Delphinium grown in across North Dakota?
North Dakota spans USDA hardiness zones 3b-4b (USDA ARS PHZM 2023). Delphinium carries a range of zones 3-7, 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). Delphinium 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.
Is Delphinium native to North Dakota?
No — the USDA PLANTS Database lists Delphinium as introduced rather than native in the Lower 48, so it is not part of North Dakota's native flora. It grows here as a garden plant; pairing it with a few North Dakota natives keeps local pollinators fed too.
Will Delphinium actually grow on my specific land in North Dakota?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores delphinium 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 delphinium against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that North Dakota delphinium averages can't show:
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Growing guides for delphinium
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