Delphinium is grown for its blooms, which open in summer. It's hardy across USDA zones 3 through 7 and shrugs off deer. Its summer flowers are a moderate draw for native bees, butterflies, and hummingbirds.
Zones
3-7
pH Range
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Sun
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Days to Maturity
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Score Delphinium on your exact land.
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What Delphinium is
Delphinium reaches around five feet at maturity. It blooms in summer. It's also deer-resistant.
How to grow Delphinium
Delphinium grows in USDA zones 3 through 7.
USDA Zones
3-7
USDA PHZM 2023
Soil pH
Data pending
USDA PLANTS Database
Sun
Data pending
Growable Ground plant catalog
Drainage
Data pending
Growable Ground plant catalog
Mature Height
5 ft
Growable Ground plant catalog
Start the season right
Plant delphinium in full sun.
Match the soil
Pull a soil test from your local Extension lab to confirm pH and drainage match delphinium's needs before planting.
Water steadily
Keep the root zone evenly moist through establishment. Match watering to the plant's drainage preference and your local rainfall.
Harvest at its peak
Cut delphinium blooms in the cool of the morning, just as they open, for the longest display.
Good to know
One caution for pet owners — delphinium is toxic to dogs and cats and horses (severe severity). Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: ASPCA.)
Delphinium offers moderate value to bees and other pollinators. (Source: Pollinator Partnership.)
Where Delphinium thrives
Delphinium is hardy across USDA zones 3 through 7. Zone is only the starting point, though: the soil pH, drainage, and frost dates on your specific land decide how well it actually does.
Zones 3–7·Where Delphinium growsOpen map →
On USDA hardiness-zone overlap, Delphinium can grow in these states:
See if Delphinium will thrive on your land
Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether delphinium actually takes — we score it against the real conditions at your address.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Frequently Asked Questions
Can I grow Delphinium in my zone?
Delphinium grows in USDA hardiness zones 3 through 7 (USDA PHZM 2023). Zone is one factor — soil pH, drainage, and frost dates on your specific parcel also shape whether it takes.
When should you plant Delphinium?
Time delphinium to your own season rather than the calendar. Your local frost dates set the exact window — a Growable Ground report reads them for your address.
What soil does Delphinium need?
Specific pH data for delphinium is pending. A soil test from your local Extension lab confirms what your site needs.
Does Delphinium attract pollinators?
Yes — delphinium's flowers are a solid nectar source for native bees, butterflies, and hummingbirds. (Source: Pollinator Partnership.)
Is Delphinium safe for pets?
Delphinium is toxic to pets (dogs,cats,horses) with severe severity. Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: ASPCA.)