Illustration
Blue Mirror
Delphinium grandiflorum 'Blue Mirror'
Blue Mirror blooms from June through August.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Blue Mirror
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 3–7. Expect it to reach about 16 in tall and 12 in wide at maturity, in roughly 2 years (not yet checked).
What this means
Written with AI assistance and not yet checked plant by plant against recorded sources, so treat every fact above as a starting point. Its scientific name was checked against botanical registries, an audit keeps its values consistent with the rest of the library, and a July 2026 review re-read the main facts of every plant then in the library against horticultural authorities without recording a source for each, which is why none of that counts as checked here. The source-by-source check is working through the whole library in the open, and a checked plant says so in this row.
When to plant Blue Mirror
Plant Blue Mirror in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 5, the middle of its hardy zones 3 to 7, spring means April to June and fall means August or September. Once settled, it blooms from June to August.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 5, the middle of this plant's hardy range, start with zone 5 in April. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Blue Mirror get?
16 intall5 ft 7 inan adult12 inwideSee Blue Mirror in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Blue Mirror
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Blue Mirror about 12 in apart, center to center, so each plant has room to reach its full width.
Add Blue Mirror to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Good to know about Blue Mirror
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
All parts are poisonous to people and pets; the diterpenoid alkaloids are most concentrated in young growth and seeds. NC State rates the poison severity High. per ASPCA and NC State
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Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.