Blue Mirror Delphinium
Blue Mirror Delphinium
The Purest Gentian-Blue in the Garden
Blue Mirror Delphinium (Delphinium grandiflorum 'Blue Mirror') offers one of the truest, deepest blues in all of horticulture — airy sprays of intense gentian-blue flowers on a compact, branching plant. Unlike towering delphiniums, this butterfly delphinium is light and self-supporting, blooming in early to midsummer and drawing hummingbirds and bees. Deer-resistant and reliably hardy, it's a jewel-blue accent for sunny borders in Edina, Woodbury, and Maple Grove.
Blue Mirror Delphinium Plant Details
| Attribute | Detail |
|---|---|
| Botanical Name | Delphinium grandiflorum 'Blue Mirror' |
| Mature Size | 12–18 in. tall, 10–14 in. wide |
| Hardiness Zone | 3–7 (Twin Cities is zone 4b–5a — fully hardy) |
| Light | Full sun to part shade |
| Bloom Time | Early to midsummer, often reblooming if cut back |
| Flower Color | Intense gentian-blue |
| Soil | Moist, rich, well-drained; amend clay with compost |
| Winter Hardiness | Reliable to -30°F; often short-lived but may self-sow |
| Deer Resistance | Rarely browsed — foliage is unpalatable to deer |
Landscape Uses in Minnesota
True-blue accents: Its rare, pure blue is stunning among warm-toned flowers and silver foliage. Space 12–14 inches apart.
Pollinator and cottage gardens: Hummingbirds and bees love it. Pair with coreopsis, yarrow, and catmint for a blue-and-gold combination.
Best Time to Plant in Minnesota
Plant in spring (late April–May) or early fall into rich, moist soil. Water through establishment.
How to Plant Blue Mirror Delphinium
Dig a hole twice the pot's width at the same depth, mixing in compost. Set the crown level, backfill, water well, and mulch 2 inches deep, keeping mulch off the crown. Space 12–14 inches apart.
Watering Blue Mirror Delphinium
First year: Keep evenly moist — water every 2–3 days at first, then weekly. Stop 2–3 weeks before the ground freezes.
After year one: Prefers steady moisture; cut back after the first flush to encourage a second bloom.
Q: Is the blue really that intense?
Yes — Blue Mirror is famous for one of the purest, deepest blues of any garden flower.
Q: Is delphinium poisonous?
Yes — all parts are toxic if eaten. Plant it away from where children or pets might nibble, and wash hands after handling.
Q: Will it survive a Minnesota winter?
Yes — hardy to zone 3, though butterfly delphiniums can be short-lived; they often self-sow to persist.
Q: Is it deer-resistant?
Yes — deer rarely browse delphinium foliage.
You May Also Like
Mini Pinks Delphinium (Delphinium): A soft pink compact delphinium.
Coreopsis: Gold daisies that pop against the true blue.
Catmint (Nepeta): A deer-resistant blue-flowered companion.