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.
How Many Blue Mirror Delphinium Do I Need?
This compact, self-supporting delphinium suits the front and middle of sunny borders. Space plants 12–14 inches apart, or group 3–5 for a concentrated pool of true blue.
| Run Length | Plants at ~13 in |
|---|---|
| 10 ft | 9 plants |
| 20 ft | 17 plants |
| 30 ft | 26 plants |
Blue Mirror Delphinium Season-by-Season in Minnesota
- Spring: Fresh, finely cut foliage emerges into a tidy, branching mound.
- Summer: Airy sprays of intense gentian-blue flowers open early to midsummer, drawing hummingbirds and bees; cut back for a possible rebloom.
- Fall: May push a second flush in cool weather before going dormant.
- Winter: Dies back to the ground; hardy to zone 3 and often self-sows to persist.
At a Glance
✔ Pollinator-Friendly ✔ Deer-Resistant
Plant It With
- Mini Pinks Delphinium — a soft-pink compact delphinium for a cottage-garden color echo.
- Aurora Blue Delphinium — a taller classic-blue spire to rise behind the compact Blue Mirror.
- Blue Fortune Hyssop — carries the blue theme into late summer and feeds pollinators for months.
- Sombrero Granada Gold Coneflower — gold daisies make the pure blue flowers pop.
Is Blue Mirror Delphinium Right for Your Yard?
Blue Mirror thrives in full sun to part shade and rich, moist, well-drained soil, rewarding you with one of the truest blues in the garden. Not a fit for hot, dry, or windswept spots, and note that all parts are toxic if eaten, so site it away from where children or pets might nibble.
Where we deliver
We deliver Blue Mirror Delphinium and the rest of our nursery stock across the Twin Cities seven-county metro — Hennepin, Ramsey, Dakota, Anoka, Washington, Scott and Carver counties — from our yard in Waconia, Minnesota.
That includes Minneapolis, Saint Paul, Edina, Bloomington, Plymouth, Maple Grove, Eden Prairie, Woodbury and the surrounding suburbs — see the full delivery area. Delivery is free on orders over $200 and $35 below that. Enter your ZIP code at checkout to confirm your address is covered, or read the shipping and delivery details.
Everything we sell is selected to survive USDA zone 4b–5a, which is what the Twin Cities metro sits in.