Guardian Blue Delphinium
Guardian Blue Delphinium
Tall, Sturdy Deep-Blue Spires for the Back of the Border
Guardian Blue Delphinium (Delphinium 'Guardian Blue') delivers the towering, classic delphinium spire — dense columns of deep blue flowers reaching 3 to 4 feet — on stems bred to be sturdier and more uniform than old-fashioned types. Blooming in early to midsummer, it's a magnet for hummingbirds and bees and a showstopper at the back of a sunny border. Deer-resistant and reliably hardy for gardens in Edina, Woodbury, and Maple Grove.
Guardian Blue Delphinium Plant Details
| Attribute | Detail |
|---|---|
| Botanical Name | Delphinium elatum 'Guardian Blue' |
| Mature Size | 36–48 in. tall, 18–24 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 | Deep blue |
| Soil | Moist, rich, well-drained; amend clay with compost |
| Winter Hardiness | Reliable to -30°F once established |
| Deer Resistance | Rarely browsed — foliage is unpalatable to deer |
Landscape Uses in Minnesota
Back-of-border drama: Its tall spires make a stunning vertical backdrop and a classic cottage-garden statement. Space 18–24 inches apart.
Pollinator and cut-flower gardens: Hummingbirds and bees love the blooms, and the long spires are spectacular cut. Pair with roses, peonies, and white phlox.
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 Guardian Blue 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 18–24 inches apart. Stake the tall spires early, especially in windy or exposed sites.
Watering Guardian Blue 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 and rich soil; cut spent spires to the base to encourage a strong second flush.
Q: Does it need staking?
Yes — at 3 to 4 feet, the tall spires benefit from staking, especially in windy spots. Stake early as growth begins.
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 with good drainage over winter.
Q: Is it deer-resistant?
Yes — deer rarely browse delphinium foliage.
You May Also Like
Magic Fountains Dark Blue Dark Bee Delphinium: A midsize deep blue with less staking.
Peony (Paeonia): A timeless companion for the early-summer border.
Shasta Daisy (Leucanthemum): A white-daisy classic cottage-garden partner.
How Many Guardian Blue Delphinium Do I Need?
For a back-of-border block of blue spires, space plants about 20 inches apart (each clump is 18–24 inches wide):
| Bed / Run Length | Plants Needed (~20 in apart) |
|---|---|
| 10 ft | 6 |
| 20 ft | 12 |
| 30 ft | 18 |
| 40 ft | 24 |
For a cottage-garden statement, group 3–5 at the back of the border and stake early.
Guardian Blue Delphinium Season-by-Season in Minnesota
- Spring: Mounded foliage emerges fast; stake as the flower stems begin to rise.
- Summer: Towering 3–4 ft columns of deep blue open in early-to-midsummer, drawing hummingbirds and bees; cut spent spires for a possible second flush.
- Fall: A late rebloom is possible if cut back; foliage fades with frost.
- Winter: Dies back to the ground; hardy to -30°F with good winter drainage.
At a Glance
✔ Pollinator-Friendly ✔ Deer-Resistant
Plant It With
- Delphina Dark Blue White Bee Delphinium — a shorter deep-blue delphinium that needs less staking up front.
- Bartzella Peony — classic early-summer companion that anchors the border below the spires.
- Sombrero Granada Gold Coneflower — gold daisies contrast the deep blue and extend the bloom.
- Blue Fortune Hyssop — echoes the blue tones at mid-height and adds more bee traffic.
Is Guardian Blue Delphinium Right for Your Yard?
It shines at the back of a sunny-to-part-shade border with rich, moist, well-drained soil and a little shelter from wind — stake early and it pays you back with show-stopping blue. Not a fit if you want low-maintenance or have an exposed, windy spot, since the tall spires need staking; and note all parts are toxic if eaten, so site it away from where children or pets browse.