Growing Delphiniums: Tall, Stately Spires for the Early Summer Garden

Why Gardeners Love Delphiniums

Few perennials command attention like delphiniums. Their towering spikes of blue, purple, pink, or white florets rise above deeply lobed foliage in early summer, creating vertical drama that anchors the back of a border. Yes, they ask for a bit more preparation than daylilies or coneflowers, but as one gardener put it, “No gardener worth his loam would stop growing delphiniums just because they are not as rugged as weeds.”

Site & Soil Essentials

• Sun: Full sun, but sheltered from strong winds that snap hollow stems.
• Soil: Deep, rich, and moisture-retentive yet well-drained. Aim for a neutral pH (6.5–7.0); amend acidic soil with lime at planting.
• Fertility: Work in generous amounts of compost or composted manure, plus a balanced slow-release fertilizer.

Staking: Non-Negotiable

Every tall variety needs support. Install stakes at planting time to avoid root disturbance. A figure-8 loop of soft twine, starting near the base and ending just below the flower head, allows stems to sway without snapping.

After the First Flush

Cut spent stalks of all varieties except D. grandiflorum ‘Blue Mirror’ to the ground immediately after flowering. This often triggers a second, smaller show in September. ‘Blue Mirror’ is the best choice for southern gardens but is short-lived there; let a few plants self-sow to maintain the patch.

Companion Plants

Pair delphiniums with peonies, Siberian iris, lupines, Shasta daisies, and roses for a classic June tapestry.