Long floral scapes lift white, blue or pink flowers well above 3 feet, which is why delphinium, or larkspur, is planted at the back of a bed as a bushy backdrop. Give it full sun, rich well-drained soil and shelter from wind — or a stake — and it repays you with bouquets that last.
| Name | Delphinium |
|---|---|
| Family | Ranunculaceae |
| Type | perennial or annual |
| Height | 20 to 60 inches (50 to 150 cm) |
| Exposure | full sun |
| Soil | ordinary, well drained |
| Flowering | summer → mid-fall |
Sowing or planting are the only things to actually do for this plant, because delphinium require absolutely no care at all.
For perennial and hardy delphinium species
Perennial and biennial larkspur species can be sown in spring and summer, preferably under a cold frame if early in spring.
It is best to plant delphinium seedlings from their nursery pot to the ground in early autumn. This gives the plantlings time to properly develop their roots before winter. They’ll grow back stronger in the following spring.
→ Propagate perennial delphinium through crown division in spring.
Sowing annual delphinium cultivars
When sowing from seed, prefer sowing in fall or until spring while avoiding frost spells.
You can sow directly in the plot if you wait for the last frost date to pass (end if spring, usually), otherwise try sowing under cover or indoors, in a tray.
Enrich the soil with special flower plant soil mix and granulated organic fertilizer to enhance the blooming and make it more dense.
Delphinium is handled differently depending on whether you grow a perennial species or an annual cultivar. This table gathers the timings and methods given above.
| Type or stage | When | How | Follow-up |
|---|---|---|---|
| Perennial and biennial species | Spring and summer | Sow under a cold frame if sowing early in spring | Divide the crown in spring to propagate |
| Nursery-grown seedlings | early autumn | Plant out from the nursery pot into the ground | Roots develop before winter, growth is stronger next spring |
| Annual cultivars from seed | Fall until spring, avoiding frost spells | Direct sowing once the last frost has passed, or under cover in a tray | Allow at least 4 weeks before transplanting to the ground |
| After flowering | As soon as blooms fade | Cut the stems off | New flowers appear |
| Perennial delphinium in autumn | Fall | Cut back to the shortest | Protect the base in colder areas if needed |
Apart from these few operations, delphinium requires almost nothing from you.
Cut stems off after the blooming, this will trigger appearance of more new flowers.
For perennial delphinium, cut back to the shortest in fall and, if needed, protect the base in colder areas.
Delphiniums range from towering border spires needing a stake to knee-high types that stand on their own. This table gathers the varieties most often found in garden centres and seed catalogues, with the colour, the group and the height band to help you match one to your border.
| Variety | Group | Flower colour | Height band | Best use |
|---|---|---|---|---|
| Blue Nile | Elatum, AGM | Bright mid-blue, white eye | Tall | Specimen border spikes |
| Faust | Elatum, AGM | Ultramarine blue, indigo eye | Tall | Bold back-of-border colour |
| Sungleam | Elatum, AGM | Cream to soft yellow | Tall | Softening strong blues |
| Black Knight | Pacific Giant | Deep violet-purple, black eye | Tall | Back of border, cutting |
| Blue Bird | Pacific Giant | Mid-blue, white eye | Tall | Back of border, cutting |
| Blue Butterfly | Grandiflorum | Vivid gentian blue | Dwarf | Front of border, pots |
| Cliveden Beauty | Belladonna | Sky blue | Medium | Airy spikes, less staking |
| Summer Skies | Pacific Giant | Pale sky blue, white eye | Tall | Pastel schemes |
| King Arthur | Pacific Giant | Royal purple, white eye | Tall | Back of border |
| Magic Fountains | Magic Fountains series | Blue, white, lilac or pink shades | Dwarf to medium | Windy sites, little staking |
| Casa Blanca | Belladonna, AGM | Pure white | Medium | Cottage borders, cutting |
| Galahad | Pacific Giant | Pure white | Tall | White borders, cutting |
| Astolat | Pacific Giant | Lilac-pink, dark eye | Tall | Mixed borders |
| Guinevere | Pacific Giant | Lavender-pink, white eye | Tall | Mixed borders |
| Bruce | Elatum, AGM | Violet-purple, brown eye | Tall | Back of border, cutting |
| Pagan Purples | New Millennium | Double deep purple | Tall | Long-lived border clumps |
This cute plant bears distinctive long floral scapes that uphold beautiful white, blue or pink flowers.
Its great height, often taller than 3 feet (1 meter), makes it a good plant to settle at the back of a flower bed where it will produce an nice bushy backdrop.
Some varieties are particularly tall and colorful, such as the beautiful Pacific Giant Delphinium.
It also makes for great bouquet flowers that will keep for a long time – even a bouquet of dried flowers!
