Delphinium elatum, D. grandiflorum
- A perennial (Zones 3 to 7) that flowers in the first season when planted from seed.
- Sow seed in 72- to 144-cell trays with seed covered. Emerges in 12 to 18 days.
- When sown in early March, can be transplanted in mid-May to the tunnel.
- Plants transplanted to the tunnel in mid-May can be harvested in early July.
- Plants produce 2 to 3 usable stems in the first year, but should be earlier and more productive in the second year.
- Root disease (Sclerotium rolfsii?) devastated plant populations in Cornell open field plantings, and less so in the tunnel.
- Sowing in late summer for earlier cropping the following year is another option.
- There are a number of D. elatum hybrids with erect spikes of large florets that make a spectacular show in the vase.
- Aurora, Guardian and Candle series offer white, blue, purple and lavender shades, with stem lengths of 22 to 30 in.
- Belladonna hybrids such as Bellamosum, Belladonna Clivenden Beauty, Oriental Blue have a more open raceme with branching, shorter stems, but longer plant life.
- Delphinium is very sensitive to ethylene, and must be stored away from ethylene-producing produce.
- Vase life of D. elatum hybrids is 5 to 7 days, for Belladonna hybrids only about 4 days, with flower life ended with petal loss.
For more information, see: Armitage, A.M. and J.M. Laushman. 2003. Specialty Cut Flowers, 2nd Edition. Timber Press, 586 pp. Available through ASCFG.