Delphiniums are perennials grown for their showy spikes of colorful summer flowers in gorgeous shades of blue, pink, white, and purple. They are popular in cottage-style gardens and cutting gardens.
Delphiniums are a favorite of many gardeners and sometimes a challenge. They prefer moist, cool summers and do not fare well in hot, dry summers. The plants also dislike sudden wind or rain.
Except for the dwarf perennials, most delphiniums need staking.
- Grow in fertile, well-drained soil in full sun to light shade, with shelter from strong winds.
- Plant in the spring. Prepare the soil, mixing in 2 to 4 inches of compost.
- Delphiniums are very difficult to grow from seed. Buy as a potted plant at the nursery.
- Dig a hole twice the diameter of the plant’s container. When planting, ensure that the top of the root ball is level with the soil.
- In the spring, broadcast lime, wood ashes, or a mixture of the two over this alkaline-loving perennial.
- Insert supports no later than midspring or when the plants reach 12 inches high. Stake the low-growing perennials with twiggy, brushwood support. The taller, large-flowered delphiniums need sturdy stakes.
- Soil should not dry out. Water plants during the summer if rainfall is less than 1 inch per week.
- For good-quality flower spikes, thin shoots when 3 inches high; leave a minimum of 2 or 3 shoots on young plants, and 5 to 7 shoots on well-established ones.
- In growth, water all plants freely, applying a balanced liquid fertilizer every 2 to 3 weeks.
- Deadhead by cutting spent flower spikes back to small, flowering side shoots.
- After delphiniums have finished blooming, cut flower stalks to the ground, and new, though smaller, flower stalks will develop. The flowers will survive the coming cold days and even light frosts.
- If delphiniums need to be divided in the spring, remove and replant the new little plants growing around the outside of the clump. Discard the hard old heart.
- This elegant flower is good for a cutting garden. If you take the blooms into the house as soon as they open, they will bloom again.
- Add sugar to arrangements of delphinium.