How to Grow Delphiniums

Delphiniums make attractive borders and cut flowers. This short-lived perennial lasts 2 to 3 years and has tall spikes of showy flowers. Though delphiniums are known for their brilliant blue flowers, there are also white, yellow and purple varieties. Two delphiniums better known as scarlet larkspur are red. Delphiniums are hardy in the cold and don't like hot climates.

Difficulty: Moderately Easy

Instructions

1. Improve poor or heavy soils with compost or well rotted manure. Newly planted delphiniums like rich, porous, well-drained soil. Add lime to strongly acid soils. Once established, delphiniums are not fussy about the soil.

2. Sow by seed in spring or set out transplants in June or July. Delphinium grows easily from both seeds and cuttings.

3. Choose location. Delphiniums like full sun. Protect from high winds by planting in front of wall or fence. In more open locations, they will need to be staked.

4. Put transplants in with 2 to 3 inches of soil over the root. Lightly tap the soil down, add more soil and then tap down again.

5. Remove all but 2 or 3 of the strongest shoots when they develop in spring. Apply a 5-10-5 fertilizer alongside plants. Re-apply again in late summer and early fall to encourage second bloom.

6. Stake flowers early. Remove stakes in the autumn after the foliage yellows when the spikes are cut down.

7. Cut back flower spikes after bloom. After new shoots are several inches high, cut old stalks to the ground.

Tips & Warnings

• Collect seeds from flower stalks after blooming in the fall.
• Protect from snails and slugs in spring.
• Too much sun will cause pinking or bleaching. If this happens, give the plant some shade.
• Too much water will cause root rot. Don't let the plant become waterlogged in the winter months. Dig small drainage channels to allow the water to escape if the season is very wet.
• Avoid over-crowding. Delphinium will do better with more space.
• Delphiniums are toxic if eaten, and many varieties are poisonous to cattle.