How to Grow Delphiniums (UK guide)
Delphiniums are spectacular perennials cherished for their towering flower spikes and vivid hues. Ideal for the backs of borders, they bring height and drama to cottage and informal gardens, thriving in sunny, sheltered spots.
How to grow delphiniums
Delphiniums prefer fertile, well-drained soil in full sun. Stake tall varieties to protect against wind, and mulch in spring to retain moisture. Water regularly, especially in dry spells, but do not overwater.
For the Bees
Striking spires for summer borders. Loved by pollinators. Perfect for cottage gardens.
How to Grow Delphiniums from Seed
- 01Fill seed trays with a fine seed compost and moisten lightly
- 02Sow delphinium seeds thinly on the surface and cover with a thin layer of compost or vermiculite
- 03Place trays in a propagator or cover with a clear lid to maintain humidity
- 04Keep at 15–18°C for even germination, providing bright but indirect light
- 05Transplant seedlings when large enough to handle into individual pots
- 06Harden off young plants gradually before planting outside in late spring
You will need
- 01Fertile, well-drained soil
- 02Full sun
- 03Protection from strong winds
- 04Regular watering
- 05Stakes or supports for tall stems
How to pinch out delphiniums
Pinch out growing tips of young delphiniums when 10–15cm tall to encourage bushier growth and more flower spikes.
Plant Calendar
What delphiniums need to thrive
Sheltered spot with sunshine
Delphiniums thrive in full sun but appreciate shelter from strong winds to prevent stem breakage.
Rich, moisture-retentive soil
A fertile soil improved with compost supports vigorous growth and spectacular blooms.
Staking or garden supports
Tall growth is prone to flopping, so use sturdy canes or frames to support stems.
Regular feeding
Balanced fertilisers in spring and after flowering help produce strong plants and repeat blooms.
Delphiniums FAQs
Deadhead delphiniums as soon as the first flush of flowers fades. This encourages a second, smaller flush later in summer and helps maintain their appearance throughout the season.
Yes, you can grow delphiniums in large, deep pots—choose one at least 30–40cm wide with good drainage holes. Use a rich, loam-based compost and water regularly, being careful not to let them dry out.
Apply a balanced, general-purpose fertiliser in early spring and again after the first flowering. Avoid high-nitrogen feeds which encourage soft growth at the expense of flowers.
Delphiniums can suffer from slugs, snails, and powdery mildew. Protect young growth with barriers or wildlife-friendly pellets, and ensure good air circulation to reduce fungal issues.
CUT FLOWERS Beautiful blooms to admire in your garden or fresh in a vase.
