Delphinium Growing Guide
What is Delphinium?
Delphinium (Delphinium grandiflorum) are a clump forming herbaceous perennial. A member of the Ranunculaceae or buttercup family they come in two sizes dwarf (30cm) or tall (1.8m). Delphiniums are treasured for their tall, stately spikes in beautiful blending hues of blue, pink, white and purple which bloom in Summer. They are relatively slow to spread. Tall varieties may require some staking. Delphinium will require Summer watering when conditions are dry. Protect from late frost as it can damage the new shoots. Delphiniums prefer a neutral to slightly alkaline soil. Add lime to raise the ph of acidic soils prior to planting.
Benefits of Growing Delphinium
Delphiniums are easily grown, frost tolerant and like sunny positions in a rich well drained soil. They make excellent cut flowers. This plant comes in a variety of shades the most common colour is blue. Hybrid colours include lavender, white, pink, yellow and red. Their flowers are bee attracting.
Delphinium are fantastic for cottage gardens or where space is limited. Their tall flowers are ideal for creating presence towards the back of garden beds or near fence lines.
How to Grow Delphinium
Delphinium Bluebird
Climatic Zones
Cool to Tropical.
Plant Size
Dwarf Height: 75cm, Width: 75cm
Tall Height: 1.5m, Width: 75cm
When To Plant Delphinium
Plant in spring.
Soil Preparation
Delphinium require free draining and rich fertile soil that holds water well. Prepare soils beforehand by working through well broken down animal manure and organic matter. An application of blood and bone whilst preparing the soil is usually beneficial.
How To Plant Delphinium
Plant in full sun in a sheltered position from wind, 30-50cm apart with the plant crown at soil level.
Delphinium Plant Care
Delphiniums require regular watering specifically during hot Summers. Mulching helps to keep the soil moist and prevent the soil from drying out quickly.
The taller varieties need staking. The stems of the plant are hollow and because of this, delphiniums cannot tolerate strong winds.
Deadheading the spent flowers during early Summer increases flowering.
They like to be fed so top dress with some fertiliser or liquid feed every 4-5 weeks through the growing season. Add a thin layer of compost in Spring to promote healthy and strong new growth.
Can be lifted during the winter months or left in the ground for many years. If lifted, store temporarily in moist peat moss.
Place some snail bait around the plants as snails and slugs love the young shoots. Watch for thrip and aphids and spray occasionally if required.
Recommended Delphinium Varieties
With their large range of colours ranging from blue, pink, yellow, red and white Delphiniums are a must for any garden particular a cottage style.
Delphinium Astrolat
Delphinium Galahad
Delphinium Black Knight
