Nothing quite beats the drama of delphinium flowers. In June and July, they produce towering flower spikes that can reach over 2m tall. They’re probably best known for their vivid sapphire blue flowers, but they also come in mauve, pink, white and even red. Delphinum flowers can be single or double, depending on the variety.
Delphiniums are a cottage garden and herbaceous border staple, bringing height and colour to displays and mixing well with roses, peonies and other vertical flowers such as lupins and verbascums. The flowers are loved by bees and look stunning in a vase.
Delphiniums are in the buttercup family (Ranunculaceae) and have been grown in the UK for centuries. The word delphinium comes from the Greek delphinos, meaning dolphin, probably because of the shape of the opening flowers. Their common name, larkspur, dates back to Tudor times.
Most delphiniums are hardy perennials, but annual and biennial varieties are also available. The Elatum Group of delphiniums are the most commonly grown and are the tallest type, with spikes of single or double flowers reaching up to 2m. Belladonna delphiniums are shorter, with a looser, more branching habit and single flowers. ‘Pacific Hybrids’ were developed in the 1950s and 1960s, and are short-lived perennials or biennials. They look similar to ‘Elatum’ delphiniums but are shorter. The ‘Magic Fountain’ series of delphiniums are short and more compact, suitable for smaller gardens.
Delphiniums need care to keep them looking good. They need protecting from slugs in spring, staking, moist soil and plenty of feeding. If you cut them down to the ground after flowering, you may be rewarded with a second flush of flowers in September.
How to grow delphiniums
Grow delphiniums in moist but well-drained soil in full sun. Delphiniums struggle in wet winter soil, so aid drainage by adding grit to the planting hole if you have heavy soil. Protect emerging shoots from slugs in spring and stake as soon as they start to grow. Feed weekly with a high potash fertiliser. After flowering, cut stems back to encourage a second flush of blooms. Mulch in autumn with well-rotted manure or leaf mould.
More on growing delphiniums:
- How to plan for year-round colour
- 20 best perennial plants
- Perennials for cut flowers
Delphiniums: jump links
- Planting delphiniums
- Caring for delphiniums
- Delphinium pests and problems
- Where to buy delphiniums
- Delphiniums to grow
Where to grow delphiniums
For best results grow delphiniums in moist but well-drained soil in full sun. Delphiniums are tall plants, so do best at the back of a sunny border. Avoid windy spots, as wind can blow the plants over.
How to plant delphiniums
You can plant a delphinium at any of time of year, but spring or autumn is best as the soil will be warm and moist. Dig a planting hole and add compost or well-rotted manure in the bottom, for a nutritious boost. Delphiniums struggle in winter wet, so add grit to heavy soils to aid drainage. Plant your delphinium at the same depth it was growing in the pot, and back-fill with soil, firming in gently. Water in well.
Delphinium black blotch is a bacterial infection that causes large black blotches on leaves. It is particularly common in wet summers and can affect the health of the whole plant. The only treatment is to remove affected plants to prevent the spread of this disease.
Advice on buying delphiniums
- Bear in mind that delphiniums can become large, tall plants so check the ultimate size of the variety you are interested in
- Delphiniums grow best in a sunny spot so check that you have the right conditions in your garden
- You can buy delphiniums at nurseries and garden centres, or from specialist retailers online. An economical way to buy delphiniums is to look out for small plug plants in spring
- Look for healthy, green foliage with no signs of pests or disease
Delphinium varieties to grow
Delphinium ‘Amadeus’ – a gorgeous blue delphinium, bearing velvety, deep-purple/blue flowers with a dark brown ‘eye’. It makes a spectacular cut flower.
Height x Spread: 1.5m x 1m
- Buy Delphinium ‘Amadeus’ from Blackmore & Langdon
Delphinium ‘Pacific Hybrids’ – tall, stately plants in a range of colours. They are shortlived perennials.
H x S: 150cm x 75cm
- Buy Delphinium ‘Pacific Hybrids’ from Thompson & Morgan
- Buy Delphinium ‘Pacific Hybrids’ from Van Meuwen
Delphinium ‘Rising Stars’ – a mix with single or double flowers in a variety of colours. Grown together they make a dramatic display, and they also make fantastic cut flowers.
H x S: 150cm x 75cm
- Buy Delphinium ‘Rising Stars Mixed’ from Thompson & Morgan
- Buy Delphinium ‘Rising Stars Mixed’ from Van Meuwen
Delphinium ‘Magic Fountain Series’ – compact plants, suitable for smaller gardens. They come in a range of colours, often with a contrasting eye at the centre.
H x S: 90cm x 60cm
- Buy Delphinium ‘Magic Fountain Mixed’ from Primrose
- Buy Delphinium ‘Magic Fountain Mixed’ from Thompson & Morgan
Delphinium elatum ‘Faust’ – bears incredibly tall spikes of intense blue double flowers, with a dark centre.
H x S: 2.5m x 1m
- Buy Delphinium elatum ‘Faust’ from Primrose
- Buy Delphinium elatum ‘Faust’ from Blackmore & Langdon
Delphinium elatum ‘Cinderella’ – a compact, pale pink delphinium with very sturdy stems and triple blooms that was voted BBC Gardeners’ World Live ‘Best New Plant Introduction for 2019’.
H x S: 1.2m x 80cm
- Buy Delphinium elatum ‘Cinderella’ from Suttons
