How to Grow Delphiniums

Bee on Delphinium

Delphiniums at a glance

  1. Red Wheelbarrow time consuming to grow
  2. Need Slug protection
  3. It is essential to stake and support Delphiniums
  4. Expect some casualties
  5. Feeding is optimum but optional.
  6. Tall, splendid spikes of flower suitable for back of the border.

Delphiniums are an impressive border plant with tall spires of flowers which bloom in mid-summer. I grow them; I love them, but they are hard work and definitely a red wheelbarrow plant. When growing Delphiniums, there are two areas which need particular attention slugs and support.

 Delphiniums are a hardy herbaceous perennial, which means they are tolerant of our winters hardy down to H5, (explanation of frost hardy.) In late autumn and winter they die back completely to bare earth and re grow each spring. 

Delphiniums grow best in moist fertile soil in a sheltered spot away from winds. Delphiniums fare best in summers which are cooler, hot dry summers are not ideal, which can exacerbate their tendency towards powdery mildew. Although Delphiniums need sun, they are best not planted in garden hot spot. Plenty of organic matter or compost worked into the planting area will help to hold in moisture, and plant delphiniums level with the existing soil, i.e. not too deep. Given the heavy flower heads supported by hollow stems, gusty winds and rain are not ideal. With good growing conditions and summer weather, Delphiniums can look just fabulous.  

Much gardening advice says to water and feed during the growing season. If the soil is reasonable, I find you can get away with not feeding them. Delphiniums will benefit from feeding if time allows, but will bloom well without being cosseted. Whilst summer feeding may not be essential, staking is. Which means if you don't have time to feed and stake Delphiniums, the more important task is to stake them so the plant and blooms supported.    

  After flowering, it is best to dead head the flower spike, and further smaller flower shoots should appear. Bees are attracted to Delphiniums drawn in part by their lovely strong blue, as bees do love blue flowers. Delphiniums are a red wheelbarrow plant as they need quite a lot of attention in terms of slug protection, staking and if time allows, feeding, as detailed below. If Delphiniums are not your first choice to plant, check out summer flowering plantsscented plants, and climbing plants for more ideas on what to plant in the garden.

Delphiniums Slugs and Staking

Slugs are keen on the fresh tender shoots which emerge in the spring. It is essential to lay down slug protection. There are lots of ways to defeat slugs and here are ideas on how to beat the slugs. 

All Delphiniums need staking as soon as they have put on growth and are getting established. Heavy summer storms or rain can damage the flower heads.  The blooms become heavy with the rainwater and it is hard to stake them enough to prevent the stems from snapping, especially if there are high winds. Delphinium has stems which are hollow and brittle, which are easily damaged.

If staking is left too late and the plant has put on a lot of growth, it is tricky pushing large canes or stakes into the ground next to a delphinium plant, not to damage the delicate stems. There is less risk of damage if the stakes are put in place early. It is also important to use soft ties, and not to tie them too tightly (which risks damaging the plant stem) and to leave room for the stem to expand with further growth. For single flowers, run a cane or stake alongside the bloom and using a soft tie link the flower stem to the stake.

Many Delphiniums can get very tall and some Pacific varieties, once established, can grow over 5ft /1.5m. This means you need tall stakes or canes to support the plants.

It is because so many supports are needed for Delphiniums that using natural supports rather than canes looks less intrusive. 

If your garden is exposed and windy, it may be more practical to grow the shorter varieties. 

delphinium stakes

Staking Delphiniums

Delphiniums are staked to support the plant and there are commercial plant supports available, but you can also make your own using Bamboo canes/or stakes and string/hoops made out of prunings.

In this image stakes have been made to make a framework and then added around are hoops made from Cornus prunings. You need to cut the stakes to the ultimate size of the Delphinium and about 3/4/5 hoops or string wrapped around will need to be added to create a supportive cage.  

red wheelbarrow delphiums are time consuming to grow

Delphiniums are one of the few red wheelbarrow plants on this website.

Good Delphiniums to Grow

Delphiniums come in lovely shades of blue, white, pink and purple, and even yellow, often with a contrasting eye or 'bee'. Many Delphiniums are tall and for this reason look fantastic at the back of a border, although there are also more compact varieties, which, being smaller, need less support. I use twigs and branches pruned off plants during the year to create more natural looking plant supports. (plant supports for free

There are three main groups of Delphiniums: Belladonna which have single flowers and grow up to 1.2 m(3-4'); Elatum group which has single, double with an eye and is most commonly grown. In this group there are small, medium and tall varieties growing from between 1.5m (5') -2m (6'). Pacific hybrids which are short-lived annuals or biennials. 

 There are a number of Delphiniums which have the RHS award of garden merit, which is always a good starting point and worth checking out, which includes varieties such as D. 'Clifford Sky' strong blue, white eye semi double. D. Margaret which is a lovely bold blue, D. Emily Hawkins a soft lavender and Elizabeth cook a white variety, there is a great number to choose from.

There is also a magic fountain series of Delphinium which are more compact in shades of blue violet and white up to .5m. 

How to grow Delphiniums from Seed

 Delphiniums are surprisingly easy to raise from seed, and some varieties will flower the first year. Thompson and Morgan list some Delphiniums to sow and flower the first year. Delphiniums plants are expensive to buy and it is worth trying to grow them from seed as they germinate easily and grow quickly into sturdy plants. 

Simply sprinkle the seed into small pots or a seed tray, cover with a little compost and spray to dampen. Either place in a propagator or make a small propagator by covering with a plastic bag held in place by an elastic band. This creates a better environment for germination. 

As soon as the seedlings are established, take out of the propagator and grow on in a sheltered spot, ideally a greenhouse. Check to make sure the compost does not dry out and pot on into individual small pots and then into a larger pot. Once the risk of frost has passed, and the plant is of a reasonable size, plant out and protect from slugs. Once established, Delphinium will come back reliably each year and the major chore is extensive staking at the beginning of the season, which is essential.  

If the wind blows......

home grow flowers Delphiniums in vase

The up side to a summer storm which tragically can snap Delphinium stems, is the chance to cut the damaged flowers and bring them inside. Whilst it is sad to see wind and rain damaged Delphiniums, they make a lovely display. Home-grown flowers have many advantages, they are lovely and fresh, as nature intended, and are a green choice having travelled no miles, air or otherwise.

Climate change is now in the foreground, and as gardeners I think we need to consider greener choices. Fewer flowers from Holland, and more from the garden, is a small, but constructive step.   

There is a revival in English cut flowers and some internet retailers are specialising in using, or using as much as possible flowers grown in the UK. Worth looking at are Great British Florist UK, The Real Flower company, Cornish Blooms and Flowers from the Farm,  ideas to think about next time celebration flowers are being ordered.

last updated 25.05.2021