How to grow Delphiniums

Delphinium and Thalictrum Alba 310 x 240 Delphinium and Thalictrum aquilefiifolium Delphinium flowers on mass 


How to grow Delphiniums

Delphiniums are an impressive border plant with tall stunning blue spires which bloom in mid summer. I grow them, I love them, but they are hard work and definitely a red wheelbarrow plant red wheel barrow difficult or time consuming to grow. Delphiniums are a hardy herbaceous perennial which means they are tolerant of our winters hardy down to H5, (for explanation of  plant hardiness.)  In late autumn and winter they die back completely to bare earth and re grow each spring. Delphiniums come in lovely shades of blue, white, pink and purple, often with a contrasting eye or 'bee' illustrated in the central image. The tall ones look fantastic at the back of a border, although there are also more compact varieties which being smaller need less staking but still need to be supported. I try and use twigs and branches pruned off plants during the year to create more natural looking plant supports. 

The other aspect of growing Delphiniums which requires attention is slug protection. Unfortunately slugs are fond of Delphiniums, especially the new tender shoots in the spring and you need to lay down slug protection. There are lots of ways to defeat slugs

When growing Delphiniums they need  to be planted in full sun and fertile soil, which is moist but well drained and most importantly, sheltered from strong winds. Much gardening advice says to water and feed during the growing season; I find if your soil is reasonable that is not really  necessary and all the images above were grown without summer feeding, it all depends on the time available. Delphiniums are hungry feeders, and will definitely benefit from feeding if time allows, but will bloom well without being cossetted. Feeding is said to improve the prospects of a second crop later in the year.

In the 1st image above left Delphinium is growing alongside Thalictrum which is a great combination; tall with fluffy flower heads Thalictrum combines well in mauve and contrasts in white.

Tips on Growing Delphiniums

delphiniums-free-standing Delphiniums need attention especially when first emerging as slugs love their tender new shoots. In a previous garden where the slug population was very high, it was nearly impossible to grow Delphiniums, because the slugs ravaged them before they got established.

All Delphiniums need staking as soon as they start to grow above 30 cms and they need plenty of support. The flower heads can be damaged by heavy summer rain or storms, when the blooms become heavy with the rain water and it is hard to stake them enough to prevent the stems from snapping, especially if there are high winds.  This is one of the reasons for the recommendation to plant in a spot sheltered from high winds. Delphiniums bloom best in summers which are calmer with less rain.

Check the variety carefully as many Delphiniums can get very tall. I have a clump of the Pacific variety which have been established for about 5 years which are now well over 5ft /1.5m. Although traditionally blues, pinks, mauves there are now some yellow Delphiniums and a greater range of colours.

Good Types of Delphiniums to Grow

There are a number of RHS merit  rhs_agm_logo-75x75Delphiniums which are good to grow  and worth checking out: D. Giotto a lovely two tones blue/mauve flowers growing up to 1.5m;  D.'Bruce' deep violet purple reaching up to 2.5m , D.'Blue Dawn' pale blue, very tall as well. Good pink varieties worth checking out are D. elatum 'Sweethearts' (New Millennium Series) tall up to 2.5m;  and D.'Rosemary Brock' smaller variety 1.5m with strong black "bee" centre to the flowers. There are many white varieties also with RHS merit  such as D. Sandpiper which is white with a black bee and smaller up to 1.2m.

There are also a magic fountain series of Delphinium which are more compact in shades of blue violet and white up to .5m. In addition there are several such as D. (Belladona Group) Atlantis which are strong blue  and D. "Atholl" white which are both around a metre.

After flowering dead head the flower spike, and further smaller flower shoots should appear.

How to Grow Delphiniums from Seed


Delphiniums are surprisingly easy to raise from seed and some varieties will flower the first year.  Delphiniums plants are quite expensive to buy and it is worth trying to grow them from seed as they germinate easily and grow quickly into study plants. Simple spring the seed into small pots or a seed tray, cover with a little compost and spray to dampen. Check to ensure the compost does not dry out and once seeded, pot on into individual small pots and then into a larger pot. Once the risk of frost has passed and the plant is a reasonable size plant out and protect from slugs. Once established they will return reliably each year and the main chore is extensive staking at the beginning of the season which is essential.



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