How to Grow Delphiniums

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.

 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 need moist good fertile soil and are best planted in a sheltered spot way from winds. Delphiniums fare best in summers which are cooler, hot dry summers are not ideal, causing the Delphiniums to tend towards powdery mildew. Although Delphiniums need sun, they are best not planted in garden hot spot.  Ensure that plenty of organic matter or compost is worked into the planting area and plant the delphinium 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 either.  Still in the right conditions during the right summer they can look just fabulous.  

Much gardening advice says to water and feed during the growing season; I find if the soil is reasonable that is not really necessary to feed them. Delphiniums are hungry feeders, and 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 are well 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

When growing Delphiniums there are two areas which need particular attention. Delphiniums need slug protection slugs are fond of Delphiniums and are especially keen on the new 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 protect Delphiniums, and your garden, from slugs, how to beat the slugs. 

All Delphiniums need staking as soon as they have put on growth and are starting to get established.  The flower heads can be damaged by heavy summer rain or storms. 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.  It is essential to get the supports in place early in the growing season. Delphinium have stems which are hollow and brittle which are easily damaged. It is tricky, when 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.  Run a single can or stake alongside the bloom and using a soft tie link the flower stem to the stake. Alternatively if there is a clump, it maybe easier to make a simple cage out of 2/3/4 stakes, and then use soft ties to link the stems to the supports.

Check the variety carefully as many Delphiniums can get very tall.  Some of the Pacific varieties once established can grow to well over 5ft /1.5m. This means you need stakes or canes which are tall in order to stake 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 not sheltered and tends to catch the wind, it maybe more practical to grow the shorter varieties. 

red wheelbarrow delphiums are time consuming to grow

Delphiniums are one of the few red wheelbarrow plants on the web site. Delphiniums need a lot of attention, protection from slugs as they start to shoot, careful staking as they grow to protect the blooms and planting in a sheltered spot if the gusty winds are not going to snap off the flowers. When spent they need cutting down as the foliage becomes unsightly.

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 are 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 are a great number to choose from.

Thompson and Morgan have a good range of Delphiniums on offer including many to raise from seed.

There are 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 quite 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. The 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 main 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 do make a lovely display. Home grown flowers have so many advantages, they are lovely and fresh, as nature intends and grows them, and 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. Less 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 taking a look at 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.

Creating a wild life friendly garden means planting to attract bees, butterflies, pollinators and birds.  There is lots of information on the wildlife friendly pages, but a good starting point with bees is blue plants, which they are irresistibly drawn to.

There is current research to suggest even listening to the tranquil garden sounds is good for health. So why not take ten and listen to the bees in a garden on a summers day.