How to Grow Delphiniums

Delphiniums are an impressive border plant with tall stunning  spires 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 come in lovely shades of blue, white, pink and purple, 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 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. (plant supports for free)  

  After flowering dead head the flower spike, and further smaller flower shoots should appear.Bees are attracted to Delphiniums drawn in part by the their lovely strong blue, as bees do love blue flowers, illustrated above right.

Delphiniums are a red wheelbarrow plant as they need quite a lot of attention in terms of slug protection, staking and possibly feeding, as set out 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. Firstly, Delphiniums need slug protection. Unfortunately, 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, slug traps of beer and pellets are among the most popular. Ideas on how to protect Delphiniums, and your garden, from slugs, how to beat the slugs. 

Delphiniums 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. Delphiniums are hungry feeders, and will definitely benefit from feeding if time allows, but will bloom well without being cossetted Summer feeding may not be essential, but 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.  

All Delphiniums need staking as soon as they they have put on any growth and are starting to get established, 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.  It is essential to get the supports in place early in the growing season. Delphinium have stems which are hollow and brittle which means they 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.

 Even with staking it is recommended to plant Delphiniums 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.  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. The colour range is traditionally blue, pink, mauve there are now some yellow Delphiniums and a greater range of colours.

red wheelbarrow delphiums are time consuming to grow

Delphiniums are one of the few red wheelbarrow plants on the web site. Delphiniums need quite 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

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: 

Blues 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" center 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 meter.

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 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.