Of all the plants in the garden delphinium has travelled furthest from the various species in the wild. More than a century of intensive breeding has produced the tall, large-flowered hybrids which are so popular today, and which make one of the most theatrical exhibits every year at the Chelsea Flower Show, usually rewarded with a Gold Medal.
The large hybrids are flamboyant plants of varying height, commonly 5 feet (1.5 m) tall or more, growing in huge spikes crowded with flat rosettes of flower, single or double, often with a contrasting eye. The most familiar colour is sky-blue, but today there is a wide range of blue, purple, pink, white, yellow, and – the breeder’s dream realized – red. This last is not yet on the general market. But will be within a few years. The leaves of delphiniums are deeply cut and make attractive mounds of light green.
The unsolved problem with delphiniums is staking. Even the shorter varieties need canes, for twigs are not strong enough. Christopher Lloyd stakes each plant with two canes in the famous Long Border at his home, Great Dixter, in Sussex, but not until the stalks are 3 feet (90 cm) tall, and then not to the full height of the flower. He says that any flower which is so bloated that it needs a cane to the top should be thrown out. Other gardeners stake all the way, with a cane to every spike, so that the delphi-nium border is a parade of flowers and canes, nature being quite forgot.
There is another range of garden varieties to please those who do not hold that big is beautiful, the Belladonna hyb-rids, which are shorter, more branched, and smaller in flower than the jumbos.
Delphiniums are a staple element in the herbaceous border during its midsummer zenith, along with Shasta daisies, Thalictrum, lilies, lupins, campanulas and many more. Miss Jekyll, in her celebrated long border at Munstead Wood, mixed the highly-bred giants with cottage plants, and lavender, catmint, pinks, grasses and even wild soapwort rubbed shoulders with delphiniums, lilies, cannas and dwarf rhododendrons.
Delphiniums like full sun and rich soil with no lime, or just a little, and if cut down after flowering there will be fresh leaves and probably side-shoots of flowers. Plant in groups 2 feet (60 cm) apart. I have not suggested varieties, though the range is always large and exciting, because the same ones are not available every year. A sound way to choose is from a catalogue, or, better still, to see with your own eyes at a flower show.
Prune the shrub thoroughly after flowering (this will take time), shortening every flowering shoot and cutting down some of the stems in the centre of the bush as low as you can reach.
Growth is too dense for underplanting, but I like to have white tulips and red Anemone x fulgens planted nearby to make a show before the Deutzia is ready.
