Border Control
Delphiniums are divine, but demanding. Here is how to manage these difficult divas to create a frame of elegance and beauty...
They’re the plants that always draw the admiring glances at flower shows or in gardens. They’re the grand dames of the herbaceous border, elegant and statuesque perennials with beautiful spires covered in blossoms. They’re delphiniums – divine but definitely demanding.
So let’s take a look at how to manage these difficult divas!
Start them off in a good, welldrained soil in full sunshine.
They rot in waterlogged soil over winter so add grit if necessary when planting. Add organic compost as well – wellrotted manure would be ideal as they are hungry feeders.
A sprinkling of blood, fish and bone every so often through the season is good too. A layer of mulch will help retain moisture in the soil.
Delphiniums are prone to powdery mildew, a fungus that thrives in dry conditions.
If they do get this fungus – which you can identify as a white powdery substance on the leaves that can also get distorted and stunted – you can treat with either organic or chemical fungicide. But prevention is always better than cure, so keep your plants well-watered.
Snails are the other great enemy – they just love to munch on fresh delphinium foliage in spring and summer.
Use all your means to deter – organic slug pellets work well and they won’t harm wildlife.
Encouraging birds to your garden is probably one of the best methods to control slugs and snails.
A homemade method is garlic drench – boil up some bulbs of garlic in water, strain off and use a couple of teaspoons of the mixture diluted in your watering can.
A regular drenching with this on your plants is said to be a big turn-off for the slugs.
Other natural methods are using nematodes – small worms which are added to the soil – and the tried and tested beer traps and copper rings.
The bigger delphs will need staking. Plant size can range from small to tall so choose accordingly if you don’t want the fuss of staking.
You can use steel ring hoops, bamboo canes or twigs from the garden as support.
Don’t tie in too tightly – allow for some gentle sway in the breeze so that the stems don’t snap.
When your plants mature over a few years, you can start to thin out the flower spikes. This is optional – it’s only if you want the plant to focus its energy on producing some spectacular spikes.
Either way, cut back after flowering and you will likely get a second, smaller flush of flowers in September.
The easiest way to propagate is by taking basal cuttings in spring. This is just snapping off a new shoot at the base of the plant – remove lower leaves and insert in cutting compost.
You can also grow from seed early in the year.
As your plant matures over a few years, you can lift and divide.
They’re wonderful at the back or middle of the border, bringing an explosion of vertical colour.
Other plants which perform a similar function are foxgloves, eremurus, hollyhock and some of the tall campanulas. But they’re also gorgeous scattered randomly, the classic cottage garden plant. And they make the best cut flower.
Their colour palette ranges from white and cream to light and dark blues, as well as some pinks and mauves. My favourites include ‘Black Knight’, which is a deep dark blue, while ‘Blue Dawn’ is a beautiful sky blue colour with a black eye at its centre and reaches up to 5ft 6ins so needs staking.