With the lazy, hot days of summer now upon us, many parts of the garden will be resplendent while other parts will have "done their thing" until next year.
One of the must-haves for the mid-summer garden is the stately delphinium.
Delphiniums received their name from the ancient Greeks, who thought the shape of the flower bud resembled that of a dolphin.
In Tudor, England, some of the species were referred to as "larkspur" because the nectary looked not unlike a lark's claw.
Today's delphinium is the result of hybridization of delphinium species from around the world. The Swiss Alps, Siberia, the Himalayas and Armenia have all contributed to the development of today's familiar hybrids.
Delphiniums need three things: Moist, well-drained soil; food; and support (staking, especially the taller varieties). Some books say delphiniums need protection from the worst heat of the day, although I have successfully grown this perennial on a site that is due south-west and figuratively fries this time of the year.
Delphiniums are thirsty and hungry, which makes sense for a plant that can reach more than two metres in height in one growing season.
When watering, water only the root area. Don't spray overhead, as getting the leaves wet encourages the spread of botrytis, a fungal disease to which delphiniums are particularly susceptible.
Never let delphiniums get either bogged or dried out or they will die.
Fertilize several times throughout the season with a water-soluble fertilizer.
A trick I've used for many years is to sprinkle wood ashes from the fireplace around the base of the plants in early spring.
And, other than this year, the ashes helped eliminate black-spot.
While we're on the subject of pests, here's hoping you never get the dreaded Larkspur worm. This nasty critter burrows down the central stalk of the plant and consequently destroys the bloom. The worm rolls itself inside new foliage and can ravage plants literally overnight. Dust the plants liberally with Rotenone or comparable insecticidal dust as soon as you notice any damage.
Once delphinium flowers have faded, cut the plants back to just above the basal leaves at a height of 10 cm to 23 cm. Do not over-water when cut down after flowering, but increase water again when new shoots are 5-8 cm high. Before you know it, you'll have a second flowering in September (assuming we don't have an early hard frost).
For variety, consider mixing several varieties for a study in blue, for example, or perhaps mix white varieties in with other tall perennials for maximum effect.
