Growing Pacific Giant Delphiniums From Seed
How to Cultivate Delphinium Species, Hybrids and Cultivars
The Pacific giant group may not be the tallest (although they’re still pretty grand at 5ft./1.5m) but the flowers are certainly the largest. Carried above deeply lobed and very attractive leaves, each spike can carry around three dozen blooms. Expect each of these to be up to 3in. (7.5cm) across.
Blooms open from the base upwards and the ones at the bottom will have died off before the youngest at the top have even opened, as is the case with so many flowers that are borne in spikes, but a decent show is guaranteed – up to around a foot or more of open blooms at any one time.
Delphinium Flowers
Many of the Pacific giant varieties have what are commonly called 'bees' at the centre of each flower. White flowers tend to have black bees and blue, pink and purple blooms have white bees, but that isn’t always the case. The bee is simply the reproductive organs and can sometimes make an unwitting onlooker take a step back before sniffing them - however, delphiniums don’t have a scent.
Where to See Delphiniums
Visit a local flower show during summer, or even the Chelsea Flower Show in west London in May, and show goers could be forgiven for thinking that tightly packed spikes are all that delphiniums have to offer. In fact there are several interesting and unusual forms that will keep all but the most knowledgeable gardeners guessing. Delphinium cardinale produces very loosely branched spikes of crimson flowers. They have quite prominent spurs which makes them look like an elf’s hat. Plants grow to 6ft. (1.8m) and are fully hardy – and come highly recommended. The spikes alone are 3ft. (90cm) tall. Get it from Chiltern Seeds.
Large-flowered Delphinium
Another cultivar worth growing is Delphinium grandiflorum ‘Blue Butterfly’, also from Chiltern. Again, it’s freely branching but the flowers are massive (for a delphinium) and a delightful mid blue. Each of the five petals has a dot towards the outer edge that makes it a real conversation piece.
Many gardeners love the combination of white and green in a flower and ‘Green Twist’ from Thompson and Morgan is a highly prized delphinium for the garden. Bred by Dowdeswell’s Delphiniums in New Zealand, the double flowers are cream or white with a pale green tinge, and plants reach up to 5ft. (1.5m) tall.
Raising Delphiniums From Seed
Delphinium seeds should be sown outdoors during July, although the seed needs to be cold-treated (stratified) first. Place the still-sealed packet in the salad drawer of the fridge for a week or two.
Then prepare a seed bed. Remove the seeds from the fridge and sow thinly, lightly covering with soil and watering with a fine rose. Keep moist. Seed can also be sown in a tray filled with John Innes seed compost and placed in a cold frame.
Thin or prick out seedlings in the seed bed to 2in. (5cm) apart as they develop. Transplant these and the tray-raised plants to their flowering positions in September to October. Provide support early the following spring before growth gets beyond 12in. (30cm).
Delphinium Pacific Giants
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Delphinium Green Twist
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