Do you like the English gardens of yesteryear and want to recreate the vintage spirit in your space? Looking for beautiful flowers to add to your garden borders? Delphiniums can do it all and you will be the envy of all your friends.
Delphiniums come in many sizes, from giant to dwarf varieties, and offer versatile solutions from pots to brightening up fences and adding colorful splendor to your space.
Delphinium is an amazing plant that will wow you and anyone who visits your garden, including bees and hummingbirds. Here’s what you need to know about growing delphiniums:
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What are delphiniums?
Delphinium by Sarah, Fantail Ridge Flower FarmDelphiniums are a short-lived perennial in USDA growing zones 3 through 8 with cooler conditions, but can be treated as a biennial or annual in warmer regions.
A member of the Ranunculaceae family, otherwise known as the buttercup family, delphiniums make up 370 of the 2,000 species of annual and perennial plants in this family. They add height, color and impact to borders and cut flower arrangements.
Newer varieties are being developed to be more heat tolerant, but generally, delphiniums like moderate temperatures. Larger ones need protection from the wind or they will tip over.
10 excellent delphiniums
With the characteristics of larkspur, but with a more prominent presence, delphiniums are available in different colors that will suit everyone’s color palette and garden. Here are some of our favorite options for growing delphiniums in the vegetable garden.
1. King Arthur
It’s a stunning example of what delphiniums have to offer, with dark purple to blue petals and a white center. It’s almost as if someone had painted this beauty by hand. Ideal in zones 3 to 8, it likes full sun without heat and can grow up to six feet tall.
2. Galahad
If you like pure white on solid green, this is a must. ‘Galahad’ grows to around 4-6 feet in the right conditions and explodes with pure white flowers on a tiered stem. He continues to give in Zones 3-8 and is part of the Pacific Giant Series.
3. Million Dollar Blush
This is a shorter variety reaching around 2-3 feet. The shorter types are worth considering if wind is an issue. Powder pink tones with large double petals on the ground. ‘Million Dollar Blush’ tolerates partial shade to full sun in zones 3-7.
This plant is more heat tolerant than other types, so if you dream of growing delphiniums but think your climate was too hot, try this.
4. Highlander Blueberry Pie
This delphinium is unique and comes with whipped cream. Its beautiful bi-colored flowers with frilly double petals start with a pink tint and then change color to blue as they mature. The flowers retain a creamy white center.
This is a shorter cultivar perfect for cut flowers or if you don’t want the height in your garden borders that giant delphiniums give. Good in zones 3-7.
5. White Magic Fountain
This member of the Magic Fountain series speaks of pure vintage indulgence. Not pure white as the brown to black centers provide a contrast that draws you into the elegance of this compact 2-3ft delphinium.
It will tolerate some more shady spots in the garden, but will also be happy with sun. This is a perfect delphinium for containers in zones 3-7.
6. Dark Knight
The vibrant deep blue to purple petals and distinctive bumblebee center of this large, impressive giant delphinium tick all the boxes. Hardy in zones 3 to 8 and reaches around 5 to 6 feet in height. This one is part of the Pacific Giant series and is suitable for newcomers to delphinium cultivation.
7. Astolate
‘Astolat’ is part of the elatum species, often called the candle larkspur. This is due to the way the flowers branch out from the stem like tall candles. Being a tall variety reaching 4 to 6 feet, wind protection is essential.
‘Astolat’ has flowers with subtle creamy white centers and offers vintage purple to pink tones. Perennial and hardy in zones 3 to 8, it is a sun lover with a reasonable heat tolerance if fed and watered appropriately.
8. Highlander bolero
It is in the top ten because its flowers differ greatly from the others available. With small, tightly packed petals on large flower heads, ‘Highlander Bolero’ offers two-tone hues ranging from electric blue to pinkish purple with cream centers. Looks like someone dyed it.
It is a smaller type of delphinium reaching between 2 and 4 feet, but this makes it more suitable for gardens that are more exposed to the wind. Perennial in zones 3 to 7, it likes at least 6 to 8 hours of sun per day.
9. The beauty of Cliveden
‘Cliveden Beauty’ bears pastel blue flowers in a unique form and is reminiscent of a Victorian mansion flower garden. With long stems of fountain flowers, it is a member of the Belladonna range, typically growing between 2 and 4 feet tall and 24 inches to 36 inches wide. Belladonna delphiniums can be tricky to grow, but it is a longer-lived delphinium. If you are a seasoned grower in zones 3-7, this is the one for you.
10. Princess Caroline
If you’re not a fan of blue to purple or vintage pink and white, check out Princess Caroline. With special coral tones ranging from dark to light as it ages, it’s quite unusual and a show stopper for the garden or cut flower arrangement.
Part of the elatum species, it produces two-headed, fountain-flowing flowers in large numbers and with sturdy stems. ‘Princess Caroline’ grows 2 to 3 feet tall and is another one that does well in partial shade in zones 3-7.
Growing delphiniums from seeds
Growing delphiniums from seed saves money and gives you more color or variety options. Delphiniums are happy direct sown or transplanted, as long as they have the right weather and soil conditions.
Delphiniums flower most prominently in their second to third year, although some newer varieties are annuals, so they flower the first year. If you let a few flowers ripen and set seed, they will go straight to seed for the following year.
Some of the new varieties arriving are more resistant to extreme temperatures, and it’s worth collecting your own seeds to save for next season.
Delphinium seeds germinate in 10 to 20 days at temperatures of around 65 to 70°F. Begin sowing eight weeks before the last spring frost or sow direct in early summer.
Delphinium seeds can be difficult to start with transplanting and direct seeding methods. Cold stratification is a good step to trigger them.
To do this, store the seeds in the refrigerator for a few months before sowing them, or place them between a damp paper towel in a plastic bag in the refrigerator for 36 hours before sowing them. Sow the seeds in the starting mix, about 1/8 inch deep.
Photo by Sarah, Fantail Ridge Flower FarmIt is not necessary to pinch the seedlings because, with certain varieties, it is necessary to promote flowering as quickly as possible. Place seedlings in an area maintaining 50-55°F.
To transplant, prepare the soil with compost and harden off the seedling. Space them 12 to 18 inches apart.
How to care for delphiniums
Place new plants in holes no deeper than the pot they were grown in with good compost and keep the soil moist but not saturated.
These plants need 6-8 hours of sunlight. Stake taller varieties to protect them from the wind. Feed with a good quality liquid fertilizer every two weeks during the flowering period.
Mulch in the fall, keeping the mulch about two inches thick and away from the base of the plant.
Delphiniums are hungry plants, so dress them with compost or manure when they start to bloom.
To collect seeds to multiply your plants, let the pollinators do their magic and let the seed pods ripen. Deadhead spent flowers or cut near the base to encourage more growth and blooms.
How to propagate delphiniums by taking cuttings
Delphiniums can be propagated by taking cuttings from new growth that sprouts in the spring. Delphiniums are herbaceous plants, which means they die back to the ground and, if perennialized, the roots stay alive for the next growing season.
With herbaceous cuttings, the new growth should be cut below the ground where the stem is not hollow. This is called basal spread, i.e. the base of the floor. Rooting hormone can be used to speed up the growth process, but it is not always necessary.
Large clusters of perennial delphiniums can be divided at the roots and placed in different parts of the garden. Early morning treatment for any propagation technique is best.
Keep all developing plants away from extreme heat or cold and wind. Moisten at soil level, but do not overwater as this can significantly reduce the success rate.
Delphinium Pests and Problems
Growing delphiniums can be difficult when young, but once established they are hardy and carefree.
Loved by many pollinators, butterflies, bees and hummingbirds, they also attract some less admired creatures, such as:
Delphiniums are poisonous. They can cause skin irritation and should not be ingested. This means they’re relatively safe from rabbits and deer, so try growing delphiniums if you’ve found herbivores eating your other flowers.
Common diseases that can affect delphiniums include:
- Powdery mildew
- Bacterial leaf spot
- Crown and root gall
- Botrytis blight
- Stem canker. This is a fungus that infects the plant by damaging the roots. Usually a sign of this is watery lesions on stems and petioles. The leaves turn yellow before rolling up. Delphinium often dies. Remove diseased plants, plant healthy seedlings and practice good crop rotation.
Be sure to space plants appropriately for good air circulation between them, don’t overwater, and keep plants healthy with a balanced fertilizer. Other than that, growing delphiniums isn’t too difficult!
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