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Planting, Growing, and Caring for Delphiniums
Delightful delphiniums! The stalwart of many summer flower gardens, these showy perennials are grown for their long, colorful spikes in blue and other gorgeous hues. Flowering all summer, delphiniums are butterfly and hummingbird magnets, too! Learn how to plant, grow, and care for delphiniums.
About Delphinium Flowers
Delphinium is a genus in the Ranunculaceae family. (They鈥檙e often confused with larkspur, but these are different plant species.) There are more than 300 delphinium species, so there is quite a variety of heights, from dwarf hybrids to 6-foot tall beauties, so they can be planted in the front, middle, or back of a perennial border. The blue delphinium is most common, but varieties also come in gorgeous shades of violet, pink, white, red, and purple. They are popular in both cottage-style and cutting gardens.
Image: Edita Medeina/Shutterstock
Most delphiniums are short-lived perennials, lasting 2 or 3 years in the garden. Some varieties will bloom throughout the entire summer if the plants are cut back regularly. Other hybrids bloom from early to mid-summer and will produce a second flower display in late summer or early fall if you cut off the old flower stalk.
What鈥檚 important to know about delphiniums is that they will thrive if you meet their specific conditions. Delphiniums prefer moist, cool summers; they do not fare well in hot, dry weather or sudden wind or rain, which can knock them down. Most varieties will need staking. See more details below.
Are Delphinium Poisonous?
Yes, delphiniums are highly poisonous. If seeds and seedlings are ingested, they can cause nausea, twitching muscles, paralysis, and even death. This is mainly a concern for grazing animals such as cattle, horses, and sheep, and it is also a caution to gardeners with small children.
Growing
- Delphinium are heavy feeders. Apply a balanced liquid fertilizer starting in early spring every 2 to 3 weeks.
- Insert sturdy stake supports no later than mid-spring or when the plants reach 12 inches high.
- Do not allow the soil to dry out but avoid puddling. Water plants during the summer if rainfall is less than 1 inch per week.
- For ideal flower spikes, thin side shoots at 3 inches high, leaving 2 or 3 shoots on young plants and 5 to 7 shoots on mature, well-established ones.
- Deadhead by cutting spent flower spikes back to small, flowering side shoots.
- After delphiniums have finished blooming, cut flower stalks to the ground, and new, though smaller, flower stalks will develop. The flowers will survive the coming cold days and even light frosts. (See local frost dates.)
- Every 3 to 4 years, divide plants in spring: Remove and replant the new little plants growing around the outside of the clump. Discard the hard old heart.
Credit: Arty Alison/Shutterstock
Catherine Boeckmann
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Well said. Snarky answers show not only the poor character of the sender, but often his or her ignoranceas well.
I love onions and chocolate. I won't give either to my dog. I love cinnamon and mint essential oils, but I won't diffuse them near my rabbits. Not every creature is the same.
Kindness always makes one seem wise. Rudeness tends to reveal the opposite.
Delphiniums are starting to grow nicely, however, noticing a shiny look to some of the leaves. Is that a sign of some disease.
A shiny residue on leaves could indicate that slugs or aphids are present. Check out our pest pages for information about dealing with them!
Thank you for your very helpful information regarding delphiniums
I live in Massachusetts. I bought some seeds this winter and am now nervous about planting them. Are Delphinium harmful to the local wildlife? Birds, pollinators, squirrels, bunnies, etc?
Delphinium are only harmful if ingested, so rabbits and deer would be most likely to be affected. Generally, these animals will only take a nibble of the plant (not enough to harm the animal) and then be turned off by the unpleasant taste. If these grazers visit your garden regularly, consider covering the delphinium while they’re young (and most toxic) or planting them in a container that can be placed out of reach.
No they aren鈥檛 only harmful if digested you can鈥檛 touch them they can cause skin irritation all parts of Delphiums are poisonous
to: Submitted by Ann Legere on June 16, 2020 - 12:39pm
I am not sure about Lupins, but I can say I had a deer come through my flower bed. Ate all the tops out of my fuschias, roses(of course), crocosmias, violets, but didn't touch my delphiniums which were only a couple feet away.
Can you me if deer are attracted or will eat Lupins or Delphiniums? Thank you for any info you can give me. Ann Legere
Both plant are considered deer-resistant and good choices in gardens without fencing. (Just keep in mind: NO plant is truly deer-resistant if deer are hungry enough; however, some plants are more resistant than others.)
