Also receive the 蜜桃恋人 Daily newsletter including gardening tips, weather, astronomical events, and more.
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
ADVERTISEMENT
Sugar will only speed the decay of delphinium or any other cut flower unless you also add a little bit of bleach and some lemon juice. Use commercial floral food instead. Here is an article about extending the life of cut flowers.
I am a certified floral designer and a Master Gardener. I would never use straight sugar in my arrangements.
Thank you for this advice鈥攚e have updated our page to reflect the information!
i live in northern southeast alaska and have a whole bunch of delphiniums, they survive very well here and it gets done to 20-30 below 0-F for a short time in the winter. i started out with sandy soil, added horse manure and in late fall, i put about 5" of straw all around the plants.
i live in Northern Ontario, and just planted 4 new 2 ' tall delpinium plants
we had a big day of rain and one was sitting in a puddle of water
our earth is nice black mud, but should i uproot the puddle plant and let them dry out a bit in a pot
or let nature take its course tks
Delphiniums don’t like 鈥渨et feet鈥 and if you have a puddle now it will happen again. The soil needs to drain well so we suggest that you dig up the plants and amend the soil with compost before replanting. Or move the plants to a 鈥渄rier鈥 location.
2 years ago I planted 10 delphinium plants. They all came back up last year and bloomed beautifully. This year I have six that did not come up. Any chance they'll return next year, or are they dead? I want to replace them if they won't return. I am in Clarkston, MI - zone 5b
There are a few varieties that are biennial and bloom every other year. If you planted 10 plants that were the same variety chances are that the six that didn’t come up this year are dead. It’s helpful to know the name of the delphiniums that you plant. You can then look them up and get details on the variety.
I bought my first dark blue delphinium in July and it already had four blooms on it. I had cut the flowers off when they lost their perkiness. After the blooms were gone I left the plant in it's original pot. About four weeks later new growth was coming from around the base while the original leaves,very dark green, slowly dried out and I cut them off at the base so more energy would go to the new leaves. I also repotted the plant. The new growth is triple the size of the original and the leaves are not dark green. Now a stalk has come up and the buds are growing. I noticed that in between the top buds are black fibers or very small skinny leaves. Is this normal? Should I pluck out the black fiber things? I live near Milwaukee, Wisconsin in a condo on the second floor. Any idea how to store it over the winter? I do have room in the basement that will go no lower than 42F degrees. Or do I put it in a styrofoam container with lid. And because of my potted situation, what care should I give it during the winter? Any help is welcome!
Cut the plant down to about 6 to 8 inches after the first killing frost in autumn. You can then store the pot in the basement. Just remember to water the plant a couple of times during the winter months just so that the roots don't get too dry.
Comments are to plant in spring, can I split and transplant now in August? I live in nw Ontario not sure of the zone.
