Growing Delphiniums

How to Plant, Grow, and Care for Delphinium Flowers

Age-Old Wisdom meets Modern Tools

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Delphiniums are perennials grown for their showy spikes of colorful summer flowers in gorgeous shades of blue, pink, white, and purple. They are popular in cottage-style gardens and cutting gardens.

Delphiniums are a favorite of many gardeners, but can sometimes be a challenge. They prefer moist, cool summers and do not fare well in hot, dry weather. The plants also dislike sudden wind or rain.

Except for the dwarf perennials, most delphiniums need staking.

Planting

Grow in fertile, well-drained soil in full sun to light shade, with shelter from strong winds.
Plant in the spring. Prepare the soil, mixing in 2 to 4 inches of compost.
Delphinium is a genus consisting of over 300 species—some are annuals, others are biennials or perennials. Some grow easily from seed, others don’t.
Dig a hole twice the diameter of the plant’s container. When planting, ensure that the top of the root ball is level with the soil.
In the spring, broadcast lime, wood ashes, or a mixture of the two over this alkaline-loving perennial. Learn more about soil amendments.

Care

Insert supports no later than midspring or when the plants reach 12 inches high. Stake the low-growing perennials with twiggy, brushwood support. The taller, large-flowered delphiniums need sturdy stakes.
Soil should not dry out. Water plants during the summer if rainfall is less than 1 inch per week.
For good-quality flower spikes, thin shoots when 3 inches high; leave a minimum of 2 or 3 shoots on young plants, and 5 to 7 shoots on well-established ones.
In growth, water all plants freely, applying a balanced liquid fertilizer every 2 to 3 weeks.
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.)
If delphiniums need to be divided in the spring, remove and replant the new little plants growing around the outside of the clump. Discard the hard old heart.

Pests/Diseases

Susceptible to slugs and snails as well as cyclamen mites.
Powdery mildew, Southern blight, bacterial and fungal spots, gray mold, crown and root rot, white rot, rust, white smut, leaf smut, and damping off occur.

Harvest/Storage

This elegant flower is good for a cutting garden. If you take the blooms into the house as soon as they open, they will bloom again.
Add sugar plus lemon juice and bleach to arrangements of delphinium. You can also use a commercial flower preservative.

Recommended Varieties

There are dwarf-sized delphiniums and medium-sized as well as tall ones (growing up to 6 feet and higher).

Belladonna Group: Upright, loose and branching perennials with single flowers that grow 3 to 4 feet tall. ‘Blue Bees’ is a Belladonna producing clear blue flowers with white centers.
Elatum Group: These are the tallest spiked hybrids growing to 6 feet or more. ‘Blue Nile’ is a medium plant bearing semi-double, bright, and mid-blue flowers with white centers (called bees). ‘Bruce’ is a tall Elatum bearing semi-double, violet-purple flowers, paler towards the center, with brown bees.
Pacific Hybrids: Similar to Elatum Group, although not as tall, this hybrid is short-lived and often grown as annuals or biennials. ‘King Arthur’ bears plum flowers with white bees with 5- to 6-foot tall flower spikes.

Wit & Wisdom

Very young delphinium plants and delphinium seeds are poisonous. If ingested, they can cause nausea, twitching muscles, paralysis, and even death.

Reader Comments

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Transplanting Delphiniums

How big should Delphiniums be before transplanting them from under the grow light to outdoors?

transplanting delphiniums

Kudos for getting sprouts, Jack. Height is a consideration but you want seedlings with “true” leaves, not just the two that initially appear. True leaves appear early, so if your plants have a couple to a few inches, you’re probably well past that stage. As for height, we’ve see suggestions of 12 to 15 inches but it depends on the strength of the plants. Before transplanting you also want to harden off the plants—get them used to the world. Here is some advice on that https://www.almanac.com/video/how-harden-plants and another https://www.almanac.com/news/gardening-news/time-get-tough-hardening-plants (these are about vegetables but the process is the same).

We hope this helps!

Delphiniums indoors In Houston Texas

I want to grow delphiniums indoors in a south-facing window with small period of shade from trees throughout the day .
A/C will be maintained to 80 degrees or less
Any chance of success?

Deep South Delphiniums

Hello, my wife and I really like delphiniums but we hear that they are very difficult to grow here in the coastal southeast, zone 8b. Nevertheless I purchased some and planted in good, composted soil. What tips can you give me that would heighten my chances of success? Also are there any varieties that would do better than others in this area. I realize that they would be only annuals. Thank you.

Delphinium Dwarf Larkspur

I live on the southeast coast of Florida, can I grow these in the ground in partial shade?

Delphinium (Larkspur) in Florida

Delphinium is technically a perennial, but it can be grown as a winter annual in Florida. Otherwise, Florida is just too hot and wet for this cool-weather plant to survive a summer season.

Delphiniums do need full Sun to grow but they prefer cool weather. So let seeds germinate in winter and the plant will bloom in early spring. Once temperatures rise in summer, the plants will fade and you’ll need to remove them.

wintering pot Delphiniums

I have 3 delphiniums (pale blue/white) growing and flowering nicely in a pot on the deck in SW Iowa. How should I winter them to see them grow and bloom in the Spring again?

overwintering delphiniums

As noted at the top of this page, delphiniums can be a challenge; not all grow as perennials. Many are short-lived plants. Knowing that, you could experiement: Cut them back as advised in Care above. Put them into a garage or basement and water them occasionally. Or, if you are in zone 7 or lower, lift them from the pot now and plant them (you could also plant the pot), then lift them in the spring and repot to see if they come back.

pH

There are two conflicting suggestions on this page regarding the ideal soil pH for growing delphiniums. The intro says they are alkaline-loving, but later you say that the soil pH should be between 5.8 and 6.5. A pH of anything less than 7 is considered acidic, not alkaline (basic). Please clarify what the ideal soil pH should be for successfully growing delphiniums. Thank you!

Delphinium pH

Thanks for catching that! The information in the intro is correct: Delphiniums prefer alkaline soil, not acidic. Your soil should stay on the lower end of alkaline (between 7 and 9 pH), however.

Overwintering Delphiniums

After many years of growing Delphiniums, I
finally figured out how to protect them during our often snowy winters in
New York. And I 'm gardening in very large pots on a terrace.

I don't have to lift them or bring them inside.
I just put sand around (not on) the plants so
that even as the snow melts, even if it's a rainy
winter, they have good drainage.

You can get the sand at most hardware stores.

I now lose very few delphiniums
I currently have 5 that are two years old
and 3 that are 3-years old.

They don't last forever, but if you their roots
have lots of room to grow, they can become very
tall--even over 2 years.
Some are now six feet tall, and even in containers,
they have spread to 2-3 tall delphiniums that bloom
twice each summer.

already planted 2nd year

I live in Minnesota. Last year I planted some potted Emperor Delphiniums (dark deep purple with white bee) And one or two light blues, they grew about 2ft. With at least 2 stalks. After fall was well over and just before winter began I cut all of them back. It’s finaly spring here no more snow all the snow I think has finaly melted and we have had 4 days of over 58* degrees in a row w/ no weather below 60 in the forecast.. other spring flowers are growing out of ground. Dafadiles etc. when will my DELPHINIUMS start to show some effort of growing my garden is bare.

Tall Pacific blue Delphinium won't bloom

Bought this plant in full bloom 2 years ago and planted it in a new bed with fresh deep earth and mulch. It has half a day in full sun and half a day in shade. It grows nice strong thick 5 to 7 leafy stalks growing tall to about a yard and a half tall, and puts all its growing to growing green and tall throughout the spring and summer but for the last two years , no flowers at all. How can I get this plant to produce flowers?

Deadheading

I don't know what the dead part looks like. Sometimes I think the white is dead, but other white looks like it's the new blooms starting. What is the green pod? Should I remove it. The only thing I am confident about is when the blue dries out!
Could you post pictures of the parts and what to deadhead?

Response

Sounds like to me, you did not get any pollinators (Bee’s or butterfly’s) that first year they were planted. Awe that’s sad. It’s best to plants several pollinator favorites together at the same time. To guarantee they smell and will come. Marigolds, purple hyssops, Phlox and candy tuff, they like keep in mind flowers are Regional and species by favorite. Meaning each region has specific butterfly’s and therefore each species has their favorite flowers. Check for the species that favor your region and plant their specific favorite flower .. I don’t know if it is too late for your flowers to bud.

Delphinium seed pods

Hi I bought some beautiful delphinium plants mid July. The nursery had them in the Perennial section. I hooked the informations to each plant but either birds ran off with them or ? Anyway...they all went to seed and I took all the little pods off and emptied the seeds into baggies. Now Im wondering if that was right? Should I go dump the seeds with the plant? Im not a good gardener...Ive been told non jokingly that I should not have a yard! I agree. So what do I do with the seeds? Deb

setting seeds

You could dump the seeds near the plant. Some delphs grow easily from seed, some do not. If you want to grow the seeds (or plants) sucessfully, you should test your soil. Here’s some advice: https://www.almanac.com/blog/gardening/garden-journal/soil-testing-bette...

Delphiniums do poorly in acidic or neutral soil. So, if you prefer not to test at this time, broadcast lime, wood ashes, or a mixture of the two over the soil you would use for this alkaline-loving perennial. Learn more about soil amendments.

Overall, re whether the seeds will set, consider contacting the source you bought them from for information. They may be able to tell you what type they are.

Delphiniums

I have just purchased 2plants in pots is it ok to plant out now

Delphiniums

I have seen delphiniums on sale now. Can I plant out now?

Delphiniums

Hi Mary,

It’s too late to plant delphiniums now; they should be planted in the spring. Delphiniums don’t like hot, dry weather like that of the summer.

moving delphinium

I know it's not ideal, but I have a delphinium in a shady garden that needs to be moved. The whole bed needs to be dug out and redone. My question is, will it be worth the effort, or will I kill it? It's a nice big plant, and I do have a better location for it. It is blooming, but the stems all fell over, and are laying flat. So I thought I would just cut them off totally, then move it. I am in zone 3b, and we are having 80degree days, 60 degree nights.

moving a delph

There may be several factors that put the plant at risk, not moving it alone. Soil conditions are key: well draining and alkaline being paramount, and a thin layer of compost each pring, followed by 2 inches of mulch to help retain moisture (soil should not dry out) and deter weeds. Lifting and dividing should be done in the spring; can you wait?? These plants are not fond of heat. So that and lack of sun (they’ll tolerate light shade) could be the reason/s its flagging. Remember, if you lose it, you can get another one.

Delphinium

I have just resented planted my first delphinium and it has been growing great. The top has blooms on it but has not bloomed yet. We had two days of downpours getting maybe 5inches in two days. Now the top of my flower has dropped over. What do I need to do? Will it snap out of it?

rain

If the soil is soggy, the blooms will drop. Let the soil dry out and the plant should recover. Also, it helps to stake delphiniums to prevent damage in a rainstorm. Use some natural twine around the plants, just below the flower heads, without actually tying them up.

Guardian Blue Delphinium

Can I plant in a large pot? Is it an annual?

Delphiniums in Containers

Delphiniums are perennials, so they will come back each year as long as they are hardy in your planting zone. You can plant delphiniums in pots, but be sure to use a pot that has a drainage hole and has loose, well-draining soil.

Heavy winds

Hello! We recently had some heavy winds and I was unaware to stake my delphiniums in the spring so they all tipped over. I tried lifting a couple but two broke at the base so I stopped moving them. Can a person still salvage them somehow? Will broken ones still come back next year?
Thanks!!

Staking Delphiniums

Good question! If your delphiniums were allowed to bloom normally, you would cut back the stalks after the flowers died. Your delphiniums should have no problem coming back next year.

"Guardian Blue" leaves are browning

I recently purchased and planted my Larkspur in a large pot on my patio The flowers are blooming, but the leaves appear to be burning. It gets morning and mid day sun. Any suggestions?

"burning" leaves

If by burning you mean turning yellow, your plant could be afflicted with a disease and, honestly, there are too many options to cite here. At this link << http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/delphinium... >> you will find a number of conditions, symptom descriptions, causes, and remedies. We hope you can find a solution…without having to destroy the plant. However, if that appears to be the best “management” as it’s called on this chart (at the link), you should consider returning the plant to the vendor, as the disease may have originated there, or at least telling the vendor of your experience.