Growing Delphiniums

How to Plant, Grow, and Care for Delphinium Flowers

Rate this Article:

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.

Planting Times

Reader Comments

You must have Javascript enabled to use this form.

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?

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.

delphinium

I bought one and it is dying I keep it watered what am I doing wrong

delphinium

I bought one and it is dying I keep it watered what am I doing wrong

Stalks Shorter second time around

I cut my first set of very tall and bountiful blooms down and the shoots that are coming up now are already set to flower. However the spikes are significantly shorter and have many less buds. Are they usually supposed to have this happen?

delphiniums' second round of blooms

It is typical of delphinium’s second bloom stalk to be smaller than the first. Take heart in the fact that you are doing everything right: Some gardeners find this a difficult plant to grow!

New foliage Yellow

I live southeast Houston and I purchased my delphinium about a month ago. I had to cut down one spike that had already flowered a week after while another was shooting up. I also managed to get rid of its cyclamen mite infection by giving it a hot water bath for 30 minutes. My question is regarding the new growth that is yellow with green veins and a lot of is drooping. The other spike is now flourishing but shows no sign of distress. I have given the plant plenty of compost and regularly bury 3 banana peels in the soil every week. Could it be that I didn't water it enough? Could it have anything to do with the very small amount of diluted urea I gave the plant two days ago? Am I applying too much neem oil? Also, what is 1 inch of rain per week in gallons?

delphinium blues

All in all, the plant has been through a lot during its month in your care: A stalk was amputated. It was soaked in hot water. Why the bananas? These are traditionally said to benefit to roses (and some dispute this). Diluted urea? Why? Neem oil? Why—does it have looper worms? (Search “neem” on this page for more on this.) Has the plant had time to get acquainted with its new home? Does it get sun? It sound like you’ve watered it plenty. Is the soil damp? If so, it’s watered. One-inch of rain per week is watering until the water soaks down 1 inch. You should just water when it is dry. Delphiniums do not like “wet feet.” We suggest that you read the care tips above and the reader comments and our responses below.

About the new growth that is yellow with green veins and is drooping: this may be a sign of an iron or magnesium deficiency and/or it could be a sign of improper pH. Do a soil test; you want a pH between 5.8 and 6.5.

You should also consult your local cooperative extension. Click here http://www.almanac.com/search/site/cooperative%20extension chose your state, and find the service nearest you. The folks here are very helpful!

Reasons

After the other stalk had been spent, I decided to cut it to make another shoot sprout later in the year. I gave it banana peels because I read that they are great organic fertilizers with high potassium and phosphorous amounts that encourage healthy blooms. I gave it diluted Urea for the high nitrogen count and Neem oil to prevent the return of the Cyclamen Mites, powdery mildew, and other diseases. I've also applied an iron/magnesium/zinc solution to the foliage per the label's instructions for faster and safer absorption. It was a very damaged plant when I first bought it so I tried to give it extra care aside from the plants natural high demands. The PH is right around 6.2.

I tried to keep the soil moist per all the discussion posts I've read but it gets very hot and windy in Houston and the plant would often dry out so fast that I wouldn't be able to keep up with it. Anyway I kept it in partial shade and watered it each time 1 inch of topsoil dried out.

The problem is that I was advised to never let it dry out but constantly keeping it moist might have let to root or crown rot. However I don't see any fungus, there's no pungent smell, and the plant is otherwise flowering through side shoots off the second stalk. I've tried to control its environment but this Delphinium has been a very challenging experiment. I'll apply some more iron application and keep the moisture level even but is there any other preventative measures I can take?

additional care...?

Our only thought is, as noted above, to contact your local cooperative extension and ask the advice of experts there. Being “on the ground” and familiar with local conditions they may have insights or comments.

Local extension

I reached out to TAMU agriculture and they were great. Thank you for all of your insights, I really appreciate it!

WHAT?

Delphiniums are very difficult to grow from seed. Buy as a potted plant at the nursery- where did you find this info? Delphiniums are so easy to start from seed, just drop them in the fall - presto your will have lost 1/2 your garden to delphs in 3 years!