Growing Delphiniums

How to Plant, Grow, and Care for Delphinium Flowers

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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Comments are to plant in

Comments are to plant in spring, can I split and transplant now in August? I live in nw Ontario not sure of the zone.

Hi, Trucia: Delphiniums are

Hi, Trucia: Delphiniums are not the hardiest plants to divide and transplant to begin with (starting from seed often works better), but if you do wish to divide and transplant, it's best to do it in the early spring, after they've had a chance to regroup over the winter. Then again, there might not be much to lose, so up to you. Thanks for asking!

I grew my first ever

I grew my first ever delphiniums from seeds and have 4 plants that are very tall and planted up against the porch rail that I use to give them support.
My question is...I live in zone 8b. Will my dephiniums come back next year or should I consider them as annuals?

For heat zones above zone 7,

For heat zones above zone 7, it is recommended that you grow them where they get afternoon shade. Consider them to be short-lived perennials in your zone or you can grow them as annuals.

Hi, I'm in Edmonton Alberta,

Hi, I'm in Edmonton Alberta, our Delphs are huge, tall, and full, we're very happy with them, except that once a season the rain or wind will pummel them or the weight of them will bring a bunch down, I didn't realize I could stake them, my question is this, if they're grown is it too late to stake them? The ones that have been knocked down from the wind, should I cut them back and see if they'll get a second bloom, if they do would I stake the second bloom? It's mid July so realistically In Alberta I'll get good weather all of August at least most of sept and some years we won't see first frost til early oct.

Hi, K-Mi: You can always

Hi, K-Mi: You can always stake anything at any time. What we mean by the advice above to stake when they are small is that this is the best way to help them get tall. But if yours get tall without any staking to begin with, that advice is irrelevant. So go ahead and stake what you have standing. Cut back what has fallen and then stake what regrows when that happens. Good luck and thanks for asking!

Our delphinium have never

Our delphinium have never done well. Out of the original three plants, only one survives (@ 4 years). Now that I've read all these ideas, we're going out back with manure, lime, and two new plants! Wish us luck! We live in central Massachusetts.

I have beautiful, green

I have beautiful, green foilage on my 3ft high delphiniums but never any blooms. When they were new, they bloomed the first few years. Now nothing. I keep thinning them out to no avail. Why won't they bloom?

How is the soil? Delphs are

How is the soil? Delphs are heavy feeders: they benefit from fertilizer and/or compost in spring and summer, and some say balanced fertilizer every 2 to 3 weeks, in growing season. Soil must also be well draining. They do not like dry, hot climates; sound like home? They like full sun to partial shade. We're betting that this, in whole or in part, is the main issue.
Do you prune/cut off lateral flower spikes? Doing so may help the main spike to bloom.
Do you cut back stalks to basal leaves in fall? This could help but not until next season, of course.

I have a healthy looking

I have a healthy looking delphinium with about 4 flower spikes but 2 of them only have a single flower at the top of the spike and no other buds down the stem! What's going on? I live in the UK.

I have one successful

I have one successful Delphinium plant at one end of a raised bed. (I planted it last year and it came back, looks OK and is budded to bloom). I planted several more this month (May) in the rest of the bed (sandy soil with accumulated compost of several years). They are not wilted or looking distressed EXCEPT that: some of the new plants' leaves are yellow, with the green restricted to the veins, although they not curled and I don't see any insect damage. The yellowed leaves have
long petioles.
I applied generous amounts of compost today (5/31) and watered it in.
I doubt the pH of that soil is as much as 7 and wonder whether I should add lime to make it more alkaline?? But if pH is the problem, why is the first Delphinium I planted last year doing all right?

Yellow leaves with green

Yellow leaves with green veins is typically an iron or manganese deficiency, which are not typically found in commercial fertilizers. However, it may be that the pH is off and those micronutrients are in the soil, but not available to the plant. There are simple pH testing kits that you can buy at most gardening stores. Make sure that the pH is between 5.8 and 6.5, which is where most plants like it to be.

About 2 weeks ago I bought

About 2 weeks ago I bought some Delphiniums at the local big box store. I wonder if they have leaf miners? All the older leaves have dead brown edges that curl under. I don't see little lines of eggs on the back, nor actual trails I can follow moving across the face of the leaf. But large areas of the leaves are covered with light tan speckles and thin lines. The area is thickened and very stiff, with a heavy, bumpy texture on the top surface. Can anyone confirm, please?

I live in North Florida and

I live in North Florida and you can imagine the summers are hot and muggy. I know it's said that growing from seeds is difficult, but I'd like to try. Do you have any tips (if seeds do their thing) for care in this climate? I'm just concerned because: "They prefer moist, cool summers and do not fare well in hot, dry summers." and I'm a mix of the two...the better two I hope. Thank in advance.

Hi Chellina, In Florida

Hi Chellina,
In Florida delphiniums are best planted in mid- to late autumn or very early winter for spring blooms during the cooler months. They will probably not survive your humid hot summers.

Jacksonville...I got about

Jacksonville...I got about two months of beautiful blooms. Started in the fall last year.

I have started these from

I have started these from seed and it is difficult but not impossible. I live in Idaho, started seeds in the early early spring. It would have been better if I had put plastic over the pot after planting seeds as a sort of hot house, you may not need to do this with your humid weather in Florida tho. Many came up but not many survived to transplant size. Good luck!

Growing delphinium from seed

I never had any luck until I planted them in a nursery bed in the fall and let them overwinter. I imagine in Florida you'd have to refrigerate the seeds before planting them out.

Easy to grow use mycorrhizal fungi

Use mycorrhizal fungi when planting and in watering. They are EASY to start and grow this way.

I purchased a couple of

I purchased a couple of Delphinium plants from Lowes on clearance because they were a little brown. I assumed they were dry and just needed to be watered so I purchased them and mixed in Miricle Grow with the soil. I watered them and kept the soil moist. They did alright for a week but then they all turned brown (stalks and leaves). When I LIGHTLY pulled on the stalks they broke off at ground level. Did the Delphinium's die or will they come back next year?

There are several reasons for

There are several reasons for brown foliage on delphiniums. Sometimes it's overwatering. Sometimes it's lack of nutrients; delphiniums are heavy feeders and appreciate compost and fertilizer.
Towards the end of their cycle, the foliage simply turns brown as it dies down naturally. They should be back next year.

Thank you very much. You

Thank you very much. You guys are great and I will keep coming back to you.

I believe what happened is

I believe what happened is you put a fertile too high in nitrogen the best fertilizer for transplanting new plants is hastagro organic fertilizer or Bills Perfect Fertilizer because it reduces transplant shock. You need something around and (not exactly ) 5-10-12

The rain has pummeled my

The rain has pummeled my Delphiniums so that they are lying on top of each other on the ground and the stems snap when I try to lift and re-stake them. Mostly they are starting to go to seed. Would it be ok to cut them close to the base so I can clean up this tangled mess or should I do my best to remove only the spikes and leave the rest until the stalks turn Brown, or something else? The flower bed is HUGE and almost completely comprised of tall Delphiniums.

Hi Juliett, Just cut the

Hi Juliett,
Just cut the spikes to the ground leaving any remaining foliage. Water and your plants may regrow another flowering spike before the end of the season.

A couple of years ago I

A couple of years ago I rebuilt our raised flower garden in our back yard using PT wood and everything we planted there (phlox, saliva, foxglove, lilies, etc.) has thrived so when it came time this year to rebuild the raised flower bed in our front yard, I felt confident using PT wood. I made a "concoction" of dirt using Scott's topsoil (they say it contains peat moss, but it can't be much), garden soil, additional peat moss (to keep the ground loose) and I threw in a little milorganite to boot. About a week ago we planted phlox and delphiniums and, after planting, I soaked the bases of the plants with Miracle-Grow's QuickStart (I followed the directions). The next day I soaked the ground with water and the third day another dose of the QuickStart. I've been watering every day since. The phlox are THRIVING!!!! It's only been a week and they all have new stems with buds coming up. The delphiniums, on the other hand, while not appearing to be dying, don't seem very "happy." The leaves are green, but all the edges of the leaves are drooping. Am I just being impatient or am I doing something wrong? Thanks!

Soory! Forgot to mention that

Soory! Forgot to mention that I live in Wisconsin, zone 5.

We really enjoyed your post

We really enjoyed your post and hearing about your gardening experience. Congrats on the phlox success. In terms of the delphiniums, perhaps it's just wilting with the heat. Be sure to deadhead delphs after blooming, too. All the best!

Not sure it can be from the

Not sure it can be from the heat. It's the end of July and we're still waiting for summer! We've had about four days in the low 90s, maybe two weeks total in the 80s, the rest of summer has been 70s (even came close to breaking a record low for last monday). If I understand correctly, once the delphinium flowers die, they should be deadheaded asap? Thanks!

Delphiniums like moist soil,

Delphiniums like moist soil, not soggy and not dry. Try to water deeply a couple of times a week. Adding mulch around the plants will help to keep the soil moist and the roots cool. Deadheading spent flowers will promote new growth and maybe more flowers before the end of summer.