Growing Delphinium: Vibrant Blue Garden Spires

Tall and tightly packed blue wands that pollinators and hummingbirds adore, the dramatic Delphinium is sure to strut its lacy foliage and vertical flowers in your landscape!

Related to Hellebores and Monkshood, and a member of the Buttercup family (Ranunculaceae), Delphinium has a long history as a medicinal, for creating blue dye, with cultural and religious significance, symbolizing open and ardent love, lightness, and levity!

Learn about how to care for and enjoy July’s birth flower!

All About Delphinium
Using Delphinium In The Landscape
Nature Hills Top 5 Favorite Delphinium!
Caring For Perennial Delphinium

All About Delphinium

There are about 300 species of flowering perennial Delphinium in the family Ranunculaceae. Grown for their showy spikes packed full of vibrant florets, Delphiniums come in brilliant shades of blue, pink, white, and purple, and many are perennials, but some are biennials or some varieties may be annuals.

Native Larkspurs have been cultivated in English gardens since the 15th century and with breeding and cultivation, the large-flowering Delphinium came about! Native forms of this perennial can be found throughout the Northern Hemisphere and the many cultivars are a favorite of many gardeners.

Common names include Bee Larkspur, Lark's Heel, Lark's Claw, and Knight's Spur, Delphiniums also include a slightly different variation, known as Larkspur. Delphiniums get their name from the Latin for 'dolphin' which refers to the nectary at the base of each flower that resembles a dolphin.

The big flower spikes bloom from the base up, creating a tapering bloom full of flat, ruffled, and colorful florets that flower for a long time as a whole. The small black dot in the middle is known as the 'bee'.

The green basal rosettes have fine-cut, deeply incised foliage reminiscent of Japanese Maples with deep grooves along the midribs for a textured effect. These tall wands bring a whimsical and magical element to the landscape and can be towering focal points very quickly!

Using Delphinium In The Landscape

Delphiniums are perfect plants for adding tall, linear pops of color throughout the summer garden! Typically flowering from June to September, these put on a long-lasting display! Also available in pink, purple, and white, Delphinium includes some of the few 'true blue' flowers!

Smaller Delphinium varieties are fantastic planter thrillers that add height without taking up much space and are wonderful front-of-the-border accents and edging!

While taller varieties are dramatic back-of-the-border accents, in rows as backdrops, and in groupings as towering focal points among sunny garden beds and borders.

Delphinium are must-haves for the Cottage Garden, but are also at home in the mixed perennial border, or along pathways and walkways without worrying about them taking up too much space. They’ll especially show off when planted in front of a picket fence or evergreen hedge!

Not only are the flowering spikes super showy, but Delphinium flowers are fragrant and attract more than people to check out their impressive fat flower clusters! The fragrance attracts bees, butterflies, and even a few curious hummingbirds! Florists love them and Delphinium is a must-have for the pollinator border, and your cut flower garden!

Nature Hills Top 5 Favorite Delphinium!

We’re sure you can find your own favorite Delphinium plants, but here’s our Top 5 Favorites!

#5 Diamonds Blue Dwarf Delphinium

Featuring pink diamond-shaped dotted petals, the 2-foot tall flowering spires shoot up flouncy spikes of flowers ranging from electrified lavender to lavender blue. These perennials form mounds of heavily lobed, deep green leaves that are perfectly sized for tucking into any garden bed or border, or even containers for a dramatic blue vertical accent!

#4 Blue Lace Delphinium

Soft sky blue double blossoms packed along a soaring 5 to 6-foot tall wand that erupts from clumps growing only 2 feet wide! The Blue Lace features enchanting petals for bees and pollinators and enormous back-of-the-border specimens! Cold hardy in USDA planting zones 3 to 7, Blue Lace stands out head and shoulders above the rest!

#3 Summer Nights Delphinium

With true blue blooms and light green foliage, the Summer Nights Delphinium has airy spires like their Larkspur cousins and grows under a foot high and wide! The flower and foliage color combo is eye-catching, to say the least! Check out other Summer Delphinium series Delphinium like the white Summer Stars, the sky blue Summer Blues, and pale pink Summer Mornings for the full range of pretty colors available in this great series!

#2 Magic Fountains Delphinium

All of the Magic Fountains Delphiniums are incredible to behold! Huge, boldly-colored, tightly packed spires full of double cuppy petals, it's no wonder they’re high on this list! The Magic Fountains Dark Blue White Bee Delphinium royal purple-blue double flowers with white eyes are incredible back-of-the-border accents 2-3 feet in height. Magic Fountains Delphinium also includes Cherry Blossom with mauvy pink blooms and white eyes, or the White Dark Bee Delphinium with white petals and black dotted centers.

#1 NEW MILLENNIUM™ Purple Passion Delphinium

Supersaturated dark purple spires shooting up 4 to 5 feet in height, these showy double flowers are each accented by a white eye. With clumps forming 2-foot wide mounds, Purple Passion will stand up and stand out with impressive form and color! Just as cold hardy and sturdy as the rest, the incredibly bold color will garner attention from everyone and every pollinator around!

Caring For Perennial Delphinium

Delphiniums have the strongest stems to support those tall flowers when planted in full sun - 6 hours or more sun per day.

Delphiniums require moist, cool summers, and it is suggested that they be bought as a plant since it is difficult to grow them from seed. While short-lived perennials, the many off-shoots that form around the base of the main plant can be transplanted or encouraged in place and enjoyed year after year!

These perennials do best in moist, well-drained soil that is organically enriched. Create raised gardens or berms if you have poor drainage. Delphiniums cannot tolerate wet saturated soil, especially during the winter months., so water new plants regularly using the Finger Test to help them get established and continue to provide supplemental water during high heat and drought.

Get your new Delphinium off on the right foot with Nature Hills Root Booster!
Deadhead stems to the ground as flowers fade to encourage a rebloom
Prune Delphinium leaves back in the late autumn after several killing frosts.
Provide regular fertility in the spring and early summer
Give taller varieties support if your area has strong winds and storms
Important to provide a 3-4 inch deep layer of mulch over the root system (not covering the crowns)

Deer and rabbit-resistant because of their thick leaves and possibly because of their strong flavor. There are few pests and diseases that attack these hardy perennials!

Dive Into Growing Delphiniums!

Bold blooms for the back of your garden borders, Delphinium adds an element of surprise and mystery to your landscape beds!

Bring this flower from antiquity to your yard today and see why it’s beloved by so many!

Happy Planting!

Frequently Asked Questions

Are delphiniums perennials or annuals?

Delphiniums are mostly perennials, though some varieties are biennials and others are annuals, so it depends on the specific cultivar you choose. The perennial types reliably return each season and are the most popular choice for gardeners looking for long-term color in the landscape. When selecting a delphinium, check the plant tag or product description to confirm whether your variety is a perennial, biennial, or annual so you can plan accordingly.

How much water do delphiniums need, and how do I avoid overwatering them?

Delphiniums prefer consistently moist but well-drained soil, typically requiring about 1 inch of water per week from rain or irrigation during the growing season. They are sensitive to both drought and waterlogged conditions, so good drainage is essential to prevent crown and root rot. Water at the base of the plant in the morning to keep foliage dry, and always check that the top inch of soil has begun to dry out before watering again.

How far apart should I space delphinium plants for the best growth?

Delphinium plants generally perform best when spaced 18 to 24 inches apart, which allows adequate air circulation to help prevent the powdery mildew they are prone to developing. Larger, taller varieties may benefit from the wider end of that range, while compact or dwarf types used as border edging or in containers can be planted closer together. Good spacing also makes it easier to stake the tall flower spikes, which can reach 4 to 6 feet in height and often need support. When planting, prepare rich, well-draining soil and position your delphiniums where they will receive full sun for the best bloom production.

Do delphiniums need staking or support to keep their tall flower spikes upright?

Delphiniums frequently grow 4 to 6 feet tall, and their large flower spikes can become top-heavy, making staking an important part of their care. Install support stakes or a grow-through ring early in the season before the plants reach full height, ideally when stems are around 12 inches tall, so the plant naturally grows into the support. Bamboo stakes tied loosely with soft twine work well for individual spikes, while a wire cage or ring support works nicely for the whole clump. Check and adjust ties as the plant grows to prevent the stems from snapping in wind or heavy rain.

How do I deadhead delphiniums to encourage more blooms?

Deadheading delphiniums is straightforward and highly effective at encouraging a second flush of blooms later in the season. Once the main flower spike has finished blooming, cut it back to a lateral shoot or down to the base of the plant, and fresh growth will emerge. For the best rebloom, pair deadheading with a light feeding of a balanced fertilizer to give the plant energy for its next round of flowers.

When and how should I cut back delphiniums after they finish flowering?

After your delphiniums finish their first flush of bloom, cut the spent flower spikes back to just above a set of healthy leaves, leaving the basal foliage intact. This deadheading encourages a second, smaller flush of blooms later in the season, typically in late summer or early fall. In fall, once the foliage has died back after frost, cut the entire plant down to just a few inches above the ground to prepare it for winter. Applying a layer of mulch over the crown after cutback will help protect the roots through cold months and set the plant up for strong regrowth the following spring.

How do I divide delphiniums to keep them healthy and blooming year after year?

Divide delphiniums every 2 to 3 years in early spring when new basal shoots emerge, as older clumps tend to lose vigor and bloom less prolifically over time. Use a sharp spade to lift the entire root mass and separate it into sections, each with at least 2 to 3 healthy shoots and a good portion of roots attached. Replant divisions immediately at the same soil depth they were growing, water them in well, and apply a balanced fertilizer to help them establish before the blooming season begins.

Why are my delphinium stems weak, floppy, or breaking?

Delphinium stems become weak or floppy most often due to insufficient sunlight, overly rich soil that promotes lush but soft growth, or lack of staking as the plants mature. These tall growers can reach 4 to 6 feet or more and almost always require support, especially in windy or exposed locations. Drive sturdy stakes into the ground early in the season when plants are about 12 inches tall and loosely tie the stems as they grow to prevent snapping. Avoid over-fertilizing with nitrogen, which encourages weak, leafy growth at the expense of strong stems.

How do I prevent and treat powdery mildew on delphiniums?

Powdery mildew is a common issue for delphiniums, especially in humid conditions or when air circulation is poor. Space plants at least 18 to 24 inches apart to promote airflow, and avoid overhead watering, which encourages fungal growth. At the first sign of the white powdery coating on leaves, treat with a neem oil spray or a sulfur-based fungicide, applying every 7 to 14 days until symptoms clear. Cutting back affected foliage after the first bloom flush and keeping the area around plants free of debris will also help reduce the risk of recurrence.

Can delphiniums tolerate drought, or do they need consistent moisture to thrive?

Delphiniums prefer consistently moist, well-drained soil and do not tolerate drought well, as dry conditions stress the plants and can cut the blooming season short. They perform best when watered deeply and regularly, especially during the active growing and flowering period from June through September. Apply a 2 to 3 inch layer of mulch around the base of the plants to help retain soil moisture and keep roots cool during summer heat. Water at the base of the plant rather than overhead to reduce the risk of fungal disease and crown rot.

Add Vibrant Blue (And More) To The Garden With Delphinium!