Most commonly grown for its beautiful, tall spires of blue blooms, delphinium has long been planted in perennial gardens. These elegant plants add a strong vertical element. Because some varieties can grow up to 6 feet tall, plant these at the back of a garden border. If blue isn’t your color, you can choose a delphinium in a few other colors, too!
Delphiniums are sought after and planted for their blue flowers, which are rare to find in other plants. These beautiful blues can come in a variety of shades and forms. Many feature a white center, which adds a bright contrast to the deep, rich blue. Most delphiniums are in the blue and purple range, but they can also be found in pinks and reds. There are some stunning coral-colored varieties, and even some rare ones in yellow. These plants have attractive foliage in a pleasing green, with palm-shaped leaves like a fern.
Delphinium Care Must-Knows
Delphinium plants are well loved, but they can be fairly short lived and picky when it comes to garden conditions. One of the most important things to keep in mind is that delphiniums don't like hot summers; they perform best in mild weather. When it does get hot, plants can melt out and die back to the ground. If you're lucky, they may come back as it cools back down. In anything warmer than Zone 7, these plants are typically treated as annuals.
Related: Big Perennials for Big Impact
Plant delphiniums in well-drained soil that has plenty of organic matter. While it's important to keep the plants consistently moist (they don't handle drought well), be sure that the soil has proper drainage. Standing water can lead to crown rot, which causes the whole base of the plant to rot, which will eventually lead to death.
Ideally, delphiniums should be planted in full sun for the best blooms and sturdiest stems. In too much shade, especially in humid climates, fungus issues can arise on the foliage. Powdery mildew, botrytis, and leaf spot are all common problems that delphiniums struggle with. The best fungal control method is prevention, so make sure plants are in well-ventilated areas and full sun to keep foliage dry. If your plant needs any supplemental watering, make sure to do it at the base of the plant so the leaves stay dry.
Because these plants are tall, they often need staking or support from neighboring plants. Once their blooms are finished, deadhead them, because you can usually get a small second bloom after.
More Varieties of Delphinium
Delphinium grandiflorum 'Blue Butterfly' grows to only 14 inches tall and has deep blue flowers with a hint of purple. It tolerates heat better than other delphiniums, blooming through most of the summer. Zones 4-7
Delphinium elatum 'King Arthur' is one of the Round Table Hybrids with 5- to 6-foot-tall flower spikes. It has reddish-purple flowers with a creamy white center, called a bee. Zones 3-7
Delphinium elatum 'Dasante Blue' is a compact selection with rich blue flowers with light purple tones. It grows 34 inches tall and 12 inches wide. Zones 4-7
Delphinium elatum Pacific Giants Series are towering plants with bloom stalks reaching up to 7 feet tall. Colors range from light blue to white, pink, and purple. Zones 3-7
Delphinium grandiflorum 'Summer Blues' offers soft blue flowers in summer. It grows 14 inches tall. Zones 4-7
Delphinium grandiflorum 'Summer Stars' is a dwarf variety that produces pure-white flowers in summer. It grows 12-14 inches tall. Zones 4-7
Delphinium Companion Plants
Joe Pye weed is a showstopper of a prairie native, producing huge, puffy flower heads in late summer. It prefers moist soils, but with its extensive root system, it also tolerates drought well. It is a large plant, growing 4 to 6 feet tall. Closely related, hardy ageratum is a spreading plant that grows to 2 feet tall. Another relative, white snakeroot, reaches 4 to 5 feet tall. All are great for naturalistic or cottage plantings and for attracting butterflies.
This hardworking group of perennials does so much. Hyssops bloom for a long time in wonderful colors atop tall, striking plants. They produce a nectar that is irresistible to hummingbirds and butterflies. Most are heat and drought tolerant. And their foliage and flowers are fragrant, with scents ranging from licorice to bubblegum. Most require well-drained soil and prefer full sun, although they will tolerate light shade.
There are hundreds of different types of salvias, commonly called sage. They all tend to share beautiful, tall flower spikes and attractive, often gray-green leaves. Countless sages (including the herb used in cooking) are available to decorate ornamental gardens, and new selections appear annually. They are valued for their very long season of bloom, right up until frost. All are not hardy in cold climates, but they are easy to grow as annuals. On square stems, clothed with often-aromatic leaves, sages carry dense or loose spires of tubular flowers in bright blues, violets, yellow, pinks, or reds that mix well with other perennials in beds and borders. Provide full sun or very light shade in well-drained average soil.
Garden Plans for Delphinium
Create a lush island butterfly garden bed of flowers that will bring beautiful fluttering insects to your garden.
Create a soothing, all-blue garden in a partly shaded spot with this garden plan.
Stately delphiniums are the backbone of this colorful cottage garden plan.