Delphiniums are delicate but striking flowers mainly known for their attractive large, showy blue and purple flower spikes.  There are other varieties that produce pink, white, scarlet, or yellow flowers. The fragrant blooms can be grown in a wide variety of climates, but they do best in full sun. They are easy to grow and will flower from May to September. Delphiniums are popular in cottage and cutting gardens. They grow best in moist, cool climates and need acidic soil.

Their flower spikes have 20 or more flowers.  Each flower has a prominent dolphin-like spur with small central flowers called bees or eyes.  The number of petals and sepals determines the form of the delphinium flower. It can be a single, semi-double, or double bloom.  The most common type of delphinium is a tall plant that has flowers with three petals that can grow up to 3-4 feet tall. There are also shorter varieties of delphiniums that are only 2 feet in height that have flowers with more petals and can be planted together in large groups.

The delphinium is a perennial plant and belongs to the Ranunculaceae family.  They have long been associated with love, faithfulness, and beauty.  The Greeks called the flowers Delphin, which means “dolphin” because they felt the buds looked like the shape of a dolphin.  The English call them “Larkspur” after the claws of a lark, while other people call them “Queen of the Border”. These plants are native to the Northern Hemisphere and high mountain areas in Africa.  There are more than 500 species of this flower throughout the world and they are the official birthday flower for the month of July.  

Planting And Care Of Delphiniums

Delphiniums are planted in the spring in well-drained soil in full sun (at least 6 hours) to light shade, and in a location sheltered from strong winds.  Different varieties of these plants are annuals, biennials, or perennials.  They can be grown from seeds or purchased as a plant. If you purchase a plant, dig a hole twice the diameter of the plant’s container.   Be careful with the roots when taking them out of the container as damage can cause root rot.  Make sure the top of the root ball is level with the soil.  This perennial does best in alkaline soil so in the spring amend the soil with broadcast lime, or wood ash, or a combination of both.

Delphiniums can grow up to seven feet in height, so have stakes ready when you plant them. Do not let the soil get dry as the plant needs moist soil for optimal growth.  If you are in an area where you do not get a lot of rain, water your plant regularly.  During its growth season use a fertilizer every 2 to 3 weeks.  Deadhead the spent flowers to encourage continuous blooming.

After your plant has finished blooming, cut the flower stalks to the ground.  You will find new flower stalks will develop.  The flowers will survive cold days and even light frosts. 

Dividing Delphinium

Delphiniums need to be divided every three years when the plant is healthy.  It is done in the early spring, right when you start seeing new growth. Dividing them will assist in more robust growth, new plants, and a longer-living plant.

Dividing your plant is shocking to the plant, so the day before you are going to divide it, water it generously. Watering the plant will help reduce the shock.  Another way to reduce the stress on the plant is to cut back the excess foliage by one-third.

Prepare a new hole to plant the divided plant in.  The hole should be larger than the plant but not as large as the original plant hole since you will only be planting part of the new plant. Make sure there is room for expansion for the plant to grown.

Start dividing the plant by gently pulling it apart.  It is important to be careful not to break the roots in the flower dividing process. Take about one-fifth of the original plant since smaller sections will produce longer-lasting blooms and growth will be more robust. Delphiniums multiply quickly.  Next year the plant will be at least double in size.  If too large, the plant will have to be divided again the following year.

Varieties Of Delphiniums

Here are four different varieties to consider planting in your garden:

Blue Donna Delphinium:  Gorgeous dark blue flower spikes are found on the Blue Donna Delphinium plant.  This particular delphinium is great for small spaces or cottage gardens as it just grows to 3 feet tall and will not need to be staked.  The flower spikes are less densely packed compared to other delphiniums. Deadhead the blooms to keep the flowers appearing from late spring to fall.  Hardy for zones 5-9.

Dasante Blue Delphinium: This delphinium produces bold blue flowers with purple highlights and white central bees similar to other delphiniums but is more compact. The beautiful tall plants will flower in the early summer and then again in the late summer or early fall.  This plant will also not need to be staked. It is easy to grow and blooms profusely. Hardiness zones 4-7.

Diamonds Blue Delphinium: I recently saw this plant at a trade show and loved it.  It is quite different than other delphiniums as it is more of a shrub compared to the tall-spiked delphiniums.  The single bloom flowers are a gorgeous and brilliant blue with a purple dot on each petal.  The plant will flower all summer long.  It likes to be pruned and will produce more flowers after a trim. Try growing it in a container, a sunny border, or a rock garden. It also will look great in a cut flower garden. It attracts butterflies and other beneficial pollinators, while deer tend not to bother with it.  Hardiness zones 3-7.

Guardian Delphinium: This beautiful delphinium produces dark blue, lavender, or white spikes of flowers.  It will bloom in early to mid-summer and continue throughout the season. Be sure to deadhead the blooms to keep them growing.  They will need to be stacked and look great in the back of your garden.  Due to their height, make sure to protect them from the wind. These flowers can also be included in any cutting garden.  They are deer-resistant and hardy for zones 4-7.

Photos are courtesy of Ball Seed.

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