Care Of Delphinium Flowers: Tips For Growing Delphinium Plants

Care Of Delphinium Flowers: Tips For Growing Delphinium Plants

By: Becca Badgett, Co-author of How to Grow an EMERGENCY Garden

Delphinium flowers beautify the summer garden with showy, spiky blooms on a tall, sometimes towering stem. Delphiniums come in a range of shades. Many gardeners wonder how to grow delphinium and some avoid planting them after hearing that the plant is difficult to grow. What are the secrets to the correct care of delphinium? Read more for tips about delphinium planting and how to get the best performance from growing delphinium plants.

About Delphinium Plants

One commonly thinks of delphinium plants (Delphinium) as having true blue flowers, which is the most common color. But numerous hybrids are available in shades of pink, lavender, red, white and yellow. Blooms may be single or double.

Delphinium planting is normally at the back of the bed, where flower spikes can reach 2 to 6 feet (.6-2 m.) tall. Delphinium flowers are often planted in masses or groups. Shorter varieties are useful in other areas of the garden.

How to Grow Delphinium

Grow delphinium plants in a sunny area with soil that is consistently moist. Don’t let them dry out. Mulch helps retain moisture and keeps roots cool. Performance of this specimen is enhanced when growing delphinium plants in neutral to slightly alkaline soil pH. Soil should be well-draining.

Care of delphinium should include regular fertilization in spring when the plant begins to grow, and during the flowering period. Work in well-composted organic material such as rotted cow manure, or use a basic 10-10-10 granular fertilizer. Yellowing foliage or stunted growth often indicates the plant needs more fertilizer.

Sun exposure is another aspect of care of delphinium that the gardener must get right for the showy blooms to appear. Gentle morning sun is preferable to the delphinium plants, which are picky about extreme differences in temperatures. Provide afternoon shade, especially when planted in hotter zones.

Special Tips for Delphinium Plants

An important aspect of caring for the thought to be difficult delphinium is deadheading the first blooms in early summer. Remove flower stalks when blooms are spent. When all blooms are removed and moisture and fertilization requirements are met, the gardener can expect a bountiful blast of blooms in late summer or early autumn. This is when delphinium flowers are at their most beautiful. Often, this may be the final show for the short-lived perennial, but the striking beauty and long lasting blooms are worth the effort.

Taller varieties may require staking, especially when planted in areas with heavy rain or wind. Stems are hollow and break easily under this type of stress.

Some disease and insect pests may attack delphiniums, keep an eye on young plants and when planting delphiniums, make sure soil conditions are right for the plant. Delphiniums may be propagated from seed or basal cuttings; however, don’t propagate from diseased plants.

Now that you’ve learned how to grow delphiniums, get started with delphiniums grown from seed, starting indoors in late winter. Add a few new delphinium plants each year so you’ll always have the showy blooms in your yard.

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Delphiniums, commonly known as larkspur, are a go-to choice for home gardeners who want to make showy statements in their gardens, and for good reason. These striking plants -- which can reach heights of 6 feet in some cases -- feature stately stems lined with vibrant white, pink, purple or blue flowers. Delphiniums are a bit finicky in their growing requirements, but the extra work is well worth the result.

Delphinium, Larkspur (Delphinium)

Delphiniums are elegant, stately plants that are stalwarts of cottage gardens. Most are perennial, but annual varieties are also available. Delphiniums are grown for their huge spikes of showy flowers in summer above mounds of dark green foliage.

The common name of ‘larkspur’ is usually used to refer to annual varieties.

There is a wide range of flower colours – not just the blues they are commonly associated with, including pink, lavender, red, white and yellow. The flowers can be either single or double with multiple petals.

If you really get the delphinium growing bug, you may want to join the Delphinium Society.

How to grow delphiniums


Delphiniums grow best in positions in full sun. Although they often benefit from some shelter from strong, burning sunlight in mid-summer.

They need a fertile soil enriched with lots of organic matter, which holds plenty of moisture in spring and summer, doesn’t dry out or become waterlogged.

Choose an area protected from strong winds to keep tall, top-heavy varieties from blowing over and being damaged.

Delphinium varieties

There are numerous varieties in a wide range of colours. These include:

  • Atholl: White flowers with a black centre
  • Blue Dawn: Pale blue flowers, tinged with light purple, with dark brown centre
  • Blue Nile: White-eyed, mid-blue flowers
  • Bruce: Violet-purple flowers, paler towards the centre
  • Cherub: Flowers pale pink and mauve with a cream centre
  • Faust: Dark-eyed, deep blue-purple flowers
  • Foxhill Nina: Pale pink flowers with a white eye
  • Min: Semi-double, white flowers, tinged violet at the edges
  • Rosemary Brock: Dusky purplish-pink flowers with a dark brown centre
  • Sungleam: Creamy-white flowers, strongly tinged yellow and with a yellow centre
  • Tiddles: Greyish-mauve, semi-double flowers

Sowing delphiniums

Although seeds can be sown directly into the ground in early spring, you’ll get better results sowing them indoors.

Sow seeds from February to June or in September to October. Sow the seed in pots or seed trays of moist seed sowing compost. Keep at a temperature of 10-15°C (50-60°F).

When seedlings are large enough to handle, transplant individually into 7.5-9cm (3-3.5in) pots. Gradually harden off the plants before planting out after all fear of frost, 60-90cm (2-3ft) apart.

Planting delphiniums

You can buy young plants from garden centres, nurseries or mail order suppliers. These can be planted at any time of year, although autumn or spring are the best times.

Dig over the planting area, incorporating lots of organic matter – such as compost or planting compost – especially if the soil is heavy clay or light, well-drained sandy soil. Dig a good sized hole big enough to easily accommodate the rootball.

Place the rootball in the planting hole and adjust the planting depth so that the crown of leaves is at soil level.

Mix in more organic matter with the excavated soil and fill in the planting hole. Apply a general granular plant food over the soil around the plants and water in well.

Then add a 5-7.5cm (2-3in) thick mulch of organic matter over the soil around the plants.

Suggested planting locations and garden types

Flower borders and beds, patios, containers, focal point, city and courtyard gardens, cottage and informal gardens, cut flower garden.

How to care for delphiniums

Water plants whenever necessary to keep the soil or compost moist during spring and summer, as this will prolong flowering.

Apply a granular general plant food around the plants in spring, and top up the mulch of organic matter.

Applying a balanced liquid plant food every couple of weeks in the growing season will also encourage more, bigger and better flowers.

The flower stems of tall delphinium varieties will need staking with bamboo canes. These should be put in place by mid-spring to ensure the plants are adequately supported throughout the growing season.

Deadhead plants by cutting back faded flower spikes to small flowering sideshoots to encourage a second flush of flowers.

In autumn, cut down all growth to ground level after it has died back.

Divide overcrowded plants every 3 to 4 years as new growth begins in spring, lifting the plants and dividing them into smaller clumps.

Delphiniums Features: An Overview

  • Delphiniums stand out due to their height, which can reach almost 2 meters with an average spread of half a meter. As such, it is best if you plant them at the back of your garden, or on the last row in flower borders.
  • They bloom in summer. Their dolphin-shaped flowers with white, brown, black, or striped centers. The centers are often called bees.
  • There are several delphinium varieties to choose from, the most popular ones being Belladonna delphinium, Delphinium Chinensis, New Millenniums, and Pacific Giants.
  • People mostly associate larkspur with blue or purple flowers. However, larkspur flowers can also be pink, lavender, red, and even white.
  • Delphinium flowers have no fragrance, but they have a rather clean smell.
  • The leaves have a palmate shape with 3-7 deep lobes.
  • Larkspurs have a short lifespan. They rarely last more than 3 years, so make sure to propagate them regularly, to always have young plants in your garden.


Delphinium flower stalks supported by stakes. Photo by: Malgorzata Larys / Alamy Stock Photo.


For best flowering, new plants should be thinned to 2 to 3 good shoots when they are 3 inches high. Established plants can be thinned to 5 to 7 of the best shoots. Cut the main stalk down after flowering to the level of its smaller side shoots, which will bloom secondarily with slightly smaller flowers. To encourage a second, but smaller, bloom in late summer or early autumn, cut the stalks to the ground just after flowering. Prune the entire plant to the ground after it wilts in autumn.

Well-drained, humus-rich soil is a must, preferably slightly alkaline. Although mulch helps preserve moisture in the soil, if it is applied too closely to the stems it can cause them to rot. For finicky delphiniums, soil quality plays a major role in success or failure.

Amendments & fertilizer:

Apply a balanced, slow-release liquid fertilizer every 2 to 3 weeks. Avoid high-nitrogen fertilizers. Composted manure applied in autumn helps supplement these heavy feeders.


Water deeply during rainless periods, but don’t allow standing water. Delphiniums like it moist, but water that lingers causes crown and root rot. Water delphiniums at the base, keeping the foliage dry to help prevent disease.


According to the National Garden Bureau, September to March is the best time to seed delphiniums. Use fresh seeds, as germination can be poor after a year. Presoaking is recommended to improve the germination rate, along with temperatures of 65 at night and 75 during the day while germinating. Cover seeds with only one-eighth inch of soil and keep evenly moist, but not wet as this can cause them to rot. Smaller rather than larger tray size is also recommended. Transplant after plants have two true sets of leaves.

It is common for delphiniums not to bloom the first year, so be patient and you should see them come to life in the second year. Seeds collected from hybrids growing in the garden may not produce offspring that bloom true to color.

Diseases and pests:

Delphiniums are susceptible to a host of diseases including powdery mildew, Southern blight, bacterial and fungal spots, gray mold, crown and root rot, rust and others. Planting your delphiniums in a well-ventilated area and keeping the foliage dry will go a long way in preventing disease. Care should be taken to protect young plants from snails and slugs, as they can cause considerable damage. Delphiniums are also commonly plagued by cyclamen mites, aphids and nematodes.

If your delphiniums are performing poorly, the book Essential Perennials offers these tips:

  • Black spotted foliage can mean cyclamen mites.
  • Curled & distorted leaves usually indicate aphids.
  • Yellow foliage and stunted growth may be caused by nematodes (this can also be from a lack of fertilizer).
  • Black, foul-smelling decay at the base is bacterial crown or root rot caused by poor drainage.
  • Disfigured stems and foliage along with stunted growth can be a sign of powdery mildew.


Other than the dwarf varieties, delphiniums require staking. Their hollow stems will break when blown in the wind or when the flowers become weighed down from rainfall. Stake them with sturdy supports and attach at 12- to 18-inch intervals.

How to Grow Delphinium Flowers

wordswag pixabay delphiniums

Native throughout the northern hemisphere and the high mountains of tropical Africa, delphinium, which is also commonly called larkspur, is a genus of approximately 300 species of perennial flowering plants in the buttercup family.

Admired for its flowers that vary in color from purple and blue to red, white or yellow, the delphinium plants produce spikes that can reach two to six feet in height. Their size makes them a good choice for planting in the back of borders.

Larkspur gets its name from the fact that its flowers have five petal-like sepals that grow together to form a hollow pocket with a spur at the end.

Its seeds are small and shiny black. Please note that delphinium seeds, as well as the rest of the plant, are poisonous. Great care should be taken to insure that delphinium is not grown in pastures where cattle graze. If eaten, the plant will cause vomiting. Consumption of larger amounts can lead to death within hours of ingestion.

The plants, which are pollinated by bumble bees and butterflies, produce beautiful blooms from late spring through late summer. Many species are grown for use in flower arrangements.

Delphiniums grow best in well-drained soil. The plants prefer full sun and require fertilization in early spring and again later in the growing season. Plants that have yellow foliage or appear to be stunted need additional fertilizing.

Fresh seeds are best for planting. The best temperature range for germination is 50 to 60 degrees Fahrenheit.

Refrigerate delphinium seeds for 24 hours and then soak them in room-temperature water for three to four hours before planting. Keep the soil moist, not wet. Do not allow the soil to dry out. Delphiniums usually germinate in 15 to 21 days.

Delphiniums do take a bit of extra work. Because of their height, the hollow and brittle flower spikes are easily damaged by wind and rain. The weight of the flower spikes can cause the stems to snap and break. One way to avoid this problem is to install support stakes in the ground early in the growing season so that you do not damage the root system.

Most species of delphiniums bloom from early to mid-summer. They work well as cut flowers and tend to last in a vase for approximately a week.

Once the plants have flowered, cut off the old stalks to promote additional flowering later in the summer or early in the fall. Don’t expect the second round of flowers to be as nice as the first.

Unfortunately, delphiniums often tend to be short-lived perennials. The average lifespan is two to three years in the garden. Plan on replanting frequently.

Crown rot is a disease that often plagues delphinium growers. A progressive wilting of the stems is a sure sign of crown rot. Plants that have crown rot need to be removed and destroyed. The soil needs to be sterilized before replanting. Spacing delphinium plants at least three feet apart in the garden can minimize the disease.

Red spider mites are also common pests, especially if junipers are planted near the delphiniums. Plants suffering from an infestation of spider mites have a brownish discoloration on the leaves. A forceful spray of water may cure the problem. If not, apply malathion or Neem oil according to directions.

Interested in learning more about delphiniums? Visit Plant Care dot com for all sorts of info.

For further information about poisonous plants can be found on the University of Missouri Extension.

Visit UC Davis to learn more about keeping cut delphinium flowers fresh.

Watch the video: HortiHugh: Delphinium care