Annual larkspur (Consolida ambigua) offers all the beauty and elegance of its perennial relative, the delphinium, but with a longer bloom time and easier cultivation. Once your annual larkspur flowers are established, they will continue to self-seed and fill the garden from late spring to early summer with spikes of beautiful blue larkspur flowers. But how do we plant larkspur to ensure a wondrous display year after year? Take a look at our step-by-step guide below for everything you need to know to grow tall, beautiful larkspurs.
Annual larkspur has many flower spikes of 1-inch-long blue/purple flowers. In addition, flower spikes come in shades of violet to pale lilac, light blue to dark blue, and deep to pale pink and white. Larkspurs prefer cool temperatures and bloom in late spring to early summer throughout most of North America.
Height: 1-5 feet tall
Spread: 1-2 feet wide
Blossoms: Pink, purple, and blue blossoms.
Foliage: Leaves are finely divided and lacy in texture. The leaves are dark green.
Blooming Season: Late spring to early summer. A second flush of flowers can happen in cooler regions if spent flowers are removed.
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Are Larkspurs and Delphiniums the Same?
No, larkspurs and delphiniums are not the same plants.
Annual larkspur and delphiniums are both popular garden flowers, but there are some differences between the two:
Larkspur, also known as Consolida, sets itself apart from its close relatives in the delphinium genus through its flower structure. Instead of dense columns, larkspur boasts open spikes of petals, giving it a looser and more relaxed appearance.
In addition, the larkspur’s color range extends far beyond delphinium’s classic white and blue flowers, and the plants themselves tend to be shorter than the tall plants of delphinium.
Larkspurs are also hardy annuals, and delphiniums are perennial flowering plants.
Step 1: Provide The Right Environment For Larkspurs to Thrive in Your Garden Beds
Growing larkspur flowers is incredibly easy as the plants self-sow year after year and are not impacted by many pests or diseases. But good growth and prolific blooms rely on planting larkspur flowers in a spot they will do best:
Larkspur flowers are hardy annuals that perform and grow best in regions with cool springs.
Plant larkspur flowers in rich, well-drained soil with a neutral to slightly alkaline pH ranging from 6.5-8. If roots stay wet or become soaked, they can develop root and stem rots. Consisently moist soil (not overwatered) will produce the best display of blooms.
You will get the best blooms and more robust plants if you plant your larkspur flower in full sun. The plants will, however, tolerate light shade.
These wonderfully tall and flowery plants are a cottage garden staple and look perfectly placed at the back of a flower bed or perennial border. To create a stunning display, you can also grow larkspur flowers in a wildflower garden, but be sure to plant the flowers in large groupings for visual impact.
***Safety Note: Larkspur flowers, leaves, and stems are poisonous. Keep children and pets away.***
Step 2: Choose the Variety Best Suited for Your Garden Needs
You can find larkspur seeds at most gardening centers or online seed suppliers. You can also see if anyone in your area has seeds they are willing to share. Some are better suited to garden beds or wildflower gardens than others, so be sure you find the ones that work best for you.
Here is a list of the ten most popular larkspur cultivars:
- “Rocket Mixed Colors” – a classic mix of vibrant blue, pink, purple, and white flowers
- “Cambridge Blue” – an intense shade of blue with tall spikes
- “Nora Barlow” – a classic variety with double flowers in shades of pink and blue
- “Pink Fairy” – a dainty pink cultivar with delicate spikes
- “Majestic Giants” – a towering variety with large flowers in shades of blue, pink, and purple
- “Black Knight” – a dramatic cultivar with dark purple flowers
- “White Knight” – a pure white variety with tall spikes
- “Imperial Strain” – a mix of vibrant colors, including blue, pink, and purple
- “Burgundy” – a deep burgundy cultivar with tall spikes
- “Cupid’s Dart” – a classic blue variety with delicate spikes and lacy foliage.
Step 3: Sow Larkspur Seeds – Indoors or Outdoors
There are several ways to get started with larkspur in your garden. You can plant seeds in the fall in a warmer zone or in the spring in colder zones. You can also start seeds indoors to plant out in late spring.
Sow Larkspur Seeds Outdoors in Fall (USDA zones 7-9)
You can plant larkspur seeds outdoors in early fall in USDA zones 7-9. However, larkspurs will die out quickly in hot weather, so add a heavy layer of mulch to keep the roots cool. Also, in warmer regions, it’s a good idea to plant larkspur in a bit of shade to protect them from hot, dry spells.
To plant seeds, scatter them on the ground and rake them into the soil and water. Larkspur seeds need darkness to germinate, so place a light layer of compost or mulch over the seeds. The mulch will also help protect the seeds from wind and birds.
Sow Larkspur Seeds Outdoors In Early Spring
For cooler regions, you can plant larkspur seeds in late spring. Keep the soil moist and cover the seeds so they can germinate.
Seeds planted in late spring may not bloom in their first season.
Sow larkspur Seeds Indoors Six To Eight Weeks Before The Last Frost In Your Zone.
If you want to plant out in spring and guarantee blooms, start your seeds in peat or coir pots 6-8 weeks before your last spring frost.
Germination takes 10-20 days and requires temperatures between 65-70 F.
- Learn More: See our step-by-step guide about seed-saving basics and learn how to tuck away hundreds of larkspur seeds for next year’s planting.
Step 4: Spring Planting Larkspur Seeds Or Seedlings
For spring planting, you can either plant out seedlings you purchased, start indoors early, or add seeds to the garden bed where you want them to grow.
When transplanting seeds sown indoors, set the entire pot directly into the ground to minimize root disturbance.
Space the plants 10-12 inches apart.
Seeds can be scattered where you want the plants to grow. Then, add a layer of compost or extra soil over the seeds and water. Keep the soil moist until the seeds germinate.
Step 5: Water Larkspur flowers once a week
Annual larkspur flowers require one inch of water a week through rain or manual watering. The plants are somewhat drought tolerant but will bloom more profusely with regular watering sessions.
- Learn More: See our list of drought-tolerant plants you can plant next to larkspurs.
Step 6: Apply Slow Release Fertilizer in Spring
Larkspurs grow best in soil rich in organic matter, so add compost to the planting site during planting time, as it will help boost root development. Or add a slow-release fertilizer in early spring.
Add a side dressing of fertilizer or compost throughout the growing season for exceptionally showy blooms.
Step 7: Watch for Pests That Infest Larkspur Flowers
While annual larkspur flowers are relatively disease-resistant, they can sometimes be attacked by insects. Here are a few common insect pests to look out for and how to manage them:
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Aphids are small, sap-sucking insects that can cause damage to larkspur leaves, stems, and flowers.
To manage aphids, try hosing them off the plants with a strong blast of water or applying insecticidal soap.
Learn More: Check out our article on natural ways to manage aphids.
Leaf miner damage will appear on the leaves of your larkspur flowers as large brown or tan spots. The foliage may also look discolored or diseased.
Larvae feed inside the leaves, so you will need to remove any leaves that appear to be infested. Destroy the leaves, and do not add them to your compost bin.
Leaves that have tiny little yellow dots and are dry is a sign that your annual larkspurs are infested with spider mites. You can control small infestations of spider mites by washing the leaves and plants, which will help remove any eggs. However, if the larkspur is heavily infested, you must remove and destroy the plants.
Unfortunately, once established, spider mites are incredibly hard to control, especially once the weather warms up and they multiply.
By monitoring your larkspur plants for insect pests and using the appropriate management techniques, you can help keep your plants healthy and free of damage. Additionally, promoting a diverse and thriving garden ecosystem can help reduce the impact of insect pests by encouraging beneficial insects like ladybugs, lacewings, and parasitic wasps.
Step 8: Learn How To Identify Diseases That Affect Larkspurs
Annual larkspur plants can be affected by various diseases, some of which can severely reduce their growth and flower production.
To identify these diseases, closely examine your larkspur plants for any signs of unusual growth or discoloration. If you suspect an infestation, removing and disposing of any affected plants to prevent disease from spreading to other plants in your garden is essential. Additionally, good cultural practices like avoiding overhead watering and providing adequate air circulation can help prevent disease outbreaks.
Crow and Stem Rots
Stem rot and crown rot are diseases that affect the roots and crowns of larkspur plants, causing them to become soft and rot. This can lead to wilting, yellowing, and death of the plant.
Powdery mildew is a fungal disease that results in a white, powdery growth on the leaves and stems of larkspur plants. This disease can reduce the overall health and vigor of the plant and make it more susceptible to other problems.
Step 9: Consider adding a Few Companion Plants
Larkspur is a beautiful and versatile flower that can be paired with many different companion plants. Here are some popular choices:
- Cottage garden favorites: Larkspur can be planted alongside other cottage garden favorites like foxgloves, hollyhocks, and poppies for a beautiful, informal display.
- Grasses: Larkspur can be paired with ornamental grasses like fountain grass or switchgrass for textural contrast.
- Herbs: Larkspur can be grown with herbs like basil, thyme, or rosemary for a fragrant and edible garden.
- Shrubs: Larkspur can be planted under spirea or hydrangea for a lush and layered look.
- Bulbs: Larkspur can be grown alongside early-blooming bulbs like daffodils or tulips for various colors in your garden.
- Wildflowers: Larkspur can be planted with other wildflowers like black-eyed Susan or coreopsis for a natural look in a wildflower garden.
Step 10: Don’t Forget to Protect Larkspurs Over Winter
Annual larkspur plants will not survive the winter, but there are steps you can take to protect the plants and ensure a strong show of flowers next year:
Collect seeds: Before the first frost, collect seeds from the mature flowers on your larkspur plants. Store the seed in a cool, dry place and sow it in the spring to grow new plants.
Cut back plants: After the first frost, cut back the dead foliage on your larkspur plants to tidy up your garden and reduce the risk of disease.
Mulch: If you live in an area with severe winter weather, consider applying a layer of mulch over the soil where your larkspur plants grew. This will protect the soil from extreme temperature fluctuations and erosion.
Label and map: If you plant seeds in the fall, label the location of your larkspur plants and make a map of your garden. This will help you remember where you planted them and avoid disturbing the soil in the spring.
Following these steps, you can protect your larkspur plants over the winter and ensure a strong show of flowers next year.
Step 11: Bring Your Fresh Larkspur flowers inside to enjoy.
Larkspur flowers make excellent indoor displays (big, bold bodacious ones!) and beautiful flowers for drying.
For the longest possible vase life, cut flowers early in the morning when the flowers are not fully open. Keep cut flowers away from animals and children, as they are poisonous if ingested.
- Learn More: See our list of the best flowers you can add to a cut garden.
To dry larkspur, cut the flower spikes when the blooms are partially open. Then, strip off the leaves, and air dry them by hanging them upside down in a dry, warm room.
You can also preserve larkspur flowers in silica gel. Place flower cluster stems in a sealable container partially filled with silica gel. Sift extra silica gel over the blooms until they are completely covered, and allow the flowers to dry for 3-4 weeks.
- Learn More: Learn how to dry flowers with five different methods.
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