Larkspur Flower Tips: Growing Vibrant Annuals

The larkspur flower is beautiful and makes a fantastic pollinator plant. It's also toxic and must be grown with care. Our guide will help!

Larkspur flower

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There are many different types of plants that produce a flower stalk that is referred to as a larkspur flower, ranging from perennial flowering plants to annual larkspur. Most of the perennial varieties are in the genus Delphinium. The perennial delphiniums are made up of over 300 species. 

Annual larkspurs are generally in the Consolida genus, which is made up of about 40 species that are native to western Europe and the Mediterranean. These have since become naturalized in other areas of the northern hemisphere, particularly the western United States. For clarity’s sake, we will focus on discussing Consolida ajacis, the most commonly found larkspur flower in the wild that has become naturalized in much of the United States. 

The larkspur flower comes in many different colors, including pink, purple, blue, and white flowers, although the most popular for the garden are the purple flowers. Larkspur puts out tall spires of star-shaped flowers and is great for attracting pollinators to your garden! Not only is it good for native bees and hummingbirds, but it’s a favorite of Swallowtail butterflies as well. 

The host plants for Swallowtail butterflies to lay their eggs on are dill, fennel, and parsley. Planting larkspur as a companion to these host plants will ensure food for the adults in your butterfly garden. One plant can produce many larkspur seeds, so you’re sure to have them in your garden year after year!

They readily self-seed, attract pollinators, and are beautiful to boot. So what is the catch? It’s worth noting that larkspur (Consolida spp) is toxic. For this reason, make sure to wear gloves while working around them. They can cause mild skin irritation otherwise. It’s also worth mentioning that all parts of this plant are toxic if ingested, especially the seeds. 

Quick Care Guide

Larkspur
Larkspur has a distinctive five-petaled flower. Source: vijay_SRV
Common NameLarkspur, rocket larkspur, doubtful knight’s spur
Scientific NameConsolida ajacis
FamilyRanunculaceae
Height & Spread3-4 feet tall and 12 inches spread
LightFull sun to part shade
SoilRich, well-drained soil
Water1 inch of water per week
Pests & DiseasesAphids and slugs/snails, root rot, and powdery mildew

All About Larkspur Flower

Side view of larkspur
A side view of the trumpet-shaped larkspur flower. Source: cotinis

Consolilda ajacis is also known as larkspur, rocket larkspur, and doubtful Knight’s spur. These larkspur flowers originate in western Europe and the Mediterranean, even in the mountains of tropical Africa. Annual and delphinium varieties have a wide range of flower colors. 

High Mountains adds a lovely bright purple flower to their resident cottage garden. The Cloudy Skies cultivar grows a misty blue flower. Imperial larkspur has a stark white flower that can break up brighter hues. Add the larkspur flower to your garden for splashes of blue, white, violet, and pink.  

Rocket larkspur is an annual that produces many seeds at the end of the growing season and will need to be re-seeded year after year. This annual larkspur is in the buttercup family and can grow up to 4 feet tall! It produces tall spires of purple or blue flowers along a thin stem covered in feathery green leaves. 

Growing larkspur flowers in your garden will ensure a spring bloom that will be available for a wide variety of pollinators. If you choose to deadhead the flowers and keep them well watered, you can keep larkspur flowers blooming throughout the summer. When they go to seed in late summer, they produce seed pods that will be bursting with next year’s larkspur seeds!

Plant larkspur away from an area where pets and small children may come into contact with it. Don’t let the toxicity prevent you from adding lovely larkspur flowers to your gardens. After all, there are plenty of commonly grown plants that are toxic, like rhubarb (toxic leaves), morning glories (toxic seeds), and daffodils (all parts of the plant are toxic, especially the bulb). 

Caring for Larkspur Plants

Consolida ajacis flowers
Consolida ajacis flowers. Source: Ken Y.

Growing larkspur flowers involves a little base knowledge about their care requirements. Once these requirements are met, you’ll find that growing larkspur is relatively easy and makes a lovely addition to any flower bed. 

Sun and Temperature

Larkspur plants prefer full sun but can also be reliably grown in partial shade. If you live in an area with extreme heat in the summer, where temperatures can be in the 90s and above for extended periods of time, then partial shade may be the better option in order to get longer-lasting blooms. 

The ideal temperature range for larkspur flowers is 65-75 degrees Fahrenheit, but they can be reliably grown in USDA zones 1-10. Larkspur flowers are very frost tender, so plan on growing them between your last and first frost date. In areas with a short growing season, they can be started indoors, but these plants put out a deep taproot and generally don’t tolerate too much root disturbance. Starting them in biodegradable pots can be a workaround for this issue and can help maintain good root development. 

Water and Humidity

Larkspur flowers don’t bloom well in a garden in extremely hot and dry conditions. For this reason, it is important to provide them with moist soil by watering them regularly. Many larkspur cultivars are relatively drought tolerant and can survive with about an inch of water weekly. However, for tall spikes full of purple flowers, it’s best to keep them well-watered in times of drought. 

Water larkspur flowers in the early morning or late afternoon. Be sure to water them at the base, as wetting the foliage can cause fungal issues, especially if you live in a humid climate. When you grow larkspur, once it has gone to seed, you may cease watering altogether. Allow the seed pods to dry on the plant, and then carefully collect your larkspur seeds for the next year! 

Soil

As mentioned above, to get the most out of your larkspur flowers, they need to be planted in moist soil but well-draining enough so that it doesn’t become waterlogged, as this can also cause fungal issues. Wild larkspur can tolerate a wide variety of soil types, but when grown in the home garden where you’d like to get the most of the blooms, it’s best to provide it with rich soil high in organic matter. 

Planting larkspur seeds in soil amended with compost will help achieve this and help retain moisture as well. Larkspur plants can also survive a variety of soil pH including slightly acidic soil down to a pH of 5. 

Fertilizing Larkspur Flowers

Consolida ajacis
Consolida ajacis. Source: dmott9

Fertilizing is not necessary when you grow larkspur flowers if the garden soil has already been amended with rich compost. If not, you may also choose to top dress with compost in early spring when they begin growing. This will be enough to support the growth of annual larkspur. That being said, organic fertilizer can be used to get the most out of your blooms and help support the growth of these tall plants. Before planting, add an all-purpose balanced organic fertilizer like Espoma Garden Tone to the planting site. 

Pruning

Pruning is not absolutely necessary to properly grow larkspur flowers. However, the main perk of growing larkspur flowers is enjoying the purple-blue blossoms. In early summer, just as the blooms open on their flower spikes, cut flowers back and enjoy them fresh in a vase or dried arrangements. This will encourage a second flush of flowers in late summer. 

Propagation: How to Grow Larkspur Flowers

The most reliable method of propagation involves planting larkspur seeds after a cold period of stratification. The seeds must experience cool temperatures during winter to properly germinate in the spring. Wild larkspurs go through this process naturally when seeds fall to the ground in autumn, lie dormant through the winter, and then germinate in the early spring. 

This process can be mimicked by placing seeds in a cold room or refrigerator for 2 weeks before spring planting. Larkspur seeds require light to germinate. For this reason, when direct sowing in the fall, it is a best practice to cover seeds with a thin layer of damp perlite to hold them in place but still allow light to filter through. 

Although larkspur is an annual, it will readily self-seed when left in place until the seed pods dry and burst. A good way to tell if the seeds are ready to harvest is to give the dried plant a shake. The seeds will rattle inside the pods sounding like a maraca! It has also been described as sounding like a rattlesnake, and brushing past the dried plant has given me quite the scare in the garden! 

Troubleshooting Perennial Flowering Plants

Unopened flower
An unopened larkspur blossom. Source: William Allen

Annual larkspur flowers make a lovely low-maintenance addition to the garden flower bed, but there are a few issues that can crop up. Wild larkspur is native to areas with hot and dry climates, so most of the issues are related to overwatering and high humidity. 

Growing Problems

The most common issue when growing larkspur flowers is when the seeds haven’t gone through the proper cold period. If you’re attempting a spring planting of larkspur seeds, store them in a refrigerator for at least 2 weeks before sowing. Otherwise, they will not germinate. The most reliable method for growing the larkspur flower in your garden, however, is sowing seeds in autumn and allowing them to stratify naturally over the winter. 

Pests

Slugs and snails can become an issue in the garden when you grow larkspur in humid and wet environments. Slug and snail damage will appear as large ragged holes in the foliage. You may even see a mucous trail near your blue larkspur plants. Slugs/snails are especially active in early spring before other insects have become active. 

A slug and snail bait made from iron phosphate is safe to use around wildlife and pets. Snail traps can also be made by burying a cup or tin of beer at ground level. Snails and slugs are attracted to it; they fall in and can’t climb back out. 

Aphids can also cause issues for larkspur flowers. The best way to battle aphids is to spray them off your plant with a blast of water as soon as you spot them. To prevent them from returning and/or overtaking your wildflowers, create an environment that includes a variety of flowering plants that will attract pollinators and other beneficial insects. Many beneficial insects love to munch on aphids, like ladybugs. In more severe infestations, neem oil or insecticidal soaps can do the trick.

Diseases

Powdery mildew will appear as white flour-like powder on the leaves. To prevent these issues, always bottom water your plants. Neem oil may also be sprayed as a preventative measure to reduce the colonization of spores on foliage. Never spray neem on your larkspur when it is close to peak pollinator activity time or in conditions above 90 degrees Fahrenheit.

In advanced cases of this mildew, it may be best to remove and destroy infected plant material to prevent it from spreading to nearby healthy plants. After removing infected material, spray neem oil or a copper-based fungicide spray onto the remainder of the plant and nearby plants to reduce the risk of further spread. 

Root rot or crown rot symptoms will appear as a soft mushy stem, wilting, and of course, rotten roots. This fungus can take hold due to poor draining soil and/or overwatering. This type of rot is harder to recover from but can be remedied if there are still fresh, white roots on the plant that have not yet turned to mush. Cut back the rotted roots and plant them into a pot of dry well-draining soil to boost root development. Let the roots completely dry out before watering again. 

Frequently Asked Questions

Larkspur flower
The larkspur flower is a beautiful sight. Source: Men In Black

Q: Do larkspur come back every year?

A: Most delphiniums are perennial. However, Consolida spp. Larkspurs are annual species.

Q: Is larkspur poisonous to touch?

A: Yes, they can irritate if touched, and all parts of the plant, especially the seeds, are highly toxic if consumed. Please use gloves when caring for larkspur and be sure to plant larkspurs in an area with restricted access to keep them away from pets and small children. 

Q: Is delphinium the same as larkspur?

A: When it comes to these two plants, yes and no. The Delphinium genus is also occasionally referred to as larkspur. However, the Consolida genus is more often referred to as larkspur. They are two separate genera, but both belong to the buttercup family. 

Q: What does the larkspur flower symbolize?

A: An open heart and love. 

Q: What to do with larkspur after it blooms?

A: Allow the plant to dry and save the seeds to plant larkspurs next year. Or cut flowers and add them to dried arrangements. 

Q: What month does larkspur bloom?

A: An early bloomer begins to bloom in late spring into midsummer. 

Q: Do butterflies like larkspur?

A: Butterflies love larkspur, particularly swallowtails! 

Q: Do hummingbirds like larkspur?

A: Yes, hummingbirds also love larkspur!

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