Larkspur Fast Facts
Larkspur, a member of the delphinium family, is a fast-growing garden favorite. Native to Europe, it has naturalized throughout North America. When planting larkspur, keep in mind that the seeds and leaves are poisonous if eaten. While mildly toxic to people or pets, larkspur is particularly dangerous to cattle.
The most commonly grown species of annual larkspur is Delphinium ajacis. Delphinium elatum is a perennial form of larkspur that has similar growing requirements.
Larkspur’s tall, upright habit makes it a good choice for fence lines and the back of the border. Flower spikes can reach heights of 36 to 72 inches.
Larkspur blossoms appear in shades of pink, white and deep blue. Foliage is lacy and dark green. Larkspur may require staking.
Hardiness and Range
Rocket larkspur is an easy-to-grow, self-seeding annual. It prefers average soil and full sun in zones 4 to 7. Perennial larkspur benefits from winter protection below zone 5.
Plant larkspur in well-drained soil. It likes to be moist but the bases can rot if the soil is too wet.
Larkspur flower spikes are used in fresh cut and dried arrangements. Bloom time is April through September.
Pull larkspur plants by hand if you have only a few of the plants in your yard. Wear gardening gloves, and thoroughly wash your hands and clothing after handling the plants. Mow large patches of larkspur before the plants go to seed. Apply an herbicide containing glyphosate according to the herbicide package's directions.
- PlantCare.com: Larkspur
- Texas A&M: Larkspur
- Fine Gardening: Consolida Ajacis (Larkspur)
- Floridata: Consolida Ajacis
- University of Maryland Extension: Larkspur Production
- National Gardening Association: Backyard Safety
- Petco: Dangerous Plants for Dogs
- Colorado State University Cooperative Extension: Poisonous Plants that Affect Livestock in Douglas County
- Journal of Range Management: Mechanism by Which Ammonium Fertilizers Kill Tall Larkspur