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How to Grow Larkspurs: The Compete Larkspur Flower Guide

Larkspur Cottage Garden Flower
Photo Credit
RockyYan
Botanical Name
Consolida ajacis
Plant Type
Flower
Sun Exposure
Full Sun
Part Sun
Soil pH
Neutral to Slightly Alkaline
Bloom Time
Summer
Flower Color
Blue
Pink
Purple
Red
White
Hardiness Zone
2
3
4
5
6
7
8
9
10
11
Special Features
Attracts Bees

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Planting, Growing, and Caring for Larkspurs

Andy Wilcox
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Larkspur are traditional cottage garden flowers that are tall, inexpensive (they grow readily from seed), and make fantastic cut flowers. Learn how to plant, grow, and care for larkspur.

About Larkspurs 

If you’re a fan of tall flowers (like me), you’ll want to check out Larkspurs and Consolida ajacis. Also known as rocket larkspur for their rapid growth in spring, these cottage garden flowers provide a vertical display and a blooming period lasting up to two months with deadheading. 

Larkspurs are sometimes confused with delphiniums due to their similar appearance. You’ll even see this plant called Delphinium consolida, further muddying the waters. Most delphiniums are perennial, and while similar in care and appearance, larkspurs are annuals–although they frequently self-seed. 

They are easy to start from seed and make a great color border and vertical filler, especially if you aren’t ready to commit to a perennial. Dreamy swatches of larkspur planted along a fence, wall, or with other tall flowers are the best way to enjoy this dramatic plant. They also do well in containers, providing a tall backdrop against a patio railing or framing a pergola post. 

Larkspurs make fantastic cut flowers. They are typically shades of blue, but they can also be found in pink, red, white, and purple. Blooms can be single, semi-double, or double, and foliage is a lacy blue-green. 

All parts of the larkspur are toxic if ingested, so don’t let people or pets munch on them. Many gardeners report them to be deer, rabbit, and even groundhog-resistant, likely for this reason. 

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Planting

Larkspurs are easy to start from seed and, if grown in a location they like, will often reseed the next year (if you leave some mature flower stalks and don’t cut them all). In hotter climates of the South, their bloom season can be extended by planting them in a location with afternoon shade.

When to Plant Larkspurs 

Larkspur does best when direct seeded in cool temperatures. The seeds will germinate in cooler soil temps, and the plants need a period of cold weather (vernalization) after germination to flower. Sow in spring as soon as the soil can be worked. 

Fall sowing in temperate and warmer areas (zone 5b and warmer) also works well and eliminates one more thing to remember in the busy spring season. For fall sowing, plant the seeds 4-6 weeks before the first frost if your weather (and soil) have begun to cool.

How to Plant Larkspurs

  • Larkspur seeds will germinate more reliably if cold-stratified. Place them in the fridge for 1-2 weeks before planting. 
  • Prepare the bed, working in a layer of compost and smoothing the soil.  
  • Direct seed ⅛ to ¼ inch deep, lightly covering the seeds. Space seeds about four inches apart. After true leaves emerge, you may wish to thin to a 8-12 inch spacing. 
  • Seed can be broadcast to plant larger areas. Spread a thin layer of compost or use a rake to lightly cover the seeds. 
     
Growing

Larkspur likes to grow in cooler weather and likes moisture. Find a happy spot for them, and they’ll likely return year after year. 

  • Larkspurs prefer consistently moist but not wet soil. Hot, dry conditions stunt their growth and inhibit blooming. Water weekly during dry periods.
     
  • Mulch larkspurs to keep the soil shaded and help maintain moisture and cool soil temperatures. Eventually, the larkspurs will likely close the canopy and shade their own soil, but mulch will work until then, improving your soil.
     
  • Deadheading larkspur will encourage more blooms. If you’d like them to self-seed for next year, leave some flowers intact to develop seed heads as blooming slows down.
Credit: Manfred Ruckszio
Recommended Varieties
  • ‘Giant Imperial’ is a massive variety sporting four-foot spikes covered in large semi-double deep blue to purple blooms. 
     
  • ‘Carmine’ is another giant with four-foot stems and spikes of coral and pink with blooms a foot long. It’s excellent as a cut flower or for drying.
     
  • ‘Fancy Smokey Eyes’ is a dreamy white with subtle lavender centers.
     
  • ‘Lilac King’ is a giant variety with soft purple flowers the same hue as lilac blooms. 
     
  • Can’t pick? Try a mix! Many seed companies sell a mix of colors, perfect for planting en masse.
Harvesting
  • For fresh bouquets, harvest flowering stems when about one-third of the blooms have opened. The flowers open first at the bottom and proceed to the top.
     
  • To pick for use as dried flowers, harvest stems when all blooms have opened but before any have gone to seed.
     
  • Fresh-cut larkspurs will last 5-7 days in the vase. Don’t forget to change the water.
     
  • To dry larkspurs, remove the foliage and hang small bunches upside down in a warm, dark place.
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Wit and Wisdom
  • Larkspurs grow tall and can be susceptible to flopping over, especially in windy locations or during summer storms. Plant them closely together, and they will help to hold each other up. 
     
  • If growing larkspur in containers (a gorgeous idea), choose pots with large bottoms and enough mass to hold these tall plants upright. You can add a large rock to the bottom to help; just don’t make a layer of them, as it can impede drainage.
Pests/Diseases
  • Root rot in poorly drained areas
     
  • Aphids
Flowers
About The Author

Andy Wilcox

Andy Wilcox is a flower farmer and master gardener with a passion for soil health, small producers, forestry, and horticulture. Read More from Andy Wilcox

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