Larkspur
Also known as: Annual delphinium · Consolida ajacis
Severely poisonous
3 types of larkspur
Earl Grey
90 daysRare smoky mauve-grey — unusual and lovely.
Giant Imperial Mix
90 daysTall 4-ft double-flowered spikes in blue, pink, salmon, white, purple. The florist standard.
Sublime Mix
90 daysExtra-tall, extra-fully-double spikes. Cutting-garden favorite.
When & where
Germination
Spacing & depth
How to plant
Sow directly in fall or very early spring — larkspur wants cold soil to germinate. Chill seed in the freezer for a week before sowing if spring-planting. Once up, plants tolerate light frost and bloom on 3–4 ft spikes.
Pre-sow treatment
Chill seed in freezer 1 week, or sow outdoors in fall to cold-stratify naturally.
Grower's tip
Basically an annual delphinium for hot summers. Excellent fresh or dried cut flower.
Soil preferences
Well-drained garden soil. Native/wildflower species prefer lean soil; cutting flowers prefer richer beds.
6.0–7.0
Work 1 in of compost into beds before sowing. Skip nitrogen fertilizer on wildflowers — it favors foliage over blooms.
Watering
1 in per week during establishment, drought-tolerant once rooted for most species.
Deep, infrequent soakings at the base. Overhead water on ornamentals promotes botrytis and rust.
Overwatered: rotted crowns, mildew, floppy stems. Underwatered: small blooms, curled leaves, quick fade.
Prefers top-watering — Top-water at the base in the morning. Overhead water batters open flowers and spreads botrytis on tightly-packed blooms.
Temperature tolerance
60–80°F (16–27°C) ideal for most annuals
50–65°F (10–18°C)
Cool-season annuals (larkspur, poppy, snapdragon) tolerate light frost; warm-season annuals (zinnia, cosmos, marigold) are frost-tender.
Container growing
Possible with the right cultivar
8–14 in (20–35 cm) wide
Compact and dwarf types do best in pots; tall cutting flowers need staking.
Detailed harvesting
Nothing here is harvested for the kitchen. Wear gloves for any cutting or deadheading, keep the sap off your skin and eyes, and wash your hands and tools afterwards.
Post-harvest storage & preservation
Do not dry, store or preserve any part of this plant near food. Bag prunings for the bin — never compost them where animals browse, and never burn them.
Culinary, medicinal & other uses
Ornamental only — this plant is poisonous and has no food, tea or home-remedy use. Grow it for looks, wear gloves, and keep it away from children, pets and livestock.
Medicinal or traditional uses are shared for interest only — this is not medical advice. Consult a qualified professional before using any plant medicinally.
Seed saving
Mostly insect-pollinated (outcrossing).
For pure strains, isolate 150–800 ft or bag heads. Wildflower mixes are meant to cross freely.
Stop deadheading favorite blooms; let heads dry brown and rattling on the stem, then collect into a paper bag.
Your zone's planting calendar
Pick your USDA hardiness zone and we'll estimate the key dates for larkspur in your area. These are regional averages — always check your own last-frost forecast before sowing.
My Larkspur notes
Larkspur seeds on hand
Track packets and loose seeds you already have. Private to your account.
Par level — leave at 0 for no alert. Anything below par shows on Seed Starting and your shopping list.
Order more seeds
Running low? Reorder from one of these seed stores.
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