Grow and Care for Larkspur

Grow annual larkspur as a one-season cut flower in a sunny bed that drains. Rocket larkspur is the same plant. It is not a perennial delphinium.

Give it full sun and soil that drains

Annual larkspur wants a full-sun bed that drains. Slightly alkaline ground helps the spikes fill out. Water during a dry spell so the buds set, and keep the soil from staying soggy, because soggy soil around the roots causes rot. [1] Tall stems flop in wind, so stake them or sow them close enough that the stems hold each other up. Light afternoon shade is fine in a hot summer, but the show still ends when the heat stays. Giant Larkspur is Consolida ajacis, a 2 to 4 foot annual with lacy leaves and spurred spikes in blue, pink, purple, or white.

Sow chilled seed in cool soil and cover it

Direct-sow is the usual start. The plant makes a long taproot and does not transplant well, so sow where the plants will bloom. Chill the seed in the refrigerator for about a week, then cover it about a quarter-inch deep so it stays dark. [2] Sow in fall in a mild-winter garden, or as soon as you can work the soil in spring. Seed fails when the soil is warmer than about 55 F, and the seedlings need a stretch of cool weather after they sprout so the spikes set.

1. Chill the seed in the refrigerator for about 7 days.
2. Sow where the plants will bloom, about 1/4 inch deep, and firm the soil so the seed stays dark.
3. Keep the surface moist until seedlings show, usually in 14 to 21 days.
4. Thin to 8 to 12 inches, or leave them closer if you want the stems to hold each other.
5. In a mild-winter garden, sow in September or October instead of waiting for spring. [3]

Not a perennial delphinium

Garden larkspur is a one-season Consolida you sow in cool soil. A perennial delphinium is a different plant with a heavier spike and different care — see How to Grow Delphiniums. Dwarf larkspur on a woodland tag is usually Delphinium tricorne. Spanish larkspur is standing cypress — see How to Grow Ipomopsis. Confirm the Latin on the tag before you count on a clump coming back next year.

Cut stems when the lowest flowers open

For a vase, cut the stem when the lowest two or three flowers have opened and the rest of the spike is still in bud — about one-third of the way up. Put the stem in water right away. Expect about 5 to 7 days in a vase. [4] For drying, cut when the flowers are open but before petals drop, strip the lower leaves, and hang the bunch upside down in a dark, dry place.

1. Cut when the lowest two or three flowers have opened and the rest of the spike is still in bud.
2. Strip the lower leaves and put the stem in water right away.
3. Expect about 5 to 7 days in a vase, or hang the stems to dry before the petals drop.

When the heat ends the bloom, sow again next year in cool soil, or leave a few seed heads if you want volunteers.