Closely related to delphiniums, the larkspur (Consolida sp.) is an annual flower that excels in the cool months of the year. Alternative names include rocket larkspur, annual larkspur or annual delphinium. Larkspur used to be included in the botanical group Delphinium, but since has been placed into its own genus. A quick way to identify an annual larkspur from a perennial delphinium is looking at the foliage. Larkspur leaves are lacy and feathery with thin lobes.
Larkspurs, regardless of species, are annual flowers. They germinate, grow, flower, set seed and die within one year or one growing season depending on climate. In ideal growing conditions in the garden, larkspurs may seem to be perennial. The production of seeds leads to germination later in the year when soil is moist and temperatures cool. It creates a situation that makes them seem perennial, as new plants continue to sprout and again flower later.
In the Deep South or in subtropical regions, gardeners sow larkspur seeds in midwinter when it's cool and there aren't any frosts. As the late winter and early spring warms, the seeds germinate and quickly grow to flower. When excessive heat builds by late spring, the plants wither away. Elsewhere, where winters bring subfreezing temperatures, gardeners sow seeds in early spring as soon as the soil is workable. Plants sprout and grow to bloom anytime from mid-spring to summer. In regions with cool, mild summers, larkspurs continue to bloom and sprout to produce more plants. Larkspurs may also be sowed again in early fall to grow and flower before a killing frost in late fall.
Sprouted and growing larkspur plants do not transplant well, so it's best to sow the seeds where they are to grow in the garden. Choose a sunny location in any fertile, well-drained soil that is evenly moist. Scatter seeds freely and lightly scratch them into the top 1/8 inch of soil with your finger tips. Supplement rainfall with irrigation to keep the plants healthy and vigorous, especially in periods of dry weather.
Helping Plants Self-Sow
Although annual, if you allow butterflies, bees and moths to pollinate larkspur flowers, lots of seeds are produced. Do not cut off old flower spikes, but allow the seed capsules to ripen, split open and shed seeds to the garden soil. As long as the soil is never soggy and temperatures remain in the range of 4.44 to 21.1 degrees Celsius, the seeds will germinate. Larkspur is an annual flower that can perennialize, thanks to self-sowing.