The sunny strip along my back picket fence went from bare dirt to a wall of color by early June. Blue and pink Giant Imperial spikes packed the whole run. That rush is larkspur bloom time at its peak, and it shows when larkspur blooms in most home gardens. Garden larkspur opens in late spring and runs through mid-summer. You can expect the first spikes around May and the last by July.
None of it started in spring. I dug no holes and set out no seedlings. I scattered the seed the fall before, right ahead of the first hard frost in my zone 6 garden. The seeds sat through winter and sprouted the moment the ground thawed. By the time warm days arrived, the roots ran deep and the plants stood ready. That head start is why the fence filled in so early and so full.
The month you see flowers depends on which larkspur you grow. Garden larkspur is the common annual most people plant from seed. It blooms from May to July across much of the country. Tall mountain larkspur is a wild perennial from cooler high country. It waits until July and August to raise its spikes. Once you know your type, the timing makes sense.
Your local climate shifts the exact month too. In warm southern zones, garden larkspur can start as early as April. Mild winters let the seed sprout sooner. In cooler northern gardens, the first spikes may hold off until June. The plant reads the soil, not the date on the wall. Even one variety drifts a little from garden to garden. So watch your own beds and let the buds tell you.
One plant does not stay in bloom all season on its own. A single garden larkspur flowers for about three to four weeks before the main spike finishes. A bed looks full for months because many plants sit at different stages. That is why gardeners plant in drifts and sow in waves, not all at once. In a wide planting, that overlap can hold steady color from May into July.
Weather shifts larkspur bloom time more than any calendar does. A cool, damp spring slows the plants in a good way and stretches the bloom. You can gain two or three extra weeks of color. A warm, dry spring rushes the whole show and cuts it short. The same seed can flower sooner one year and later the next. Elevation and shade nudge the bloom a week in either direction too.
You can stretch the bloom by hand as well. Deadhead the spent spikes once the lower flowers brown out. Snip each stalk back to a healthy leaf, and the plant pushes fresh side shoots. Those side spikes come in smaller, yet they keep the color going. Stay ahead of the spent stalks and you buy more bloom before the heat wins.
For the earliest and longest color, sow your seed in late fall or very early spring. Cool soil lets the roots settle before summer heat arrives. Larkspur is a cool-season annual, and it fades fast once the bed bakes. To stretch the larkspur flowering season, sow a fresh batch every two or three weeks. That habit keeps new spikes opening as the first wave burns out. Two or three rounds can carry the color a full month longer.
Do not wait for warm weather to sow. Larkspur roots best in cold soil, so a fall or early-spring start gives you the earliest spikes.
Read the full article: Larkspur Flower: Meaning, Growing, and Safety
