The Best Time of Year to Start Each Type of Flower Seeds

Flowers delight the gardener with their colors and aromas and please insects with their nectar and pollen, so they belong in every garden. A huge selection of flowers can be grown from seeds sown directly into prepared beds, allowing you to explore new blooming opportunities without spending a lot of time or money.

But there’s a catch. Different flower seeds need different conditions to germinate and grow, so they should be sown in favorable seasons. For example, poppies, larkspur and many hardy perennials are best sown in winter, while late spring is the best time to tuck warm-natured sunflower and zinnia seeds into the ground.

In addition to following nature’s ways, sowing flower seeds in season leads to a long season of bloom, which is just what pollinators and gardeners want. December-sown poppies and larkspur bloom in June, bachelor buttons/cornflowers and cosmos sown in early spring take over a few weeks later, and high summer brings butterfly-friendly marigolds and zinnias. The season winds down with bright orange cosmos and scarlet sage, which put on a great autumn show from early summer sowings. Ready to get started?

First Flower Sowing: Early Winter

In early winter, direct-sow corn poppies (Papaver rhoeas) or breadseed poppies (P. somniferum) and Larkspur (Consolida ajacis) in open soil and pat the little seeds into place. Cover with a thin layer of potting soil and mark the planted spot. Don’t mulch, because good light exposure on sunny winter days triggers germination. The plants will be well established by early spring, at which time they can be weeded and thinned, but cannot be transplanted due to their brittle roots. Poppy and larkspur seedlings are highly animal resistant, which is important during the hungry season.

Second Flower Sowing: Winter

After your first hard freeze, sow biennials and hardy perennials under a surface cover. A long list of flower seeds benefit from exposure to winter weather, which follows the natural cycle of seeds falling to the ground in autumn. Rudbeckias, coneflowers, columbines, and beautiful blue forget-me-nots fit here, along with anise hyssop and other showy perennial herbs. Just don’t get carried away, because sowing only a few species makes it easier to distinguish seedlings from weeds.

After patting the seeds in place, cover the bed with a light cover such as a double thickness of row cover or a thin cotton sheet spread atop the bed and held in place with boards or bricks. Any cover that admits light while keeping tiny seedlings from being washed about by heavy rains will do.

Most of the seedlings will appear in early spring, along with plenty of little weeds. Winter weeds are easy to pull, and should you have too many seedlings, they are easy to lift and transplant when they show vigorous spring growth.

Third Flower Sowing: Early Spring

In early spring, six weeks or so before your last frost date, sow cool-season annuals under a row cover tunnel held aloft with wire or hoops. Bachelor buttons (Centaurea cyanus), pink cosmos (Cosmos bipinnatus), calendula (C. officinalis) and sweet alyssum (Lobularia maritima) are fast to sprout and grow, tolerate late freezes, and bloom in early summer. Provide stakes, grow-through hoops or other support for bachelor buttons, cosmos and other annuals that grow more than 24 inches (60 cm) tall.

If you are working with a wildflower seed mixture, this is the time to sow about half of the seeds, especially the smaller ones. Sow more seeds three to four weeks later. Splitting the sowing times gives the tiny seedlings more time to grow, and larger seeds like borage and sunflower sprout better under warmer conditions.

Fourth Flower Sowing: Late Spring

As your last frost passes in late spring, sow warm-season annuals including borage, marigold, plus plenty of zinnias, because they are butterfly magnets. This is also the best time to sow flower mixtures that feature sunflowers and other late summer standouts. Once the soil has warmed, these and many other summer annuals are fast and easy to sow in open soil. As long as they get plenty of water, extra seedlings can be dug up and moved to wherever they are needed.

[You can use our Garden Planner to work out your last frost date and the best dates for all the flowers mentioned in this article]

Fifth Flower Sowing: Early Summer

As spring annuals fail, replace them with sulfur cosmos (C. sulphureus) and scarlet sage (Salvia coccinea). No other annuals bloom as quickly as these two when sown in warm summer soil. Simply clear a place in a bed, water in a fair dose of rich compost or balanced organic fertilizer, and plant the seeds well covered with soil. In hot dry weather, shade covers are a terrific way to boost germination of summer-sown flower seeds.