This calendar provides a general framework. Adjust by 2–4 weeks earlier for warm zones (8+) and later for cold zones (3–4). Your local frost dates are the anchor for all timing.
Start lisianthus seeds indoors (16–20 weeks before last frost). Order seeds and tubers. Review the seed-starting schedule.
Start snapdragons, stock, eucalyptus, delphinium indoors. Start rudbeckia, ageratum, scabiosa.
Start celosia, strawflowers, marigolds indoors. Begin hardening off early starts. Direct sow sweet peas, larkspur, nigella (cold zones). Harvest spring bulbs.
Transplant everything after frost. Direct sow zinnias, sunflowers, cosmos. Plant dahlia tubers. Pinch established transplants. Install netting. Harvest peonies, late tulips.
Succession sow zinnias, sunflowers, cosmos. Harvest sweet peas, snapdragons, larkspur, foxglove. Fertilize all beds.
Peak harvest season. Zinnias, dahlias, sunflowers, lisianthus, celosia, cosmos all in full production. Continue succession sowing. Water deeply. Deadhead spent blooms.
Harvest continues. Start drying flowers for everlasting arrangements. Start snapdragon seeds for fall transplanting (zones 8+). Begin planning fall planting.
Plant spring bulbs: tulips, daffodils. Plant ranunculus and anemone corms (zones 7+). Sow larkspur and nigella. Plant peony roots. Clear spent summer flowers.
Finish bulb planting. Lift dahlia tubers after frost. Mulch perennials. Amend soil with compost.
Rest. Browse seed catalogs. Plan next year's garden and place early orders. Enjoy dried arrangements.