Growing Annual Flowers from Seed: Easy Direct-Sow and Indoor Varieties

Some Annuals Are Especially Easy to Grow. Learn How.

Zinnias are easy to start from seed.

As a founding Gardener's Supply employee, I now run Johnnie Brook Creative. My Richmond, VT gardens include large vegetable garden, seasonal greenhouse, cutting garden, perennial gardens, rock garden, shade garden, berries, containers, and meadow. No place I'd rather be.

Easy Annuals to Start from Seed

Direct-Sow Outdoors (Right in the Garden)

Little advantage to starting indoors. Most are tender—sow after frost danger. (Exceptions: sweet peas, sweet alyssum, poppies, larkspur tolerate cool).

• Sunflower
• Marigold
• Morning glory
• Bachelor button
• Calendula
• Castor bean
• Cosmos
• Nasturtium
• Sweet pea
• Sweet alyssum
• Larkspur
• Annual poppy
• Ammi majus
• Zinnia
• Hyacinth bean

Start Indoors Under Lights (6-8 Weeks Before Transplant)

Especially small seeds (nicotiana, petunia, snapdragon) broadcast on small tray, then tease apart at first true leaves.

• Cleome
• Coleus
• Snapdragon
• Ageratum
• Amaranth
• Nicotiana
• Lavatera
• Petunia
• Impatiens
• Salvia
• Statice

For more: Seedstarting Made Easy and Gardening Under Lights.

Types of Annuals: Hardy to Tender

Hardy Annuals

Plant directly as early as soil can be worked. Tolerate light frost to ~25°F.

• Bachelor button
• Calendula
• Spider flower (cleome)
• Pinks (dianthus)
• Forget-me-not (myosotis)
• Pansy (viola)
• Larkspur (Delphinium consolida)
• Linaria
• California and Shirley poppies (papaver)
• Love-in-a-mist (nigella)
• Pincushion flower (scabiosa)
• Snapdragons (antirrhinum)
• Lavatera
• Annual baby's-breath (Gypsophila elegans)
• Stock
• Sweet pea (Lathyrus odoratus)

Half-Hardy Annuals

Start indoors 6-8 weeks before transplant, or direct-sow once soil warms. Most tolerate light frost.

• Statice
• Marigold
• Nicotiana
• Painted-tongue (Salpiglossis sinuata)
• China aster (Callistephus chinensis)
• Various salvias and chrysanthemums

Tender Annuals

Direct-sow only after all frost danger. Or start indoors 4-6 weeks before last frost. Transplant when nights stay above 40°F.

• Morning glory
• Zinnia
• Coleus
• Sunflowers and tithonia (Mexican sunflower)
• Cosmos
• Amaranth
• Ageratum
• Celosia
• Gomphrena (globe amaranth)

Why Start Annuals from Seed?

Cost: 12-foot zinnia row or 40 white impatiens = $50+ at nursery vs. $4 for seed packet. That's $46 for other essentials!

Availability: Best garden centers don't offer worthy annuals like love-lies-bleeding (Amaranthus caudatus), Nicotiana langsdorfii, Phlox drummondii, Salvia horminium, lavatera (Lavatera trimestris). I start them myself.

Most annuals are easy from seed. Challenge: figuring out when and where to plant. People stare at colorful packets with no idea where to begin.

Seed packets rarely provide basic info: indoors vs. direct sow, light/dark germination, frost hardiness. Exotic varieties (Himalayan blue poppy Meconopsis betonicifolia) challenge even experts.

Start with super-easy seeds (sidebar). Give yourself 1-2 years before tackling challenging annuals.

Key Questions Before Starting

• Seed size? Direct-sow or peat pots need handleable seeds (⅛"+ for easy list). Dust-like seeds (petunia, snapdragon) get lost if direct-sown.
• Special germination needs? Most prefer darkness; some need light. Tough coats (lupines, sweet peas, morning glories) need soaking/nicking. Some take 3-4 weeks to germinate.
• Seedling growth rate? Genetically programmed but influenced by conditions. 80°F greenhouse vs. cool basement lights. Impatiens ready at 8 weeks; zinnias root-bound by then. Fast growers (sunflowers, bachelor buttons, calendulas, zinnias, nasturtiums) best direct-sown—not worth indoor trouble for 3-4 weeks plus transplant shock risk.
• Days to bloom? Packet should say. Short season + 80-90 days = start indoors for pre-frost flowers. Easy annuals often bloom 50-70 days.
• Cold hardiness? Hardy: direct-sow early spring, tolerate 25°F. Half-hardy: indoors 6-8 weeks or direct-sow when soil warms, protect if temps drop. Tender: direct-sow after frost, or indoors 4-6 weeks before last frost, transplant when nights >40°F.

For serious seed-starting, invest in a reference like Eileen Powell's The Gardener's A-Z Guide to Growing Flowers from Seed to Bloom (500+ flowers, germination, hardiness, bloom time). The more you know, the better you'll grow.