The seed bed should be worked well and raked so that the soil is fine, without large clumps or clods. Direct-seed annual flowers after the threat of frost is past in the spring and when the soil warms ups.
Some species germinate faster if the seeds are given a special treatment prior to planting. This treatment, called "scarification," breaks the hard seed coat and allows the seeds to imbibe water more quickly, resulting in earlier germination. Morning glories, for example, will germinate faster and more uniformly if the seed coat is nicked slightly. This can be done using a nail clipper to snip off a small piece of the seed coat on one end. Scarify sweet pea seeds by filing the seed coat on one side. After scarifying the seeds, soak them in warm water for 24 hours before sowing.
Sow the seeds in shallow furrows then cover them lightly with fine soil. Keep the seed bed moist. After germination, thin the young seedlings to the appropriate plant spacing. The excess seedlings can either be discarded or transplanted to fill empty spaces in the row.
Annual garden flowers that can be direct-seeded into the garden are listed below:
Annual garden flowers that can be direct-seeded into the garden.
| Species | Days to germination | Final plant spacing | Special considerations |
|---|---|---|---|
| Bachelor's button (Centaurea cyanus) | 7-14 | 6-12" | bury seeds; needs darkness for germination |
| Spider flower (Cleome hasslerana) | 10-14 | 2-3' | |
| Cosmos (Cosmos bipinnatus and C. suphureus) | 5-10 | 10-24" depending on variety | |
| Annual baby's breath (Gypsophilia elegans) | 10-15 | 18" | |
| Sunflower (Helianthus annuus) | 10-14 | 24" | |
| Morning glory (Ipomoea purpurea) | 5-7 | 4" | |
| Sweet pea (Lathryrus odoratus) | 10-14 | 4-6" | scarify seeds; bury seeds; needs darkness for germination |
| Love-in-a-mist (Nigella damascena) | 10-15 | 8" | |
| Rose moss (Portulaca grandiflora) | 10-15 | 12" | |
| Creeping zinnia (Sanvitalia procumbens) | 10-15 | 6" | do not bury seeds; needs light for germination |
| Marigold (Tagetes spp.) | 5-7 | 6-18" depending on variety | |
| Nasturtium (Tropaeolum majus) | 7-12 | 8-12" | scarify seeds; bury seeds; needs darkness for germination |
| Zinnia (Zinnia elegans and Zinnia angustifolia) | 5-7 | 6-12" |
This article originally appeared in the May 16, 1997 issue, p. 71.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Yard and Garden, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on May 16, 1997. The information contained within may not be the most current and accurate depending on when it is accessed.