Direct-Seeding Annual Garden Flowers

Gardeners who plant a large cutflower garden or like to edge their vegetable gardens with annual flowers find it is more economical to direct-seed these flowers into their garden than to purchase transplants. Many fast-growing annuals will be flowering within 7 weeks of sowing the seed. Unfortunately, there are a few disadvantages to direct-seeding. The obvious problem is the plants will not be flowering as soon in the garden as compared with those started indoors and set out as transplants. Also, after the seedlings come up, they will need to be thinned out to a uniform plant spacing.

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.


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