Self-Seeding Annuals Can Be A Surprise!

BY MARY LOU MAYFIELD

Every spring, I get “little surprises” in my garden of plants that self-seeded from last year’s annuals. In New Jersey, the Columbine were downright invasive! Since we moved to Iowa, we have been pleasantly surprised by delicately blue “Love-in-a-Mist,” which I had never seen before. The “Sweet Alyssum” hanging planter left behind a cluster of seeds that came up and bloomed in the shelter of our house. The children’s learning garden at Home Ties has a whole bed of French marigolds—both those planted by the children and seedlings from last year’s plants.

I started to research which annuals can be planted in the fall because they have “winter-hardy” seeds. One article even suggested scattering seed on top of the snow—which I tried with no success— probably because the birds and chipmunks found them before the snow could melt, or the wind blew them away. I had much better luck with planting seeds in late fall before the first snow, or early spring, during the first thaw. Garden plants that tend to re-seed and can be planted at those time include, besides the Love-in-a-Mist, Sweet Alyssum, and French (mini) Marigolds: Bachelor Buttons, Cosmos, Hollyhocks, Larkspur, Morning Glory, Pansy, Portulaca, Snapdragons, Sweet Pea, Sweet William (actually a perennial), and Violas (both perennial and annual). Some of these, like the Morning Glory, might need heavy thinning in the spring, so they don’t take over!

Native annuals and biennials have winter- hardy seeds, too. In N.J., I had Purple Coneflower (Echinacea) and Black-eyed Susans (Rudbeckia) volunteering in my Daylily bed. I have had less luck with them self-seeding here in Iowa City. It took me a while to find the bed location for Bee Balm (Monarda), but now I have an established patch that comes up every year. Also both blue Lobelia and Cardinal Flowers. I have an established patch of Butterfly Milkweed, and some Common Milkweed (Asclepias) that come back every year.

Plants recommended for fall planting by the “Empress of Dirt” for zones 4-5, include: Blanket Flower (Gaillardia), Blue Flax (Linum), native and cultivated Columbine (Aquilegia), Tickseed (Coreopsis), Cupid’s Dart (Catananche), Painted Daisy (Chrysanthemum), Lavender (a perennial) Lady’s Mantle (Alchemilla), Nasturtium, Penstemon, Pincushion flowers (Scabiosa), Thrift (Armeria), Poppy (Papaveraceae), Prairie Coneflower (Ratibida), and Rose Campion (Silene).

According to “High Country Gardens” https://www.highcountrygardens.com/ (located in Utah), many perennial wildflower seeds can be sown in winter (before February and just before a snowstorm). This provides the benefit of “cold stratification” necessary for certain species to sprout with the first thaw.

The annuals will bloom the following season. Perennials and biennials usually need a season to grow before they bloom the next year. Some will bloom the following summer if planted in fall. For best results, prepare the flower beds in the fall. Mix the seeds with sand to help them distribute evenly. For tiny seeds, I use a spice shaker with large holes.