CORVALLIS, Ore. – Annuals live a short, sweet life. They bloom, make seed and die. Fortunately for us, they return year after year if left to go to seed.
Besides being lovely to look at, annual wildflowers attract pollinators that sip their nectar and/or cart off their pollen, feeding the insects, butterflies and hummingbirds who, in turn, pollinate the plants.
“True wildflower patches will take on a natural, informal appearance in the garden,” said Amy Jo Detweiler, Oregon State University Extension Service horticulturist. “They will evolve over time and change as the dominant seeds in the mix spread more quickly.”
There’s more to growing wildflowers than just sprinkling them on the ground, sitting back and watching them grow, Detweiler said. First select an appropriate site. Most wildflowers prefer full sun, well-drained soils and open areas free of weeds.
Water the site you chose for several weeks to germinate and bring up any existing weed seeds, Detweiler said. Then, remove any weeds by manually pulling, tilling, or using a non-selective type of herbicide. Once the weeds have died and been removed you are ready to gently loosen the top 2 to 4 inches of the soil. Deep tilling tends to bring up too many weed seeds and will cause problems later, Detweiler said. You may need to amend the soil with some kind of organic matter or compost to improve nutrient-deficient soils in Central Oregon and drainage in garden west of the Cascades.
Commercial wildflower seeds can be successfully planted in spring or fall. Seeding rate is one ounce of seed per 125 square feet or as directed on package. A hand seed spreader is a good tool for broadcasting the seed. You’ll get more uniform coverage.
For planting in spring, gently water the site for up to a month prior to planting to improve germination after seeding. Seed in mid-April in western Oregon and the beginning of May in central Oregon. For western Oregon gardeners who missed the window for watering the site for a month before seeding, it’s okay to only water for two weeks this year. Keep the area lightly irrigated while seeds are germinating if it doesn’t rain.
If planting in fall, broadcast the seed late enough that germination will not occur until spring (early November). Most annuals’ seeds need light to germinate so do not cover the seeds – rather let them sit on the surface of the soil. Make sure you leave the dead plants long enough so they drop all their seed.
Detweiler has these suggestions for annual wildflowers:
- Black-eyed Susan (Rudbeckia hirta)
- Blue flax (Linum perenne)
- California poppy (Eschscholzia californica)
- Purple coneflower (Echinacea purpurea)
- Foxglove (Digitalis purpurea)
- Godetia (Clarkia amoena)
- Lance-leaf coreopsis (Coreopsis lanceolate)
- Mountain hollyhock (Iliamna rivularis)
- New England aster (Aster novae-angliae)
- Pot marigold (Calendula officinalis)
- Scarlet gilia (Ipomopsis aggregate)
- Sweet William pinks (Dianthus barbatus)
- White meadowfoam (Limnanthes alba)
- Globe gilia (Gilia capitata)
- Large baby blue eyes (Nemophila menziesii var. atomaria)