Clarkia flowers come in a variety of colors.
image by Tom Hilton/Flickr.com
Clarkia, also known as farewell-to-spring, is an annual flowering plant native to the Pacific Coast of North America. The genus was named after William Clark of Lewis and Clark fame, who brought the plant back from his travels in the early 19th century. Clarkia quickly became popular in cottage and cutting gardens, and remains so today. Plants produce flowers in a variety of colors including white, yellow, orange, red, pink and purple, which bloom in early summer through fall. Once established, clarkia requires very little care.
Sow clarkia seeds directly in the garden during early spring after all danger of frost has passed. Choose a planting site that receives full to partial sun, and has average well-drained soil. In very warm climates, choose a place where the plants will receive some shade from the afternoon sun.
Broadcast clarkia seeds on top of the soil, as they need light to germinate and shouldn't be buried. Use a flat board to press the seeds down on top of the soil after spreading, which will prevent them from being washed or blown away. Germination will occur in seven to 14 days.
Water the soil thoroughly after broadcasting the seeds and keep the soil evenly moist until the plants are fully established. Water approximately twice per week for the first month of growth, and then reduce watering to once per week throughout the summer. Do not water on weeks that receive more than one inch of natural rainfall.
Spread a 1- to 2-inch layer of organic mulch around the base of clarkia plants in areas with very hot summers. Clarkias do not like hot, humid conditions, but mulching and planting in partial shade can help them thrive. Use organic bark mulch, hay or grass clippings for the best results.
Thin clarkias to one plant every 4 to 6 inches after the plants become established. They have an upright growth habit, but their stems are weak. Clarkias are best grown close to one another so they can lean on their neighbors for support. Thinning is required, however, to prevent the plants from forming too close, where there won't be room to grow.