DESCRIPTION: These are hardy annuals of western North America. They are named after Captain William Clark of the Lewis and Clark Expedition. Clarkia's height ranges from 1 to 3 feet. They provide a profusion of flowers that, given favorable conditions, will bloom for quite some time. Clarkias are great for growing in flowerbeds and borders where the summers are cool. They may also be cultivated in greenhouses for blooming in the winter and spring and they provide excellent cut flowers. C. elegans, a native of California, grows about 2 feet high and produces loose sprays of crimson flowers. Some pretty double varieties have been raised. C. pulchella grows 12 to 18 inches high and bears flowers ranging from white to purple. They only need 9 inches spacing. Both of these species grow taller under greenhouse cultivation.
POTTING: C. elegans makes a handsome plant for cultivation in the greenhouse. After they are 3 inches high, three plants may be potted in each 6- or 7-inch pot or they may be planted in beds or benches, 9-12 inches apart. C. pulchella may be grown indoors in the same way as C. elegans, though they should be spaced 12 to 18 inches apart when planted in benches or beds. When Clarkias are planted outside, they will survive in regular garden soil, though well-dug and manured soil will provide the best results. Clarkias go to seed easily; to prolong the flowering season, you should remove the flowers as soon as they fade.
PROPAGATION: Seeds can be sown thinly, directly outdoors, early in the spring. They will be in bloom from June to July. In mild climates, they can be sown in September to provide flowers in the spring and early summer. Thin the seedlings out, 9-12 inches apart, according to the eventually height of the variety. Seeds can also be sown in late August or September in well-drained flats or pots of sandy soil that are placed in a cool greenhouse. The baby plants are then set, 3 inches apart, in flats filled with loam, leaf mold and sand. Pinch the tips off when they're 3 inches high and two or three weeks after they've been potted in the soil. In February, they are repotted into their final pots as described above in potting.
VARIETIES: C. elegans; C. pulchella.