Codonopsis.—These hardy perennials are best grown in sandy peat and loam. They are easily raised from seed or cuttings, and produce their flowers in July and August. Height, 1 ft.
Coix Lachryma (Job's Tears).—A half-hardy, annual, ornamental grass bearing clusters of beautiful pearl-like seeds. Sow in a warm spot in April, barely covering the seed with fine soil, and keep the surface of the ground moist till germination is ensured. Height, 1-1/2 ft.
Colchicum (Autumn-Flowering Crocus).—Plant the bulbs in February in light, loamy soil, placing them 2 in. deep and 3 in. apart. They are readily increased by off-sets from the bulb. September is their flowering season. Height, 3 in. (See also "Bulbocodium.")
Coleus.—Tender perennial shrubs of some merit, requiring the protection of a greenhouse. Keep the plants root-bound and near the glass, with a good supply of heat and moisture. They succeed best in a mixture of loam and peat. Cuttings of shoots 3 in. long planted in sand, covered with a glass, and plunged in heat 60 to 70 degrees, will strike. Pot off singly in loam and sand. Bloom in June or July. Height, 2 ft. to 3 ft.
Colletia.—Ornamental evergreen shrubs. A mixture of peat and loam, with a sheltered position, is their delight. Cuttings will strike in sand if covered with glass. They produce their flowers in July. Height, 2 ft. to 3 ft.
Collinsia.—Most elegant hardy annuals, doing well in any garden soil. The seed is sown in autumn for early flowering, and in spring for a later display. Bloom May to August. Height, 1 ft.
Collomia.—Hardy annuals, possessing little beauty. Treat as Collinsia. Flower in July. Height, 1 ft. to 2 ft.
Colt's-foot.—This hardy perennial flowers before the leaves appear. It grows best in a moist, clayey soil, and may be increased by pieces of the running root.
Columbine.—See "Aquilegia."
Colutea Arborescens (Bladder Senna).—A shrub with Acacia-like leaves and producing yellow Pea-shaped flowers in July, followed with bladder-shaped seed vessels. It will grow in any soil, and may be raised either from seed or cuttings taken in autumn. Height, 10 ft.