Cockscomb.--These tender annuals should be sown on a moderate hotbed
in March or April, in pans of leaf-mould and sand, covering with 1/4
in. of soil. When a couple of inches high place them in small pots,
replace them on the hotbed, and give shade till they have taken fresh
root. When the weather is favourable let them have a moderate amount
of fresh air. Afterwards shift them into larger pots, and when the
combs are full grown place them in the greenhouse, taking care not to
allow any damp to lodge on them, at the same time supplying them
well with water and all the air possible. Height, 9 in. (_See also_
"Celosia.")
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.