Corn Salad (_Lamb's Lettuce_).--Sow in drills--the plants to stand 6
in. apart--from March till August, in well-drained sandy loam. Autumn
sowings will stand the winter and prove useful in early spring. It
must be gathered young.
Cornus Canadensis (_Canadian Cornel_).--A pretty herbaceous plant,
suitable for moist parts of rock-work. It is very hardy, likes a light
soil, and produces flowers from June to August. The roots may be
divided in autumn, or in the early part of spring. Height, 8 in.
Cornus Mas (_Cornelian Cherry_).--This hardy deciduous shrub does
well in common soil if a fair amount of moisture be given. Its yellow
flowers are produced on bare stems from February to April. It may be
increased by seeds, cuttings, or layers, autumn being the time to
propagate.
Coronilla.--The greenhouse shrubs should be grown in peat and loam.
They are raised by seeds and by cuttings. Most of the hardy perennials
need protection in winter, therefore they are best grown in pots.
These are propagated by seed or division. The annuals need no special
treatment.
Coronilla Iberica.--A pretty creeping hardy perennial suitable for
rock-work, on which its bright yellow flowers are very attractive
during June and July. It thrives best in a mixture of peat and loam,
and may be increased by seeds or division of the roots. Height, 6 in.
Correa Cardinalis.--An evergreen greenhouse shrub. Place in equal
parts of sand and loam, and propagate by cuttings, which should have
plenty of room, as they are liable to damp off. July is its flowering
season. Height, 4 ft. C. Magnifica is also a capital plant.
Cortusa Matthioli.--This ornamental hardy herbaceous plant thrives
best in a mixture of peat and loam. It is advisable to give protection
to the roots in winter. It may be increased by seeds or by division of
the roots. It makes a good pot-plant, and produces flowers in May and
June. Height, 1 ft.
Corydalis (_Fumitory_).--These low-growing perennials are suitable for
dry positions on rock-work. They are not particular as to soil, and
may be increased by division of roots, while some scatter seed in
abundance. Their flowering period extends over many months. Height, 6
in. to 1 ft.
Cosmea Bipinnata.--A very pretty half-hardy annual which flowers in
July. Sow the seed early in spring on a slight hotbed covered with
glass, and transplant to the flower border at the end of May. Height,
2 ft.
Cosmos.--Pretty plants, the flowers resembling a single Dahlia. They
are mostly hardy, but some need protection. The annuals should
be raised on a hotbed in February and be planted out in May. The
perennials, too, are brought forward in heat. Some flower in June,
others in September. Height, 1 ft. to 3 ft.
Cotoneaster.--Evergreen shrubs which will grow in any soil and are
easily increased by layers. C. Hookeriana attains the dimensions of
small trees, and produces a profusion of white flowers and bright
crimson berries. C. Simonsii is largely used as a hedge. Height, 6 ft.
to 8 ft. C. Rupestris is a small-leaved, prostrate perennial species,
bearing white flowers from May to August, followed by red berries.
Height, 3 in.
Cotyledon Chrysantha (_Umbilicus)._--A choice Alpine succulent which
thrives in a sandy loam, or in well-drained pots of the same soil. It
flowers from May to August, and is multiplied by cuttings, which must
be left to dry for a few days in a sunny place. Flowers are produced
from May to August. Height, 3 in.
Cowslips.--Well-known hardy perennials. These require the same
treatment as Primulas. Plant in a mixture of loam and peat, and divide
as soon as the bloom has died off. Height, 6 in.