Callirhoe (_Digitata_).--Hardy annuals demanding but little attention.
The seed is sown in the open in March. Height, 1 ft.
Calochortus Luteus.--This very handsome hardy perennial thrives best
in sandy peat with a little loam. It produces yellow flowers in July,
and is propagated by offsets from the bulbs. Height, 1 ft.
Caltha.--Early-flowering, showy perennials, all thriving in a moist or
boggy situation. C. Leptosepala is especially choice, its pure white
flowers resembling a water-lily. They may be increased from seed, or
by division. Height, 1 ft.
Calthus Palustris Flore-Pleno (_Double Marsh Marigold_).--This hardy
herbaceous perennial is very useful for mixing with cut flowers. It
will grow anywhere, but prefers a clayey soil and a boggy situation,
and may be increased by dividing the roots in spring. A succession of
flowers are borne from April to June. Height, 9 in.
Calycanthus Floridus (_Allspice_).--This shrub likes an open loamy
soil; flowers in July, and is propagated by layers. Height, 6 ft.
Calystegia.--A perfectly hardy climbing convolvulus, and a beautiful
plant for covering arbours, etc., growing 20 ft. to 30 ft. in one
season. It thrives in any loamy soil or situation; flowers from May to
September, and may be increased by division of the roots.
Camassia Esculenta.--A handsome, hardy, bulbous plant, bearing
clusters of beautiful blue flowers in July. It needs a sandy peat
border under a north wall, and is increased by bulbs or seeds. Plant
the bulbs early in October, 4 in. deep and 5 in. apart. Height, 1-1/3
ft.
Camellias.--The best soil for these beautiful greenhouse evergreens is
a mixture of rough peat, plenty of sand, and a little turfy loam. The
greenhouse should be kept rather close, at a temperature of 55 degrees
to 60 degrees, while the plants are growing; but abundant syringing is
necessary at all times. Induce a vigorous growth of wood, and let this
be well matured by exposure to the sun and free ventilation. Old and
straggling plants may be renovated by cutting them hard back as soon
as they go out of flower, and placing them in a warm house where
a moist atmosphere is maintained. This will induce them to break.
Comparatively little water should be given for some time after they
are cut back. When the state of the roots require the plants to be
re-potted, remove as much of the old soil as possible without injuring
them, and put them into the smallest sized pots into which they can
be got, with fresh soil. This may be done after the last flower has
fallen, or after the buds have fairly commenced to push. The plants
may be placed out of doors at the beginning of June, and returned to
the greenhouse in October. There are several varieties suitable for
growing in the open. These should be provided with a soil, 2 ft. deep,
composed of peat, leaf-mould, and cows' dung. The roots should
always be kept moist and cool, and the plants disturbed as little as
possible. A top dressing of fresh soil may be given each winter, and
the plants protected from frost by binding straw round the stems.
Campanula.--A showy genus of plants, mostly hardy perennials, which
need no special treatment. They are readily raised from seed, or
division of roots. The less hardy kinds may be sown on a hotbed or in
the greenhouse, and when large enough potted off. Campanula Mayii is a
grand plant for hanging baskets, and also grows well trained up
sticks in a pyramidal form. A rich, gritty soil suits them all. The
tall-growing varieties make fine pot-plants. Flower in July. Height, 1
ft. to 5 ft.
Canary Creeper (_Tropaeolum Canariense_).--This is eminently suitable
for trellis-work or for walls. Its elegant foliage and bright yellow
flowers make it a general favourite. It may be raised from seed on
a hotbed in spring, gradually hardened off, and planted out in May.
Height, 10 ft.
Candytuft (_Iberis_).--Very pretty hardy annuals. Sow the seed in
autumn in a light, rich soil, or in spring if a less prolonged
flowering season will give satisfaction. Bloom in May or June. Height,
1 ft.
Canna (_Indian Shot or Hemp_).--For pot-plants on terraces, gravel
walks, and such like places, few things can equal and none surpass
Cannas. They are half-hardy perennials, and may be increased from
seed or by dividing the roots late in autumn, allowing them first to
partially dry. File the tough skin off one end of the seed, and steep
it in hot water for a few hours before it is sown, then stand it in a
hot place till it has germinated. Harden off and plant out, or shift
into larger pots in June, using a rich, light soil. Lift and store the
roots in autumn in the same way as Dahlias. Different kinds flower at
various seasons, so that a succession of bloom may be had throughout
the year. Height, 2 ft. to 10 ft.
Cannabis Gigantea (_Giant Hemp_).--This half-hardy Hemp is grown for
its ornamental foliage, and is treated as above described. Height, 6
ft.
Canterbury Bells.--Showy hardy biennials, which may be raised from
seed sown in the spring. Transplant in the autumn to the border where
they are intended to flower. The seed may also be sown in a sheltered
position in August or September. Flower in July. Height, 2 ft.