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.

Cape Primroses.—­See “Streptocarpus.”

Caprifolium.—­See “Honeysuckle.”

Capsicum.—­Sow early in March in well-drained pots of rich, light, free mould; cover the seed with 1/2 in. of soil, and keep it constantly moist at a temperature of 65 degrees.  When strong enough to handle put two or three plants in a 5-in. pot, and replace them in warmth.  Keep them rather close till established, then shift them into 7-in. pots.  When established remove them to a cold frame and harden off.  Plant out at the end of May in a warm situation.  Keep them well supplied with water in dry weather and syringe the leaves.  By stopping the shoots they become nice, bushy shrubs.  Flower in July.  Height, 1-1/2 ft.

Cardamine Pratensis (Cuckoo Flower, or Milkmaid).—­This hardy perennial thrives in a moist, shady situation.  It produces its purple flowers from May to August, and is easily propagated by seeds or division.  Height, 1-1/2 ft.

Cardamine Trifolia.—­A hardy herbaceous plant; will grow in any soil, flowers in May, and is easily raised from seed.  Height, 1-1/2 ft.

Cardoons.—­Sow two or three seeds together in clumps 1 ft. apart, in trenches prepared as for Celery, in April or May.  When 6 in. high pull up the superfluous plants, leaving the strongest one in each case.  When they have attained the height of 1-1/2 ft, tie the leaves lightly to a stake and earth-up the stem.  Keep them well supplied with water, adding a little guano.  They will be ready for use in September.  Another sowing may be made in June for a spring crop.

Carduus (Milk Thistle).—­Coarse hardy annuals; somewhat ornamental, but are hardly more than weeds.  They grow freely from seed, and flower from June to August.  Height, 2 ft. to 4 ft.