Clarkia.--These hardy annuals make a pretty display in the borders during summer. Seed ripens plentifully, and merely requires sowing in the open in March, or in September if protected in winter. The bloom lasts from June to September. Height, 18 in.

Claytonia Sibirica.--A hardy herbaceous plant which yields light yellow flowers in June. It is not particular as to soil, and may be raised from seed sown either in autumn or spring. It stands division of the root. Height, 4 ft.

Clematis (_Virgin's Bower_).--These plants like a dry situation. They will grow in smoky districts, and may be increased by cuttings of firm side-shoots under a gla.s.s in summer or by layers in September. With the protection of a greenhouse they come into flower early in spring.

They are the most beautiful of all flowering hardy climbers. The stove and greenhouse varieties are best planted in loam and peat, though they will thrive in any light soil. Any good garden soil suits the hardy kinds. The herbaceous varieties are increased by dividing the roots early in spring. They bloom at various periods. After they have ceased to flower, the Jackmanni and Viticella sections should be cut down to within 9 or 12 in. of the ground. The Patens and Florida do not require pruning; those of the Lanuginosa should be cut back moderately, but not too close. A good dressing of leaf-mould and manure should be dug in about November. Heights vary from 2 ft. to 20 ft. (_See also_ "Traveller's Joy.")

Cleome.--The species of this genus are very pretty and free flowering, some being half-hardy climbers notable for their foliage. They like a rich, light soil. Cuttings of the stove kinds root freely under a gla.s.s. Some of the annual species require to be sown in a hotbed frame or in a hot-house, then potted off and placed with tender annuals. The hardier ones may be sown on a hotbed, and afterwards planted out in a sheltered position. They flower in May, June, and July. Heights vary from 6 in. to 8 ft.

Clethra Alnifolia.--This hardy deciduous shrub bears in September deliciously scented pure white flowers on the side-shoots of the previous year's growth. It needs a light soil and a dry, sunny situation. It may be propagated by cuttings placed under gla.s.s in sandy loam, or by suckers taken when the leaves have fallen, but is more generally increased by layers. Height, 3 ft.

Clianthus.--A genus of very elegant, free-flowering, evergreen greenhouse shrubs. They flourish in the border of the conservatory (or against a south wall if protected from cold) in an equal mixture of loam, peat, and sand. Cuttings root freely in the same soil under gla.s.s. Seed sown early in spring produce flowers the first year, in May. Height, 3 ft. to 4 ft.

Clintonia.--Very pretty half-hardy annuals; useful for beds, edging, pots, or rock-work. They produce an abundance of Lobelia-like flowers in August. Sow the seed in the open in spring. Height, 6 in.

c.l.i.toria.--A greenhouse climbing or trailing plant, which thrives in a mixture of loam, peat, and sand. Cuttings will strike in heat, but it is more readily grown from seed.

Clivias (_Caffre Lilies_).--Most beautiful evergreen plants for the greenhouse. The soil most suitable for them is a compost of leaf-mould, loam, and sand. Give a liberal supply of water when in full growth, but from September to February keep them only moderately moist. Shade from strong sunshine, and keep the temperature at from 60 to 70 degrees. They will not bear much disturbance. Seed may be sown in bottom-heat early in spring, or they may be increased by suckers.

Cobaea Scandens.--This rapid climber is well adapted for the conservatory, but it will thrive in the open air if the root is protected during the winter. If planted against a rough wall its tendrils will catch in the crevices and support it without any a.s.sistance. It requires plenty of room and a rather poor soil, otherwise it runs to leaf instead of to bloom. The tops of the shoots should be constantly pinched off, to induce thickness of growth.

Cuttings of firm side-shoots taken in summer will root under gla.s.s in a little moist heat; but it is best raised from seed, sown sideways, in a hotbed in March. Its blue and purple flowers are produced in August. Height, 10 ft. to 20 ft.

Cob Nuts.--_See_ "Filberts."

c.o.c.ks...o...b..--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 gra.s.s bearing cl.u.s.ters 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.

Colchic.u.m (_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 gla.s.s, 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 gla.s.s, 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 gla.s.s. 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.

Commelina Sellowina (_Blue Spider Wort, or Day Flower_).--A pretty greenhouse climber, bearing cobalt-blue flowers. It should occupy a sunny position, and be watered freely from March to September, after which very little should be given.

Commelina Tuberosa.--Perfectly hardy plants, bearing in June blue or white flowers the size of a shilling. The bulbs may be planted in spring in any garden soil; the plants are increased by off-sets.

Height, 1-1/2 ft.

Compost Heap.--Get a heap of dead leaves and press and jam them down as closely as possible. Then take as much manure, in appearance, as you have dead leaves, and for each cartload have two bushels of unslaked quicklime and some earth. Now spread upon the ground, in some out-of-the-way corner, a layer of the dead leaves, upon which sprinkle a layer of lime, and over that a thin layer of earth. Next lay on a covering of manure, then a layer of leaves, and one of lime and earth as before, and proceed in this way till all the materials are used up.

It will be well, however, to give the heap a good watering whenever you come to the layer of leaves. This slakes the lime and hastens the decomposition of the vegetable matter. After letting it stand for about six weeks, begin at the top of the heap and turn it completely over, so that what was at the bottom will be at the top. Repeat this operation from time to time at intervals of six or seven weeks, until it has become perfectly friable and will powder through a garden-fork like dust. It will then be ready for use. This compost is invigorating to flowers of all kinds, and is so ready for them to a.s.similate.

Comptonia Asplenifolia.--This ornamental deciduous shrub is quite hardy, but requires a light, sandy loam or peat soil and a shady situation. It is increased by layers. Blooms in April. Height, 4 ft.

Cone Flower.--_See_ "Echinacea."

Conifers.--Conifers (so called because they bear cones in place of ordinary seed) are mostly of tall growth, yet among the cla.s.s are many low--growing evergreens well adapted for the lawn or border. Indeed, any of the specimens may be utilised in this way, but of course must be removed from the shrubbery or border before they attain undue proportions. They are hardy, and, generally speaking, not particular as to soil or situation. Firs, Pines, Cedars, etc., come under this heading, and mention is made in other parts of this work of those most suitable for the amateur's requirements.

Convallaria Prolificans.--This is one of the most beautiful hardy perennials known. It has large, deep-green foliage, with erect and much-branched flower-stems. The flowers are white, internally flushed rose; are very fragrant, and are produced from May to September. The plant will grow in any ordinary soil, and may be increased by dividing the root. Height, 2-1/2 ft.

Convolvulus (_Morning Glory_).--Showy plants. The tender species are well adapted for the stove or conservatory, and are best grown in loam and peat: cuttings strike freely in sand under a gla.s.s. The half-hardy annual kinds should be sown on a gentle hotbed in February, and when large enough transferred to the open; or they may be sown in the open in April. Hardy kinds merely require sowing in the open, early in spring. The stove and greenhouse annuals and biennials require to be sown in heat, and treated as other stove and greenhouse annuals and biennials. Flowering season, May to July. Height, 6 in. to 15 ft.

Coral Plant.--_See_ "Erythrina."

Corchorus.--_See_ "Kerria."

Cordyline.--A stove evergreen shrub, which may be grown in any light, vegetable mould or in peat and loam, and is easily increased by suckers. It flowers in spring. Height, 3 ft.

Coreopsis.--Very pretty and long-flowering. They all like a light, rich, and sandy soil. Cuttings of the stove kinds root freely under gla.s.s. Hardy perennials may be divided at the roots. The annuals may be sown either in the autumn or in March; they bear transplanting.

Longipes flowers in April; Grandiflora in August. Useful as cut flowers. Height, 1-1/2 ft. to 3 ft.

Cornel.--_See_ "Cornus."

Cornflower.--_See_ "Cya.n.u.s."

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 gla.s.s, and transplant to the flower border at the end of May. Height, 2 ft.