Jacobaea (Ragwort).—­May be raised from cuttings in the same way as Verbenas, and will grow freely from seeds sown in autumn or spring.  It delights in a rich, light soil.  The purple Jacobaea is a great favourite of the public.  Flowers in August.  Height, 1 ft.

Jacob’s Ladder.—­See “Polemonium.”

Jasione Perennis (Sheep Scabious).—­A hardy perennial which produces a profusion of heads of blue flowers in June, and continues to bloom till August.  It enjoys a peat soil, and should have the protection of a frame during the winter.  It can be propagated by seeds, cuttings, or division.  Height, 1 ft.

Jasminum.—­These are favourite plants for training over arbours or trellis-work, and for growing against walls.  The hardy kinds will flourish in ordinary soil.  The stove and greenhouse sorts should be provided with a mixture of sandy peat and loam.  They may all be increased by cuttings of ripened wood planted in a sandy soil under glass.  J. Nudifolium produces an abundance of bright flowers after its leaves have fallen, and is very suitable for town gardens.  J. Unofficinale is likewise adapted for town, bearing confinement well, and has very sweet flowers.  J. Revolutum needs protection in severe weather.  They bloom in July.  Height, 12 ft.

Job’s Tears.—­See “Coix Lachryma.”

Jonquils.—­These are quite hardy, and may be grown in the open in the same manner as Hyacinths.  Five or six bulbs in a 5-in. pot make a very pretty bouquet.  They are excellent early flowers, and very odoriferous.  Plant in autumn, placing sand round the bulbs.  Best not disturbed too often.  The leaves should not be cut off when withering, but allowed to die down.  They bloom in April.  Height, 1 ft.

Joss Flower.—­See “Chinese Sacred Narcissus.”

Juniper (Juniperus).—­These useful conifers prefer dry chalk or sandy soils, but will thrive in any ground that is not too heavy.  J. Japonica, Sabina, and Tamariscifolia do well on steep banks and rock-work.  They may be propagated by seeds, grafting, or by cuttings of firm young shoots planted in a sandy compost, kept shaded, and covered with a hand-glass.

K

Kadsura Japonica.—­This is a beautiful creeper for a south or west aspect.  It thrives best in loam and sandy peat.  Cuttings may be struck in sand, placed under a glass, and subjected to heat.

Kale.—­See “Borecole.”

Kalmia Latifolia.—­This hardy, dwarf evergreen shrub is deservedly a great favourite.  It produces a wealth of flowers in large clusters.  It requires to be grown in peat or good leaf-mould, and needs pure air.  It is increased by pegging down the lower branches, which soon become rooted.  The flowers are produced from June to August.  Height, 2 ft.

Kalosanthes.—­Showy greenhouse succulent plants.  A light, turfy loam is suitable for them, and they may be increased by placing cuttings of the young shoots in a sandy soil on a slight hotbed in spring.  Pinch them back so as to produce a bushy growth, and give support to the heavy heads of bloom.  The cuttings should be left for twenty-four hours to dry before they are planted.  The plants require very little water, and they flower in July.  Height, 6 in. to 1 ft.