Ipomopsis.—A very beautiful half-hardy biennial, but difficult to cultivate. Some gardeners steep the seed in hot water before sowing it; but the best way seems to be to sow it in July in 3-in. pots in equal parts of sandy peat and loam, ensuring good drainage, and place it in a cold frame, giving it very little water. When the leaves appear, thin out the plants to three or four in each pot. Replace them in the frame for a week or so, then remove them to a light, airy part of the greenhouse for the winter. During this period be careful not to over-water them. In spring shift them into well-drained 4-1/2-in. pots, using the same kind of soil as before, and taking great care not to injure the roots; still give the least possible amount of water. If plenty of light and air be given, they will flower in July or August. Height, 2 ft.
Iresines.—Take cuttings of these greenhouse plants in autumn; insert them thinly in 48-size pots filled with coarse sand, loam, and leaf-mould, and place in a uniform temperature of 60 or 70 degrees. When they have taken root place them near the glass. Height, 1-1/2 ft.
Iris.—The Iris is the orchid of the flower garden; its blossoms are the most rich and varied in colour of hardy plants. For cutting, for vases, table decoration, etc., it is exceedingly useful, as it is very free-flowering, and lasts a long time in water. It thrives in almost any soil, though a sandy one suits it best, and is strikingly effective when planted in clumps. It soon increases if left undisturbed. The English Iris blooms in June and July, bearing large and magnificent flowers ranging in colour from white to deep purple, some being self-colours, while others are prettily marbled. The German Iris is especially suitable for town gardens. The Spanish Iris blooms a fortnight before the English. Its flowers, however, are smaller, and the combinations of colours very different. The Leopard Iris (Pardanthus Chinensis)is very showy, its orange-yellow flowers, spotted purple-brown, appearing in June and July. They are quite hardy. The best time for planting them is October or November, selecting a sunny position. Height, 1-1/2 ft.
Isopyrums—Hardy herbaceous plants of great beauty, nearly related to the Thalictrums. They will grow in any ordinary soil, but flourish best in vegetable mould, and in a moist, yet open, situation. They are readily raised from seed, or may be propagated by division of the roots in autumn. They flower in July. Height, 1 ft. to 1-1/2 ft.
Ivy (Hedera).—A deep, rich soil suits the common Ivy; the more tender kinds require a lighter mould. To increase them, plant slips in a north border in sandy soil. Keep them moist through the autumn, and plant them out when well rooted. The following are the principal choice sorts:—Aurea Spectabilis, palmate-leaved, blotched with yellow; Cavendishii, a slender-growing variety, leaves margined with white, with a bronzy shade on the edge; Conglomerata, crumpled leaves; Elegantissima, slender-growing, with silvery variegated leaves; Irish Gold-Blotch, large leaves, blotched with yellow; Latifolia Maculata, large white-blotched leaves; Lee's Silver, silver variegated; Maderiensis Variegata, leaves broadly marked with white; Marmorata, small leaves blotched and marbled with white; Pupurea, small leaves of a bright green changing to bronzy-purple; Rhomboides Obovata, deep green foliage; Rhomboides Variegata, greyish-green leaves, edged with white; and Silver Queen, a good hardy variety.
Ixias.—Plant out of doors from September to December, in a sunny, sheltered position, in light, rich, sandy soil. For indoor cultivation, plant four bulbs in a 5-in. pot in a compost of loam, leaf-mould, and silver sand. Plunge the pot in ashes in a frame or cold pit, and withhold water until the plants appear. When making free growth remove them to the conservatory or greenhouse, placing them near the glass, and give careful attention to the watering. Ixias are also known under the name of African Corn Lilies.
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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.