Forcing. Asparagus can, if properly treated, be obtained from December onwards; and at Christmas time the produce is very valuable; but, in order to obtain it at this season, it will be necessary to resort to forcing. Prepare some beds to secure a lasting heat, and on these place about 3in. of ordinary garden soil, not very stiff. Then take the roots, and place them crown upwards, and moderately close together, shaking the soil well amongst the roots, and covering about a couple of inches deep. Water well, to settle the whole, and put on the lights, allowing a little ventilation, to let out any steam which may arise. Unless the weather be very cold indeed, give a little air at all times, and only cover the lights in actual frost. From time to time, apply fresh linings of hot manure, and in cold rains, or wind, cover the outsides of the frames with old sacks, or other things which will keep in the heat. A regular and steady temperature of 60deg. will force this plant with better results than a higher one. Houses that are fitted with hot-water pipes to give bottom heat can be used equally as well as manure beds, and so long as the soil is kept moist, the heat thus obtained is as good as any for the purpose, and much less trouble than fermenting materials. To keep up a regular supply, a succession of beds will be necessary. Asparagus can be forced, or rather forwarded, in pots or boxes, in a warm greenhouse or vinery, and, of course, when the plants are done with, they can be cast away. We give an illustration (Fig. 160) of a bearing crown fit for gentle forcing; but, of course, it must not be left so bare of earth as appears here, which is done for the purpose of clearness.
Varieties. Connover's Colossal, and Giant, are the most esteemed. Strains are frequently largely advertised as improvements on the sorts above-mentioned, and the charges are higher accordingly. The difference may be generally attributed to the culture the plants receive more than to an improved variety. When saving seed for home sowing, they should be taken from the strongest growths, or deterioration will ensue.
A. æthiopicus ternifolius (ternate). fl. white, in shortly-stalked racemes, very profuse. August. l., false ones in threes, flattened, narrow, linear; prickles solitary, reversed; branches angular. h. 30ft. South Africa, 1872. A greenhouse evergreen.
A. Broussoneti (Broussonet's).* fl. very small, succeeded by small red berries. May. l., lower ones solitary, the others ternate, 1in. long, needle-shaped, persistent, distant, glaucescent; stipules with reflected spines at the base. Summer. Stem tapering, streaked, shrubby. h. 10ft. Canary Islands, 1822. A very pretty hardy climber.
A. Cooperi (Cooper's). fl. axillary, one to three, from the same nodes as the false leaves; perianth cream-coloured, one line long. April and May. l. minute, deltoid, scariose, reddish-brown; false leaves six to fifteen to a node, subulate, moderately firm, ¼in. to ⅜in. long, spreading or ascending. h. 10ft. to 12ft. Africa, 1862. A greenhouse climber, with a shrubby terete main stem, 1½in. to 2in. thick at the base, sending out crowds of spreading branches, which bear abundant slender, firm, alternate branchlets; nodes of branches and branchlets, furnished with distinct red-brown, subulate prickles, those of the main stems ¼in. long, deflexed, but not curved.
A. decumbens (decumbent).* Stem unarmed, decumbent, much branched; branches wavy; leaves setaceous, in threes. Cape of Good Hope, 1792. A greenhouse evergreen herbaceous perennial.
A. falcatus (hooked-leaved). l. fascicled, linear, falcate; branches round; prickles solitary, recurved; peduncles one-flowered, clustered. h. 3ft. India, 1792. A greenhouse evergreen perennial.
A. officinalis (officinal). Common Asparagus. fl. greenish-white, drooping. August. l. setaceous, fasciculate, flexible, unarmed. Stem herbaceous, mostly erect, rounded, very much branched. h. 1ft. Said to grow on "Asparagus Island," Kynance Cove, Lizard, but we have never found it there, and it has probably long since been exterminated.
A. plumosus (plumed).* fl. white, small, produced from the tips of the branchlets. Spring. l., true ones in the form of minute deltoid scales, with an acute ultimately reflexed point; the false ones are grouped in tufts, each being ⅛in. to ¼in. long, bristle-shaped, and finely pointed. South Africa, 1876. An elegant evergreen climber, with smooth stems and numerous spreading branches. It forms an excellent plant when trained in pots, and is invaluable for cutting.
A. p. nanus (dwarf).* A very elegant dwarf variety of above. Stems tufted, slender, and gracefully arching. South Africa, 1880. For bouquets, the cut sprays of both type and variety have the advantage of much greater persistency than any fern, retaining their freshness in water from three to four weeks. See Fig. 161, for which we are indebted to Messrs. Veitch and Sons.
A. racemosus (racemose). fl. greenish-white, in many-flowered axillary racemes. May. l. bundled, linear-subulate, falcate; branches striated; prickles solitary. h. 3ft. India, 1808. Greenhouse evergreen shrub.
FIG. 161. ASPARAGUS PLUMOSUS NANUS.
A. ramosissimus (very branching). fl. solitary, at the tips of the branchlets; pedicels hardly perpendicular, one and a-half to two lines long; cream coloured. June. l. obscurely spurred at the base; false leaves three to eight-nate, flattened; linear-falcate acute, ¼in. to ⅜in. long, spreading. South Africa, 1862. A wide climbing, copiously branched, slender greenhouse shrub, with very numerous spreading or ascending branches and branchlets.
A. scandens (climbing).* fl. whitish, axillary on the ultimate branchlets, succeeded by round orange-coloured berries. The annual, much-branched, unarmed stems bear, usually in threes, numerous small linear-pointed leaves, which on the ultimate branches spread nearly in one plane. Cape of Good Hope, 1795. An elegant climbing greenhouse perennial.
A. virgatus (twiggy).* A remarkably elegant feathery looking plant, of shrubby habit. The stems, which issue from the crown of the stout fleshy roots, are of a dark green colour, and bear at the upper end a corymbose head of erect branches, of which the lowest is the youngest or most recently developed. These branches are again twice branched, the ultimate branchlets being furnished with needle-shaped false leaves, ½in. long, which usually grow in threes. South Africa, 1862.
ASPARAGUS BEETLE (Crioceris asparagi), or "Cross-bearer." This beautiful little insect is blue-black or greenish; the thorax is red with two black spots, and the wing-cases are yellow, with a black cross on them; the legs and antennæ are black. The short grey larva is flat underneath, arched on the back, and covered with hairs. The sides are of an olive hue, and the little legs and head are black. It ejects a drop of blackish fluid from the mouth when touched. When full grown, which takes about a fortnight, the larva measures about two lines in length; the average length of the perfect Beetle is about three lines. Although this insect does not actually destroy the plants, it inflicts much damage on the foliage, and checks the growth of the stems after they have attained some size, in consequence of which the foliage becomes much less in the next season. The eggs are fixed to the shoots, and are small, dark, pointed bodies. The larvæ do the harm, as they feed on the bark and tender portions of the plants. The mature Beetles should be picked off by hand, and, by commencing early enough in the season, their numbers will be greatly reduced. Syringing the plants with water, heated to a temperature that will not injure the plants, is found a useful method for removing the grubs.
White Hellebore. Freshly-ground White Hellebore, sprinkled over the foliage while it is damp, and repeating the operation at intervals of about eight days for a season, will generally effect a riddance; but the following will usually be found better in such cases. Neither must be applied until after cutting ceases, as they are very poisonous.
Paris Green. This, mixed and used as for Cherry Fly (see [Black Fly]), will generally got rid of the Beetle, if applied about thrice each season for two years. It should, however, only be used in severe cases.
Soot, applied in the same manner as White Hellebore, and in liberal quantities, will, in a season or two, clear the beds. If a bushel of salt be mixed with each twenty bushels of soot, it will enhance the effect.