Trees and Shrubs for English Gardens

by E. T. Cook

HARDY SHRUBS IN THE GREENHOUSE

Hardy shrubs have for many years brought colour and fragrance to the greenhouse in the depth of winter, but we think it is only within recent years that they have been used in such beautiful variety as at the present time. The great show of the Royal Horticultural Society in the Temple Gardens, and many of the delightful fortnightly displays, have been responsible for much of their present popularity, and the picture of a group of Plums, Peaches, Almonds, Wistarias, and many other things in flower long before their natural season, is refreshingly pleasant when perhaps winter still lingers.

So many shrub families may be used for gently forcing into bloom before their time that it is impossible to lay down hard and fast rules with regard to culture. In some cases the plants may be lifted in the autumn, then potted, and placed out of doors until they are removed under glass, when the flowers will open in profusion; but the shrubs that can be treated in this way make dense, fibrous masses of roots, therefore scarcely feel the check of removal. Some shrubs, however, transplant so badly that it is needful to grow them entirely in pots.

Shrubs for flowering under glass are grown in large quantities by the English nurserymen, and very beautiful they are when in flower, bringing the beauty of early summer to the opening days of spring. Many grow their plants in pots, the general method being what may be regarded as a modification of pot culture and planting out, that is to say, although the plants are potted, and that in fairly large pots, they are plunged in the open ground over the rim of the pot, and in a position fully exposed to air and sunshine. Although a few roots may be pushed out over the rim, and also through the hole in the bottom, this treatment has the effect of keeping them far more compact than would otherwise be the case, hence the check of removal is not so great as if they have unlimited room. This partial confinement of the roots checks a too luxuriant growth and promotes flower-bud formation.

In the cultivation of shrubs for this purpose, whether they are confined in pots or planted out, choose an open, well-exposed position, carefully guarding against overcrowding, as this tends to leaves instead of flowers. With the same object, they must be kept free from weeds, and not allowed to suffer from drought.

With few exceptions, the best time to lift and pot the plants is as soon as possible after the leaves have fallen in the autumn. When done at this time the young roots recover from the check, and get hold of the new soil before the flowering season. The pots must be plunged in leaves, spent hops, or cocoa-nut refuse, to keep them in an even condition of moisture, and after potting never allow the roots to suffer through dryness. Whether intended for very early flowering or later on, the plants should at first only be taken into a comparatively cool structure, and, if necessary, brought to a greater heat by degrees, and the lower the temperature, say about 55 degrees, the more beautiful the flower colouring; while, when they are only required in bloom a little before the natural season, mere protection from sharp frosts and keen winds is alone essential. The advantage of early potting is shown conspicuously in the case of Azaleas. The flowers produced by plants that have been potted soon after the leaves have fallen will remain twice as long in beauty as on those not potted until after Christmas.

In a general way, plants that have been forced hard to get them into flower early cannot be depended upon to bloom satisfactorily the following season, no matter how carefully they may have been treated, but those merely brought into bloom a little in advance of those out of doors will undergo the same ordeal next year. Too often, when the flowers are over, the shrubs are put away in some corner and forgotten, and the result is injured leaves and general upset. Shrubs so treated cannot perform their duties in the year following. Shrubs that have finished flowering under glass before the time of frost and cold winds is past should be at first carefully protected and gradually hardened off. Where a cool house is not available, a frame in a sheltered position is suitable, but even then avoid overcrowding. By the middle of May this precaution is not so necessary, although keen frosts and winds are experienced that would injure foliage developed under glass. Where potting is necessary, that is, in the case of plants grown permanently in this way, it should be done before they are placed in their summer quarters. For this the pots should, if possible, be placed on a firm bed of ashes and plunged in some moisture-holding material, such as partially decayed leaves, spent hops, or cocoa-nut fibre refuse. Occasional doses of liquid manure during the growing season are beneficial, particularly in the case of shrubs that have not been re-potted, as the limited amount of nourishment in the soil will have gone by that time.

The following is a list of the best shrubs for flowering under glass:—

Andromeda (known also as Pieris and Zenobia).—The Andromedas are beautiful shrubs, with lily-of-the-valley-like flowers, and form such a mass of fibrous roots that they can be lifted from the open ground and potted without receiving any check. When placed in a cool house they flower profusely. The best are A. floribunda, which has crowded, somewhat stiff spikes; A. japonica, known by its drooping racemes; and A. speciosa pulverulenta, which has hoary leaves and waxy-white bells. The first two may be had in flower by the end of March, but the other is later.

Azalea.—One of the useful classes of shrubs that we have for this purpose, quite as valuable for hard forcing as for flowering later in spring. Although the formation of the roots is dense and wig-like, they are, as already stated, all the better for being potted early, while they may be permanently grown in pots in a satisfactory way. The Chinese A. sinensis, or mollis, as it is more popularly called, is of close and compact growth, with massive clusters of large flowers, varying in colour from pale yellow to deep orange salmon, and innumerable tints and shades. Among the most beautiful are Alphonse Lavallé, bright orange; Anthony Koster, deep yellow; Dr. Pasteur, orange red; General Vetten, orange; Hugo Koster, salmon red; and J. J. de Vink, soft rose. The varieties grouped under the head of Ghent Azaleas are very beautiful, and quite as suitable for forcing as the preceding. The individual flowers are smaller, but they are borne in such profusion that the whole plant is a mound of blossom. The colour varies from white, through all shades of yellow, orange, pink, rose, and scarlet, to bright crimson, so that plenty of variety is available, and some forms have double flowers. These are not so showy as the single Azaleas. Azaleas, when planted out, require a certain amount of peat or other vegetable matter in the soil, and this is even more important when they are grown in pots. A suitable compost consists of equal parts of loam, leaf-mould, and peat, with half a part of sand. Very little pruning is needful, and this to consist only of shortening an occasional shoot that threatens to upset the balance of the plant, and thinning wiry and exhausted growths; but remove seed pods directly the flowers are over, as these are a drain upon the plant's strength.