Trees and Shrubs for English Gardens Part 33

The shrubby Spiraeas may also be used sparingly in a fairly light and open place, though plenty of sun is required as a rule to enable them to flower properly. In addition, though their flowers are insignificant, _Cornus alba_ with its red stems in winter, the s...o...b..rry (_Symphoricarpus racemosus_), which is laden every year with white berries long after the leaves have fallen.

The question about shrubs growing under trees is so frequently asked that the names of those most successful are given, but generally the beauty of the tree is lost when smothered up with evergreens and other shrubs beneath its spreading branches. A tree is a picture in itself, and it is pleasant to see the gra.s.s creep to the branch edge and then cease, leaving a brown earth patch under the canopy of foliage.

Shepherdi Holly, Tree Ivies, and _Berberis stenophylla_, it may be mentioned, are a success under trees.

CHAPTER x.x.xIII

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 gla.s.s, when the flowers will open in profusion; but the shrubs that can be treated in this way make dense, fibrous ma.s.ses 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 gla.s.s are grown in large quant.i.ties 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 gla.s.s 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 gla.s.s. 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 gla.s.s:--

ANDROMEDA (known also as Pieris and Zen.o.bia).--The Andromedas are beautiful shrubs, with lily-of-the-valley-like flowers, and form such a ma.s.s 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. j.a.ponica_, known by its drooping racemes; and _A. speciosa pulverulenta_, which has h.o.a.ry 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 cla.s.ses 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 ma.s.sive cl.u.s.ters of large flowers, varying in colour from pale yellow to deep orange salmon, and innumerable tints and shades. Among the most beautiful are Alphonse Lavalle, 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.

BERBERIS.--Few Berberises are of much account for greenhouse decoration, the best being the orange-flowered _B. Darwinii_ and the rich yellow _B.

stenophylla_. They will not flower well if forced hard, but in a cool house, with very little heat, they are very charming. A successful grower of shrubs under gla.s.s writes: "I knew of some bushes of _B.

stenophylla_ that had been treated in this way for five years, and little trouble was taken with them, yet they were so beautiful as to be much admired every year. After flowering, the weakly growths were cut out and the pots plunged in the open ground. Manure water was occasionally given, and with this treatment they did well."

CARPENTERIA CALIFORNICA.--This evergreen shrub, even in the south of England, is all the better for slight protection, and it is delightful in the almost cold house, the white flowers, reminding one of those of the j.a.panese anemone, appearing about May. It is a very beautiful shrub.

CARYOPTERIS MASTACANTHUS.--This Chinese shrub will bloom freely in light and warm soils, bearing lavender blue flowers in profusion during the autumn; indeed, so late that when cold and wet weather occurs they often fail to expand at all. This difficulty is overcome when the plants are grown in pots and taken into the greenhouse for the flowers to open; it is then very pretty and much liked. After flowering, the shoots generally die back almost to the ground, but break up with renewed vigour in spring.

CEANOTHUS.--Some of the early-flowering Ceanothuses are very valuable; they may be grown in pots, and their flowers are of pleasing blue colouring, which is unusual and therefore welcome. Among the best for this purpose are _C. dentatus_, _C. papillosus_, and _C. veitchia.n.u.s_.

Ceanothuses do not transplant very well, and if intended for flowering in pots should be lifted in the autumn, potted carefully, and wintered in a cool house. They may be kept altogether in pots, giving them much the same attention during summer as _Berberis stenophylla_.

CERCIS SILIQUASTRUM.--This is the Judas tree, and as many know, while the leaves are still absent the stems bear cl.u.s.ters of rosy-purple flowers. It may be lifted and potted in the autumn or kept altogether in pots, but on no account indulge in hard forcing, as it resents this treatment. Well-grown specimens are very pretty when in flower in late March.

CHIONANTHUS.--There are two species of Chionanthus, viz. the North American Fringe tree (_C. virginica_) and its j.a.panese representative _C. retusus_. They resemble each other very much, but the American form is the better of the two. The Fringe trees are very charming when in pots. Prune back hard after flowering and fully expose to the sun to ensure plenty of flower buds. A moist soil is essential.

MEXICAN ORANGE FLOWER (_Choisya ternata_). This will bear its white fragrant flower cl.u.s.ters in March in a greenhouse, and a succession is maintained for some time. It is most satisfactory when grown altogether in pots and plunged outside during the summer.

CLEMATISES.--Of late years the various forms of Clematis have been grown largely under gla.s.s and used for various purposes, not only in the shape of large specimens, but in pots five inches in diameter, the plant being secured to a single stake and carrying several big showy flowers. Two somewhat new continental varieties, Marcel Moser and Nelly Moser, have proved very useful for this treatment. The plants flowered in small pots are those that are propagated in the preceding spring and plunged out of doors during the summer. The Himalayan _C. montana_ that flowers naturally so early in the season readily responds to a little heat, and in the greenhouse in spring it is almost as welcome as the New Zealand _C. indivisa_.

CLETHRA.--Although _C. alnifolia_ does not flower until the autumn it may be had in bloom in spring. Of course, it will not be so early as shrubs that are naturally in beauty in the spring, but in May its white, fragrant flowers should be seen. It requires a cool, moist soil and sunshine, while prune moderately immediately after flowering. Lifted in the autumn soon after the leaves drop, it will succeed well.

CORYLOPSIS SPICATA.--This reminds one of a small Hazel bush, and in early spring before the leaves appear, the drooping cl.u.s.ters of fragrant yellow flowers appear in profusion; simple protection is all that is needed to get flowers quite early in the year, when it is very pretty in the greenhouse. It thrives well kept permanently in pots, or it may be lifted and potted in the autumn. No pruning is necessary.

CYTISUS (Broom).--The various Brooms are much admired, whether in the open ground or under gla.s.s, and for the latter purpose they must be established in pots, for their roots are few, descend deeply, and therefore transplanting is difficult. They will not bear hard forcing, but in a greenhouse may be had in flower by the end of March, or soon after. If kept altogether in pots, cut them hard back after flowering to encourage vigorous shoots for another year. Numerous sorts may be grown in pots, particularly the Spanish Broom (_C. albus_), the common Broom (_C. scoparius_), with the hybrid Andrea.n.u.s and the sulphur-coloured _C.

praec.o.x_.

DEUTZIA.--The pretty _D. gracilis_ is well known as one of the best of all shrubs for early forcing, and the whole family is of great interest as pot plants and out of doors. Of these smaller Deutzias some beautiful hybrids have been raised, particularly _D. Lemoinei_, _D. hybrida venusta_, and _D. kalmaeflora_, all of which may be forced almost, if not quite, as readily as _D. gracilis_. The old and exhausted shoots of these Deutzias should, if the shrubs are kept in pots, be cut away to allow young and vigorous ones to develop. Though they may be had in flower early, they are much appreciated in the greenhouse, even as late as the month of May. The larger growing _D. crenata_, with its numerous varieties, _Candidissima flore-pleno_, _Wellsii_, and _Watererii_ will not bear hard forcing, but can be had in flower with little trouble in April and May. Good, well-ripened bushes may be lifted in the autumn, and if potted and carefully attended to they will flower well the following spring.

DIERVILLA (WEIGELA).--Many of the Bush Honeysuckles, as the Weigelas are called, will flower well in a cool house, but they do not last sufficiently long in bloom to make them of great value for this purpose.

The best is the dark-coloured _Eva Rathke_, which grows naturally into a neat bush; the flowers are of claret colouring.

HEATHS.--_Erica carnea_ is very pretty in a cool house in mid-winter, all that is needed being to lift the clumps from the open ground, pot, and keep watered; while the large-growing Portuguese Heath, _E.

lusitanica_, which flowers naturally in February in the open ground, when the weather is not too severe, well repays gla.s.s protection at that season.

FORSYTHIA.--The Forsythias flower in the open ground by the month of March, and indoors, of course, much earlier. The most effective is _F.

suspensa_, which is naturally a climber, or, at all events, of loose and rambling growth. When needed for pots, tie the princ.i.p.al shoots to a stout stake, and let the smaller branches grow at will, the result being a fountain of yellow flowers. After flowering in the greenhouse, cut back the shoots hard, leaving only an eye or two at the base. These eyes will break up and produce flowering shoots for another year. By this method of treatment the same plants may be kept for many years, provided they are carefully attended to and given occasional doses of liquid manure during the summer.

HYDRANGEA.--The many varieties of the common Hydrangea are all valuable for the greenhouse, particularly _Cyanoclada_, _Mariesii_, _Rosea_, _Stellata_, and Thomas Hogg. To obtain small flowering plants the cuttings are struck in spring or early summer, grown on freely for a time, and well ripened by full exposure to air and sunshine before autumn. Plants grown in this way readily respond to a little heat in the spring. Larger specimens, too, may be brought on in the same way. The j.a.panese _H. paniculata grandiflora_ needs quite different treatment, the plants being generally grown in the open ground, from whence they are lifted and potted in the autumn. Before potting prune the long, wand-like shoots back hard, leaving only about two eyes at the base. By so doing the plants are kept dwarfer, and the flower heads are larger than if no pruning were done. By some the Hydrangea is grown as a standard, and is very effective when in beauty.

ITEA VIRGINICA.--A neat little bush, about a yard high, with dense spikes of white flowers. It needs a sunny spot in a cool and moist soil, and under these conditions will flower freely if carefully lifted in the autumn and potted. It must not suffer from dryness afterwards. No pruning is necessary.

JAMESIA AMERICANA.--A pretty little white-flowered shrub from the Rocky Mountains. It will bloom freely under gla.s.s, but must not be forced hard; it may be treated in the same way as the Itea.

KALMIA.--All the Kalmias are good pot shrubs. The roots are dense and wig-like, reminding one of those of a Rhododendron, so that well-budded plants can be lifted in the autumn and potted without risk. They must be brought on gradually in a cool house, and never suffer from want of water. The earliest to bloom is _K. glauca_, followed by _K.

angustifolia_, while later on there is the largest and best-known species, _K. latifolia_, the Mountain Laurel of the United States, which has pretty pink flower cl.u.s.ters.

KERRIA j.a.pONICA (the Jews' Mallow).--The single Kerria is a twiggy bush, with bright yellow flowers, like those of a single Rose, and expand quickly in spring. The major form of the double Kerria is much better than the ordinary one; they can be potted in autumn or grown permanently in pots. After the flowering season is over the double variety can be spurred back hard to prevent a tall weakly growth.

LABURNUM.--This has long been used for the greenhouse, and very effective it is when well flowered. It is as a rule most successful when in large pots, in the shape of a standard. Prune back moderately after flowering.

LONICERA (Honeysuckle).--As _L. fragrantissima_ flowers naturally out of doors soon after Christmas when the weather is mild, it is evident that no forcing is needed to obtain it at that season, and in a cool greenhouse the little white flowers are remarkable for their delicious perfume. As spring advances the early Dutch may be flowered under gla.s.s, while the scarlet Honeysuckle (_L. sempervirens minor_) is a delightful greenhouse plant, not used so much as it deserves to be for rafters and similar purposes in the greenhouse.

LOROPETALUM CHINENSE.--This Chinese shrub, with its long, pure white, strap-shaped petals, bears much resemblance to the Chionanthus, and is quite as desirable for flowering in pots. It may be either lifted in the autumn or grown altogether in pots.

MAGNOLIA.--The Magnolias can be grown under gla.s.s. If allowed to come gradually into bloom in a greenhouse the large flowers will open freely.

As a rule they transplant badly, and for that reason, at least the choicer ones, are kept in pots for convenience in removal. From this it will be understood that as a rule it is more satisfactory to keep them permanently in pots than to lift them in the autumn. _M. purpurea_ can be grown more easily than any of the others in this form. When grown in pots for the greenhouse, if they get too large for that structure they may be planted permanently out of doors and their place taken by smaller plants. Of those particularly valuable for this treatment are the little _M. stellata_, a charming shrub; _M. Lenne_, which has ma.s.sive chalice-like flowers, rosy-purple outside; _M. conspicua_, _M.

soulangeana_, and _M. purpurea_ among the early Magnolias; and of those that flower later the j.a.panese _M. parviflora_ and _M. Watsoni_ do well in pots.

OLEARIA.--The best known of the Daisy trees of New Zealand is _O.

Haastii_, which flowers freely in August. One at least of the species blooms naturally much earlier, namely _O. stellulata_ (_O. gunniana_), and very pretty it is under cover and with its daisy-like blossom. To be seen at their best, grow them altogether in pots and give the protection of a cool house in winter.

TREE PaeONIES.--The magnificent varieties of the Tree Paeony that have appeared in recent years have led to a great increase in their culture.

Though hardy in many places, their young leaves and flowers are frequently injured by late frosts, hence they are often flowered under gla.s.s. In this way they make a gorgeous display in the greenhouse, which is sufficiently warm for them in all stages. If forcing is attempted they are quickly spoilt. They must be potted in good loamy soil, and are most satisfactory when grown altogether in pots, as many of the long fleshy roots will be injured in digging up established plants.

PERNETTYA MUCRONATA.--Though grown chiefly for its ornamental berries, neat little bushes are very pleasing in the greenhouse when thickly studded with little white lily-of-the-valley-like flowers, so pretty against the dark-green colouring of the leaves. The treatment recommended for Kalmias is suitable for the Pernettyas. The fruits are very charming.