Flowering shrubs in a greenhouse

In considering suitable plants for the unheated greenhouse, it is better-partly for the sake of easy reference and partly because their cultural treatment is, in most cases, likely to run on the same lines-to group them under specific headings. Flowering shrubs, both hardy and half-hardy, form a most important decorative class, whether from the standpoint of the spacious winter garden, or of the modest conservatory for which plants in 5-in. to 10-in. pots are the most suitable and convenient.

The winter garden is pre-eminently fitted for the permanent planting of some of the countless grand shrubs and rafter plants, such as the Himalayan Rhododendrons, Acacias, Magnolias, and others, which flower naturally during the earliest part of the year, for it is likely enough to stand idle, as far as show purposes are concerned, during the summer months-not for lack of material to make it delightful, but for lack of interest at that season on the part of the owners of it.

For late autumn, a season when the winter garden begins once more to be attractive to the house party, such fine things as the deep-purple-flowered Desmodium penduliflorum and Asparagus umbellatus, which is charming in flower as well as graceful in greenery, may be cited as examples less familiar than they might be.The glass corridor, being often a passage-way from the house to a billiard-room or to the gardens, might give suitable place to such mid-season subjects as, for example, Carpenteria californica, so impatient of fire heat, but so lovely with its great heads of wax-white flowers, though this fine shrub is even now not very well known. The finest specimen I have ever seen was one which had to be planted, for want of a better place at the moment, at the end of a centre-border in a large Rose house, and there it remained till it had to be removed for want of room. It was a wonderful sight when in bloom, with every branch weighed down with lustrous flowers. It is easy enough, however, to keep it within due bounds by judicious pruning, therefore it can be safely recommended.

There are many shrubs of this almost hardy class which refuse to flower in pots, because they require a certain amount of undisturbed, if somewhat restricted, root-room. They are so eminently beautiful that a wide corridor devoted to their culture would be a grand feature. To name a few, there is Fremontia californica, craving shade during the hottest sunshine. Another is the South American Poinciana Gilliesi, graceful in its pinnate foliage, and with golden-hued flowers glorified by their flowing crimson stamens.

There is Abutilon vitifolium, with its grey-green, mealy looking leaves and bunches of exquisite pale mauve (or white) recurved flowers, so distinct in every way from other Abutilons that it would scarcely be recognised as such, but quite intractable for pot culture. Buddleia Colvillei, too, said by Sir Joseph Hooker to be one of the handsomest of Himalayan shrubs, would be suitable for such a position. Its flowers are not rolled up into Orange balls like the B. globosa of our gardens, but hang in clusters of white-throated crimson Pentstemon-like flowers from the ends of the branches. At Kew this fine plant is found to be better fitted for the cold house than for any other method of culture. To these may be added Veronica hulkeana, scarcely hardy in the open, but one of the very best of the New Zealand Veronicas, growing from 3 ft. to 4 ft. high, and giving a mass of its pretty light mauve spikes during late April and May. Another suitable shrub is Weigela hortensis nivea, somewhat unsatisfactory out of doors in most gardens, but worthy to take high rank both for its pretty netted leafage and its bouquets of delicate white flowers.

For winter and early spring flowering, Daphne indica is a useful shrub, content with a back-wall so long as it can be undisturbed at the root and can have room to develop. Cantua buxifolia, a fine Peruvian evergreen, bearing red pendulous flowers at the ends of the branches in early summer, is suitable for clothing a supporting pillar. For this purpose Cestrum (= Habrothamnus) elegans is also invaluable, flowering later in the year. All these, and many others, will thrive in a light, airy glass shelter in a good aspect with a minimum winter tem perature kept just above freezing-point. Most of them are hardy enough to live out of doors in favourable positions, but the severe strain upon their endurance prevents such free-flowering as we may fully expect under glass.

It is impossible to do more than suggest plants likely to succeed under cool treatment, but there are enough of all kinds to suit any and every purpose-the choice must be in accordance with individual tastes and requirements. Three shrubs, to use a comprehensive term, which may be found in flower in many a Devonshire garden in November and December, occur to mind as being well worth growing in less propitious climates for the absolutely cold greenhouse. Young plants of the Box-leafed Myrtle flower at a very small size, and though they will grow into big bushes, are neat and compact at all times.

Beginning to flower in September, they go on continuously, often till Christmas, out of doors, until compelled to give up by stress of weather. Their creamy-white flowers and pearly buds are welcome indeed in a pot at that dull season. About November the homely little Coronilla glauca, brave and bright, begins to set about its winter work, and though it cannot boast the beauty of the less known South European species, C. Emerus, which blooms in the spring, yet its fresh, blue-green leaves and numerous heads of pale yellow flowers for six dull weeks are not to be despised.

To complete the trio, we have the winter-flowering Jasmine (J. nudiflorum), so often cut off by unkind frosts in the midst of its bloom. Grown in a i o-in. pot and fastened not too strictly to a pillar or rafter to allow scope for its pendent branches, it is very effective under glass. It may be used also as a fountain plant for a corner and made to droop over a low trellis-like contrivance, which suits its habit better than being treated as an upright semi-climber. It must be carefully cut back, however, soon after flowering. Laurestinus-of which Viburnum lucidum is the best species-is also very welcome. For this season, too, a curiosity may be grown in the Glastonbury Thorn (Cratmgus monogyna prwcox), for though it might be risky to predict that it would actually open its blossoms on Christmas Eve, according to tradition, yet it is, in truth, a winter-flowering Hawthorn, and might very probably keep up its reputation.

Many kinds of hardy spring-flowering shrubs, such as Hawthorns, Wistaria, Malus floribunda, Prunus, and others, may be educated to flower in pots, year after year, at a very early season. The main secrets are to keep such things in compact form by skilful pruning and to ripen the wood thoroughly in open-air quarters during the summer. Any amateur can try his hand at the cultivation of such shrubs for this purpose, for they are all worthy in their way and not difficult to manage, but they are mainly grown by professional gardeners who have large conservatories to " furnish "-a term not congenial to the true lover of plants.

Prunus japonica fl. pl., however, with double white flowers, is a very charming shrub, adapted for either a small or large greenhouse, for, by frequent transplanting when young to keep it within due limits, it may be flowered in a 6-in. pot. It is naturally of low-growing, bushy habit, and will, after pruning, which should be done as soon as flowering is over, send up many strong shoots from the base during the summer ; these will flower their whole length the following season to a height of from 2 ft. to 3 ft. Being perfectly hardy, flowering shrubs of this latter class take up no room under glass when their purpose is accomplished, but they must receive kindly shelter in good time to bring them into bloom before their normal season.

More than one kind of Cytisus is well adapted for the cold greenhouse, besides the well-known C. racemosus. A beautiful weeping standard may be grown by grafting the Teneriffe broom (C. filipes) upon a laburnum stock, when the drooping branches will be covered with pure white flowers in early spring. This elegant species may also be grown from seed in pyramid form by leading up the main stem and leaving the rest of the branches to themselves.

Several of the shrubby Spireas are popular as pot plants, notably the fine S. Van Houttei, which produces masses of white flowers in early spring under glass. Amongst such smaller-growing shrubs, Deutzia gracilis is an old favourite which we cannot do without, one of the most graceful of any when in flower, blooming well in a 4i-in. pot if desired, and only asking to be cut back immediately after flowering to do better every spring-how it would be prized did we not know it so well ! Hybrid forms of these beautiful shrubs are being raised by M. Lemoine of Nancy, who has taken them in hand. One of these, called D. Kalmixflora from a fancied resemblance, may prove to be an acquisition, as it has flowers of pale pink, edged with a deeper blush.

Hardy Rhododendrons of the very early flowering section deserve the protection of glass, for in two seasons out of three their flowers are apt to be spoilt by snow and inclement weather. One of the first to bloom is the crimson-flowered R. nobleanum. For planting out in large conservatories, this and many still more decorative species may be grown, and in early spring are of course amongst the most splendid of flowering shrubs, but most kinds can also be made amenable to pot culture.

There are two or three early flowering and smaller-growing species, however, which may be noted as being especially valuable for the unheated greenhouse of moderate size. The little Siberian R. dauricum opens its lilac flowers naturally in January and February, therefore it is thankful for protection at that uncertain season. A little larger in growth and later to bloom is R. ciliatum, a fine Himalayan species, with pink buds which expand into white flowers. Between these two comes a useful hybrid form, R. pratcox, with rosy-purple flowers. R. racemosum, which should not be overlooked, is a little-known but very charming dwarf species from China, of quite different character, as its pale pink flowers are produced in spikes. It is astonishing how spreading shrubs like Rhododendrons can flower and flourish in so small a space, but they may often be seen with several fine trusses, quite happy in 5-in. pots. It is better, however, to flower them one year and rest them the next by planting out in a reserve-bed in the open air, though the very slight amount of forcing which they receive in the cold greenhouse does no harm, and if they set their buds well there is no reason why they should not be lifted and potted every season.

Of miscellaneous shrubs coming under no special class there are many which might be suggested : Choisya ternata, though found in most gardens out of doors, may yet be given a place for early flowering under glass. The hardy Abelia rupestris, with its pendulous mauve-white flowers imbedded in red-brown bracts, is charming either in a large basket, or, if planted out in a greenhouse border, will make a handsome autumn-flowering shrub, good enough to join the choicest company. Nerium Oleander, though more tender, is worth growing, especially in some of its less common single white or pale yellow and buff forms. It flowers freely, whether in small pots or in large tubs, but requires protection from actual frost and abundance of water in the growing season.

For late summer, both the Brugmansias are good and not very commonplace half-hardy plants, either for a greenhouse border or for large pots or tubs. In fact, B. sanguinea, with long orange-mouthed tubes, treated as a herbaceous plant, succeeds well out of doors up to a point, but beyond that it will not go. It springs up strongly from the stool in the spring, and in the course of the summer the robust branchlets cover themselves with fine buds, which just begin to open when frost cuts them off. Under glass they are safe, but the same plan of cutting down ruthlessly to the ground-level after blooming, even for pot plants, may be recommended, as it keeps them in better shape. They may, however, be preferred as standards-a form which often comes in very usefully for grouping purposes. The flowers of B. suaveolens are white and trumpet-shaped, and though it is perhaps a trifle more tender, it requires much the same cultural treatment.

Two little-grown plants must close the list, which might be much prolonged. How seldom do we see the Pomegranate (Punica granata) in English gardens, except occasionally on a warm wall in the southern counties, yet there is no shrub more worthy of planting out, if there be a fitting position for it in corridor or glass-covered veranda, or for growing in a tub, as we may see it 'so frequently abroad. The dwarf variety may be seen in Germany flowering well even in 5-in. pots. The brilliant scarlet flowers, whether single or double, are suggestive more than any others of warmth and sunshine, while the shining foliage, red-tinted in the young spring shoots, is always beautiful.

The other plant of very different character is Echium fastuosum, little known and less grown. It may be called a shrub by courtesy, since it is not herbaceous. This remarkable bushy Bugloss was figured in a coloured plate in one of the earlier volumes of The Garden. Falling in love with its portrait, I obtained seed and raised it, and in due time reaped a rich reward for my pains in its magnificent heads, some 8 in. or 9 in. long, of deep gentian-blue flowers. A very similar species, E. callithyrsum, is equally handsome, and only a trifle paler in hue. They come from the Canary Islands, and are by no means hard to grow.

The foliage, as in all Echiums, is rough and shaggy, and the bush grows large and spreading, but any one who has seen its uncommon beauty would consider it worthy of some trouble to grow well. Whether as a fine specimen in a o-in. pot, or planted out in a wide border, few things are more striking in their way than these two species of half-hardy Bugloss for the decoration in April and May of the unheated greenhouse.

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