Half-Hardy and Greenhouse Plants for Cut Flowers

The greenhouse will certainly yield its full quota of material for decorative work, including pot plants, forced shrubs and cut flowers, both from temporary and permanent occupants of the greenhouse.

The range of shrubs which can be used is quite extensive, and one advantage is that entire branches may be cut and used in such a way that very few other flowers are needed for an effective display. Roses and lilac are grown in greenhouses on quite a large scale by specialist nurserymen.

While it is possible to gather sprays of suitable shrubs as they are growing in the garden, it is really more satisfactory to grow shrubs specially for the purpose of forcing. There are several ways of doing this. Individual branches may be cut, or the entire plants lifted and placed in the greenhouse border, or they can be potted up. In the latter case the potting is done in early autumn and the pots plunged in the border until winter, making sure that the soil does not dry out. Plants brought in straight from the open ground without being potted will be found satisfactory, especially on peaty or similar soils, which remain on the roots of the plants when lifted.

half hardy and greenhouse plants

Obviously the cutting of branches from the shrubs and placing them in water in a forcing house is the easiest method, although usually the blooms come just a little smaller.

Where branches are brought indoors, it is best to wait for definite signs of the buds beginning to swell before any cutting is done. As far as possible, and when the weather is reasonably mild, select strong-looking branches in preference to thin, spindly ones, and before standing them in water, split the bottom of the stems about an inch or so. Keep them standing in water and give the upper parts a spraying of clear water night and morning. Slow forcing is best for obtaining a good show, for great heat, which hastens development, will not bring satisfactory results.

Among the less common shrubs which can be forced are the flowering peach, Cydonia japonica, Kerria japonica, Viburnum opulus, and witch hazel. The coloured Japanese maples can also be included. Perhaps the easiest and most useful of all is forsythia, which is naturally very early flowering. The variety known as F. intermedia spectabilis is particularly good, since it produces long, straight shoots on which the large, yellow flowers open quickly, whereas various other types like suspensa, as the name suggests, have rather drooping branches. Furthermore, since forsythia can be propagated easily, it does not matter how heavily the branches are stripped. A good plan is to maintain a regular supply of young plants, so that every winter a plentiful amount of branches will be available.

Other good shrubs to force include deutzia, cornus, diervilla and the malus species.

There are a large number of winter- and spring-flowering bulbs and bulbous plants which can be grown in the greenhouse, and either brought in their bowls to the living-room or have the individual flowers cut and arranged. Narcissi, including trumpet daffodils, tulips, crocuses, hyacinths of many types, Iris reticulata and scillas are among them.

One of the secrets of success is to plant early. The end of August or the first half of September is ideal for the hyacinths and narcissus. Keep them in the cool, preferably outdoors, covered with peat, leaf mould or something similar. Leave them there for a couple of months. When an inch or so of top growth has been made, bring them into dull light, so that the foliage gradually assumes a green colour.

There are many other choice bulbs which may be grown in pots in the greenhouse. These include freesias, ixias, sparmds and the lovely Streptanthera cuprea coccinea, which has salver-shaped, scarlet flowers on 9-in. Stems. All of these do better in loamy soil rather than in bulb-fibre mixtures.

The nerine is another beautiful bulbous plant which should be potted in August or September. Each bulb should be put in a 3- or 3 ½-in. pot or several in a larger receptacle, which should be well crocked. A compost of loam, silver sand, decayed manure and bone meal is ideal. The flowers appear on 12-15-in. Spikes, each with 6—so individual blooms. The leaves usually develop just after the flowers. A few applications of liquid manure will help the bulb to build up the next year’s spike. There are many varieties, and a good colour range, including various shades of red, orange and pink, all with glistening spots like gold dust on the petals.

Requiring similar treatment is the haemanthus or Blood Flower, which has broad, thick leaves and speckled flower-stems 12-18 in. high. The flowers are produced in umbels. H. coccinea is red-marked brown; H. katharinae, brilliant red.

Polianthes tuberosa is usually referred to as the Tuberose. Half- hardy plants, they produce in August and September sweetly scented blooms which are greatly prized for cutting. The narrow leaves often 15 in. or more long, are spotted reddish-brown on the undersides, while the flower-spikes grow 1-3 ft high. Each of these stems is clustered with funnel-shaped, waxy-white flowers. The double forms are the most popular and of these ‘The Pearl’ is very dependable. The bulbs, which are best grown in pots, should be planted firmly in February or March; either one in a 5-in. pot or several in a bigger size, will give good results. Use a moist compost of two parts loam and one part each of leaf mould, silver sand and rotted manure.

Plunge the pots in peat or fibre, where, if possible, there is a bottom heat temperature of about 6o-65° F., watering only as necessary.

Eucharis bulbs are best planted in spring, and may be given the same treatment as nerines, excepting that they prefer a humid atmosphere. Among the species is E. grandiflora or .E. amaTonica, with pure white flowers on 18-24 in. stems. It will often go on flowering for many years in the same receptacle.

Hippeastrums or amaryllis also produce their umbels of flowers on 18:–30-in. Stems, and these, too, require similar treatment. The flowering time extends from December to April. There is a small-growing amaryllis, named gracilis, which is ideal for table decoration, as it is dainty and about half the size of the larger varieties.

There are some orchids which are easy to grow in a greenhouse where a temperature as low as 50° F. can be maintained. Among the basic requirements of these plants are the temperature mentioned, shade in summer and water as needed. The easiest of all for the amateur are the cymbidiums, which are available in a variety of colours. These plants will last for very many years. The flowers remain decorative from 4 to 6 weeks when cut, and even longer when left on the plants. As a rooting medium, use three parts good fibrous loam and one part osmunda fibre, plus a sprinkling of bone meal.

Amolig the more useful but highly decorative plants which should be kept for at least part of each year in the greenhouse, are Azalea indica, begonias in variety, calceolaria, cineraria, gloxinia, kalanchoe, pelargonium, primulas including the ever-blooming obconica, and saintpaulia. These, if kept in the full light, out of draughts and watered intelligently, will remain in good condition for a long time, and may be brought into the living-room when cut flowers are in short supply.

There are a number of half-hardy annuals which are charming when brought into the house in their pots. They are of the simplest culture, and should be sown in pots of sandy compost, the seedlings being well thinned out so that the remaining plants have room to develop sturdily.

Among these are cuphea, dimorphotheca, lobelia, French marigolds, mimulus, petunia, phlox, salpiglossis, schizanthus, stocks and venidium. Sown in the autumn in the greenhouse, they will flower in the early spring.

Greenhouse ferns are important, for they provide the greenery essential for many arrangements. Asparagus sprengeri has needle-like foliage, and so long as it has plenty of moisture during the summer it is not difficult to grow. Asparagus plumosus nanus has thin, feathery foliage and is of special value where ‘trails’ of fern are required. The Maidenhair fern, adiantum, has dainty, divided leaves. It dislikes full sun, drought and a dry atmosphere. The shiny leaves of Asplenium nidus and the dark green or reddish-tinged pteris are both ornamental and suitable for many purposes. All ferns should have a compost of loam, leaf mould or peat, silver sand and decayed manure or bone meal.

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