Plants That Grow Well In A Greenhouse

Now for the cultivation of just a few of the most popular of green house plants—plants with which the novice Would do well to make his first experiments in glass gardening, since they are profitable comparatively easy, and on account of their popularity they are not too expensive.

Begonias. Horticulturally, begonias are of two groups, the tuberous-rooted and the fibrous-rooted kinds. Among the fibrous rooted are several hybrids between the two groups.

Tuberous-rooted begonias include some dwarf bedding begonias and those grown in pots for bedding or for greenhouse decoration They can be grown from seed sown in February in a temperature of 65 degrees or from leaf cuttings. Tubers can be stored dry fro season to season, and restarted into growth in trays of damp fibre in slight heat in February. If for summer bedding, the plants are hardened off during May and planted out about the first week I June, in moist, leafy soil in a sunny position.

Fibrous-rooted begonias are also grown for bedding and for greenhouse decoration They are mostly rather tender, and more suitable for greenhouse culture than for the open. Increase is by means of cuttings. Some of this section are winter flowering, an many are grown as much for the beauty of their foliage as for their flowers. After flowering, they are kept in a lowered temperature and with a minimum of water for some weeks, then restarted, an cuttings are taken from the fresh basal shoots.

Carnations. These are all-the-year-round flowering plants; that is to say, if you can give them a little heat in winter, you can hay blooms from some of your plants all the season. Light is even more important than heat, but since the average amateur cannot artificial sunlight, this need not concern us, except that it is important to have clean glass during the winter months.

For glass culture, perpetual carnations are potted up, as layers, in autumn, in good clean compost containing sufficient sand and coarse grit to keep it open. Sterilized soil is preferable.

The young plants are grown on in cool conditions and repotted in spring into 6 and finally into 8 in. pots. They can stand in the open during summer, and when about 6 in. high the tops should pinched out. They are brought under glass towards the end of the summer, and flower well for some time.

By layering fresh plants (or taking cuttings) in February and again in late summer, and by keeping back some plants in the open long as possible, pinching them back rather late in the summer, an then bringing the pots under glass in September, flowers are encouraged through the winter months.

Malmaison carnations and border carnations are also increased b layering in July or August, the border carnations (hardy) bei *hen wintered in the open or a cold frame for spring planting the borders. Malmaison carnations, however, are grown all the year round in the greenhouse.

Perpetual carnations can be pinched back twice if bushier plants are desired, or if it is desired to keep them back, but Malmaison carnations should not be pinched more than once.

Chrysanthemum. The cultivation of late-flowering chrysanthemums can only be carried out where glasshouse protection is available, since the blooms come so late in the season that they would otherwise be ruined by frost. Very little artificial heat is needed, however, and the cultivation of Japanese late-flowering chrysanthemums is therefore an ideal branch of horticulture for the owner of the little, cool greenhouse.

These plants can be raised from seed sown in February, but the better named varieties are grown from cuttings. The cuttings are taken from the old stools, as soon as suitable new growths have been made, i.e., not too long after the flowers cease for the season. When the flowers fade, the flowering stems are cut down, and the pots kept moist to encourage the fresh shoots. These are taken off generally in February, though some may be taken earlier, and some later. They are rooted in sandy soil in a propagating frame or pit, and as soon as new growth commences on the cuttings, they are potted up singly into small thumb pots.

From then onwards, the plants are moved gradually to larger pots, as the roots fill the soil of the smaller sizes, until they finally reach 8 or 9 in. pots, in which they will flower. Two-thirds loam, rather lumpy, particularly at the bottom of the large pots, with the remainder made up of leaf-mould, or old stable manure, sharp sand, crushed mortar, bonemeal and soot make an excellent compost, but it is best to mix it well at the beginning of the season, and use from the stock gradually.

Staking and pinching and disbudding are three important features in chrysanthemum culture. While pots stand in the open, i.e., from about April or May until September they must be protected from high winds, and a good way to do this is to stand the pots in a straight row, stretch wires along the row above the pots, and tie the stakes (three in a pot) to the wires. Winds will do no damage to plants staked in this way.

Pinching, i.e., the removal of the centre-growing tip, is recommended in all chrysanthemum culture. The flowers on the side branches that result after such pinching are better in form, and more gracefully placed than the central flower bud which might open if the pinching were neglected.

After pinching, disbudding may be needed to make a bushy plant. This means that one bud of those that develop on each stem is selected to remain and open, while all other buds are rubbed away as soon as they form. The question of which bud to retain is one that every grower will find by experience, though most nurserymen who specialize in chrysanthemum culture give detailed instructions on this point in their catalogues.

Convallaria. This, the popular lily of the valley, can be grown very easily indeed in the warm greenhouse. If early flowers are required, the specially prepared crowns for forcing should be bought about October or November, and potted up in ordinary potting compost. An inverted flower pot with a little coconut fibre inside it, set over each pot of lily crowns, keeps the soil and young growth moist. When the top growth is 2 in. high, the pot can be taken off, and the lily flowers will quickly open.

Fig. The Fig is one of the fruits often grown under glass. Normally there are three crops of Fig one borne on young stems of the previous summer’s growth, one borne on new stems of the same season’s growth, and a third batch of fruits that grow on the side growths of the current season’s stems. This third batch of fruits is useless and should not be allowed to remain.

Figs fruit best when their roots are somewhat confined, and culture in a tub in the greenhouse is very satisfactory. Soil should consist of turf, fibrous loam, and crushed mortar over good drainage material. Plant in February and keep up the water supply while the plant is actively growing. Keep unnecessary wood cut out, and pinch back growths when the fruit has set, to leave only five or six leaves. Syringe freely and frequently until the fruit begins to ripen.

Grapes. The grape vine is a very suitable climber for the amateur’s greenhouse. It needs only a small amount of heat, but needs a maximum of care in pruning or feeding to make it a profitable investment. The vine can be planted in a border dug inside the greenhouse or, if more convenient, a vine can be planted outside the house, and brought inside through a speciaf opening near the soil level.

Hard pruning for the first few years is desirable to form the vine into a skeleton of the desired shape. This will depend on the shape of the house, and the inclinations of the owner. A single vine is often allowed to make two main stems which are trained horizontally in opposite directions. From these, lateral stems are allowed to develop, on the upper sides only, so that they ascend to the roof of the house. During the period of forming the vine, unwanted buds are rubbed off immediately they appear.

Pruning is done annually at two seasons. In summer the side growths bearing the trusses of flowers are pinched back when fruits have formed, leaving only about two leaves beyond the fruits. In winter the side stems are shortened to leave one leaf bud only, at the base, pointing outwards.

On indoor grapes, some thinning of the bunches is desirable, and this is done by degrees, with sharp scissors, fruits being cut out here and there to allow the remainder to grow to full size.

Fertilization is important, and the use of a camel-hair brush, passed from flower truss to flower truss on a warm dry day, is advisable.

Heliotrope. The old-fashioned cherry pie, or heliotrope, should be more widely grown as a greenhouse shrub. In the beds it is used as a summer plant only, but under glass it will grow on from year to year and become quite a tall shrub. Its perfume alone ‘justifies its inclusion. No special treatment is required, but if desired the plants can be hard pruned each spring.

Lilies under glass need very little special care. Deep pots should be used for them, with adequate drainage crocks, and good potting compost containing leaf-mould and sharp sand. Particularly in the case of stem rooting lilies, plenty of room should be left at potting time for further top dressings of fresh compost to be given as the plants grow.

Melons. Seed is sown in January, one seed to a pot of light soil. Press each seed 4 in. into the soil, on edge. Further seeds can be sown at any time up to the end of June. Pot on into a 5 in. pot, in good loam with well-decayed manure. Pot firmly, with the soil surface sloping down towards the rim of the pot. Plant out into a prepared bed of two parts good loam, one part well-decayed manure (old mushroom beds do well) and a potful of bonemeal to each barrowload of compost. Grow on a main stem, with five or six side stems. Stop the side stems at every joint until a number of laterals are formed, each one having a female bloom. Stop the shoots one leaf beyond the flower. Melons need brisk heat at sowing time.

Fertilize the flowers at midday by carrying the pollen-laden centre of the male flower to the female. During this time do not spray

frequently, but keep.the atmosphere rather drier than usual. When the fruits are forming, thin out unwanted shoots, spray frequently, give plenty of water and liquid manure, and provide nets or other supports for the fruits.

Orchids. Because of the fact that these plants need special atmospheric conditions, they are not recommended for culture in the amateur’s single greenhouse. There are a few that will succeed in the mixed house collection, and of these I should recommend Cypripedium insigne, Masdevallia Veitchii and Odontoglossum crispum —all fairly easy to manage and well worth the trouble. If the amateur remembers that sudden changes of temperature are objectionable, that a slight rest (not a complete drying off) after the growing season and plenty of water when fresh growth begins are all needed, he will find the cultivation of these plants simple enough. Repotting, when necessary, should be done just as new growth begins for the season, and the compost used should be fibrous loam, chopped fibre, and sphagnum moss with plenty of drainage material.

Palms and Ferns. These and other foliage plants are useful in the little greenhouse as in larger houses. Compost for these is merely ordinary potting compost with the addition of peat or leaf-mould. A very little fertilizer of a general character added to the water used during the active growing season is usually sufficient to keep these plants in good condition. Repotting, when necessary, should be done in early spring. A small pellet of sulphate of iron on the surface of the soil will prevent yellowing of the leaves on palms.

Peaches, Nectarines and Apricots. These are frequently grown under glass, for the sake of earlier and more certain fruits. They need a sunny, well-ventilated house, and a temperature of 45 degrees in very early spring to encourage the opening of the flowers. After the fruit is set, syringing should be done daily until the fruit begins to turn colour. Pruning is carried out in the same way as for outdoor grown fruits.

Richardia. The arum lily. Pot in compost of half fibrous loam, one quarter sand and one quarter leaf-mould, and keep in a cold frame through the summer. Do not allow the pots ever to become dry, and when the flowers are developing give plenty of water and weak liquid manure. From September onwards they should be brought into the greenhouse with a temperature of 40 degrees (minimum). They should flower at Eastertime.

Salvia. There are a great many salvias, and several of them (generally used for bedding) make good pot plants for greenhouse decorations. None is better than the blue salvia patens. This should be treated in the same way as dahlias, re-started into growth in the spring and stored dry during the winter.

Salvia splendens, a scarlet salvia, is grown from seed in the manner of any half-hardy annual, and makes a fine display of colour in the greenhouse, if grown on in 5 in. pots instead of planted out in June.

Violets. As subjects for frame culture, violets are ideal. They can be grown from single crowns, by dividing the plants immediately after they have flowered. These crowns can be planted out 10 in. apart on a prepared bed, and left outside all summer. In September they can be potted up and set into a frame, with old tan packed round and under the pots. Or, if preferable, a portable frame can be set over them without lifting the plants. The lights should be kept in position over the frames through the winter, but ventilation can be given so long as the temperature is above freezing point. Mats may be needed in severe weather during the night.

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