'In curious order set The fairest flowers of Eastern land.'
THE Tuberous Begonia was, once upon a time, a monotonous flower, as seen in England. Probably nine gardeners out of every ten are now unaware of the marvellous beauty to which it has attained, or the amazing diversity of colour and shape that it can offer.
Some persons regard it as just a bedding plant. Well, it may be used in the beds during summer, for the sake of the garden - never for its own sake. Why expose petals of wax - wax with a peach-bloom on it - to hail, and wind, and sun heat after rain? Does it not stand to reason that if one wants perfect flowers of this plant one must cause them to open under shelter? And glass is the ideal protector. I am not sure that Begonia growing is not the easiest hobby the amateur greenhouse gardener can take up.
Obtain tubers from a Begonia specialist, if possible; if not, from a reliable firm of bulb merchants. If there is a glass-house temperature of from 6o° to 70o start culture in January; otherwise wait till March.
The first procedure is to induce the tubers to sprout. Press them lightly into damp compost, or coco-nut-fibre refuse, in a shallow pan or box, leaving the top of the crowns visible; place in a genial spot, but do not let sunshine reach the tubers. Water sparingly. Very soon growth will begin; tiny irregular markings of pink, red, green, on the tubers will turn out to be the commencements of leaves. When growth is 2 inches high lift each tuber very tenderly, soon after watering them, so that compost does not fall away from the roots. Four-inch pots should be ready filled to contain one each, even the little hole to drop each into should be there. Use a compost of two parts turfy loam, one part leaf-mould, one part thoroughly decayed horse-manure, with about a quarter of a part of coarse silver sand.
Growth, in the hot greenhouse, will be rapid, and, as soon as the roots reach the sides of the pots, the plants should be shifted on into the next-size-larger pots, never into any bigger. That is the routine for culture - shift on gradually. I generally use four-and-a-half inch pots after the four-inch, then five-inch, then six-inch, for flowering in. But a few big specimens can be flowered very handsomely in a seven-inch pot, or three Begonias may be grouped in a nine- or ten-inch.
Full sunshine will be damaging, and lack of water will be ruining. Of course, soil may go sour if kept overcharged with water. If the atmosphere of the house is too dry it is prudent to spray the Begonias, after sundown, using a small scent-spray; but it is easy to prevent over-dryness in air of any glass-house, since a few uncovered pans or buckets of water stood there will cause heat on the roof to draw up moisture, and that will descend again in drops. Needless to say, flowers, and many kinds of handsome leaves, should be out of the way of any drip.
Though Begonias require much air, special precautions should be taken against cold winds and rough winds, or concentrated draughts; the two last-mentioned evils will shake off the blooms, possibly even the buds, and blow leaves against petals sufficiently to bruise them.
Directly the plants are nearing full growth, or even rather before that stage, they may be encouraged by a weak solution of mixed farmyard manure and of sheep-manure alternately, every fourth day. Sticks and ties should be provided early, because the stems are exceedingly brittle.
It is a mistake to let pot Begonias flower themselves 'out,' I believe: when the blooms have been very handsome a crop of smaller ones may follow, but before long the stamina of the plant suffers; and it must be remembered that tubers are valuable. So, instead of greedily persuading plants to yield bloom after bloom, lessen the water supply, gradually withhold water, and allow the soil to become quite dry. Range the pots on their sides on a high sunny shelf until November, when remove the tubers and place them in dry coco-nut-fibre refuse until they are required for potting again, from January to March.
Tuberous Begonias can be grown well from seed, which must be sown on the damped level surface of compost, in shallow pans, in a temperature of 65o in March; or in a lower temperature if pans can be plunged in a hot-bed. However, seedlings will need 55° when growing on, after being potted. Cover each pan with a sheet of glass, and lay brown paper over the glass, until growth appears, when remove the paper, and wipe and reverse the glass twice a day. Directly the seedlings are a quarter-inch high the glass should be supported on bits of cork so that it stands a trifle above the pan's edge, and a little air is admitted. Gradually raise the glass sheet higher, and then remove it; but beware of allowing sunshine to play on the seedlings.
It is a convenient plan to stand four big cotton-reels outside a pan, and lay the glass sheet upon these.
Most of the charming types of Begonias are obtainable from seed. Tubers of separate coloured varieties can be ordered, or the chances taken of a mixture.