The tuberous-rooted section comes from the cooler parts of South America and is very distinct from the shrubby sorts. They are entirely deciduous. They make fine bedding plants as well as splendid pot plants for the greenhouse from June to October. As a window plant they are not to be commended, soon dropping their showy petals. It is as a bedding plant they are chiefly valuable. When I say that I have seen in our city large beds of these begonias surpassing in brilliancy of color, and certainly in variety, any bed of geraniums, it must be recognized as a good bedding plant. The cooler the summer the better they do and in localities where the heat is excessive they may not be desirable.
They are easily raised from seed, which should be sown in January or February. The seed of all begonias is very minute and no covering of the seed with soil can be done. Water the soil in the pan well before sowing and then sow on the surface, covering the pan with a pane of glass till the seed germinates. When large enough to handle prick out the seedlings into flats, keeping them on a light shelf, and when grown so as to be nearly touching put into 2-inch pots and grow on. The seedlings hardly make bedding plants the first year, but can be planted on a good piece of soil and will make fine bulbs for the succeeding year. When the tops are killed, before there is any danger of frost at the root they should be lifted, dried in a sunny place and then stored away in some perfectly dry material (dry sand will do), till it is time to start them again in the spring.
Group of Begonia Semperflorens Gigantea Rosea.
A House of Tuberous Begonias Grown for Exhibition in England.
For the busy florist it is, however, advisable to leave the raising of seedlings to the specialist who grows them by the hundred thousand and be content with buying the dormant roots each year. It is cheaper, for the price is now lower than you could afford to raise them for. The double varieties are about twice as costly as the single ones and are no more effective as bedding plants.
The middle of March is early enough to start them, which is best done by putting the tubers into flats of sandy soil. Half leaf-mold and half sand is a good mixture and two inches of it in the flats is enough. Place the tubers just below the surface and an inch apart. We place the flats above the hot-water pipes and remove to the bench as soon as the young leaves are showing. By middle of April the leaves will be crowding and every tuber will have made a mass of roots. There is now only one place for the plants and that is a mild hotbed. No great heat is needed. We pot into 4-inch and plunge in the bed. By middle of May the glass can be removed except on cold nights. By this method you will have fine, sturdy plants inured to the weather and broad sun and they will receive no check when bedded out.
As a bedding plant they need lots of water and for that reason the beds should not be rounded up, but should be flat so that the water will soak in and not run off to the sides to nourish the grass. They should not be watered overhead as you would a bed of geraniums, but the hose, running an unobstructed stream, should be guided among the plants. I said unobstructed because the different kinds of sprayers and attachments they have for spraying with a hose are an abomination to a gardener. A good light soil into which has been dug a liberal dressing of rotten cow manure will suit the begonias.
Begonia Globe de Lorraine.
Plants grown in pots want a liberal sized pot and plenty of air, and to do them well they should be shaded only from the brightest sun. Few insects trouble the begonias. Bust is their greatest trouble under glass and this is caused by heavy shade and a damp, stagnant atmosphere.