How To Hybridize
When one rose is cross—fertilized with another, it may produce an entirely new variety. For this purpose a small dry greenhouse must be set apart.
Young rose plants of good varieties that naturally pod freely must be procured and allowed to grow on slowly, watered and syringed exactly as if grown for normal purposes. Mildew must be treated with flowers of sulphur, and should green fly appear the plants should be fumigated. In April, operations can be started as soon as two or three blooms are out. The apparatus needed is a small pair of sharp-pointed scissors, a small camel hair brush, a few pill boxes, labels and a note-book.
Pluck out the inner petals of a partially developed bloom until the eye is disclosed. Cut away the male stamens. These surround the centre cluster of shorter female carpels, which are probably not ripe for crossing.
Select now a bloom of some other variety with which the cross is to be made and again pluck out the centre petals. When the stamens of these flowers become dusty with pollen and sticky film appears on the surface of the pistils of the first plant, the cross can be made. Either the pollen may be taken away from the flower, or the bloom may be cut off and carried to the prepared flower to dust the pollen on it. If blooms are scarce the first method is better, otherwise to cut off a flower may be recommended as ensuring the loss of no pollen. To save the bloom, while using the pollen, the male stamens are removed and tilted carefully from the flower into a pill box, from this the pollen can be taken up with the brush and put on the flower awaiting it. The plant should be labelled with a figure or number and recorded in the notebook. Care must be taken to keep the air of the house as dry as possible to prevent the damping-off of the special plants. As time goes on the pods will swell, and by January it will be time to think of sowing the seeds. This must always be done under glass.
Take tiny thumb pots, about 1-1/4 in. across the top, and sow each seed singly,mixed with coco-nut fibre or leaf-mould being used. Plunge the pots into a thoroughly moist, finely-sifted cinder ash bed about 3 in. deep. Label carefully. A sprinkling of fine silver sand on the surface will keep the soil from becoming mossy.
When theare developing, water on a bright day, using a fine spray with water of the same temperature as the house. They are not rapid growers, but they will in time make sufficient growth to be carefully tapped out of their little pots and replanted into slightly larger ones filled with good gritty loam. It is essential not to disturb the soil of the first pot.
If space is limited the seeds can be put in rows in a fibre bed, again being carefully labelled. They are slower germinating in this way unless supplied with a little mild bottom heat.
Briarshould be rooted in the garden as they will be needed to bud with eyes from the seedlings, when they are sufficiently grown. After flowering, the seedlings themselves may die off, and unless an eye or two is secured and budded upon the growing stock the new variety may be lost. Varieties which bud freely are Madame Abel Chatenay, Betty Uprichard, Los Angeles, Golden Emblem, Ophelia, Madame Herriot (the Daily Mail rose).
If the first batch of seedling roses are good in growth and habit it is better to continue to cross these. A distinct and valuable rose is more likely to result. The rudimentary principles of hybridizing are simple. Hybrid perpetual roses crossed with others of the same class will give hybrid perpetuals again. Hybrid perpetuals crossed with Teas will give Hybrid Teas.
Three years at least are needed before the grower can tell whether the progeny is of any real value or not.