Growing Roses Under Special Conditions
Roses under Glass
Roses can be bought any day in the year as cut flowers if the price can be paid. The winter ones are necessarily greenhouse grown.
For the smaller greenhouse the best method for producing flowers is by pot plants. Top dress them with fresh, manure in the autumn, and bring them into a cool greenhouse. Give little water, and about a fortnight later prune hard back to three or four eyes from the base. This applies to all the ordinary Pernetianas and Hybrid Teas. Weak and useless wood must be cut out and the pots set on a thin layer of cinder ashes. In sunny weather keep the atmosphere moist and syringe the heads daily, using water of the same temperature as the house.
If a pot, when tapped, gives a dull soft sound it is moist enough; if a sharp high sound it is too dry. Water standing on the surface indicates that the drainage is blocked, and a small piece of stick must be thrust into the drainage hole to loosen the blockage.
Ventilate the greenhouse from the top, but as draught causes mildew be wary on a cold or windy day. Flowers of sulphur dusted on will cure mildew and fumigating will destroy Green Fly. Maggots and Caterpillars must be dealt with by hand picking. When watering, a weak solution of liquid manure (such as cow droppings and soot) can also be given, or a light dressing of Rose fertilizer dusted on the surface of the pot.
With a powerful sun, light blinds may be needed for shade. Alternatively syringe the roof and sides with a mixture of skimmed milk and whitening.
Forcing for Winter Flowering
For this purpose pot plants must be taken under glass in the very early autumn and given considerable heat. Ordinary plants from the open ground cannot be forced in the first season, but must remain in a cool frame and allowed to flower a little about May or early June, only being forced for early flowering the following winter when their roots are well established. Climbing Roses planted out in the greenhouse, such as the climbing Niphetos, Fortune’s Yellow, or Marechal Neil need pruning each season. The weakest shoots must be cut hard back each year to encourage new growth from the base, and the long shoots shortened by about a third.
Rambler Roses require little pruning except to take out all small stubby growth, and tip the ends of the longer shoots. In flower they take quantities of water.
A Rose for the Rock Garden
For a rockery, a charming little Rose never more than 9 or 10 in. high is Rosa Rouletti, which is covered all the summer with pretty pink tiny Roses. It is probably a remote descendant of the Persian Rose, and was discovered in a Vaudois village a few years ago.