130 
JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
may be passed by. Judicious watering is, perhaps, the greatest 
secret of success. Over-watering will produce mildew, and in- 
sufficient water will be mischievous in other ways. There can 
be no rule laid down as to how often plants in pots require to 
be watered. When asked the question, I invariably reply, 
** When they want it." As the spring advances and drying 
winds and bright sunshine take the place of duller and cooler 
weather, increased vigilance is necessary in the matter of water- 
ing, and during the brighter days in March, April, and May it is 
necessary to syringe freely the whole of the Roses, whether 
planted in the ground or in pots, also the back walls and paths 
night and morning, and again in the middle of the day, in order 
to maintain a moist atmosphere ; for if the atmosphere be 
allowed to become dry, red- spider will soon make its appearance, 
and a dangerous and troublesome pest it is. The necessity for 
a moist atmosphere will be better understood when it is remem- 
bered that Eoses in the open derive much benefit from the heavy 
dews which invariably follow hot days and charge the foliage 
with moisture. It is this purpose that the syringe under glass 
is intended to serve, so in using the syringe the spray should be 
made as Hght and fine as possible. 
As the young growth progresses, it will be discovered that 
all the pests with which the Rose-grower has to battle outside 
are hideously conspicuous under glass, excepting red-rust or 
orange fungus. This, I am happy to say, I have never seen in 
any Rose-house. 
The worst pest of all, perhaps, is mildew, more frequently 
caused by injudicious watering and careless ventilation. If 
great attention be paid to the two primary causes, it may be 
avoided, and prevention is better than cure ; but once apparent 
(and it is quickly seen by the curling of the young tender fohage, 
accompanied by a spot or two of white-like dust on the under 
side of the leaf) it must be immediately dealt with. 
If the house has a hot- water pipe in it, as before recom- 
mended, the water in the pipe should be made to nearly boil, and 
then the pipes must be painted with a mixture of sulphur and 
milk, which will elfcctually destroy all spores for the time. 
Where hot-water pipes arc not available, the affected foliage, 
and tliat surrounding it, must be dusted with flowers of sulphur 
after syringing. 
