the establishment must be small indeed if it does not contain some place
where the bed is so arranged that the heat at the bottom is from ten to
fifteen degrees above that of the house proper. Here lies the whole
secret as to whether it is a part of a single green-house or a house
devoted exclusively to propagating purposes. For the purpose of being
able at all times to control the temperature of the top, the propagating
house has often a northern exposure, except in the very dead of winter.
With a bright, clear sun above it is almost impossible in the daytime to
keep down the temperature of the house sufficiently to prevent the young
cuttings from wilting, after which disaster is very likely to follow in
their final rooting. Given a top temperature never above 55 or 65
degrees, with a bottom always from 10 to 15 degrees higher, if the
cuttings are in good shape it is a simple matter to root them in from
seven to fifteen days; though the time it takes depends, of course, upon
the plant and condition of the wood. At first efforts used to be
contrived to get this bottom heat by means of the old flue system, with
plenty of material covering the bricks, to break, in part, the dry
burning nature of the heat.

Then hot water came in and furnished what was thought the acme of a
propagator, and tanks of elaborate workmanship, and made of the finest
material down to the commonest wood, were made so a circulation of hot
water was kept up over as large an area as the necessity of the owner
might require.

The results seemed excellent, but lo, every now and again, disastrous
failures would occur. A material would spread all around called by the
florist the cutting bench fungus, that would sweep through his crop like
a plague; all sorts of theories would be given, and numberless articles
appear in the horticultural periodicals of the day on its cause and