Jan uary 10, 1903. 
THE GARDENING WORLD 
7 
UNDER GLASS: The Cold Greenhouse. 
Gardeners, professional and amateur, do not, as a rule, give 
the cold greenhouse so much attention as it deserves, for the 
idea among many people—especially amateurs with a small 
glasshouse—seems to prevail that a glasshouse must be kept 
a great deal warmer than the outside air. Even in large 
gardens, where a considerable number of glasshouses are to be 
found, 'we rarely come across a really cold greenhouse. In 
name', the house very likely exists, but if it is inspected, in 
nine cases out of ten it will be found to be kept at a fairly 
high temperature^ to accommodate plants whicli ought really 
to be growing in another house. 
That a cold greenhouse can be made a very delightful place 
I shall endeavour to show, for there is a very large number 
of beautiful plants that are nearly hardy, but require .slight 
protection from very severe frost, or protection when in 
flower, or when making their growth early in spring. The 
amateur with one small house, who tries to keep a night tem¬ 
perature of 50deg. with an inferior heating apparatus, would 
do far better, and be under a great deal less expense, if he 
were to grow only such things as would thrive in a low tem¬ 
perature, for his coal bill ‘would be reduced' to a minimum, and 
lie would know that his plants would come by no injury, even 
if the temperature of his house fell to freezing point. Plants, 
again, that are grown in a low temperature do not require so 
much attention as plants that are grown in a. lot of heat, con¬ 
sequently a man who is away from home all day, and has 
to look after his plants either early in the morning or late at 
night, will not have the same fear of things going wrong in a 
cold house as he would have in a warm one. 
A cold greenhouse might be provided with, or be built 
without, heating apparatus. If the former is the case, heat 
should only be applied in very severe weather, when a maxi¬ 
mum temperature of 33deg. to 35deg. should be kept-, and a 
minimum of 31 deg. to 32deg., and in very damp weather, once 
now and then, to air the house. If the house is ‘without fire 
heat many plants may still be grown, but in the case of very 
severe frost flowers 'are sometimes destroyed, although the 
plants are uninjured. Anyone with a small unheated house 
could, however, if he chose, save his flowers in the case of a 
■sharp spell of frost by covering the glass with mats or by 
placing an oil stove in the house to keep the temperature up 
to freezing point. 
The plants suitable for growing in such a house are many 
and varied, and come from almost all the temperate and sub¬ 
tropical parts of the world, South Africa, the Himalayas, 
Australia, Japan, China, and partis of South America contribut¬ 
ing large numbers. As a rule, it will be found advisable to 
grow hard-wooded plants in preference to' those of herbaceous 
character, for in very dull, wet weather there is always the 
danger of the leaves and flowers .suffering from damp. The 
items to be taken into consideration in the cultivation of cold 
greenhouse plants are not to re-pot after the end of summer— 
all potting being done in time for the roots to get well through 
the nefr soil before the cold and dull days of late autumn 
and winter come—to give abundance of ah' on 'all favourable 
occasions, even in mid-winter, keeping the house, of course, a 
little closer in March and April, when the young shoots are 
being made and the general repotting being done', and not 
to light the fire until the temperature has got down to within 
a degree or so of freezing point, and do not with fire heat 
allow the temperature to rise above 34deg. or 35deg\ at the 
highest. 
The period of the year at which a cold greenhouse may be 
expected to be at its gayest is from the end of February until 
the end of May, though flowers may be had nearly the whole 
year round. 
When selecting plants for the cold greenhouse, the 1 genus 
Rhododendron .stands out prominently as one of the most 
useful of all, for there is a large number of species and varieties 
galore which can be pressed into service. Species and varieties 
which grow and flower luxuriantly out of doors in Cornwall, 
South Wales, and Ireland must have protection m most other 
places, and even many species and varieties which are hardy 
about London at all other times require the protection of a 
house to have their flowers at their best. Selecting a few 
from among the many fre tiiid among the taller growers, 
It. grande, a tall-growing, large-leaved Himalayan species, with 
massive heads of waxy white blossoms; It, arboreum, with 
compact umbels of blood-red flowers; It. fulgens, with deep 
red flowers; It. barbatum, with flowers of much the same 
colour; and It. griffithi'anum—better known to some jreople 
under the name of It. Aucklandii—with veiy large, waxy white, 
saucer-like flowers; and many others. 
Of dwarfer growers there is a much wider field for selection ; 
species alone are numerous, ‘while of varieties there are very 
large numbers, .and it is from these that the amateur with a 
small house would do well to make his selection. The species 
for the most part are Himalayan, though China and Japan 
also give contributions. Of the former, R. ciliatum, a bush 
growing from 1 ft. to 5 ft. high, bearing veiy large numbers of 
white hloissoms flushed with pink; R. iormosum, with fragrant 
white flowers; R. Edgeworthii, a plant with somewhat 
straggling habit, bearing dark green leaves covered with a 
dense brownish tomentum on the under surface, and immense, 
white, deliciously-scented flowers with beautifully-fringed 
petals, are conspicuous; while R. veitchianum, also bearing 
large, fragrant, prettily-fringed blossoms; R. Dalhousice, a 
straggling grower, with tubular flowers 3 in. to 4 in. long, of a 
greenish yellow colour; and R. IN uttallii, with veiy large 
trumpebsliaped yellow blossoms, require attention. 
Chinese and Japanese .species are numerous, an example or 
two being R. ciliicalyx, somewhat similar to some of the 
forms of R. formosum and R, indicum (better known as Azalea 
indica), with its array of varieties so largely grown in gardens. 
A set of varieties raised principally by the intercrossing of 
R. Edgeworthii, R. veitchianum, C. ciliatum, and R. formosum 
exists, and a selection of these should be grown, for they all 
flower well and have fragrant blossom®. Selected) from many 
others, the following may be relied on as being particularly 
good : Countess of Sefton, Lady Skelmersdule, La Belle, Beauty 
of Exmouth, Lady Alice Fitzwilliam. and fosterianum, the 
latter two being probably the best of the set', the flowers being 
large, with lovely fringed margins and exquisitely scented. 
Countess of Haddington, a variety frith blush-coloured, 
fragrant, tubular blossoms, is worthy a place. 
Camellias, like Rhododendrons, must have a place in the 
cold house, for they do remarkably well, and flower with great 
freedom. C. japonica and its pumerous varieties are well 
known; of the varieties, 'Chandler! elegans, Monarch, imbri- 
oata., alba plena, mathotiana, and mathotiama alba call for 
special mention. Other specie® not so well known as the 
foregoing, but veiy lovely, are C. reticulata, a Chinese plant, 
with large, Preony-Iike, red flowers, and C. Sasanqua, with 
single red flowers, reminding one very much of a single rose, 
are very handsome. 
So far, reds and whites have been the chief colours among 
our flowering plants, but with the Acacia a variety of shade® of 
yellow is added. A large number of species may be used, of 
which the following selection may be relied on as being a good 
one for general purposes : A. armata, A. cultrifo rm is , A. Drum- 
mondi, A. leprosa, A. platyptera, A. ovata, A. pulcliella, 
A. riceana, A. vemiciflua, and A. verticillata. 
Tree Pseonies may be depended on to- make a gorgeous 
display, provided they are given rich .soil and plenty of sun 
and air frhile growing, to enable them to make sturdy shoots 
and strong buds, which will become well ripened before winter 
sets in. 
