November, 1916 
THE GARDEN MAGAZINE 
127 
Tropics brought to the cold North! Stately tree Ferns, Palms 
and other decorative plants thrive in the “ stove ” house 
contact with the water passages of the boiler), 
the grate surface, and the required minimum 
temperature. 
The glass area should be figured in square 
feet, taking one surface at a time and adding 
all walls, doors, etc., of other material than 
glass by letting every five feet of these areas 
equal one square foot of glass. Suppose, for 
example, that our house is of the three quarter 
span type with one wall formed by the side 
of a barn or shed. Suppose the actual glass 
area is 7,500 square feet and the wall 6 .x 30 ft., 
or 180, and the other opaque surfaces sufficient 
to total 220 sq. ft. Then our total estimated 
glass area would be 220 5 = 44 + 7,500 = 
7,544 sq. ft. For safety add 25 per cent, 
more, or 1,886 ft., and we would have 
9,430 sq. ft. as the area that our furnace 
must heat. 
Now most furnace manufacturers publish 
catalogues with their boiler ratings all worked 
out, so that knowing the glass area you can 
order at once a suitable heater. It is often 
well, however, to know the relations between 
the other units of construction. 
In a well-built house, in an average location, 
where the outside temperature is not liable 
to go below — 10 degrees F. i sq. ft. of pipe 
will keep 3 sq. ft. of glass at 60 degrees or 
better. For every 5 degrees variation in the 
temperature desired, increase or decrease the 
glass area heated by i sq. ft. of pipe, one-half 
a square foot. 
For instance continuing with our example, 
8,294 actual or 9,430 estimated sq. ft. of glass 
9>430 
could be kept at 60 degrees F. by = 
. 3 
3,144 -|- sq. ft. of pipe. But if we wished to 
raise melons and to keep the house at 70, we 
would need 9430 
= 4,715 sq. ft. of pipe. 
2 
The commonest sizes of pipe for heating are 
35 or 4 inches for hot water and 25-3 inches for 
steam. With these sizes we have the following 
data: 
I sq. ft. of pipe =5 ‘ ^ 
1.33 linear feet of 2J" pipe 
“ “ 3" 
“ “ ii" “ 
84 ‘ " ‘ 4" 
In other words we will need 4,715 -F .95 or 
4,479 ft. of 3^ pipe to heat our greenhouse. A 
heater with a capacity of 4,400 feet or more of 
The spring season is pulled into the lap of winter with a 
profusion of early bloom in the “ cool ” house 
in estimating the size of the boiler needed, 
is the necessity of allowing plenty of leeway. 
Add 25 per cent, to the actual glass area, and 
never skimp when allowing for the radiating 
capacity of the heater. Also pay attention 
to the chimney: see that it is large enough. 
You can’t get efficiency from a boiler with a 
choked draught. 
FUELS 
A complete list of available fuels would 
include oil, gas, wood, and coal, both soft and 
hard. Under the majority of conditions hard 
coal would be first choice, if not too expensive. 
It is most efficient, clean, and, in most locali- 
ties, easily obtained. Soft coal is oftentimes 
cheaper, but it is less efficient, tends to clog 
up the flues and prevent perfect heating, and 
requires more constant attention. Only where 
the greenhouse range is sufficiently large to 
keep a fireman always on duty does it pay to 
use soft coal. 
Wood is becoming less and less available, 
except in a few well-forested localities. It 
also needs much attention, if a uniform tem- 
perature is to be maintained. 
Natural gas and gasolene vapor are suitable 
only for small boilers and the former, of course, 
only over a limited area. 
Kerosene is likewise suitable for heating 
only upon a small scale. However, a number 
of small oil-burning heaters have been devised 
and appear to give excellent results. 
THE BEST HEATING SYSTEM 
Of the three methods of heating the small 
greenhouse, there is little question that the 
hotwater system is by far the best. It is more 
economical of fuel, it can be left alone for a 
longer period, it maintains its heat longer, and 
the heat, being less intense, is more satisfactory 
to the plants. A steam system has the advan- 
tage of attaining a desired point of heat rapidly 
and of having a greater heating capacity (in 
terms of both glass and radiation areas), but 
it needs more attention, and in a few years the 
increased cost of maintenance overcomes the 
advantage of the lesser initial cost. 
The two systems really differ but Hightly. 
Both consist of a boiler wherein water is 
heated to a certain point, an outlet or flow 
pipe, a series of pipes in the house and a return 
pipe, through all of which the steam or water 
circulates. However, in the steam system 
35-inch pipe would be entirely satisfactory, 
presupposing that good fuel is available. 
The relations between this data and the 
heating and grate surfaces are rather technical 
and need rarely be considered by the layman. 
Roughly speaking we may say that i sq. ft. 
of grate surface to 20 sq. ft. of heating surface 
to 200 sq. ft. of radiating surface is a fair 
average progression. 
The most important point to remember 
The problem of heating. It is necessary to decide on the 
demands to be made and provide a system adequate to defy 
the coldest outside weather at night 
TEMPERATURE GUIDE FOR THE 
GREENHOUSE 
An important fact for the beginner in “under glass 
culture” to learn is: 
That although the greenhouse makes it possible 
to grow in cold regions many plants native to a warmer 
climate, and also enables us to produce crops out of 
season, yet there are sharp limitations to the possible 
combinations. It is obviously not possible to grow 
at the same time, and under the same conditions, 
plants from the Arctic and others from the Equator. 
Experience has taught the gardener that he can group 
his plants into four ranges of temperature, and that 
any attempt to mix the temperature groups is at the 
price of the welfare of some of the plants. The fol- 
lowing groups are suggestive: 
COOL, 35-45°, night; Agave, Aucuba, Bay trees. 
Calceolaria, Campanula, Chrysanthemum, Cheiran- 
thus. Cineraria, Endive, Erica, Genista, Iberis, 
Lettuce, Magnolia, Mignonette, Myosotis, Nerium, 
Parsley, Radish, Rhododendron, Stocks, Sweet 
Pea. 
INTERMEDIATE, 45-55°, night; Agapanthiis, 
Allium, Altemanthera, Alyssum, Antirrhinum, 
Anguloa, Asparagus (edible). Beans, Beets, Cactus, 
Canna, Carnation, Carrot, Cauliflower, Cypripe- 
diura, Epiphyllum, Erythrinum, Geranium, Gladio- 
lus, Hyacinth, Hydrangea, Iris, Katanchoe, Lettuce, 
Lapegeria, Mushroom, Odontoglossum, Onion, 
Omithogalum, Oxalis, Passiflora, Pea, Pelargonium, 
Plumbago, Primula, Rhubarb, Seakale, Spinach, 
Stevia, Lilac, Wistaria. 
WARM, 55-65°, night; Abutilon, Amaryllis, Aralia, 
Araucaria, Asparagus (ornamental). Aspidistra, 
Aspidium, Astilbe, Azalea, Begonia, Bougainvillea, 
Bouvardia, Cactus, Calla Lily, Camellia, Cattleya, 
Celosia, Chorizema, Clerodendron, Clivia, Coelo- 
gyne. Coleus, Cyclamen, Cyperus, Dendrobium, 
Freesia, Fuchsia, Grape, Heliotrope, Jasminum, 
Laelia, Lilium, Lycaste, Nasturtium, Nectarines, 
Nymphaea, Oncidium, Peaches, Roses, Smilax, 
Spirea, Stephanotis, Strawberry, Swainsona, To- 
mato, Vanda. 
STOVE, 65-80°, night; Achimines, Adiantum, Al- 
lamanda, Alsophila, Anthurium, Areca, Aristo 
lochia, Asplenium, Banana, Begonia, Bertolonia, 
Borassus, Caladium, Calathea, Calanthe, Caryota, 
Cephalotus, Chamaedoxa, Cibotium, Cissus, Citrus 
fruits. Pineapple, Clitoria, Cocos, Corypha, Croton, 
Cucumber, Cyathea, Cycas, Davallia, Dicksonia, 
Diffenbachia, Dracena, Eggplant, Epidendrum, 
Eucharis, Euphorbia, Ficus, Gardenia, Gloxinia, 
Hoya, Kentia, Lantana, Lily of the Valley, Livis- 
tona, Maranta, Muskmelon, Nepenthes, Pandanus, 
Phalrenopsis, Philodendron, Phoenix, Platycerium, 
Poinsettia, Rhapis. 
