March 31, 1892. ] 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
283 
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ROOF-HEATING and GLAZED 
POTS. 
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N O doubt the connection of two subjects so distinct in character 
as heating glass structures by the agency of pipes near the 
roof instead of near the floor of a house, and growing plants in glazed 
pots may appear incongruous, yet as satisfactory examples were 
seen together they may be described together not inappropriately. 
Neither of these methods is by any means new, and both have 
been referred to in tbe Journal of Horticulture from time to 
time during the past ten years. Glazed pots have several advocates^ 
roof-heating comparatively few, because perhaps few have tried 
it, and certainly not many persons have adopted both the system 
of heating plant houses from pipes under the roof and growing 
plants in the structures in glazed pots systematically. Mr. Cuthbert 
Johnson has done so to his complete satisfaction. For years his 
fine tropical winter garden at Daventry was heated by pipes at the 
top next the glass ; and Orchids suspended from the rafters, 
and Ferns with ornamental foliaged plants below, proved by their 
luxuriance how well their wants were met. The owner was a little 
proud of this house as he bad reason to be, forit was a very delightful 
adjunct to his home. One among many notable plants was a 
Colocasia esculenta with leaves 4 feet 6 inches long and 3 feet 
6 inches broad, this being cited as typical of the health of the 
collection. But something besides the roof-heating contributed 
to the results achieved. Mr. Johnson was then a medico with an 
extensive practice, therefore a scientific man. He studied planls 
and their wants, and as some of his Orchids and other kinds did 
not appear quite so well as he wished he prepared a mixture for 
them, and with this mixture, roof-heating, and glazed pots, he could 
do all he wished in his garden under glass. 
Mr. Cuthbert Johnson now resides at Croydon in the first house 
that was built, by his uncle, on a portion of Hayling Park of 
Elizabethan fame. Some of the royal Oaks remain in his grounds, 
and one, a wonderful specimen, said to be a thousand years old, 
appears yet in youthful vigour, a consequence of the deep rich 
soil, but another has been killed by the goat moth, and there are 
thousands of tunnels in the ancient trunk. In the late Mr. 
Cuthbert Johnson’s ‘‘ History of Croydon ” (manuscript, and un¬ 
published), it is stated that the Oak tree mentioned as 1000 years 
old was measured by Dr. Bindley in 1856, and then estimated by 
him to be of the age named. The tree has been recently 
measured by a surveyor. The circumference of the trunk at 3 feet 
from the ground is 29j feet, height 61 feet. One arm extends 
49 feet, others 45 and 46 feet from the centre of the butt. It 
is a grand old monarch of the forest primeval, yet still as in the 
vigour of youth. As evidence of the depth of the soil a Parsnip 
dug up with its tap root unbroken to a length of 5 feet 5 inches 
is hanging in an Apple tree. Thus Waldronhyrst is a fertile 
spot, and at the same time picturesque and historical. 
In an excellent range of glass, erected by Messrs. Foster and 
Pearson, are plants of many kinds in glazed pots of nearly all sizes. 
They are distinctly preferred to the ordinary pots, which are also 
used, because the glazed ones are always clean, the plants in them 
do not require water nearly so frequently as in the others, and 
consequently the soil’s fertility is better conserved—not washed 
away. The owner likes these pots, and clearly the plants like 
them too. The objection to them because not porous is devoid of 
validity. Air in sufficient quantity for the roots of plants always 
No. 614.—VOL. XXIV., Thied Sbeies, 
follows water as it sinks through the soil, and there is a great 
deal too much air—dry air next the sides of many porous pots, 
the result of evaporation. Mr. David Thomson’s success at Drum- 
lanrig, the late Mr. Woodhead’s wonderful collection of Auriculas 
at Halifax, and Mr. Johnson’s experience, all demonstrate the 
innate suitability of these pots for plant growth. 
The houses at Waldronhyrst—Mr. Johnson’s residence—were 
well heated in the ordinary way, but he had pipes placed under the 
roof also. These he regards as the more effective. The cold air next 
the roof is tempered ; there is no condensation on the glass ; the air 
below is not parched, but, on the contrary, refreshing dew is often 
deposited on the plants, and the arrangement gives the greatest 
satisfaction. Mr. Bull once erected a large Orchid house at 
Chelsea, but the plants through some mysterious cause did not 
thrive ; a pipe was arranged under the roof at the base of the 
rafters, and from that time forward the Orchids flourished. A 
range of vineries could be named in v?hich splendid Grapes are 
produced, except towards the top of the structure, which has a 
small hip roof facing the north. The Vines are chilled at the top, 
and a 2-inch pipe there would almost certainly improve their con¬ 
dition materially. Mr. Cannell has long relied on roof heating, 
and thoroughly believes in its usefulness, and it has no doubt 
something to do with his marvellous winter displays of Zonal 
Pelargoniums. As an adjunct, at least, to orthodox methods, hot- 
water pipes under the roofs of many houses and pits would 
probably be highly advantageous, and it is certain Mr. Cuthbert 
Johnson would not sleep comfortably without them. 
Passing now to tbe mixture with which he doctors his plants 
here is the formula—equal parts in weight of phosphate of 
ammonia, sulphate of ammonia, nitrate of potash, and sulphate of 
magnesia. It is sprinkled on the soil of plants in pots occasionally, 
on beds and borders, and is used as a refresher for lawns ; a^so the 
powder at the rate of 2 ozs. dissolved in 3 gallons of water makes 
excellent liquid manure. Mr. Johnson has also found that a 
solution of nitric acid, 1 oz. dissolved in a gallon of water and used 
for syringing purposes, invigorates his plants. It also cleanses the 
leaves of any calcareous matter that may have been deposited by 
syringing with hard water. 
Many a good hint may be gleaned from amateur gardeners 
whose actions are guided by the light of science. Mr. Johnson was 
himself guided by a shining light in the horticultural world—his 
talented father and founder of the “ Cottage Gardener,” which 
developed into the Journal of Horticulture. Mr. Steadman, the 
careful and industrious gardener at Waldronhyrst, likes the method 
of heating and the pots described, and there is not a doubt they, 
as well as the plant medicine, answer their purpose well. 
SLUGS AND LIME WATER. 
Several of your correspondents are interested in these 
enemies of the gardener. Some years ago I took charge of a 
garden that was overrun with slugs and weeds, and the soil was in 
a poverty-stricken state. The first spring and early summer was 
showery, and it was almost impossible to raise seedlings of the 
Brassica family or Lettuce without sowing two or three times for 
one crop. Dwarf and Runner Beans had to be sown three times 
for only a part of a crop. Even the soft stems of Potatoes and 
the young leaves of the Globe Artichoke were welcome as food by 
the slugs. 
I tried most of the so-called remedies, but found them almost 
useless. Dusting the plants with soot and lime did almost as much 
harm as good, as cove.^’ing the foliage thickly hindered the plants 
from making headway. I tried brewers’ grains, bran, old board?, 
slates and tiles, then ducks. These became very fond of the tips 
of the shoots of growing Peas and Asparagus, and also spoiled 
many Lettuces. I found if ducks cm be driven on the infested 
No. 2270.—VoL. LXXXVI., Old Series. 
