292 JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. [ April 12, 1883. 
sunnier south. Even on sun-warmed raised borders 
they seldom do well; but when a foot of fresh stable- 
yard manure is put under the upper foot of'soil success, 
even in such woeful years as last (1882), is nearly cer¬ 
tain. Six plants of Muir’s New Hybrid were last year 
planted on the level and nursed for a month under 
handglasses. They never bore a fruit, though pinched 
and trained as carefully as Melons. The earth heat 
was never over 57 p . Six on a raised vinery border 
with a good slope bore twenty-nine fruits, although the 
spot was more exposed than in the first instance. The 
earth heat reached and remained some time at 61 Q ,but 
was not over 59° till August (June and July were very 
wet), and none ripened. Only nine reached full size. 
In a position more exposed than either of the other 
two, six other plants were placed out on a border 
raised 1 foot by that thickness of very fresh hot stable 
litter under the soil. This material was laid flat 8 feet 
wide, 1 foot under the surface. Four days after—the 
weather was very bright then and also hot (18th May)— 
the plunged thermometer stood at 72°, a month after 
it was (37°, and at that it remained till the end of 
August. What it was in September I was too ill to 
ascertain, but in October it was still 60°, and that after 
a peculiarly sunless season. But, in fact, by July the 
heat was protected by the covering foliage. The pro¬ 
duce was, up till September, forty-five fully grown fruits, 
many of which in a very bad year and on an exposed 
spot in a peculiarly exposed late locality, ripened. 
After August the gathered produce was as my man 
expressed it, “ a big barrowful,” some of which were 
being used in February, and all this because of extra 
bottom heat alone ; this heat being secured for only a 
little trouble, the manure remaining being as good as 
at the beginning, for it was never wet enough to lose 
its virtue. No doubt the raising of the border con¬ 
tributed to the result, and also the heat in the manure 
when first buried. This raised the heat at once. The 
non-conducting nature of the material and the thick 
leafy covering preserved it, and this made all the 
difference between a moderately good crop in a season 
and in a locality where without such assistance the 
plants only cumbered the ground. The use of blacking 
might have secured a degree or two more, for when 
this was tried on French Beans the plants produced a 
moderate crop of beans by the third week in August; 
without it they only produced half-formed pods, which 
never came to be of any use at all, they were so late, 
so stunted, and tough. 
Very much may be done to secure a higher earth 
temperature than natural by the use of coverings. By 
covering at night the surface of a 14-inch pot, plunged 
in ashes with dried sphagnum at one time and sawdust 
at another, the soil maintained a temperature of 63° 
through July and August. One exposed at night was 
barely G0°. Mr. Thomson of Drumlanrig mentions 
the following striking instance of how earth heat may 
be preserved. In October he covered a vinery border 
with 18 inches of wheat straw laid on like thatch. At 
midwinter the earth heat was 60°. An uncovered border 
was as low as 40°. The difference to the plants, 
supposing both to be forced into growth, would be very 
considerable. The sap feeding the one would be 20° 
below that of the other. Under such conditions the 
one would do welJ, the other might fail—and failure 
from such a cause has resulted before now. 
Watering tends to lower earth temperatures : rain 
has the opposite effect. This may seem a paradox. 
Watering is only resorted to during drought. But 
under such conditions the water applied evaporates 
rapidly, and there is nothing that lowers the temperature 
of the soil so rapidly as evaporation. But when rain 
falls the atmosphere is saturated, and evaporation 
proceeds slowly or even not at all. Then we must 
remember that heat descends slowly. It is this fact 
which accounts for the coldness of the under soil. 
Heat inclines to ascend. But when rains falls in the 
summer it carries heat down into the soil. It changes 
the air in the soil, too, by displacing it. As the rain 
afterwards leaves the soil, warm air follows. Thus rain 
warms, and artificial watering cools, the soil. This fact 
is taken advantage of by those who find their climate 
too hot for the particular plants they cultivate. 
Watering, for this and other reasons, should not be 
indulged in unless absolutely necessary. Many check 
all growth by their perpetual dribblings. After watering, 
as soon as the soil is dry enough, means should be 
taken to preserve not only the water but the earth 
heat by checking evaporation. In hot seasons short 
grass, manure, leaf soil, cocoa-cut fibre, &c., may be 
employed as a mulching. But even a hoeing, in 
order to produce a loose layer of surface soil, will do 
much to check evaporation, while it will allow sun 
heat to pass on. In the case of many tender plants 
this is a very important matter. 
Draining raises earth temperature. Soil that is 
wet is also cold. Instead of using sun heat to raise 
its temperature it employs it to evaporate the water. 
Wet soils are always cold, and a plant on a cold soil 
draws up cold sap, which keeps the plant cold no 
matter what the air heat may be. Nay, a watery 
diet produces even a greater degree of cold, for, in 
order to get rid of the superfluous water in the over¬ 
diluted food, the plant must evaporate more than is 
necessary, and thereby renders itself colder still. It 
is this that makes corn on wet land late. Draining, 
then, is of paramount importance, for thereby the soil 
is warmed, the sap plants draw up warmed, and this 
is seen to be as good as an increase of air heat 
for the plants. Corn, vegetables, fruit mature sooner 
and improve in quality as they do when transplanted 
to a better climate. 
We spoke of the better Onions that we raised by 
darkening the soil, and hinted that another method 
was used to promote a higher ground temperature. 
That other method was to keep the surface soil con¬ 
stantly stirred with the hoe, especially after being 
battered by rain. Even in such a sunless year as 
last the results were markedly superior; but in sunny 
years we have even seen a greater difference. 
In the application of bottom heat by means of hot 
water or fermenting material sometimes too much is 
given. It is necessary to guard against this. Often 
Seakale and Asparagus are “ drawn ” so much as to 
be useless by too much bottom heat. A safe rule is 
to keep within 5° of the earth heat in the warmest 
summer month outside for most hardy plants. But 
“ drawing ” is not always an evil. In the case of 
forced Lily of the Valley, for instance, drawing is 
systematically practised. 
The earth is a vast storehouse of heat. By cover¬ 
ings much of the heat thus stored might be utilised. 
To some extent this is already done. By mulchings 
of manure Boses are protected. Many tender herba- 
