236 
THE FLORIST AND POMOLOGIST. 
through; it turns out a bright sunny day : there is a dry circulation of air; rapid 
evaporation takes place from the side of the pot: the heat is carried off along with 
the moisture, and the temperature of the soil is reduced to the lowest point, just 
when the leaves and branches are enjoying the highest, and when in nature the 
roots would be also. Then follows a reaction, as evaporation ceases the heat 
increases; if the roots were frozen before, they are roasted now, until—as often 
happens in the case of pot-bound plants—the ball of soil shrinks away from the 
side of the pot; under such circumstances to lift the plant out of the pot entirely 
and set it upon the shelf would be an aggravation of the evil, but nothing more. 
No doubt strict attention to shading and watering lessens such evils considerably; 
but no amount of attention that the gardener is able to bestow can altogether 
compensate for the disadvantages of such a system. I fully believe that a large 
proportion of the disease and difficulties that we encounter in the cultivation of 
some of our more select stove and greenhouse plants arises chiefly from this cause. 
The liability of some plants to the destructive attacks of red spider and thrips is 
greatly increased when grown in pots, and remarkable instances of this often 
come under the gardener’s attention. I have seen pot Vines, when not plunged, 
brown with spider, while others that have been planted out beside them would 
escape almost unmolested; and it is well known that nurserymen who often 
plunge their pot Vines in order to save labour in watering and such like seldom 
suffer to any extent. The prevalence of this disease more or less, which is 
certainly one of the most formidable that the gardener has got to contend with, is 
generally attributed to the character of the season—a cause no doubt that exerts 
great influence in inducing diseases, especially of the parasitical class; but the 
occurrence of red spider in particular cases cannot be accounted for by such 
general causes. In such cases the cause is entirely local, and one of the most 
common I believe to be dryness at the root. Evidence of this is abundant every¬ 
where ; but we cannot wait to enumerate more than one or two instances. It 
will be found that in shallow soils, upon dry subsoils, that fruit trees, in general, 
and everything liable to its attacks always suffer worst, and sometimes to a very 
great extent. Plants grown in pots, often and unavoidably subjected to severe 
checks from being irregularly supplied with moisture, suffer in the same way; and 
every one who has forced a few Strawberries knows that if he keeps their roots 
regularly supplied with moisture that he has little to fear from its attacks ; but 
allow them to suffer but once or twice from drought, and the pest will develope 
itself with a rapidity that is perfectly astonishing, and the same may be said of 
other things as well as Strawberries. When a plant is in a vigorous growing state 
and the leaves full of sap red spider will seldom make its appearance. This fact 
is well known, and until Vines and Peach trees have about completed their growth 
and commenced to ripen their wood, gardeners seldom dread its appearance. If 
it does appear before then, it is owing to the causes before mentioned. This seems 
to confirm the idea that it is only when the leaves are suffering from an insufficient 
supply of moisture that the insect is able to make progress, as when the leaves 
and wood have attained their full growth, and the ripening process commenced, 
the free and active circulation of the sap may be said to have ceased to a certain 
extent. I find I have diverged too far from my proper subject, however, upon 
this question, but it is one oi importance to gardeners, and the opinion of your 
readers upon the subject would be valuable. So to return to my subject. 
I have no radical measure of reform to propose in our present system of 
in-door gardening, nor have I any desire to discard the flower-pot altogether. 
No, I think we may safely predict that, as long as horticulture is a science, its 
services are always likely to be in demand; but I am desirous of advocating a 
more general practice of plunging our pot plants, both stove and greenhouse, as far 
as practicable at least. I consider it to be the only plan of insuring perfect health 
and guarding against the evils I have pointed out. By so doing a plant enjoys all 
the advantages of being planted out, without any of the drawbacks consequent upon 
too much freedom of root-action. I may be told that good plants have been grown 
in the ordinary way without plunging; granted, but that is no argument against 
the adoption of a better plan. The present construction of our plant-houses may 
also be urged as an objection to the system, but that objection is also indefensible. 
