Vick’s Magazine p. 86-87 (March, 1888)
HOT WATER FOR PLANTS
It is a fortunate circumstance that a plant will endure a scalding heat that is fatal to most of its minute enemies. Water heated to the boiling point, poured copiously over the stem of an enfeebled peach tree, and allowed to stand about its collar, will often have the happiest restorative effects. Trees showing every symptom of the yellows have often been rendered luxuariantly green and thrifty again, by this simple means. The heat is presumably too much for the fungus which had infested the vital layers of the tree, immediately under the outer bark.
The London florists recommend hot water, up to 145° F., as a remedy, when plants are sickly owing to the soil souring—the acid, absorbed by the roots acting as a poison. The usual resort is to the troublesome job of repotting. When this is not necessary for any other reason, it is much simpler to pour hot water freely through the stirred soil; it will presently come through tinged with brown. After this thorough washing, if the plants are kept warm, new root points and new growth will soon follow.
A lady friend had a fine Calla in a three gallon pot, which showed signs of ill health. On examination the outer portion of the filling was found mouldy, it being in large part fresh horse manure. As repotting was inconvenient, the plant being in flower, hot water was freely used; it killed the mould, and the plant began to revive and was soon all right. — W.