Many young gardeners and amateurs flounder befogged, attributing failure of crops in the garden, or want of health of plants in the green-house, to. bad seeds, uncongenial soil, or fertilizers, when it is much oftener the case that the cause is of a totally different nature, and entirely within their control. A temperature at which seeds are sown and plants grown must be congenial to the nature of the variety, else success can not follow. In a temperature at which a Portulacca will vigorously germinate, a pansy seed would lie dormant, or at least show a sickly existence, and vice versa. Nearly half of the Lima beans sown annually, perish by being sown from two to three weeks too early, by the impatience of our embryo horticulturists. On the other hand, the colder blooded carrot or turnip seed all but refuse to germinate in the sultry days of July. Seeds of calceolarias, cinerarias, Chinese primroses, and pansies will germinate more freely and make better plants by delaying the sowing until the middle of September than if sown earlier.

Many failures are attributable to want of knowledge of this fect, and without question laid to the charge of the seedsman.

The same necessity of accommodating the temperature to the nature of a matured plant exists even to a greater extent than it does in the seed; and one of the main causes of want of success in cultivating plants under glass is a want of knowledge, or carelessness in keeping a temperature nnsuited to the growth of the plants. In ordinary green-house collections the fault is oftener in the temperature being kept too high than too low, for it is much easier - requiring far less watchfulness by the person in charge to keep up a high temperature. The injury done by this is gradual and will not, like the action of frost on the plants, show in the morning. In consequence of this, we often see the temperature of green-houses containing camellias, azaleas, pelargoniums, carnations, etc., etc., sweltering under a continued night temperature of 60° or 65°, when their nature demanded twenty degrees lower.

It is true, we too often see collections of hot-house and green-house plants intermingled, and attempts made to grow them, which of necessity result in failure to one or other. The temperature to grow in healthy condition coleus, bouvardia, or Poinsettia (hot-house plants) would not be likely to continue long in a healthy state verbenas, carnations, or geraniums. The same rules follow as to the propagating-house, showing the necessity, even in a greater degree, of the strict requirements of their different natures; coleus, bouvardia, begonia, and lantana root in a bottom heat of 75°, with atmospheric temperature of 65°, in ten days; at twenty degrees lower they will not root at all, and will perish. And although cuttings of plants of a more hardy nature will root in some conditions of growth at this temperature, yet we prefer, to insure plants of vigorous health, verbenas, carnations, geraniums, roses, etc., to be rooted in a temperature at least fifteen degrees lower both in the bottom heat and temperature of the house.

The subject is one embracing so many varieties and different conditions of organism at the different seasons of growth, that it is impossible to convey to the unexperienced what these varieties and conditions are; but the object of this article is to impress upon your young or inexperienced readers what I have long believed to be an important truth - that the supplying the proper conditions of temperature to plants under glass, according to their different natures and conditions, has as much, or more, to do with their welfare than any other cause; and that often when ascribing the unhealthy state of a plant to uncongenial soil, or defective drainage, or the "damping off" of some favorite cutting to the way it was cut or the sand it was put in, the true and sole cause was nothing more than condemning them to an atmosphere uncongenial to their nature. South Beegen, N. J., Feb. 10,1868.