The Magazine of Horticulture July 1843 p. 264-265

Charcoal.—During the past year, various experiments have been in progress to ascertain what effects would be produced upon plants by potting, or striking them, from cuttings, in charcoal; or by mixing it in various proportions in the soil in which they are to be grown. From what has been published in Liebig's Organic Chemistry, and elsewhere, I had been led to expect some very decided results ; but after varying the experiments in many different ways, nothing has happened which proves charcoal to be useful as a chemical agent in the growth of plants. When pounded and used by itself, it is very apt to get too dry, and then runs together and sets very hard. Some orchidaceous plants, gloxinias and Cacti were potted in it, but they did not succeed, evidently from causes above mentioned. When mixed with soil in the proportion of two thirds of charcoal to one third of soil, and also in smaller quantities, such plants as oranges, Ipomaea scabra, gesneras and Cacti, grew very well in the mixture, but not better than others which were treated in the common way. Cuttings of the common Caper, Ficus elastica, Euphorbia Jacquinaeflora, Ipomaea, and various other kinds, were planted both in pounded charcoal and in different proportions mixed with sand; but the results were not more favorable to the charcoal than to the common sand usually employed for that purpose. The caper rooted freely in both ways, but the others did best in the sand. Many cuttings, when planted in pine charcoal, or even when that formed a principal part of the mixture, threw off their leaves in a short time and rotted at the base. From what has come under my observation during these experiments, I would not recommend this substance to be used by itself for the growth of plants or for striking cuttings; and if it does produce any good chemical effects when mixed with the soil, these will probably depend in a great degree upon the constitution of the soil, in the same way as lime and chalk are only good manures for certain lands. But it is very possible that these effects are only mechanical, tending to keep the ground open in the manner which renders ashes so very beneficial to stiff soils.—(R. Fortune in Proceedings of the London Horticultural Society, No. 17.)

[We believe Mr. Fortune to have given a correct opinion in relation to the use of charcoal. It may benefit some soils, but for the ordinary purposes of greenhouse culture it [charcoal alone] has less effect than good prepared soils, such as are generally made use of.—Ed.]