The Magazine of Horticulture 10(2): 48-51 (Feb 1844)

Art. II. Experiments on the Cultivation of Plants in Charcoal.
J. E. Teschemacher

I PERCEIVE in the horticultural papers received by the last steamship, that there is an animated discussion on the value of charcoal in horticulture, and that Mr. Robert Rigg, an excellent chemist, has proceeded so far as to publish a book, with the extraordinary assertion that carbon is a compound body made of plants. Assent to this proposition cannot of course be expected from chemistry, in its present state; but we do not know to what strange discoveries the searching inquisitiveness into the laws of nature, of the present age, may lead.

Having made various experiments on the action of charcoal, for the last two years, I have concluded to add my share to the discussion.

The first view I took of the value of charcoal in horticulture, arose from the arguments on the different powers of well rotted and of fresh manure; my prejudice from constant practice being rather in favor of the former. And one of my imaginary reasons for this prejudice, (for proof was not to be expected,) was that the carbon of the vegetable part of the old manure was reduced by fermentation and complete decomposition (combustion, Liebig) to the finest possible state of comminution, such as is totally impossible to imitate by the most laborious mechanical pulverization. In this finest of all states, carbon, if used at all by the living vegetable, could be most easily appropriated. My experiments were, therefore, all made with finest pulverised wood charcoal I could procure, such as is used in making gunpowder:

1st. I planted a young, thrifty plant of Daphne odora in this charcoal altogether; in 12 months it was alive, the leaves quite yellow. On examining the roots they had not in the least increased or altered. I then repotted it in loam with one quarter charcoal and watered with a very weak solution of nitrate of soda; in four weeks the leaves had become of a dark blackish green, and the plant was beginning to push vigorously.

2d. I planted a fine root of Fuchsia fulgens, with a stem, in charcoal alone. It immediately began to vegetate; the leaves were, however, extremely diminutive and soon dropped off; the flowers appeared also diminutive and finally dropped off likewise just after opening. It then, with the others, went to rest; but to my surprise, in August it again began to vegetate and went precisely through the same process as in spring — others which were by its side remaining dormant—after this it went again to rest.

3d. I potted several seedling camellias in one quarter charcoal, one quarter old manure, one half loam; these grew with great luxuriance, and the color of the foliage was dark, healthy green.

4th. I potted several young pelargoniums with various quantities of charcoal, never exceeding one quarter, often very much less. In these the effect was the same, both coming very near to the luxuriance and size of foliage of those treated with Guano.

In August last, I made up my mind to re-pot and top dress a large number of exotic plants, of various kinds, many of which were in a bad state from neglect; of these the chief number were camellias. I made up a compost, consisting of about two thirds Roxbury fresh loam, and one third a compost, chiefly consisting of old manure; to this I added about one fortieth part of charcoal, and had the whole very carefully and intimately mixed; with this I operated. In September, when I thought the earth had got well settled round the roots, I began to water, every Saturday, with water in which Guano had been mixed, in the quantity of about one ounce to ten gallons.

I was perfectly astonished at the alteration which appeared in about four weeks, in the general health of all the plants—it seemed to me like magic; and many who visited the Public Conservatory, previous to the late calamitous fire, can bear testimony to their beauty and luxuriance. The earth of one large camellia, (double white,) with about 250 blooms was nearly altogether changed, the tub having fallen off with much of the earth. I hardly expected to save the blossoms, but they opened in as great splendor as the others. It seems to me that the period of the opening of the flowers was also generally accelerated. We had 20 or 30 out the first week in November, and the first week in December, just previous to the fire, I counted above 500 in full beauty; this was certainly earlier than we had them in previous years.

Passiflora Loudonii, which, under the best of common cultivation, has always yellow and unhealthy looking leaves, was placed in this mixture with the addition of charcoal drainage. The rapid change in its appearance was surprising, and although, from unavoidable circumstances, it was removed into this soil just previous to flowering, yet instead of being checked, fresh flower racemes shot forth, and, with the others, opened their beautiful blossoms in the greatest splendor; the foliage becoming of a fine healthy green and spread open, not curled in at the edges.

I had several other experiments in progress on the use of charcoal, some of which I had hoped would have thrown light on its immediate action on the roots of plants—a subject on which we are at present in the dark; unfortunately, these with many others were destroyed by accidental fire.

My impression from these trials is, that although charcoal alone is nearly useless, yet when mixed in due proportion with the earths and salts, usually found in soils and manures, its presence is highly beneficial, and greatly promotes the luxuriance of vegetation, as far as regards stems and leaves. Of its value in the production of flowers and seeds, I am not, for the reasons before stated, able to give an opinion of any worth.

It may be thought, and probably is in part true, that much of the luxuriance of the last named experiments arose from the use of Guano water; but from other experiments with charcoal, instituted for the purpose of making comparisons with Guano, and in which of course none was used, I cannot hesitate to believe that some portion of this luxuriance was also due to the charcoal. I trust, therefore, that other horticulturists, who have the means, will undertake farther experiments on this subject, so that we may not in this country be behind the rest of the world, in the astonishing advances which are every year being made in that most delightful of all pursuits—Horticulture.

J. E. Teschemacher.
Boston, Jan. 24, 1844.