Trans. Hort. Soc. 2: 97-100 (1822)
XXIII. On the Culture of the Shallot, and some other bulbous-rooted Plants.
By THOMAS ANDREW KNIGHT, Esq.F. R. S. &c. President.
Read December 6, 1813.

THE habits of bulbous-rooted plants of different species, relatively to the depths to which they naturally retire beneath the soil, admit of much variation, some occupying its surface, and others descending considerably beneath it. These circumstances do not appear to have been sufficiently attended to, and injurious consequences have probably been the result, in many cases.

I have been led to adopt this opinion, and to make the experiments, which are the subject of this communication, by a complaint of my gardener, that the greater part of his crops of Shallots had, during several years, generally become mouldy and perished: and I found, on enquiry, that the same thing had very often occurred in other gardens of the vicinity. The bulbs had in all cases been planted, according to the directions of different writers upon Horticulture, two or three inches beneath the soil; and to this cause I attributed their failure.

A few bulbs of this species, which were divided, as far as practicable, into single buds, were therefore planted upon the surface of the ground, or rather above it, some very rich soil having been placed beneath them, and the mould having been raised on each side to support them, till they should become firmly rooted. This mould was then removed by the hoe and watering-pot, and the bulbs in consequence were placed wholly out of the ground. The growth of these plants now so closely resembled that of the common onion, as not to be readily distinguished from it; till the irregularity of form, resulting from the numerous germs within each bulb, became conspicuous. The forms of the bulbs, however, remained permanently different from all I had ever previously seen of the same species, being much more broad, and less long; and the crop was so much better in quality, as well as much more abundant, that I can confidently recommend the mode of culture adopted to the attention of every gardener.

A few experiments similar to the preceding were made upon bulbs of the Oriental Hyacinth. Some of these were planted in the ordinary method beneath the soil, and others wholly above it, the mould being raised upon each side to cover them, and subsequently taken away; and I found that those under the latter mode of culture flowered most strongly and in every other respect succeeded best. A compost, of great richness, formed of matter collected just without the gate of my fold-yard, and probably consisting of nearly equal parts of earth and cow-dung, by weight (if each substance had been perfectly dry), appeared to be exceedingly well adapted to this plant; which expends much in a very short period of time in the production of leaves and flowers, and retains its foliage only a short time afterwards, and therefore probably requires more nutriment than it can generally obtain under the ordinary modes of culture. It is true that this, and some other bulbous-rooted plants, protrude their leaves and flowers as strongly, when supplied with water only, as when growing in good soil: but this growth is chiefly germination only, and during this process, in which the organs of the plant are merely formed out of matter previously assimilated, it may be questioned whether a single particle of new matter be ever vitally united to it.

A plant, of a very beautiful variety of the Oriental Hyacinth, which had been made to blossom with water only was, at my request, put into my hands in the last spring, just when its blossoms had begun to lose their beauty. Those were immediately taken off, but the stem was suffered to remain, and the plant was removed, from the bottle of water, in which it grew, into a pot sufficiently deep to receive its roots. A quantity of the rich compost above-mentioned was then, in successive portions, put into the pot, and washed in amongst the roots; which were kept properly separated from each other. The bulb itself remained wholly out of the soil, with which it was not in contact, a thin layer of light and dry sandy loam, intervening between it and the rich soil; and the bulb was also thinly covered with the same material. As the roots of the plant had been accustomed to live in water, the compost in the pot was at first kept very wet; and the quantity of water subsequently given was lessened very gradually; and as its leaves had been little exposed to light, it was retained under glass till the leaves perished. The bulb was then examined, and was found as solid, and apparently as perfect, as it would have been if it had germinated, as well as ultimately only grown, in a rich soil. The water in this case occasioned the extension of the roots, and the developement of the leaves, and thus was instrumental in forming organs capable of collecting and assimilating new matter; but exclusive of some impurities it contained, it probably had not given a particle of organizable matter to the plant. The formation of organs, and the action of those organs when formed, must not therefore be confounded, as has generally been done, and constantly by chemists who have endeavoured to ascertain the action of the leaves upon the surrounding air; and hence appear to have arisen the confused and contradictory results of their experiments.

I am wholly ignorant of the mode of management by which bulbous roots of different kinds, acquire so much greater perfection in the hands of the Dutch gardeners, than in those of our own countrymen: but I suspect that the Dutch gardeners employ subsoils of very great depth and richness, with which the bulbs are prevented coming into contact by the intervention of a thin layer of dry sand, with which substance they may be also thinly, or only partially, covered; and I am in part led to adopt this opinion, by observing the similarity of character in the external membranes of their bulbous roots, and of those of the Shallots, which had been wholly exposed to the sun and air.