A Selection from the Physiological and Horticultural Papers,
published in the Transactions of the Royal and Horticultural Societies by the late Thomas Andrew Knight, Esq. 1841

[Read before the HORTICULTURAL SOCIETY, August 3rd, 1819.]

A WISH has been expressed by the Council of the Society, that a method of cultivating the Amaryllis Sarniensis, or Guernsey Lily, should be discovered, by which the bulbs of that plant might be made to afford blossoms, regularly, through successive seasons: and I, in consequence, address the following communication upon that subject; believing, that I can satisfactorily account for its sparing production of blossoms in our climate, and point out a mode of cultivating it, by which it may be made to blossom, much more freely than it usually does, though I have not attained the object desired by the Society.

*See Horticultural Transactions, Vol. III. p. 95.

Bulbous roots increase in size, and proceed in acquiring powers to produce blossoms, only during the periods in which they have leaves, and in which such leaves are exposed to light; and these organs always operate most efficiently when they are young, and have just attained their full growth. The bulb of the Guernsey Lily, as it is usually cultivated in this country, rarely produces leaves till September, or the beginning of October, at which period, the quantity of light afforded by our climate is probably quite insufficient for a plant, which is said to be a native of the warm and bright climate of Japan; and before the return of spring, its loaves are necessarily grown old, and nearly out of office, even when they have been safely protected from frost through the winter. It is, therefore, not extraordinary, that a bulb of this species, which has once expended itself in affording flowers, should but very slowly recover the power of blossoming again. The operation also of a cold climate, in retarding its period of vegetation, must have led the plant into late habits, like those of the vines, described by Mr. Arkwright, in our Transactions*; and, consequently, instead of being naturalised, and adapted to our climate as plants become, which propagate by seeds, it is, probably, now less capable of producing a regular annual succession of blossoms, than a similar variety of the same species of plant, immediately imported from Japan, would be. Considering, therefore, the deficiency of light and heat, owing to the late period of its vegetation, as the chief cause, why this plant so fails to produce flowers, I infer that nothing more would be required to make it blossom, as freely, at least, as it does in Guernsey, than such a slight degree of artificial heat, applied early in the summer, as would prove sufficient to make the bulbs vegetate a few weeks earlier than usual in the autumn.

Early in the summer of 1816, a bulb, which had blossomed in the preceding autumn, was subjected to such a degree of artificial beat, as occasioned it to vegetate six weeks, or more, earlier than it would otherwise have done. It did not, of course, produce any flowers; but in the following season, it blossomed early, and strongly, and afforded two offsets. These were put, in the spring of 1818, into pots, containing about one-eighth of a square foot light and rich mould, and were fed with manured water, and their period of vegetation was again accelerated by artificial heat. Their leaves, consequently, grew yellow from maturity, early in the present spring, when the pots were placed in rather a shady situation, and near a north wall, to afford me an opportunity of observing to what extent, in such a situation, the early production of the leaves in the preceding seasons had changed the habit of the plant. I entertained no doubt but that both the bulbs would afford blossoms, but I was much gratified by the appearance of the blossoms in the first week in July. Wishing to obtain seeds, I then removed the plants to a forcing-house, in which they have flowered very strongly; and the appearance of the seed-vessels gives much reason to suppose that I shall succeed in obtaining seeds, though I am not at present able to speak decisively.

From the success of the preceding experiment, I conclude that if the offsets, and probably the bulbs, of this plant which have produced flowers, be placed in a moderate hot-bed, in the end of May, to occasion the early production of their leaves, blossoms would be constantly afforded in the following season: but it will be expedient to habituate the leaves, thus produced, gradually to the open air, as soon as they are nearly full grown, and to protect them from frost till the approach of spring.

Should seedling plants be obtained, the powers of life in those, will probably prove more alert: and I think it probable, that, with a moderate degree of care, these may be made to afford blossoms in successive seasons; though it should be found impracticable to give that habit to the offsets of the individual seedling plant, now in cultivation.