This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
Some people are passionately fond of Ferns, - lovers of all kinds, whether exotic or indigenous, whether of plain appearance or the most beautiful. We doubt if there be many, comparatively, who are not fond of Ferns; there is something so elegant, graceful, and chaste about many of them, that they are sure to attract the attention even of those who care but little for flowers generally. We must confess to a feeling of "softness" towards these paragons of gracefulness; but none of them, as a whole, do we like so much as the subject of the present paper. The genus Adiantum contains a large number of species, many of which are very distinct in character; the treatment required to grow them well also differs considerably in the case of some species, some doing best in a strong and moist heat and thoroughly shaded, whilst others are most at home in a cool temperature, and nowise averse to a little sun, if it be not too powerful. They luxuriate in a compost of equal parts fibrous peat and turf, with a liberal admixture of coarse sand: bits of charcoal or coal-ashes that will not pass through a 1/2-inch sieve are also of value in the compost.
Some of the smaller-growing species do well in small pots; but to have the stronger-growing ones in perfection, they must be liberally treated in the way of repotting. For exhibition purposes, some of them are very fine - such as Farleyense, formosum, cuneatum, curvatum, concinnum latum, trapeziforme, Sanctre Catherine, tenerum scutum, pedantum, assimile, amabile, and capillus-veneris. There are also some newer sorts which we have not had experience with, which are said to be fine for exhibition. Some cultivators dry off their plants in cold houses in the autumn, letting them lie dormant through the winter till early in spring, when they are started into growth and repotted, growing them on in a brisk heat, thereby getting magnificent plants up for exhibition in summer. But where there is not a strong heat at command early in the season, it is best not to dry them off at all, nor to pot them in the spring, the end of July being as good a time for this operation as any. Of course, in the case of plants which are being grown on from small plants to specimens, this mode of treatment must be modified to suit the case.
Take, for instance, a plant which has been potted into a 6-inch pot in spring; in summer it will require shifting into a 10-inch pot, and kept growing on without check from any cause. For the following spring repot into a 12 or 15 inch pot, and again in summer into a 15 or 18 inch one, as the case may be. It will not require anything more till the following summer, when the inert soil may be picked off round the ball of the plant, repotting in the same-sized pot. Adiantums do not root deeply, and accordingly require the pots well filled up with drainage, more especially so in the case of large-sized pots. They are all more or less adapted for house and table decoration; Farleyense, cuneatum, amabile, tenerum, and concinnum, being best adapted for this purpose. The subjoined list of species contains only those with which we are acquainted, and is not given as being by any means complete: however, it may be of use to some whose experience is not so large as our own.
Farleyense, when well grown, holds first place in its class. It requires a very strong moist heat to do it well, and to be shaded from the sun; treated thus, with liberal pottings, it is a fast grower, and develops large fronds and beautiful pinnce. Cuneatum is the commonest of all, and is one of the most useful plants in cultivation. It succeeds in any temperature, from that of a greenhouse to that of a very hot stove, which latter is best for getting up plants for exhibition. Tenerum is an exceedingly graceful species, and very fine for table decoration. Tenerum scutum, when well grown, produces very large fronds. Both these species require a moderate stove temperature. Colpodes is a remarkably delicately-fronded species, the young fronds being delicately tinted; too much damp, combined with a temperature as low as 60°, is injurious to it in winter. Decora, a congener of cuneatum, is a most useful sort for cutting from, and of the easiest cultivation. Amabile, in general appearance, resembles the old assimile, and is one of the prettiest and most graceful of Terns. The drooping character of the fronds, the delicate black rachis, the almost transparent pinnte, light green in colour, and its obliging behaviour under cultivation, all combine to make this a first-class species.
Capillus-veneris, indigenous to Great Britain, though very rare, requires a place under glass, and is suitable for exhibition purposes. Capillus-veneris Dapbnitis we cannot say much about, as our plant is very small as yet; so far, it looks more curious than beautiful. Sulphureum has the under sides of the pinnas covered with a golden-coloured powder; it likes plenty of heat. Excisum multifidum is one of these crested abnormalities which have become so common amongst Ferns of late years. It thrives best in a strong heat. Excisum Leyii is one after the same style, though rather more divided. Macrophyllum is a most distinct species; the young fronds are tinted: requires a strong heat, and to be shaded well from the sun. Concinnum is another distinct species, and most beautiful; the fronds are arched as compared to drooping, and have a character entirely their own. It is seldom seen in good condition, though it is not difficult to manage. Concinnum latum is broader in the fronds, stronger and more erect in growth, though not nearly so attractive as the last; it makes a good plant for exhibition. Trapeziforme is one of the finest for exhibition purposes. It does not require a strong heat, but it must have liberal treatment at the root to induce it to throw up large fronds.
Sanctae Catherinae is another fine thing for exhibition, throwing its fronds up thickly, and in great numbers. Formosum is one of the very freest growing and useful of Adiantums: a strong-grown plant is most effective. It is also one of the most useful for cutting from. Curvatum is another indispensable species: it is quite a treat to see a good plant of this. The fronds grow in sets, one set growing a few inches above the previously developed one. The pinnre are curved backwards, and in the young state are of a metallic olive-green colour. Curvatum must be grown in dense shade to prosper, the least glimpse of sun effectually destroying its beauty. Setulosum is a small-growing and lovely species, the fronds having the same metallic lustre as the last. Pedatum is a handsome cool-house species, and suitable for exhibition. Hispidulum is another of the same section; the young fronds are coloured: altogether a nice species, requiring a stove temperature to do well. Pubescens and diaphanum are in general appearance much alike, though quite distinct; they are both useful for cutting from, and do best in a stove. Caudatum is distinct from all others we know.
It may be grown in a basket or a pot suspended in the stove.
It must be borne in mind that although this genus does not object to a humid atmosphere when growing, yet they decidedly object to being syringed: they ought to have a side of the stove, or wherever they are grown, entirely to themselves, associating Gymnogrammas and Nothochlasnas with them. Green-fly sometimes infests them; in such cases gentle fumigations with tobacco must be resorted to; but the more delicate species especially are averse to tobacco, therefore great caution is necessary in using it. Scale will be troublesome only if it is allowed to prosper on other plants in the same house, and must be carefully destroyed, without injury to the fronds.
R. P. B.