Ferns
Whether viewed collectively as plants of extreme beauty and interest when grown as specimens, or for their general usefulness in arrangements with flowering subjects, Ferns are indispensable, and possess attractions peculiar to themselves. The very large number of genera now in cultivation, including native and exotic, stove, greenhouse, and hardy, supply means of making a suitable selection for every requirement. Remarkable variation in size and habit is most noticeable among Ferns, apart from the extreme conditions under which the different ones succeed. The now almost universal use of plants and cut fronds intermixed in floral decorations, has led to their production in immense quantities annually, to supply the demand for a few of the more popular of genera and species that are suitable for the purpose. The popularity of Ferns is ever increasing, as ideas regarding the supposed difficulty in their culture, and the amount of heat required, have been of late considerably modified, many being found to succeed in much cooler positions than was at one time supposed to be suitable. The majority require more or less heat, but many that are kept in a high temperature would be healthier and do better in a somewhat cooler one. Hardy Ferns are, perhaps, more plentiful in varieties than in distinct species, although the latter are numerous. Both are interesting and useful for various positions outside, and are in combination extremely diverse in general habit. It will be impracticable, on account of space, to describe here separately the cultivation of every genus referred to this heading. The following general remarks respecting the treatment of the different groups, according to the amount of heat or other special requirements, with cultural notes on some of the principal genera, may, however, with the description accompanying each individual genus separately, prove sufficiently suggestive for the treatment of all.
PROPAGATION. This is effected in various ways, according to the different habits or modes of growth exhibited in the several types. The most general plan of propagation is by spores, but will many species it is at best difficult, and in many cases quite impossible, to obtain these, and raise plants from them successfully. The most popular of Ferns, Adiantums, and several species of Pteris, are easily raised in immense quantities from spores. All Ferns that form several crowns may be increased by division; and those with creeping rhizomes, like many of the Davallias, are easily perpetuated either by layering the points or removing portions that have formed roots. A few-Aspleniums particularly-produce small bulbils along the upper portion and at the end of the fronds, and these eventually form plants, if removed and placed in soil. The increase of filmy Ferns is, in most cases, an extremely delicate operation. Plants imported from their native habitats, with every care taken in transit, frequently do not live to become established, even if they arrive in fairly good condition. These may be propagated by carefully made divisions of such plants as become established and grow well. Three Ferns are imported in quantities, and a large proportion generally succeed. Young plants may be raised from spores, where obtainable, but it would take many years for them to grow to the size of imported steams. The spores of many of the Tree Ferns germinate freely enough, but, under cultivation, never advance beyond the prothallus stage. Spores. The fronds from which spores are required should be carefully examined at frequent intervals, when they are beginning to ripen, in order to obtain the spores at the proper time. When the sori begin to turn brown, the fronds should be cut and allowed to dry in close paper bags. The sooner they are sown after being kept a few days, the better, as any part of the year is suitable for the operation, early spring being, however, preferred for the majority of species. They should be sown in pots or shallow pans that have been half-filled with crocks, the remainder being filled to within 1/2in. of the top with a mixture of fine sifted loam and very small pieces of crushed brick. An even surface may be obtained by pressing firmly with the bottom of another pot. The soil should then be watered and allowed to drain before the spores are sown, as by watering afterwards the latter might be washed away. Fern spores are extremely minute, and, consequently, should be scattered very thinly over the surface of the soil, pieces of glass being placed over the tops of the pots. The pots. The pots should be stood in saucers of water and placed in a close frame of a propagating house, being kept shaded at all times during sunshine, but not in dull weather. Laying pieces of paper on the outside of the frame, and removing them when not required, is a handy method usually adopted. When the spores are sufficiently grown to be visible as very minute plants-a stage that varies considerably, with different Ferns, in the time taken to reach it-they should be very carefully pricked off in pots of similar soil, filled, this time, level with the top. Very small patches must be taken on a stick, having the least notch cut in the end, and they should be merely pressed into the new soil about 1in. apart. No water should be applied overhead until the little plants have been pricked off some time, and have formed fronds. Sufficient will have been supplied by the pots being placed in water, and the moisture contained inside the frame, which is not usually one will bottom heat. Adiantums are frequently fit for pricking out in a month or six weeks after being sown. These, or any others, should be returned to a similar frame afterwards, and kept close until small plants are established, when air should be very gradually admitted. It conditions are suitable, the young ferns grown fast in the spring or summer; and the next shift should be into pots singly, or, in the case of Adiantums, each little bunch of plants may be treated as one, for quickly forming decorative subjects. Raising Ferns of any description from spores is an exceedingly delicate operation, and one that requires considerable care and attention to accomplish successfully. It frequently happens that spores obtained from fronds of any particular Fern which may have been kept separated from others, will, when sown, apparently produce a host of young plants that eventually are found to belong to another and commoner species or genus. The fact of spores being so light as to be removed and carried by a breath of wind, may account for the presence of the commoner one, that would probably overgrow the other; or good spores of the one desired may not have been present at all. The mode of treatment above described applies to the raising of both stove and greenhouse Ferns, and, with the exception of a cooler temperature, will be also suitable for the hardier species. Young plants should be potted on before they are very full of roots, as, if allowed to become starved in the younger states, it is a long time before they recover.
Divisions, &c. the best time for dividing Ferns, or for propagating by means of the creeping rhizomes, is just before growth commences, in February or early spring. It is best not to divide too severely, as small plants are much better obtained from spores if that plan be practicable. Rhizomes should be pegged to a piece of peat, or on small pots of soil, and allowed to form roots before being detached. The insertion of the little bulbils in pots of soil, in a close frame, will soon increase the stock of those species which produce them.
STOVE FERNS. An idea is often formed that tropical Ferns require a great heat at all times, with constant heavy shading in summer, and but little air and that season as well. This is altogether a mistake, as the result is invariably weak, elongated fronds, that are at once subject to all insect pests, and are rarely strong enough to stand any change to which it may be necessary to subject them. Binds on rollers, that admit of being let down and removed as desired, should be used. Although Ferns delight essentially in shade and moisture, both may be carried to an excess, especially in winter time, when all should be at rest. The growing and resting periods are as necessary with many Ferns as with flowering plants, although the ripening in autumn, as ordinarily understood, is not of so much importance. The general arrangement of stove Ferns greatly depends on the structure and space at command. Adiantums, Davallias, Gymnogrammes, and Platyceriums, may be cited as examples for situations where most light is obtainable, and only a thin shading applied in sunny weather; while Acrostichums, and the stove species of Aspidium, Asplenium, Nephrodium, and Pteris, succeed indarker or more shady positions. The introduction of Tree Ferns produces a fine effect where there is sufficient height, but, if planted out, these soon require much more room than it is possible to obtain in the majority of stoves. By growing them in tubs, and plunging, a more suitable appearance is presented, the restriction of the roots having a corresponding effect on the rate of growth in the fronds. Any repotting should be performed before growth commences, as, if it is deferred till afterwards, many of the young fronds will become crippled. For stove Ferns, a growing season of eight months should be allowed, namely, from February till September inclusive. The other four months should be the resting period, when a night temperature of 50deg. To 55deg. will be sufficient, with a minimum rise by day of 5deg. more. A drier atmosphere must also be maintained, and less water applied to the roots, at the same time avoiding an extreme in the latter case. When growth commences, the minimum night and day temperatures may be gradually raised, until in summer, the former will seldom go below 60deg. or 65deg. Air should be carefully admitted, and plenty of water applied to the roots and amongst the pots, with a view to the production of fronds of moderate growth and good substance-conditions not to be insured by a close atmosphere and very high temperature. Light syringings may be occasionally applied to most stove Ferns in summer, but too much has a tendency to weaken many of the fronds. Adiantums, Gymnogrammes, and, generally speaking, species with powdery or very hairy fronds, should not be syringed at any time. The whole beauty of Ferns consists in the full development of the fronds; and if these are to be kept in good condition afterwards, until the new ones of the following year appear, it is important that the plants be kept properly watered and subjected to treatment, in summer, calculated to produce a moderate amount of solidified growth, that, in the autumn, should be thoroughly ripened by the admission of sun and air to the structure in which the Ferns are grown. If, as before recommended, blinds on rollers are in use for summer shading, they will, of necessity, have to pass over the roof ventilators. This has an advantage both of breaking the force of the wind and preventing an undue evaporation of moisture from the inside. If found to fit too closely, blocks may easily be fixed to the rafters at the top, to keep the shading a little open.
GREENHOUSE FERNS. A large number of Ferns, usually grown and treated as stove subjects, succeed equally well, but do not grow quite so fast, in a greenhouse temperature, and, wherever employed, either alone or in combination with flowering plants, are much appreciated. A more interesting structure than a cool Fernery attached to a conservatory, when well stocked and carefully arranged, can scarcely be imagined. The majority of Ferns succeed in comparatively small pots, and are consequently well suited for mixing with other occupants of the side stages. The stronger-growing ones are also well adapted for planting in permanent beds or amongst other plants, such as Camellias, &c., where not too much crowded, the partial shade and moisture suiting the Ferns admirably. Nearly all Adiantums do well under greenhouse treatment in summer, but must be removed to warmer quarters for the winter. Many Nephrodiums and species of Pteris, particularly P. longifolia, P. serrulata and its varieties, and P. tremula, do better planted out in a cool structure than anywhere else. Lomaria gibba, and other species, are among the most beautiful of cool decorative Ferns, and the same may be said of Asplenium bulbiferum, and others from Australia and New Zealand: Davallia conariensis, Nephrolepis exaltata, Onychium japonicum, Woodwardia radicans, &c. Todea Barbara is well adapted for planting out in a position where considerable space can be allowed for its large fronds to develop; it may also be grown in pots, any cool house, or even a sheltered position outside, with protection in frosty weather, suiting it. The genus Gleichenia contains many beautiful species that do not require much heat, excepting two or three from tropical countries. If grown in large pans, and tied out with neat stakes, beautiful specimens maybe obtained under greenhouse treatment. These are propagated by layering the slender rhizomes, or by separating rather large pieces from established plants, and potting separately. The shade necessary for ordinary greenhouse flowering plants in summer will also be suitable for Ferns, plenty of moisture being at that season supplied at the roots and, with few exceptions, such as Adiantums, overhead.
FERNS SUITABLE FOR BASKETS. Hanging baskets, either in the stove or greenhouse, are, at all times, an additional attraction, and the elegant and graceful habit of many Ferns constitutes them excellent subjects for use in that way. Baskets, made in different sizes, of stout galvanized wire, may be suspended from the roof, and, if carefully watered, the plants will succeed extremely well in most cases. Many are seen to much better advantage, especially those with long and drooping fronds, than when grown in pots for stage decoration. Some of the fast-growing Selaginellas are most useful to plant with basket Ferns, for covering the soil or hanging down. Adiantums will, again, be found very attractive, particularly A. caudatum, A. cuneatum, A. graceillimum, and A. Moorei, with Asplenium Belangeri, A. longissimum, and A. viviparum; Davallia dissecta and D. pallida; Gymnogramme schizophylla; Nephrolepis davallioides and N. Exaltata, and many others that are of somewhat similar habit. Nearly all of these are amenable to cool-house treatment in summer.
FILMY FERNS. These constitute a distinct class, requiring different treatment from any other members of the family. Very few do well in an open house, as sufficient atmospheric moisture cannot be obtained. On the whole, they do not require much heat, being often found to grow stronger and keep in better health when cultivated in close cases, in a cool Fernery, than when placed in similar cases in the stove. Filmy Ferns should never be watered overhead, but the stones and moss amongst which they are generally grown must be kept continually moist by having water poured on from the small spout of a can. This, when evaporating inside the inclosed case, becomes condensed on the extremely numerous divisions of the fronds as represented in the majority of species, and its continued presence there invariably indicates good health and the frequency with which it will be necessary to give water. Pieces of rough fibry peat and loam, with charcoal and sphagnum, are most suitable for Filmy Ferns. Nearly all that grow in soil succeed better when planted amongst stones, while those that form rhizomes should be placed on blocks of peat, dead pieces of Tree Fern, &c. They must always be shaded from sunshine; and not much light is required at any time. The difficulty generally experienced is in establishing the plants; when once they begin to grow and increase, the treatment is, in most cases, simple enough. Hymenophyllum, Todea, and Trichomanes, are three of the principal genera among Filmy Ferns. Todea superba is a vigorous species, having large fronds of a filmy texture; and T. hymenophylloides is smaller-growing, but very desirable; both being beautiful and more easily grown than the majority of the plants in this section. WARDIAN CASES. Ferns used for decorating Wardian cases must only include those of small or moderate growth, the space inside being very limited. The system admits of more moisture being kept round the plants than would be possible in an open room where the air is frequently dried either by burning gas or a fire. It is always important, in changing plants in these cases that become unhealthy, to substitute others from a cool house, as, if insufficiently hardened, the young fronds soon wither and die. Ample drainage must be provided, and, if plants in pots are used, the latter should be covered with growing sphagnum. Ferns in Wardian cases keep fresh and attractive for a long time if they receive proper attention. Cases somewhat similar in construction, may be used in cool houses for small collections of Filmy Ferns.
TREE FERNS. Considerable space and lofty houses are essential for growing and exhibiting Tree Ferns in their true characters. In Ferneries of limited size, where a few are cultivated, it is best to restrict their root growth in large pots or tubs, which also allows of their being re-arranged occasionally when overgrowing other smaller plants. In very large conservatories, a few permanent specimens planted out in well-drained borders, succeed, perhaps, better than in any other position, and always present a majestic appearance unexcelled by any other plants similarly employed. Alsophila australis and A. excelsa, Cyathea dealbata and C. medullaris (the latter is probably the tallest-growing of all our cultivated Ferns), with Dicksonia antarctica, are the best for culture in the greenhouse. All these may also be used in sub-tropical gardening outside in summer, in sheltered, shady places. There are many stove species of Tree Ferns, all of which are beautiful, and worthy of cultivation in large heated structures. They all, especially Alsophilas, delight in plenty of atmospheric moisture and shade. The stems of imported Tree Ferns should, on their arrival, be covered with damp moss or canvas, and be kept moist by syringing until the new fronds appear. The time this takes varies according to the condition in which they arrive, and the season. When the head of fronds is established, the covering may be removed from the stem; but frequent syringing in summer time is of the highest importance, as by far the greater portion of the stems of many is literally a mass of roots requiring a quantity of water. Tree Ferns, in bad health, may often be greatly improved by covering the stem from the base to the fronds with 1in. of sphagnum, and tying it on with string. If kept moist, the roots soon fill the moss, and the stem is thus considerably enlarged. Tree Ferns that are dead on arrival may be utilized by covering with epiphytal or other small Ferns for stove or greenhouse decoration the top being scooped out, and a free-growing variety with a pendent habit inserted and planted in soil; others being fastened on the side with blocks of peat and some small wire. HARDY FERNS. These are all attractive, and the majority succeed best when planted on rockwork in a shady situation, sheltered from high winds. A great diversity, both in size and habit, is represented by the British species and their innumerable varieties, apart from those introduced for North America, Japan, &c. Many suitable positions for hardy Ferns may be found in most gardens where their culture is not now attempted. They should have a good depth of soil, and plenty of water in summer. In the case of a collection, a pile of rockwork, built with rough stones, allows of a place being selected for all, according to their size and habit. A good clump of those which are plentiful should be planted together, and sufficient space allowed them to grow and develop, as in this way the different characters are much better shown than when only single plants are used. Attention in their arrangement should also be directed in placing the evergreen and deciduous species irregularly throughout the space covered, so that the whole may be, more or less, furnished at all seasons. In building a rockwork for hardy Ferns, the requirements of the plants must be the main object, large, well-drained pockets being insured in preference to the appearance of the stones, that are, in great part, hidden by the fronds. Loam and peat, with a quantity of crushed stone or brick, intermixed and used round the roots when planting, materially assist them to become established. The Royal Fern (Osmunda regalis) is one of the most handsome, and succeeds best when planted in a partial bog, or by the side of water.
UNDERGROUND FERNERY. This is an interesting structure, to be seen only in a few places, where the owners bestow special attention on Fern culture in its various aspects. It consists of a large cavity, dug in the middle of a hill, and covered with sheet glass, the hill itself being surrounded on the summit with trees. A flight of steps communicates with the interior, where Ferns are grown on the inside of the cavity in prepared soil, narrow paths or stepping stones being provided on which to walk amongst them. A fountain, or other arrangement for water, supplies the necessary moisture. The plants do not require artificial heat, as they are not much affected by fluctuations of temperature outside, and a subdued light is constantly admitted by the glass overhead. A view of an underground Fernery is shown in Fig. 7. SOIL, POTS, &c., FOR FERN CULTURE. Nearly all Ferns require a quantity of water in summer, and rarely need to be dry at the roots at any season, consequently a very important matter is that of efficient drainage. Anything like a sour or waterlogged soil is either detrimental or fatal, even to those which are not quickly injured in other respects. Success in the cultivation of established plants depends more on this, with careful watering, temperature, atmospheric moisture, proper shade, &c., than on any soil in which they may be grown. Adiantums, for instance, succeed well either in peat or loam alone, the texture of the fronds being firmer in the latter instance, and presenting apparently the only difference. A large proportion of peat was at one time considered necessary for all Ferns, but the superior qualities of leaf soil in their culture, where it can be obtained, have been more fully recognized of late, with considerable advantage to the plants. Soft sandstone, mixed with the soil, tends to keep it porous, and suits some varieties better than others; and charcoal may be used freely with all. The different habits will often suggest the mode of treatment required. It will not be far wrong to say that a compost of half loam, to which is added an equal quantity of leaf soil and peat combined, and sufficient charcoal, small pieces of crocks, or sharp sand, to keep the whole open, may be used successfully for all Tree Ferns and any established plants of Adiantum, Aspidium, Asplenium, many species of Davallia, Gymnogramme, Lomaria, Nephrodium, Pteris, and any others of similar habit. The species of Acrostichum, Devallia, &c., that form slender rhizomes, must be attached to something on which they can grow. A good plan is to cultivate in pans, placing an inverted pot or a piece of Tree Fern stem in the middle, and then building a small mound on the top with lumps of peat, loam, and sphagnum, afterwards fixing the rhizomes to the surface with small pegs. Epiphytal Ferns, of which Platycerium is a well-known and distinct genus, often succeed admirably if fastened with a little moss and peat to a block of wood, and suspended in the stove. They should be kept rather dry in winter. Similar composts, as advised above, if passed through a sieve, may be used for young plants. Ferns succeed in pots comparatively small for the size of plants, if due attention is given to watering. Small pots have also an advantage in appearance; and any deficiency in the quantity of food contained in the soil may be supplied with applications of manure water during the growing season.
Insects. Ferns, especially those under stove treatment, are liable to be attacked by several destructive insect pests. Thrips are their greatest enemies, causing irreparable damage to the fronds. Frequent fumigating becomes a necessity; this must be done lightly and with the greatest care, on account of the tender growth. Any Aphides will also be destroyed by the smoke at the same time. Brown and White Scale are sometimes plentiful, and these must be removed by sponge or brush. The first-named is the one most common on Ferns, the other, fortunately, being more rarely found, as, when once established, it is very difficult to eradicate. Mealy Bug must be destroyed in a similar way to Scale, as an insectieide strong enough to kill either, will, to say the least, be dangerous to use, in consequence of causing injury to the fronds of delicate texture. In winter, when the plants are at rest, the whole should be examined and cleaned, as stronger measures may then be adopted, by fumigation or the use of an insecticide, than would be safe after growth commences. At all times, a watch must be kept for the first appearance of insects, as proper means for destruction then applied are always more effective in their results.