On the cultivation of the plants belonging to the natural order of Proteeae/On the cultivation of the natural order of Proteeae
ON THE CULTIVATION OF
THE NATURAL ORDER OF PROTEĒÆ.
The genus of Protea, it is left in the work of that indefatigable traveller, Professor Thunberg, contains 60 species, 25 of which he himself discovered, and all which he probably saw growing wild at the Cape of Good Hope: these he described after his return to Europe, from dried specimens, but it must be confessed very imperfectly; nevertheless his specific differences have been copied, almost word for word, by Professor Willdenow. In the Chelsea garden, still containing many venerable relics of Philip Miller's labours, only 3 species had been cultivated previous to the year 1770, about which time several were raised in his Majesty's garden at Kew, from seeds collected by the late Mr. Francis Masson; and a still greater number both of known and unknown species, have since been collected by Mr. James Niven, many of which have at length flowered in this country, and no where more luxuriantly, than in the collection of my late master, George Hibbert, Esq. at Clapham, by whose liberality most of them are now in my possession.
Besides these treasures, our gardens have been enriched with various plants allied to them from New Holland, which being often singular in their foliage, are sought for with avidity by most collectors; and their fructifications being now better understood from an examination of living specimens, it appears that they constitute many genera, some of which, as Dr. Sims observes, are already accurately defined, by the author of the Paradisus Londinensis. His names, with those of other scientific botanists, will therefore be adopted, in the following detail of the method of cultivating this tribe of plants, which succeeded so well at Clapham; and I shall feel very proud, if from the hints now given, they are preserved longer, or rendered more plentiful among us.
As in all cases, it is the business of an intelligent gardener, to imitate nature, as far as may be practicable, the soil and particular situation, in which each species grows wild, has never been omitted, when it could be ascertained; many delighting in dry rocky places, while others will not thrive without richer and more loamy earth; some again require schist, and several a great portion of sand.
To avoid repetitions, the general method of treating the whole Natural Order is first given, any exceptions to this, or other necessary remarks, being inserted under the respective species to which they apply. In enumerating them moreover, anxious to find out distinctions that might be useful to an unlearned gardener, rather than to the scientific botanist, their generic and specific characters have in no instance been drawn up, on the mere authority of preceding writers, or without examining the plants themselves; neither are they arranged systematically, but according to the natural affinity, which in my humble opinion they have to each other.
The Soil in which I have found at least two thirds of these plants succeed, is a light soapy loam, mixed with a greater or less proportion of sand. Chuse a spot that has never been pared or burnt, especially on higher ground not inundated in wet seasons; and in digging the earth, only take from 5 to 6 inches of the top, including the turf. Let this earth be laid in heaps, in some dry airy part of the premises, placing the turf downwards: in 6 months, (or if longer the better,) it will be fit for use. To prepare it for sowing seeds, or potting, it is necessary to pass it through a sieve; that for seeds, and small young plants, should have meshes, or openings, about ¼th of an inch diameter; but that for larger plants, may have openings ½ an inch diameter.
The pots in which vegetables ought to be cultivated, not even excepting some aquatics, should neither be baked very soft, nor very hard; the former are of short duration, unsafe to carry about, and preserve valuable plants in, being so liable to break; the latter being less porous, often retain moisture, and exclude the air so completely, as to render a plant unhealthy, if not actually kill it. The roots of many species in this Order, delight to enter the veins and cracks of rocks, in search of moisture; which may with little trouble be imitated at the time of potting, by placing among the earth, large pieces of broken pots, or sand-stone, free from Lichens and Mosses. These large broken pieces, besides the usual drainage, will also prove beneficial, in carrying off any superabundant moisture, from injudicious watering, or heavy and continued rains: nor will they be found less useful in very dry summers; for these hard yet porous substances, retain a kindly moisture when covered with earth, a much longer time than the earth alone would; consequently the small fibres which cling to them, receive nourishment in much the same way, that nature affords her liberal assistance, where they grow wild.
Old pots should never on any account be used, unless previously well washed and scrubbed with a brush inside and outside, after which they must remain till thoroughly dry; for by use, their pores become so obstructed with Confervæ, and other minute vegetables, as to be very injurious to plants growing in them/ It is also a point worth attending to, especially in extensive collections, to keep all pots not in use under cover; for by being exposed to the open air they are soon covered with millions of flying seeds of cryptogamous plants, which vegetate the instant, that the pots are moistened.
In the neighbourhood of London, garden pots are made of two shapes, and denominations, viz. upright and flats: they are sold in casts of the following numbers, 60, 48, 32, 24, 16, 12, 8, 4, 2, besides extra sizes: each cast is the same price, and of the cast 60, three sorts are made; thumb 60s, small 60s, large 60s.
When you prepare a pot for use, first place a piece of hollow broken garden pot, with its concave side downwards, over the hole in the bottom; I object to an Oyster shell, though ever so hollow, it being hard, and less porous than unglazed earthern ware. Then proceed to drain it more effectually, by filling it about a third part with smaller pieces of broken tiles or pots. In making these drainings, they should be shaken in a sieve, to take out all the smaller pieces, as well as dust; and by using sieves of different meshes, two or three sorts of drainings suitable to different sized pots, will be obtained with little trouble; for they require to be effectually drained, even when planted in the smallest 60s. The coarse riddlings of the earth in which they are potted, may be used as drainings for very large plants; such refuse is also particularly proper for those species, that require more moisture than others, which the flagging of their leaves in hot sunshine always indicates.
For sowing seeds, the pots called flats are most suitable, of the casts 40 or 38. After draining these, fill them up to about an inch and a half below the top, with moderately fine sifted soil, upon which add about an inch of still finer sifted mould. Then make the surface quite even, with a piece of lath bent, which should be used like a Plasterer's trowel. Observe carefully however to leave the earth as light as possible.
The best season for sowing seeds is from December to March, as they will then produce strong plants before the following winter; but it is by no means intended to say, that they will not succeed at other periods, and it is a common practice with most gardeners on the receipt of fresh seeds, to make trial with a few, whenever they arrive. If sown in the latter end of summer, or in autumn, the young plants will require a particularly favourable exposure, and dry shelf that receives all the rays of the sun during winter, otherwise they will too frequently become sickly, and damp off.
In this Natural Order, we find fruits and seeds, of very different sizes as well as shapes, but fortunately they are so similar in species of the same genus, that a gardener who is not learned in botany, after having seen one of each, may have a tolerable guess, at the genus of any new ones, he receives from abroad. In sowing them, much must be left to the discretion of the gardener; generally they ought not to be buried deeper than half an inch in the earth, nor closer to each other, than from a quarter of an inch to an inch, according to their size; taking special care to place them regularly near the edge of the pot, where the circle is largest; for there if any where they will certainly succeed, not only often vegetating sooner, but thriving better after they do vegetate than in the middle, probably in consequence of air and moisture there percolating more freely. After the seeds are sown, water the earth gently through an exceedingly fine rose, so as not to disturb its equality of surface, and let it be given very sparingly at first, as hasty watering upon fresh sifted mould generally occasions the surface to cake, then place the pots level upon the stage of a green-house exposed to the full sun. At night, and in wet weather, cover them with strong brown paper, to prevent drops of water from the roof making holes in the mould, which however should at all times be kept moderately moist: also, let all those sown between May, and September, be so shaded as to be quite in darkness from about 6 o'clock p. m. to the same hour a. m., for in our long days of summer, too much light and heat prevents many seeds from sprouting kindly.
Some of those seeds which are covered with hard shells, such as Protea Argentea and others, do not always vegetate the first year after sowing; on the contrary, an instance has been known of a bag of seeds furnishing a succession of young plants for many years, and it is hoped that the particulars of this curious circumstance, may be in some degree amusing. Nearly twenty years ago a respectable friend of mine, had the good fortune to obtain about a quart of the seeds of Protea Argentea which had been procured at Cape Town by a trading Captain, to feed the turkies, on board his ship; part of these were sown in two pots, and in order to forward the growth of the seeds, one pot was placed in a hotbed, with cucumbers, where it remained during summer, without the least signs of growth in the seeds; the other pot was placed in a cool situation, where several plants made their appearance, and became tolerably strong by the autumn, when in transplanting the plants, the remaining seeds appeared fresh as when first sown, and on examining those sown in the hotbed, they proved the same, which gave cause to the whole being washed and carefully preserved until the following spring, when they were again sown and placed in a cool situation: more plants made their appearance during summer, but as the seeds did not all vegetate, they were again examined, and being found fresh, they were washed, and preserved as before: thus with a few additional ones, an annual sowing was continued, and a regular supply of young plants obtained, for many succeeding years; and the experiment shews, that those hard shelled seeds may be preserved for many years, and should never be thrown away, without previously examining them with care; but I think the whole family have a great dislike to be sown in artificial heat.
These seedling pats must have air admitted freely, when it is not frosty, more or less according to the external temperature of the atmosphere. In May, June, and July, after the plants appear, it will be necessary to shade them from the hottest rays of the sun during the middle of the day; in very brilliant days, from 10 o'clock a. m. to 4 o'clock, p. m.; but as the sun declines in height, and the plants gain strength, expose them fully, both to air and sun, at all times.
I believe the best time to transplant the seedlings, is as soon as their cotyledons are fully grown, and the future stem beginning to elongate; for they have then few or no fibres attached to the tap-root, nor have I ever found them checked by this early removal: it should unquestionably never be delayed later, than when they are from an inch to two inches high, potting them singly into small 60s, and taking great care, not to break any lateral fibres they have then made: this operation should also be performed in a close shed where the wind does not blow, watering small parcels together through a fine rose as you proceed, and when all are finished, place them in such a frame as is used for Cucumbers and Melons. Keep them rather close, as well as shaded with a thin mat when the sun shines, for a week or ten days, until they have struck fresh root, after which they must be gradually exposed to the open air.
About the end of September or beginning of October, according to the mildness of the autumn, the plants should be cleaned and moved into their winter quarters, which, both for those transplanted, or any sown later remaining in seed pots, should be the most light and airy part of the greenhouse. Look them over every morning between 9 and 10 o'clock, watering such as stand in need; at this season it should be done, by pouring the water gently upon the earth near the edge of the pot, so as not to wet their stems and leaves more than can be avoided. Whenever dead leaves or branches appear, let them be removed, keeping the surface of the earth at all times free from Mosses, which are the most pernicious of all weeds to many of these plants, especially when they attach to the base of their stems.
Air is indispensably necessary for them at all ages: after they are housed in autumn, if the weather continue temperate, admit it both day and night, by keeping off the glasses entirely, or in large houses all the windows and doors open. When there is any appearance of frost however, shut up the frames and houses, early or late in the afternoon, according to the degree of cold, opening them the following morning, as soon as the temperature rises to 36 degrees of Fahrenheiy's thermometer. In the depth of winter, when the frost is intense, cover the frames with mat, as well as the houses where it can be done conveniently; and by the help of fireheat, keep the temperature within, as near as may be to 34 degrees of Fahrenheit, during the night. It should never be higher than this in frosty weather during the night, for though it is not adviseable to let the temperature sink lower, very few of these plants will be injured, by occasionally experiencing 32 degrees of cold at that season: as these plants in general in their native state are subject to great violence of winds, particularly those that are inhabitants of mountains, which may in general be known by their robust and tree like habit, they should all be placed, so that the wind can circulate freely, not only amongst the branches, but also round the stems and pots, which in my opinion is of the utmost consequence to preserve health in the plants; and by close attention, I have often fancied an improved appearance between morning and evening, after a full exposure to a brisk wind during the daytime.
In one of the largest and most healthy collections of Cape and New Holland plants in this country, exposed on a bleak hill, the temperature of the principal house, during the months of December, January, and February, was always suffered to sink to 32 degrees of Fahrenheit during the night, if the external air was so cold; yet none of the plants usually kept in green houses suffered by it, and the plan there pursued, for sixteen winters, was never to permit a plant to grow at all during that season, if it could be prevented; bringing them out in spring, as nearly as possible with the same foliage, which they had when housed in autumn.
In training and pruning these plants, the knife must be used with caution; as they advance in stature, such as are weak or straggling, ought to have the principal stem neatly tied up to a stick, and when they are from two to three feet high, by cutting off the tender branches, they may be formed into narrow or spreading heads, according to the taste or caprice of the owner. At Clapham, they were generally left to assume their natural direction and form; only removing any very luxuriant branches, when ill placed, before they became old and woody. Nothing injures these plants more than crowding them close together; and I cannot avoid the hazard of giving offence to some of my best friends, by saying, that in many collections about London, both large and small, the wisest thing the owners could do, would be to order a third part of their plants, to be cut into faggots, for lighting the fire, of the greenhouse, in frosty weather.
A large portion of water is necessary for most of these plants in dry seasons; and it should if possible be such, as has been exposed to the sun and air, several days. In the excessively hot weeks of summer, give it them every evening about sunset, so as to soak the whole pot thoroughly, but in such weather, never apply it in the middle of the day, if it can be avoided; for I have seen plants killed by watering them, when the earth and pot were in all probability, at that instant heated by the sun, to more than 100degrees of Fahrenheit. If by accidental neglect of watering the preceding evening, any plant is discovered flagging so much in the which fit the pots intended to be used, exactly. It requires more skill to know, when and which part of a branch will soonest strike root, than almost any other part of their management, nor is it possible perhaps to lay down any other general rule, than that the branch should be well ripened: after that I believe, the sooner it is taken off the better. When the parent plant is dying at the root, or damping off near the bottom, which many of these plants are subject to, when least expected, the ends of its branches will frequently all succeed, as I have already experienced in Leucadendrum Hypophyllum, and others. I can only account for this, from the state of rest and inactivity that the branches had been thrown into; the descending sap imbibed by the leaves, being arrested, and overflowing in those parts of the stem yet living, so as to heal over the wound more rapidly, and form that callosity at the bottom of the cutting, from which the young fibres commonly first issue. The leaves of all cuttings should be taken off with a sharp knife as far as the cutting is meant to be planted in the sand, taking care not to bruise or tear the bark, and to cut the bottom perfectly even, just under the insertion of a leaf. Contrary to the practice in sowing seeds, I think it is of great importance to press the sand in the pot very firmly down upon the drainings. After marking the dimensions of the Bellglass upon the sand, then proceed to plant the cuttings with a small blunt dibble, just so deep, that its base may rest solid without the smallest hollow under it, finishing one at a time, by pressing the sand firmly round it. When all you intend to plant in one pot are finished, give a moderate watering, and as soon as the leaves of the cuttings are dry, place the Bellglass firmly over them.
In general, cuttings of Proteas have not succeeded; but, after repeated experiments, I am of opinion, that the failure has been occasioned by stripping off, or shortening, the leaves: and I have found, that, if the leaves are only taken off from the part which is inserted in the earth, and those left uninjured which are above the surface, the chances are in favour of their striking root; while the contrary is the case, where the whole of the leaves are taken away, or shortened.
If cuttings are judiciously chosen, they will succeed in various situations; such as are taken off in spring, will do well, in general, either in, a warm part of the greenhouse, or in cucumber heat; those taken off in summer, may he placed in frames, either with or without artificial heat, especially in close warm aspects, shading them with a thin mat, when the sun is powerful; those cuttings taken off in autumn, or winter, should be placed on elevated shelves, in the hothouse. From time to time, as the Bellglasses become foul, wipe them clean, taking the opportunity to do this always when they are moved for watering, so as not to disturb the cuttings unnecessarily. If any die, or become mouldy, remove them instantly, for their contagion would spread rapidly.
In the time required for sending out roots, different species vary exceedingly: some are furnished with fibres in two or three months, while others, especially the hard-wooded species, require six, nine, or twelve months, nay from this period, even to two years: but, whenever the fibres begin to issue, it will be visible in the cheerfulness, and deep verdure of the leaves, or by their buds swelling; and as soon as a fresh shoot pushes, the Bellglass must be raised by degrees, and at length entirely removed, hardening the cuttings to the full air; after which they ought to be treated like seedlings.
Many species of this tribe of plants, ripened seeds at Clapham; but I was careful to promote their impregnation, by repeatedly rubbing Pollen upon the Stigma, and exposing their flowers as much as possible to the sun, never suffering any wet to fall upon them at this period; nor have I any doubt that most of these plants, if not all, by attention on the gardener's part at the critical time, when the stigma exudes its viscous liquid, may be made to ripen seeds with us. In the hermaphrodite genera of Paranomus, Erodendrum, and Serruria, some species afford them annually without any care at all.
With respect to their diseases, I have only observed one, but that is too often fatal. It commonly appears towards the end of summer, and in the autumn, mostly attacking the largest and healthiest plants. This gangrene, if I may use the term, always begins in that part of the stem near the root, and with close attention may be soon discovered, as the diseased part immediately changes colour. The only remedy I yet know, is to cutaway all that is discoloured, not leaving the smallest unsound speck, and paring the wound quite smooth; then close it up with grafting clay, under which lay a sufficient quantity of dry wood or bone ashes to dry up the moisture of the wound, and then press the clay tight to prevent any water flowing towards the stem till a new bark is deposited over the wound. I am unable to assign any cause for this disorder, except it is the effect of hot sunshine immediately succeeding heavy thunder showers, at which time the bark may probably be scalded near the surface of the earth, which is the place the disorder generally first appears in, and which makes rapid progress.
In dividing the Natural Order of Proteēæ, into genera, those who are more learned than myself, think that the Inflorescence is of primary consequence, Tournefort, Boerhaave, and most botanists who lived before Linne, had no scruples in employing it: but, though the last named immortal naturalist made a law, always to exclude inflorescence from generic characters, he was nevertheless often forced to admit it himself; and this he managed with great cunning, by calling the Umbel, Catkin, Spathe, &c. of vegetables, which are only different sorts of Inflorescence, a Calyx. Among modern writers, I believe that Mr. R. A. Salisbury first dared publicly to dissent from the abovementioned canon of Linne, asserting not merely the utility but absolute necessity, of employing the Inflorescence in many Natural Orders; and it must be confessed that such generic distinctions are peculiarly useful to working gardeners, being always obvious if a plant flowers at all, as well as intelligible to the poorest capacity: in this point, accordingly, he has at length been followed by other eminent botanists. Next to the Inflorescence, the various modifications of the Fruit, and Seeds, as they are in many species unphilosophically denominated, seem to afford the best generic distinctions, in Proteeæ. As for their habit, no certain guess at the genus of an unknown species can be deduced from it; for this sometimes differs amazingly, not only in the same genus, but in individuals of the same species, and several are found with leaves, of very different shapes, growing at the same time upon one branch.