540 



THE GARDENERS' CHRONICLE. 



[Aug. 10, 



in proportion, more carbonic acid than either carbonate 

 of potash, soda, or lime ; hence, when it decomposes 

 salts of lime, there is more carbonic acid than the lime 

 can combine with, and this excess, which remains in the 

 water, renders the carbonate of lime formed also soluble. 

 On the other hand, carbonate of potash or soda contain, 

 in proportion, just as much carbonic acid as the carbonate 

 of lime ; consequently, when they are employed, there is 

 no excess of carbonic acid set free, and the whole of the 

 lime is precipitated. If, however, hard water of this kind 

 is exposed to the air for some time after the addition of car- 

 bonate of ammonia, the whole, or at least by far the greater 

 part of the lime is precipitated. Any liquid containing 

 carbonate of ammonia (such as common liquid manure) 

 may be used for this purpose ; but it must always be 

 remembered that the carbonate of lime will not precipi- 

 tate until the excess of carbonic acid is expelled or has 

 escaped. — E. Solly . 



\ 



TREATMENT OF HALF-HARDY PLANTS 



DURING WINTER. 

 The two principal things to be guarded against in the 

 preservation of half-hardy plants during the winter 

 months, are frost and dampness— both very destructive 

 in their influence, and both exerting that influence in a 

 different manner. But although the natures of frost 

 and dampness are of very opposite characters, and their 

 modes of influence widely different, the presence of the 

 one materially augments the influence of the other; and 

 it follows, that by preventing one, we in a great measure 

 guard against both. 



The first thing, then, that should engage our attention, 

 is dampness, for if this is present, frost is more severe. 

 To prevent dampness there must be a free emulation of 

 air ; the plants must be placed on a dry bottom, and if 

 they are in a situation which will admit of a fire occa- 

 sionally, it will render the pits or house dry, but it should 

 be used very sparingly, and only when absolutely neces- 

 sary. When plants are housed for the winter, it is a 

 common practice with many gardeners to plunge them 

 (I speak only in reference to half-hardy kinds) in some 

 moist substance, whereby they may, by the porosity of 

 the pots, absorb sufficient moisture for their support, 

 without having recourse to the watering-pot. There are 

 no doubt many advantages in such a system, but the dis- 

 advantages far outweigh them. Damp is engendered ; 

 there is a continual evaporation going on; and if the 

 weather should be such (as is often the case for weeks 

 together) as to prevent the removal of the lights, in order 

 to produce a free current of air, the moisture finds no 

 means of escape, and thus accumulating, causes the 

 young and imperfectly organised wood often to damp off. 

 But even with all care and attention, damp will attack 

 some plants, and generally those that are most succulent 

 in their nature, or the young and tender tops of others. 

 We should therefore watch narrowly, and remove every 

 leaf or shoot affected, as damp not only destroys the in- 

 dividual immediately affected, but extends its influence 

 to those in the neighbourhood of the one so affected. It 

 is contagious. It engenders mould, which being a species 

 of Fungus, is rapidly disseminated, attacking and de- 

 stroying wherever the damp has prepared the leaves for 

 its reception. Neither should plants be too much 

 crowded, as that obstructs the free circulation of air. 



Watering should of course be done sparingly, but 

 still it will be required occasionally. Care, however, 

 must be taken to preserve the foliage as dry as possible, 

 as there being but little sun in winter, and that not of 

 sufficient strength to evaporate the superabundant mois- 

 tnre rapidly, it quickly rots the leaves, especially of 

 Pelargoniums, and similar plants having leaves which 

 form a kind of dish in which the water accumulates in 

 considerable quantities. When fire is had recourse to 

 for drying the house or pits, choose a fine day, and give 

 all the ar possible, so that the moisture dislodged by 

 the heat may be dispersed. It is an absurd custom (but 

 still often practised) to attempt to dry a building by lire- 

 heat when every aperture is closed. The damp is cer- 

 tainly removed from all the crevices, but the confined 

 atmosphere becomes saturated with moisture, and 

 coming in contact with the walls and other objects at a 

 lower temperature than the atmosphere itself, this mois- 

 ture becomes condensed, and runs down in streams, or 

 stands upon the walls in large drops, not a particle of 

 it escaping, there being no aperture for it to do so. 

 Many plants are no doubt placed for convenience, and 

 from other causes, in shady situations. Some kinds re- 

 quire such treatment. In all such cases, however, they 

 should be removed, as autumn approaches, to some 

 place where they may enjoy the full benefit of the sun 

 and air, in order that their juices may become elabo- 

 rated, and their young and tender shoots get well 

 ripened — Walter Wakefield. 



between them, into which a penny-piece might be in- 

 serted, and the lower leaves falling down so as, in a 

 measure, to conceal the stem. On the 28th July, Mr. 

 J. Smith found that this flower-stalk had already gained 

 a height of 6 feet 8 inches ; and on the 20th, of 8 feet 6 

 inches. To-day (August the 1st), at noon, its height 

 was 10 feet, and in girth, at the base, 1 foot 2| inches. 

 Its present appearance is similar to that of a young shoot 

 of Asparagus, but more tapering, coming indeed to a 

 very sharp point at the top. The scales are distant, and 

 the lower ones are beginning to spread, while the rest 

 are pressed close to the stalk ; but none of them exhibit 

 at present an appearance of flower-buds. The growth of 

 the flower-stalk in the two plants has kept pace, the one 

 with the other, in a very remarkable manner ; there is 

 scarcely a perceptible difference in height between them, 

 and as each is in a tub about 3 feet high, the whole 

 height of the plants from the floor may be estimated, at 

 noon on the 1st of August, at 16 feet 6 inches. The 

 inside of the stove where they are placed being 2G feet 

 high, some of our friends have congratulated us on 

 having ample space, without removing the lights ; but, 

 calculating from the few instances upon record of the 

 flowering of this stately plant in England, we must 

 reckon upon a length of 30 or 32 feet from the flower- 

 stalk ; and instructions are already given for an opening 

 to be made over each plant in the roof. Those of your 

 readers who may be disposed to see them, will find them 

 in the house usually called the Conservatory, or that one 

 which is distinctly seen from the green (of Kew) before 

 entering the gardens. Fourcroya gigantea appears to 

 have flowered for the first time in Europe in the Botanic 

 Garden of Sehonbrun, Vienna, and it was figured by 

 Jacquin, in the "Icenes Plantarum Rariorum/'vol. ii. p. 

 379. Its flowering panicle was 32 feet high. Another 

 specimen blossomed in the Paris garden in 1723, and 

 was figured by De Candolle'in the " Plantes Grasses," 

 tab. 126. Ventenat has given the height of the flower- 

 stalk at different dates. It was from the 9th of August 

 to the 4th of September before it had attained to 10 feet. 

 By the 25th of October it had reached its greatest eleva- 

 tion, 22 feet ; its more rapid growth having been checked 

 by exposure to cold. In 1821, a Fourcroya gigantea 

 blossomed at the seat of the Right Hon. Earl Powis, of 

 Walcot, in Shropshire, and a figure was given of it by 



Dr. Sims in the " Botanical Magazine," tab. 2250. It 



Correspondence. 



Fourcroya gigantea.— Two noble Agave-Jike plants 

 in the stove of the Royal Botanic Gardens of Kew, which 

 are considered to be the Fourcroya gigantea, Ventenat 

 (Agave fcetida, L.), give promise of flowering in a very 

 short time. They are nearly of the same size, caulescent ; 

 the stem is 2 feet 4 inches high, crowned with a noble 

 tuft of sword-shaped leaves five to seven feet long, spread- 

 ing in all directions, their thickened bases giving a 

 height of 1 foot 2 inches additional (in all 3 feet 6 inches), 

 from the summit of which, in the centre of the foliage, 

 the flower-stalk springs. This flower-stalk was first per- 

 ceptible on Wednesday of last week (July 24th) ; and 

 attention was directed to it by a remarkable appearance 

 of the plant, the thickened bases of the leaves separating, 

 as it were, from each other, so as to leave a space 



had attained a height in the flower-stalk of 30 feet. 

 None of the figures now mentioned give anything like a 

 good idea of the stateliness of the species of Fourcroya, 

 partly owing to the necessity of giving it upon a very 

 reduced scale, and partly owing to the vast size of the 

 panicle, in proportion to the foliage, gigantic as the 

 latter are. The crown of leaves is in all shown to be 

 sessile, or nearly sessile ; whereas our plants are, as all 

 authors describe them, caulescent. According to the 

 first edition of the " Hortus Kewensis," it was cultivated 

 at Hampton Court garden in 1690. Being a species of 

 slow growth, it is possible the Kew plants may be of 

 that age, and derived from Hampton Court. The Four- 

 croya longseva, of Karwinski, a species allied to this, is 

 said by the Mexicans to flower only once in 400 years ; 

 but our species is but a dwarf in comparison of that, of 

 which beautiful representations are given by Zuccarinf, 

 in the 16th vol. of the "Nova Acta Acad. Nat. Curio- 

 sorum," and which is said to have a stem 40 to 50 feet 

 high, and a flower-stalk 30 to 40 feet high. — JV.J.H., 

 Kew, Royal Botanical Gardens. 



Scorching Effects of the Sun. — The spotting of Vine- 

 leaves under glass, so fruitful a source of speculation at 

 present with your correspondents, and on which some 

 conflicting opinions are entertained, depends in many 

 instances on sun and water, but not in the manner 

 pointed out by the lenticular theorists. A drop of water, 

 as you have shown, on the surface of a leaf, cannot con- 

 centrate the sun's rays, so as to burn the leaf on which 

 it rests. The under-surface of the glass of a hothouse, 

 however, on being bespattered with water from a syringe 

 or engine, will leave drops of water adhering to it, of 

 various sizes and degrees of convexity, forming plano- 

 convex lenses, which will concentrate the sun's rays and 

 act as burning-glasses on the leaves adjacent, scorching 

 them with brown spots and destroying their beauty, 

 independent of the loss of green surface for the vital 

 functions of the plant. Although pointing this out as 

 one of the causes of the spotting of the Vine and other 

 plants near the glass of hothouses, I would by no means 

 hold it forth as the only one ; but the above may satisfy 

 the anti-lens gentlemen that water may burn the leaf of 

 a plant, although not exactly in the way hitherto held out 

 by the opposite party. Scoresby, when in Greenland, 

 set fire to gunpowder with a double-convex piece of ice ; 

 no wonder then that a leaf may be scorched with a plano- 

 convex lens of water.— Vidimus. [With much deference 

 to our correspondent, we must regard his explanation 

 quits as unsatisfactory as the others. Water lenses will 

 no doubt act as well as those of glass or ice : but how 

 do the lenses get into focus ? Are not the leaves too far off 

 the glass ? And do not the drops of water shift and 

 change their form, and run down the glass before they 

 can act? Besides other obvious difficulties. 



Scorching Effects of the Sun — I have a plot of Scotch 

 Firs two to three feet high, about 5000 in number ; on 

 the .night of the 25th July it was a drizzling rain, and 

 the next morning, being the 26th, the sun got out very 

 hot ; early that morning, about 9 o'clock, I passed by 

 them and found them quite brown, and now they look 

 as if they had had a fire amongst them. This must 

 either be the effect of the sun and dew, or there must 

 have been a frost in the night ; but either way the sun 

 must be the cause of it. The plot faced the east; 



on the north-west side I had several plots of Scotch 

 and Larch, and only a few scorched. I perceive for the 

 last month in this neighbourhood we have had several 

 frosts in the night.— F. X. O., Cliff Vale. [This ig t 

 specimen of the sort of reasoning applied to this subject 

 The scorching was caused by the sun, or the dew, or 

 the frost— or something else. Very likely ; but by 

 which ? Not by the sun, because the same thing hap. 

 pened on the north-west side.] 



Charcoal, Preparation of Cuttings, &fc— The follow- 

 ing are the results of a few experiments relative to the 

 application of charcoal in the propagation of plants, and 

 also on the preparation of cuttings for insertion. Iq the 

 spring of 1842, I propagated a considerable number of 

 various kinds of plants in different ways, and some of 

 these in charcoal ; I sifted some rather fine, into which 

 I inserted cuttings made from the young wood of Abu- 

 tilon striatum, and Lantana Sellowii, together with others 

 made from Fuchsias, and various other kinds of green* 

 house plants: these became well rooted in a comparatively 

 short space of time. The Abutilons emitted roots in great 

 abundance, and seemed particularly fond of charcoal- 

 grains, small particles of which adhered to the rootlets 

 in great quantity. These cuttings were inserted in' charcoal 

 alone; but notwithstanding the success attending the ex- 

 periment, I prefer mixing the charcoal with a little good 

 soil and silver-sand. Sand is, no doubt, the best ingre- 

 dient for propagation, but where it is scarce (as it is in 

 some places), charcoal will be found advantageous. I 

 also used charcoal in propagating Pelargoniums, for which 

 I prepared a mixture of charcoal and loamy soil of about 

 equal parts ; the charcoal was not sifted very fine ; 48- 

 sized pots were used, at the bottom of which 1 placed 

 a little Moss, and filled up the remainder with the pre- 

 pared compost. I inserted one cutting in the ceutre of 

 each pot, and the whole of the pots were plunged to the 

 rim in the bark-bed in a propagating-house, containing a 

 gentle and steady heat. I never saw cuttings do so well 

 as they have done, many as I have seen ; in the space. of 

 ten days or a fortnight the roots were protruding through 

 the bottom of the pots. The cuttings were then taken 

 out of the bark-bed and hardened off, and in a short 

 time they became fine healthy plants ; although it was 

 evident that the compost was suitable for them, it is not 

 to that alone that I ascribe my success, but, in a great 

 measure, to another cause, viz. that of properly prepar- 

 ing the cuttings. It is the common practice to cut 

 through the joint and remove three or four of the lower- 

 most leaves, but the removal of these (I am fully con- 

 vinced) is of great disadvantage, as it is generally 

 admitted that the foliage has an office to perform, viz. 

 that of elaborating the sap or juices of the plant. The 

 sap ascends up the minute vessels of the cuttings, and, 

 entering the leaves already formed, and undergoing the 

 elaborating process, is converted into cambium, or the 

 proper juice of plants, by exposure to the influence ot 

 light and heat. Afterwards it descends, forming wool 

 in its course : but in considerably less quantity in cuttings 

 than in rooted plants. After it has reached the base of 

 the cutting, it comes into immediate contact with the 

 soil or compost, of whatever nature that may be, ana- 

 there it assumes a congealed appearance, or white warty 

 substance, which, owing to the sap continually descend- 

 ins-, enlarges until it is forced into different directions in 

 the shape of roots. These supply the plant with iooa, 

 growth commences and proceeds, and the plant elon- 

 gates and soon becomes established. If we deprive a 

 cutting of its lowermost leaves, we deprive it of a con si 



uuL.iiij ui uo xwvf^* i**v*.jw * v *~.^.~7 — i have 



derable portion of its power to emit roots. 1™ 

 inserted a great quantity with every leaf attached, ana 

 these retained the same healthy appearance as be.ore 

 they were taken off the parent plant; manj o " tbeo 

 rooted rapidly, and not one leaf died ?nt.l after they had 

 become well-established plants. , It 11 widen that^ be 

 leaves were of service to the cuttings, from t « «^» , ° 

 ing so healthy ; these cuttings were inserted deep enough 

 to bury in the soil the whole of the l****^ "£ 

 lowermost leaf. It is worthy of remark tha^those c« 

 tings having the largest leaves, rooted *»«£«*' \ aj 

 showing that the descent of the sap was stronger an 

 quicker°in them than in others with °™ ller ^'^eat 



which, nevertheless, also succeeded well. " ow in , 

 was the case of some tried on the old plan of r env '5 

 the leaves ! Many soon became l^u'd, ~' "maca 

 withered away, and those which did sucueeu we 

 slower in emitting roots. I" removing the ^ aves g 

 rally a sma.l portion of A. f.o£ tnlk » le ft, wh fc 

 enters, but on account of the leal oeu, d 



elaborated , consequently, these become drop «« , ^ 

 damping off very often, kill the cutting. JU» fc 

 not have been the case, had the .leaves been _Ieftm 

 preparing cuttings, do not cut through the joi , 

 close at its base, as the vessels connected \m th the 

 most leaves are then retained entire, which mm ^ 

 tagenot to be lost sight of; the cut should ^be * 

 with a sharp knife, in order that the ^t^ 

 receive the slightest bru.se. For fear of disorg 

 the vessels, the cut shouldhkew.se not b »»nn 

 become dry before insertion, as th.s to a great 

 deprives the cutting of the power or -W^th* 

 perhaps, in some plants, altogether. Shadmg U a 

 essential point. Plants breathe, as it were, .^ 

 under the solar influence ; consequently cutt' "J^er « 

 without roots, are not possessed of sufficient P te 

 absorbing a requisite quantity of moisture to c o f 

 balance the evaporation, and the consequence ^ 

 shading is not resorted to) the cutting wj^ t , iem to 

 or droops, and is soon past recovery. *° hole sys ten>, 

 flag at all, is giving a severe check to" faad t o 



and in order to obviate this, recourse most 





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