an invariable law, and must consequently be regarded as a fundamental principle in horticulture, upon attention to which all success in the adaptation of plants to a climate less warm than their own will essentially depend. The destructive effects of frosts upon the succulent parts of plants may thus be accounted for independently of the mechanical expansion of their parts; indeed, it is chiefly to that circumstance that the evil effects of cold in spring may be ascribed, for it has been found that trees contain nearly eight per cent. more of aqueous parts in March than at the end of January, and all experience shows that the culti vation of plants in situations where they are liable to be stimulated into growth and, consequently, to be filled with fluid by the warmth and brightness of a mild protracted autumn, exposes them to the same bad consequences as growing them in damp places, or where their wood is not ripened; that is to say, exhausted of superfluous moisture, and strengthened by the deposition of solid matter resulting from such exhaustion."

The ripening process consists in the slow but gradual and complete removal of watery matter, and the conversion of fluid organizable materials into the more solid substances which are necessary to form woody fibre; and its effects are not only seen in the power conferred of resisting cold, but also in providing an abundance of the secretions necessary to sustain the growth of the following spring, and produce the flower-buds upon which future hopes depend; for it is well known that flower-buds will not be produced unless the elements of growth have been maintained in due relative proportions.

We can thus partly see how far it is in our power to assist nature in supplying the requisites for perfect maturation of growth. The fruit grower will be careful to avoid planting in wet or highly enriched soil that would tend to encourage prolonged growth in the fall; he will see that his strawberry plants are not neglected during summer after the crop is gathered; that weeds are prevented from gaining a foothold; that the plants are thinned and fully exposed to sun and air, in order to perfect flower-buds for the following spring; that his raspberry plants have been divested of the old bearing wood, the young shoots thinned and disposed at proper distances so as to allow them a free enjoyment of light; that his grapevines have an abundance of healthy foliage, so as to ripen the young wood for his future crop; and that his peach trees are not suddenly denuded of their foliage, while it is as green and fresh as in the month of June.

When a fundamental principle is once determined and understood, operative details are suggested, and from them the best practical mode of application is readily deduced; for instance, many of the most beautiful evergreen ornamental trees, such as the Asiatic conifers as well as those from the western coast of this continent, cryptomerias and deodars, sequoias and taxodiums, have, in our moist fall growing weather, a tendency to make a luxuriant growth which never ripens, and, as a natural consequence, it is destroyed by winter cold. Now, if these growths are checked in September by judicious root-pruning, the wood will mature, shoots become hard and woody, and, instead of being unripe and filled with watery fluid, be solid and firm, and fully prepared to stand the extremes of our wintry climate. The whole subject of the acclimation of plants is based upon maturity of growth.

ROTATION OF CROPS

Among the essentials requisite to maintain a high degree of success in culti vation, a proper system of rotative cropping occupies a prominent place. The advantages of rotation in farm crops are well known; yet, in the garden, the practice is very common to grow the same kind of crops for years in the same spot of ground. It is, perhaps, within the bounds of possibility to pursue this course successfully, but to do so will require an annual return to the soil, in

some form, of the several ingredients extracted by the plants. Our knowledge of the application of science will not warrant much faith in this direction, even if chemists were decided as to exact respective amounts of the ingredients used by various crops. But allowing it to be practically attainable, and looking at it in the light of mere economy, a change of crop is every way desirable; since by proper care two dissimilar crops may be produced on the same ground in the same season; and, further, the operations necessary for the culture of one kind of crop are of a nature to form a good preparation for the succeeding one.

Physiologists do not altogether coincide in their opinions with regard to the principles upon which the beneficial results attending systematic change of crops are based. Some support what may be termed the repletion or excretory theory, which proceeds on the supposition that the roots of all plants during their growth give out certain substances peculiar to themselves, which, in time, impregnate the soil to such an extent as to render it unfit for the growth of that particular plant, but has no deleterious effect upon the growth of a different family of plants, if, indeed, they are not rather to be considered as capable of promoting growth and acting as stimulants to such.

It is a well ascertained fact that certain if not all plants do impart to the soil, through their roots, a portion of their juices. The soil surrounding the roots of the oak tree has been found impregnated with tannin. The roots of the spurge laurel impart an acid, resinous matter. The poppy exudes a substance analogous to opium; the root of any plant growing in water will soon render it turbid, but the quantity of such matters hitherto detected has not been considered sufficiently important to account for the remarkable beneficial results which have followed a rotative system of cropping.

The above theory has been supported by very high authority, but it seems to be giving way to the following, viz: that although plants are made up of the same primary elements, yet different species require them in widely varying proportions, so that each plant has a characteristic formation peculiar to itself. It therefore follows, that if there is a lack in the supply of these peculiar ingredients of plant food, the plant will not be maintained in healthy growth. From this it appears that the reason why a crop, if constantly grown upon the same spot of ground, shows a yearly loss in productiveness, does not arise from a repletion of any substance, but rather from exhaustion. In a practical view, it is evident, from either of the above theories, that a change of crop is requisite to successful cultivation.

In cultivating garden vegetables great facilities are presented for a frequent change of crop, and there is, also, a wide field for experiment in order to ascertain the kinds best suited to succeed one another in a regular system. For instance, it has been asserted that melons will produce best when grown on soil previously occupied by tomatoes. In general, long, tuberous, rooting plants, as carrots, beets, parsnips, &c., should be followed by those that root near the surface; plants that are cultivated for their seeds should be followed by those grown for their foliage. The seeds of all plants contain a larger amount of the mineral ingredients than their leaves, so that plants grown for their seeds will exhaust the inorganic matter of the soil to a greater degree than will be effected by plants grown only for the use of their leaves.

In the arrangement of crops in the field or garden, there are two methods that may be adopted, either of which will provide for rotation. In the first place a spot of ground is occupied wholly by one crop, and when that is removed its place is immediately occupied by another; or two or more crops are so planted on the same piece of ground that the one will be ready for removal before it interferes with the growth of the other. The first method may be illustrated by planting with early peas or potatoes, which will be removed in time for planting cabbages or celery, or sowing beets, turnips, or spinach. Early crops of carrots and beets will be removed in time for a planting of late dwarf beans. Many

modifications will be suggested in practice. Perhaps the most economical method, especially where ground is limited in quantity, is to grow several crops at the same time on the same piece. For instance, peas may be sown in March, in rows, six feet apart; in May a row of melons may be planted between the peas, the shade afforded by the peas will benefit the young melon plants, or, between the peas a row of dwarf beans may be planted, and when the peas are removed their place may be occupied by cabbages, and the beans be'succeeded by a crop of turnips. It does not seem necessary to multiply examples, as those who are inclined, and will exercise due foresight, will suggest many expedients. Much variety can be produced in even a small garden by this method, and it affords great facilities for sheltering young and tender crops by those of more matured or robust growth. It may, however, be remarked, that although most plants are benefited by a little shade and shelter when young and delicate, it is highly injurious when long continued.

FOREIGN GRAPES IN GLASS STRUCTURES.

The simplicity and certainty with which the foreign grape can be produced in glazed houses is not generally known. Many amateurs, whose success with other fruits is quite satisfactory, feel doubtful of their ability to manage the exotic grapery.

To those whose only acquaintance with the subject is derived from perusing publications on the growth of this fruit, the supposition of inability is pardonable; for there is certainly much to appal the beginner, in perusing the various ideas of soil and border making, the conflicting opinions relative to watering, and the multitudinous, fussy details of management, which he will find in print. So much has been written of late years on this subject, that it would not now be referred to were it not with a hope that information might be imparted that would tend to dispel the idea of difficulty or mystery, in connexion with the culture of this, without exception, most economical of fruit productions. It is well known that, in favorable locations, the Chasselas, Black Hamburg, and many other of the varieties of the foreign grape will occasionally produce perfectly ripened fruit with no further care than that usually given to the Isabellas, or any other native variety. But although the result may occasionally be reached, it is well known that all attempts to cultivate the foreign grape in the open air, east of the Rocky mountains, have, sooner or later, proved abortive.

That these failures are attributable either to a deficiency of sunlight or to a deficiency of summer heat are questions easily answered; for we find that in the climate of Britain, where the dull, sunless days are more abundant, and the summer heat of less intensity and of shorter duration than with us, the Hamburg and other exotic grapes ripen yearly, trained on outside walls and trellises, and this in a climate where the heat is not sufficient to mature Indian corn, tomatoes, or even peaches, in common field culture as with us. Neither can it be supposed that our own summers are too hot, or our winters too cold, as it is well known that there is scarcely any plant that will withstand extremes of summer heat and winter cold so well as the grape, provided it maintains good health. But unfortunately, there are climatic conditions here during which the grape is rendered subject to the attack of fungoids, by which its growth is checked, the wood prevented from maturing, and a general debility engendered which enfeebles the plant to a degree that, sooner or later, ends in its total destruction. This tendency to mildew is, then, the only obstacle in the way of successful open air culture, in this section, of the best wine and table grapes of Europe; and is the only reason why glass structures have to be employed in their culture, where an artificial temperature, more in accordance with their requirements, may be maintained. The tendency to mildew in the foreign grape, having been found so great a barrier to its extended culture in the open air, recourse was

had to glass houses where protection could be afforded and means adopted for the exclusion of this malady; but in many cases, even here, success has not been equal to expectations. The mistaken eagerness of many to keep the plants in an artificial instead of a natural condition, has led to frequent failures. It appears very obvious that a plant which occasionally succeeds in the absence of any particular protection, would be enabled to do so uniformly by a very slight additional care, provided that this additional care was bestowed in the proper direction; and that such is the case has been proved beyond a doubt.

Having on another page of this report treated more particularly on mildew and its origin, it may suffice to remark here, that it is altogether dependent upon the amount of atmospheric moisture, and proper ventilation; and without proper attention to these points, mildew is just as likely to destroy the plants under glass, as it would be those in the open air. Keeping in view that these remarks are intended to refer to the general routine management of what is now more definitely known by the term cold grapery, we will briefly allude to what is considered the main points of treatment.

The principal points, then, are a low night temperature, exclusive top ventilation, and the constant presence of moisture available for evaporation. The baneful effect of a high temperature in plant-houses has been shown in previous reports. It has been proved repeatedly that low or bottom ventilation in a grapery is conducive to mildew, and aridity must be prevented by the presence of moisture.

It would require considerable space to enter fully into the elucidation of all the principles involved; it will, therefore, be considered sufficient for the present to briefly trace the course of practice deduced from many years' extended observation and experience in the growth of the foreign grape.

As soon as spring growth commences, attention is at once directed to the night temperature, so that it will fall at least 20 degrees below the average heat in the house during the day. In dull, cloudy weather, of course, this difference between day and night may not be so great, and if the nights are frosty, it will be necessary to close the house; but in the absence of actual external freezing, the ventilators should not be wholly closed, even during night. When all danger from night frosts is passed-which will vary, according to locality, from the middle of May to the middle of June-the ventilators may be left open day and night. During dull cool weather it may be necessary to partially close the ventilation both day and night; but as a general rule, the same amount is used day and night. We have seen graperies where the ventilators were never disturbed from the period of blossoming until the ripening of the fruit. constant anxiety is, therefore, felt about sheltering or opening sashes, and the liability to create sudden changes of temperature, that frequent alterations of the ventilators are sure to produce, is prevented. The temperature of the house will, therefore, participate in the general changes of external atmosphere, and though warm during sunlight, will be cool during darkness. During the warmest portion of the summer, the day temperature may vary from 90 to 110 degrees by day, to 65 to 80 degrees during the night. This lowering of temperature during darkness insures a hardihood of growth that enables the plants to endure any unfavorable change that may occur, without sustaining the least injury.

No

As air is heated, its capacity for abstracting and containing moisture increases, and unless the moisture is supplied from other sources, it will be drawn from the plants. To supply this evaporation, the soil should be kept damp on the surface. Once a day at least, in bright weather, the soil will require to be sprinkled. It is a good rule never to allow the surface soil to be entirely dry until the fruit is coloring to ripen; but it is important to know that, unless in connexion with constant night ventilation, this treatment may prove injurious. So far as the management of the atmosphere is concerned, this is all

the care required, and a crop of grapes is thus as easily grown as a crop of pota toes, only with more certainty, because more under our control.

With regard to soil, pruning, &c., we will at present only remark, that soil capable of growing good cabbages will grow good grapes, and the strongest yearly growths give the best fruit.

MULCHING.

This is an auxiliary operation in cultivation, that would be more generally practiced if its beneficial effects were better understood.

The objects to be attained by mulching are twofold, viz: to preserve a uniform degree of moisture in the soil during summer, and protect the roots of plants from severe frosts during winter. These conditions are obviously important to vegetation, and they can be very efficiently secured by covering the surface with a stratum of porous materials, such as tan bark, charcoal dust, leaves, or strawy manure, which will prevent the surface soil from becoming compact or hard, and, at the same time, assist in maintaining a uniformity in its mechanical texture favorable to the retention of moisture. Air is the best non-conductor, and bodies are represented as good or bad conductors, just as they are solid or porous. Iron is a better conductor than wood, granite stone a better conductor than brick, hard pressed soil is a better conductor than soil that is loose and porous. A hard trodden path is warmer in summer and colder in winter, than the cultivated ground alongside of it. When the soil particles are in pressed contact, the condition is favorable to rapid conduction; summer winds passing over such a surface, carry off the moisture which the heat evaporates; the surface is speedily parched dry, and vegetation languishes.

When the surface is covered with a mulch of such porous materials as those enumerated, it in effect secures a stratum of air in repose between the soil and the causes of radiation and evaporation. In the case of recently planted trees, the preservation of a uniform degree of moisture in the soil surrounding their roots, is a great point towards their successful growth; and, other things being equal, they will languish or flourish in proportion as this condition of uniform moisture is secured.

Although mulching is really a very simple operation, yet serious losses have occurred from its misapplication. We have seen trees destroyed from too heavy mulchings of grass, manure, and tan bark. Before applying the mulch to a recently planted tree, if in spring, shape the soil around it in basin-form, extending the rim beyond the extremities of the roots; by this configuration of surface, rains will be retained and, if required, artificial waterings can be applied to best advantage. With regard to fall planting, the process should be reversed and a slight mound formed towards the stem of the plant, so as to throw off the heavy rains of winter. Of course such mound should be removed before the following summer.

As already remarked, the principal use of winter mulching is to prevent frosts from reaching the roots. The best material for this purpose is charcoal dust. Where manure is used, it should not be thrown close up to the stem of the plant, otherwise it might prove a harbor for ground mice, which in rough ground, or under a coarse covering, are sometimes very destructive, by eating the bark of young trees. When they are troublesome, the precaution should be taken to trample firmly over the roots and around the stem after heavy snows, and keep the surface clear and compact.

In order to be effectual, it is not necessary that summer mulchings should be heavy. When tan or charcoal dust is used, a layer of two inches in depth will be quite sufficient. Grass cut from lawns is very suitable, but a mere sprinkling only should be applied at a time. Thick coatings promote fungoid growths, which frequently destroy trees. Fruit or ornamental trees that have been trans