ON PREPARING LARGE TREES INTENDED TO BE TRANSPLANT

ED, BY CUTTING OR SHORTENING THEIR ROOTS. By Mr MACNAB, of the Royal Botanic Garden, Edinburgh.

THE removing of large trees has of late attracted consider

able attention. In fact, so much has been written on the subject, that it may probably appear that little now remains to be said. It seems to me, however, that much is yet to be learned in this single department of arboriculture, and that service is rendered to the art by any one who will communicate observations tending to increase the success, and diminish the expense, of the operation.

The subject of this paper is to point out what observation has taught me to consider the best method of preparing the roots of trees previous to removal.

In transplanting large trees, that is, trees of about three or four feet in circumference at one foot from the ground, and about thirty-five or from that to forty feet high, it is a pretty general practice to have the roots cut to a certain distance from the stem of the tree, a year or two previous to removal. This I consider a most excellent practice, which should be adopted in all cases where time is allowed, or where the operation is contemplated a year or two beforehand.

I am aware that it is a very general opinion, that the chief advantage which a tree derives from having its roots cut previous to removal (in the way I shall hereafter mention), arises from the encouragement thus given to the formation of young roots or fibres, and that these young roots or fibres being preserved to the tree when removed, act like so many mouths to take up the proper food for the subsequent nourishment of the tree. Now, I think I shall be able to show, that whatever advantage trees may derive from these new formed roots (an advantage which we may perhaps be forgiven for thinking overrated, when we reflect upon the injury they must sustain in the removal of a large tree), there is another consequence of the mutilation, the importance of which has been overlooked. I am strongly inclined to think, that the principal advantage which a

transplanted tree derives from having had its roots cut or shortened a year or two before removal, has proceeded from the check thus given to its growth, by which it had been brought from a vigorous to a more stunted state.

Every tree must receive a check when transplanted, and that check is less injurious if inflicted gradually. This observation, however, I mean only to apply to large deciduous trees, such as I have mentioned; for small plants, whether in a stunted or a vigorous state, may (if the directions I have given in my Treatise on the Cultivation of Evergreens be attended to) be removed with so much care,-the whole operation being perhaps completed in a few minutes,-that the young roots may be preserved perfectly entire, and therefore must be of advantage af terwards.

It is of little importance at what season trees are prepared by having their roots cut; any time between the fall of the leaf in autumn and spring will answer.

I will now point out the different methods practised in preparing trees for transplanting, and comparing the one with the other, endeavour to show which of them is the best. I will, at the same time, endeavour to impress the reader with the belief, that the idea which I have thrown out, of the advantage derived from checking the vigour of a tree previous to transplantation, not only possesses some interest in a speculative point of view, but may be made to affect the economy of the process, and to correct some measures which have been recommended, but which I think very injurious.

First, with regard to economy.-This can easily be made the subject of experiment. Let three trees of the same kind, and as much alike as possible as to age, size, health, situation, soil, and exposure, be selected, each about 3 feet in circumference at a foot from the ground, and from 35 to 40 feet high.

Let a trench 18 inches wide be cut round each, at the distance of 8 feet from the stem, and down to the subsoil, so as to divide every horizontal root at the inner side of the trench. Let this trench be left open in the first tree till the period of transplanting, but in the other two let it be filled again with the earth which had just been taken out of it. At the period of transplanting let the three trees be removed with equal care, and

planted in similar situations and soils, the whole operation being conducted in the same manner, with this difference only: In the first, let any new roots which may have formed at the cut extremities, in consequence of earth having accidentally fallen into the trench, be disregarded; in the second, let all the new roots which have formed in this situation be cut off; in the third, let them be preserved with as much care as possible. At the end of two or three years,—and we can rarely judge sooner of the ultimate success of our operations, we shall find the whole to have succeeded alike; and it is evident that the first and second will have been removed with a saving of labour, and therefore at a cheaper rate, than the last.

The length of time which should be allowed to elapse between the cutting of the roots and the transplantation, will vary with the season; after one wet season the trees will be as fit for removal as after two dry years.

My observations apply only to the roots formed at or near the cut extremities of the old roots. Every judicious operator will leave as large a mass of undisturbed earth about the roots towards the stem as can be got to adhere during the operation; and in trees of the size of which I am now treating, this will be a ball of from four to six feet in diameter.

It often happens that large trees are transplanted, and successfully too, without any previous preparation, and this is done at the same expense as the tree first mentioned in the above experiment; but, in general, the same success will not follow as where the roots have been shortened, and therefore this should always be done when there is sufficient warning of the intention of removal.

In proposing the above experiment, I have mentioned three methods of preparing the roots of trees previous to transplantation other two have been recommended; the first of which I consider bad, the second worse. This leads me to the second application of the principle with which this essay began; namely, to correct some methods which have been recommended, but which I think very injurious.

The two methods which I have now to mention, consist in the application of manure to the roots of the trees previous to their removal. In the one method, the trench cut round the

tree is directed to be filled up with good prepared compost; in the other, where the branches are fewer than could be wished to form a handsome top, and the roots long and scraggy, we are directed to lay well prepared compost on the ground all round the stem, and as far as the roots extend, to the depth of one foot at the stem, and six inches at the extremities of the roots. These two methods are mere modifications of each other, and are only bad in a greater or a smaller degree, because they produce a greater or a smaller degree of luxuriant growth in the roots, and therefore a greater or a smaller excess of vigour in the tree, at the very period when I am persuaded its growth ought to be checked, and when we take one step to do so by cutting its roots.

Both methods are bad, but the last, as being very expensive, and productive of the greatest growth in the rootlets, ought especially to be condemned.

By it the constitution of the tree will be brought into an artificial state, in which it will be much less able to bear the shock of removal than if it had been let alone. I do not intend to say any thing here on the treatment and care that trees of such magnitude should receive after they have been transplanted. I may mention, however, that a similar practice to the one last noticed is an excellent one for trees after they have been removed; but this should not be continued for many years after transplanting, for even then the tree would be thrown into an unnatural state of growth, which it could not continue, unless this top-dressing could be repeated from time to time, which would be both unnecessary and expensive.

This top-dressing after removal should never be continued longer than till the tree is brought to the state of health and vigour, which we are entitled to expect the soil and situation in which it is placed are capable of sustaining afterwards.

There cannot be a doubt that a tree taken up and transplanted without any previous preparation (even although the roots and branches are deficient), will make a better appearance at the end of four or five years after removal, than one that has got the top-dressing will do in the same period, supposing all other things alike both in transplanting and in subsequent treat

meut.

We may be assured that it is a good practice to starve and stunt trees before removal, and to feed and encourage them for a time after they have been transplanted.

Many examples might be stated to prove that the principal advantage derived from cutting the roots of a tree some time previous to its removal, is the consequence of checking or stunting it in its growth, rather than of providing it with young

roots.

I shall state one or two examples which are of pretty frequent occurrence, and which I an confident are quite consistent with good and judicious practice.

When we wish to take up a plant that is growing in the open ground to put into a pot or tub for any particular purpose, and when the plant is in a vigorous state of growth at the time, the common practice is to open a narrow trench and cut the roots at some distance from the stem, if the plant be large; or, if the plant be small, to cut the roots with the spade, without removing any of the earth, at such a distance from the stem, as will not give the plant too sudden a check. This should be done if possible in a dull or cloudy day. The plant should be allowed to remain in this state one, two, or three weeks, according to its size and nature, and then taken up and put into a pot or tub. This may be done without the plant losing a leaf. If the object of removing the plant into a pot or tub be to exhibit its flowers (as it commonly is), the plant will flower as well as if it had not been removed.

But if a similar and equally vigorous plant be taken up at once, without having its roots previously cut, it will scarcely be possible to prevent its suffering considerably; and it often happens that most of the flowers drop off, and scarcely any of them expand. Now this difference can only arise from the first plant having been checked in its growth,—not from any advantage which it could derive from the formation of young roots between the preparation of the plant and its removal, because the roots are scarcely ever cut so short at first as to go into the pot, lest the check should be too sudden, but require either to be shortened a second time, or bent round in the inside of the pot; and even in this last case it is hardly possible