Lawns And Economical Grading
( Originally Published 1906 )
The Contour—Rolling or level surface—Preferred exposure—No model grade—Making the most of the offscape—Scope for the artist—The routine of the work—Marking roads and paths—Repairing the grade—Levelling made easy—Filling around trees—Underdrainage and . its purpose—Importing top soil—Dangers involved.
The ideal lawn, except it be less than a quarter of an acre, is of a gently rolling con-tour, rather than a perfect level—Nature does not, as a rule, lay down her surfaces in absolute levels. She does so in a bog or with water, but surely, we do not wish to create the impression that the spot selected for our country home has characteristics in common with these. We do not want the impression that the site is low lying and damp. The slightly rolling contour obviates this, and, further, it is pleasing to the eye in a variety of ways. It facilitates the future planting and enables the landscape picture to be more harmonious, better balanced.
The very small lawn, however, had perhaps better be a level one. There is not within its confines room for rolling contour in proportion to the surrounding masses of shrubs. And further a level spot sufficient for a tennis court is desirable in the majority of cases. If the ground itself slopes to such an extent that there is any great difference between the two ends of such a space, the result will be better by resorting to a terrace, and here let it be said that wherever possible the more pleasing effect will be attained by placing the house on the high part of the terrace.
One cannot always choose the exposure for the lawn. By preference it should be to the south and east rather than to the north and west, because of the greater warmth of those aspects and the consequent earlier appearance of verdure in the spring.
GeTTING A GRADE
In reality it is far easier to do the grading of the ground than it is to explain lucidly how to set about it. Since there are no absolute laws to be followed—the whole matter of the grade being one of artistic appreciation—it is only possible to explain the routine of the work and the general principles that should be adopted.
There can be no such thing as a model grade for any one place. There may be a model grade for a certain combination of circumstances, but as these are changeable factors, varying according to the fancy or taste of the individual, it cannot be said that any given grade is the right one for a given area at all times. There may be a variety of equally good contours which would fit in with the surroundings just in the same way as there are a variety of bad contours which cannot be harmonious.
As a general rule the grading should be in harmony with the general slope of the land and designed to hide, more or less, paths and driveways that would otherwise be too prominent. To take a concrete example, for in-stance, refer to the illustration, Plate xxxi The grading in this case has been very skilfully accomplished to obscure the driveway which runs completely around the lawn and in front of the belt planting of rhododendrons and other shrubs. Though to all appearances a perfect level, the entire lawn is actually shaped like a shallow saucer—that is, it is higher at the sides than it is in the centre The consequence is that, standing at any given point, the driveway is not seen, unless the position of the observer is right on it. Even then there is only a few feet of drive seen in the very foreground. The belt planting fits in well with this particular contour.
Grading to a pleasing roll is a matter purely of artistic appreciation for which no paper rules can be made. It is here indeed that the landscape architect has the greatest chance for expressing his art. The best contours are never apparent. So sure as the rolls be-come obtrusive and prominent they are bad. An unbalanced contour will destroy the sense of proportion between the lawn and its surroundings and very often has the effect of making the house look like an excrescence on the landscape instead of nestling comfortably into it.
SEQUENCE OF OPERATIONS
After the ground has been smoothed over in the first rough treatment, is the time to establish the grades, after which the other construction work should be attacked in- this order:
1. Ploughing, following the first plough with the subsoiler in the same furrow, if the subsoil is hardpan.
2. Harrowing, using a disc harrow to cut the clods and finishing with a fine toothed or smoothing harrow.
3. Clearing and cleaning, removing any large stones and roots of trees that have been left in the ground.
4. Seeding, using a minimum of two bushels of good lawn mixture to the acre.
5. Light harrowing to cover the seed about one half inch.
6. Seeding again, travelling at right angles to the first seeding.
7. Light harrowing to one half inch depth.
8. Rolling with not less than three hundred pounds' pressure.
After the ploughing, and before any other operation is begun, is the right time to mark the courses for roads and paths which can be laid off on the ground by means of stakes, and excavated. The advantage of attending to that detail at this time is this : the soil can be easily taken up, as it is loose and does not have to be broken apart, and it will be available for filling in any hollows or particularly deep places that have not been sufficiently filled during the grading process.
Of course if the grading has been perfectly done there will be no such fills necessary, but in actual practice it usually happens that there are some depressions that had better be modified.
On the other hand, if the soil is not needed in that way, it can be evenly distributed over the rest of the surface, thus adding to the depth of available top soil; or, if the whole construction work is being carried on at one time, it can be deposited in the sites where the flower borders or shrubberies are to be planted. The ideal method, however, is to have the larger plantings done before the seeding of the lawn, thus avoiding traffic over the surface before the grass becomes established.
LEVELLING MADE EASY
The eye cannot be trusted to make perfect levels. It will inevitably, and quite unconsciously, seek to adjust the surface of the lawn in such a way as to make a generally harmonious contour with the general run of the ground. Therefore some mechanical means must be adopted to secure the perfect level.
The practical way, when there is no engineer or landscape architect engaged, is to drive stakes here and there in the ground, and sight from any one to a third stake by balancing a carpenter's level on the top of stake number one. By carrying this out over a series of three stakes in various directions, using each stake in turn as a support for the instrument, a perfect level can be assured. When once a stake has been driven or raised to the requisite height, it should be marked with paint, and it should remain in position until the final steps of the ground preparation are complete. By using a straight edged stiff board that will not sag, balancing it between two stakes, the ground can be brought up or cut down to the requisite level; and the intervening spaces may be filled in and levelled either by means of working a board over the surface in the same way as plasterers or masons work or by relying on the eye and using a rake.
Another method is by using the spirit level and theodolite, when stakes can be driven at various points and the height of a fill indicated by marking on the side of a stick the height of the future level. Where soil is to be removed a hole is dug and a stake inserted at its bottom is sunk to the right level. A distinct scheme of marking should be adopted, a common practice being to paint the top of such a stake with red.
FILLING AROUND TREES
Any specimen trees with well developed trunks should be retained so far as practicable. The effect of well-established specimens around the home is worth a great deal of effort to retain them. If only of moderate size it will possibly be better to raise them bodily, doing the work preferably in the winter time when the ball is frozen, after making the necessary provision for it in advance.
With old trees, or with those that are indigenous, not nursery grown, the risk involved in disturbing the roots is often too great. In such cases it will be better to leave them in situ and protect the base of the trunk from actual contact with the filled in earth. By ,no means bury the bole. Build up around the base of the trees with stones loosely piled one. upon the other so that the air can have free access. If possible make this stone cylinder clear of the trunk by some few inches. A wall of this type (see Plate xv) will in nearly every instance preserve the tree in its normal health. In the case of a tree interfering with the slope of a terrace, the same method should be employed making the stone wall, however, only on the side where it is necessary to retain the earth (Plate xv).
It is useless to attempt making a lawn on a site that is so wet that it holds water in pools after a rain. Wherever these conditions are encountered a system of underdrainage must be put in. The matter of tile draining is not properly a detail of lawn construction, how-ever, for it should be given attention in all parts of estate construction. Drainage has the effect of improving the fertility of the soil by making it warmer, which also causes vegetation to start earlier in the spring. From these points alone it is a very essential detail in all garden work. The bright green appearance of the early lawn is particularly gratifying.
All heavy, cold soils will be improved by underdraining. In general, on lands which need drainage, tile should be laid three to six feet deep and at a distance of six to fifteen feet apart. There can be no absolute rule for the number of drains necessary. It is possible to over drain, but this is a result that is not likely to occur on a majority of soils. Sandy and very light leachy soils do not usually need drainage.
The drain ditch should be dug by a special draining spade which is very long and narrow, and care must be taken that the whole system of tiles runs on a gentle uniform slope to the lowest portion of the estate or to any other point where there is a suitable outlet. Drain tiles are of various sizes, and the smaller (two inch) tile should be used for the secondary or branch drains, larger ones being employed for the main courses.
A decision should be taken on this question of drainage at the very first, so as to allow time for the proper settling of the soil in the trenches. Six months before sowing the grass seed is none too soon.
Very often it is necessary to bring from a distance good top soil for the purpose of filling in hollows or for improving the natural soil of the site so as to get a sufficient depth for the grass roots. Inasmuch as different grasses have likings for different soils, it will readily be seen that the perfect lawn must consist of a uniform soil.
When importing top soil from a distance there is great danger of unevenness in the growth of the grasses on the future lawn unless precautions are taken to insure this uniformity of surface. No matter what soil you are dealing with, it is far better to thinly spread the additions over the entire surface rather than to fill in patches.
Where a rich top soil is being introduced from another source and there is a sufficient quantity available to make the entire lawn from the new soil, there will be no necessity to more than loosen the original. There-fore grading should be roughly finished be-fore the new soil is introduced.
Where the supplies are being drawn from various different sources, bring in the heavier soil first, finishing off with the lighter, finer, and more friable. The only remedy for a patchy lawn, one part being on clay and the other part on sand, is to turn under the entire sod and start remaking the lawn.
The danger in imported soil when drawn from unknown sources lies in the possibility—I had better indeed say probability—of its containing weed seeds, which, worse still, would be different in the different lots of soil.