Coming down to the present day, in our search for facts and information in regard to the propagation of varieties of the walnut, we may find it interesting to visit California, which, of all the States of the Union, is perhaps the best adapted to nut culture in general; besides, a larger number of nut trees of various kinds have been planted there than elsewhere in this country. It is in California that we find such men as Felix Gillet, of Nevada City, an enthusiastic propagator and cultivator of fruit and nut trees, and especially of the latter, if we may judge by his works and writings on this branch of horticulture,—and so far as I have been able to learn, he is the only nurseryman in the United States who has grafted walnut trees of many different varieties for sale.
In regard to modes of propagation, Mr. Gillet says that the common mode of shield budding, as employed on fruit trees, fails entirely with small walnuts from one to three years from the seed, and it does but seldom succeed even on larger stocks. When tried on large, old stocks, he advises removing all the wood from the inner side of the strip of bark on which the bud is situated, and at the same time have this strip not less than two inches long and as broad as possible. He describes his mode of grafting walnuts, which does not differ materially from those already given. That he has never attained any very remarkable results may be inferred from the following:
"We will add that the 'grafted walnuts' that we offer were grafted expressly for us, regardless of cost, by the most reliable firm to be found in the walnut district in France, through a process discovered several years ago, and which we will briefly describe for the benefit of people who may be inclined to try this new method of grafting very young walnuts.
"One-year-old seedlings of the size of the little finger, or about one-half inch in diameter at the butt, are selected, the root cut back short enough to permit the planting of the trees in pots of three inches in depth; the trees, previously to being potted, are grafted with cions exactly of the same size, whip or cleft grafting being used; the pots are then taken to a hot or propagating house, and a glass bell set over them to prevent the outside air getting to the grafts, the temperature of the house being kept day and night, at least for fifteen days, or till the grafting has taken, to 70° F. When the grafts are well taken and growing, the glass bells are removed, and the grafts allowed to grow three or four inches, before the little grafted trees are set out in nursery rows; it may be preferable, especially in certain parts of the country, to keep the trees in the pots till the ensuing spring. Forty to fifty per cent of the grafts will succeed, and it is the best that can be done.
"This mode of grafting the walnut, besides requiring a hothouse, needs the care of a skillful person to make it succeed. So are grafted the little trees that we import from France, and that we plant in nursery rows and offer to the public."
For other modes of root grafting, I refer the reader to those recommended for the hickories, in the preceding chapter. Propagating walnuts by layers is practicable, where the small trees have been cut down to force out new shoots near the surface of the ground, then bent down and covered with soil in the usual method of layering woody plants.
Planting and Pruning.—The plants will produce a greater number of fibrous roots if the nuts are planted in light, loose, but rich soil, than in a heavy, tenacious one; but with all kinds it is best to transplant when one or two years old, and cut off a portion of the taproots, as recommended for the hickories. When removed from the nursery rows for final planting, prune away nearly or quite all side branches, leaving only the terminal bud if the trees are not more than six to eight feet high. After final planting where the trees are to remain permanently, very little pruning will ever be required, further than to cut away branches that may cross each other, or to shorten some to give proper form to the head. No tree in cultivation requires less pruning than walnuts.
As a genus of trees the walnuts flourish best in deep, rich loam, rather light than heavy, and in this country require considerable moisture at the roots, and some, like the butternut, succeed best in bottomlands, near creeks and larger streams. If the soil is naturally too dry for such trees, the fault can be readily remedied by the use of some form of mulch applied to the surface of the soil around the stem after planting, renewing this annually, or oftener if necessary, until the trees are large enough to shade the ground.
Walnut trees, as well as the closely allied hickories, are well adapted for roadside planting, and when set in such positions are far less likely to be injured by insects than when planted in orchards or large groups, besides serving a double purpose, being ornamental as well as useful. They may also be planted around buildings, and where other and less valuable trees are generally grown. There are also millions of acres of rocky hill-sides and old fields which might be utilized for nut orchards, and if rather widely scattered over such land they would prove beneficial in shading the pasture grasses. First of all, however, let us have rows of these trees along all our country roads, after which it will be time enough to begin planting them elsewhere.
SPECIES AND VARIETIES OF WALNUTS.
Native of the United States (Juglans cinerea. Linn.). Butternut. White Walnut.—Leaflets fifteen to nineteen, oblong-lanceolate and sharp-pointed, rounded at the base, downy, especially on the underside, petioles covered with viscid hairs; fruit oblong, two or more inches in length, with a clammy husk, not opening when ripe, but closely adhering to the deeply corrugated and rough, thick shell. Trees with wide-spreading branches, and of medium hight, or from forty to fifty feet, but in deep forests sometimes sixty to seventy, with stems two to three feet in diameter. A common tree in moist soils almost everywhere, from the Canadas southward to the highlands of northern Georgia, Alabama, and sparingly in Mississippi and Arkansas, and all the States bordering the Mississippi river northward to Minnesota. A valuable timber tree, with soft, light wood, much used of late for furniture and inside house finishing. In early times the inner bark was employed for making a yellow dye, also as a medicine, the extract being a mild cathartic, hence one of the specific names, Cathartica.