Propagation. By Cuttings.—The olive may be freely propagated by means of cuttioge. In making .a nursery with cuttings, if the soil is not naturally sandy, some sand may be advanta geously put into the holes as the cuttings are stuck in. In this case, the cuttings need not be more than 8-12 iu. long ; they should be neatly trimmed with a sharp knife, to avoid bruising the bark, and only one good bud should be left above ground. The cuttings may be from either branches or roots; the latter are best planted entirely under ground, but they possess no special advantage, and are not recommended, except when removing or thinning out the trees, or when at a loss for material from which to raise a large nursery stock of a particular variety.
By Layers.—Of course, a tree reproducing itself so readily from cuttings, will grow from layers ; but in adopting this method of increase, it must be remembered that the form and general welfare of the parent tree are prejudicially affected, until the layers are detached, and the sap again enters into free and natural circulation. This method is condemned by the best Continental horti culturists.
By Suckers.—Suckers, which often rise from the roots of old trees, if strong, may be carefully and neatly detached. They make good trees, as far as concerns their having a well-formed .stem to commence with; but they are considered by the foremost authorities to yield less and live a shorter time, possessing the germs of all the maladies of the parent tree.
By Seed.—Seedlings can very readily be raised in a light and well-drained soil. Before sowing the olives, it is necessary to remove the oily pulp surrounding the kernel, so that moisture may reach the latter. This is effected by a process of decomposition, which may he brought about by steeping the fruits for 12 hours in hot water or in yeast, or by 21 hours' immersion in an alkaline ley, producing a soap from the oil, readily soluble in the moist earth. The seeds used should he the finest fruit, and chosen from the healthiest trees, and, being some months in germinating, they should be sown as soon as ripe. The sowing should be pretty thick, in a sheltered place, in furrows 6 in. apart and 2-3 in. deep. The ground needs previous trenching 3 ft. deep, and good manuring. During the spring and summer, careful occasional watering is necessary, as well as the removal of weeds as fast as they appear. When the little plants begin to shoot, small green branches are stuck in the ground between the furrows, to shelter the shooting plants, which con tinue to progress during the rest of the autumn, and even during nearly the whole winter, unless it be cold. If frosts are expected, the plants are covered with dry leaves, straw, or litter. If the plants succeed, they come up thickly in this seed-bed ; the weakest are plucked out during the second spring, or, if pulled up early, may be replanted elsewhere. There is a two-fold object in raising seedlings, primarily to obtain stocks for grafting on, and secondarily as a means of securing new varieties suited to the climate—an important consideration in commencing the culture in a strange region.
By Grafting.—.Grafting is much practised on the olive, and is among the most certain methods of procuring strong trees of approved varieties. The grafts known among horticulturists as "shield," "cleft, " and "crown" are all used, and variously recommended. It is probably immaterial which is adopted, provided the scion and stock suit each other in point of age and size. Underground grafting is considered decidedly preferable in Australia, not more than 2 eyes of the scion being left above the surface. The union is better ensured by binding the point of junction with a strip of calico steeped in a mixture of mutton, tallow and bees'-wax ; the earth should afterwards be heaped into a mound above the graft. The operation is performed in spring, when the sap is rising ; and the scions are of 2-year-old wood. Seedling-stocks may be successfully grafted at 2-6 years old; but in using 2-year-old scions, it is as well that the stock should not be much more than the same age, so that there may not be more than sufficient sap to effect the junction, thus avoid ing the necessity for keeping down suckers and surplus shoots.
By Truncheons.—" Truncheons" are very stout cuttings, 1-10 ft. long, and in. in diameter, according to the method in which they are to be planted. There are two ways of doing this. By one, the pieces have a length of 4-10 ft., and are placed in holes 20-50 in. deep, according as the soil is deep and well drained. The process is as follows. Holes are opened to the depth suited to the character of the ground, either in early spring, or better during the previous summer, the soil being left in the rough to get mellow. The truncheons are planted upright in the holes on a good layer of chopped leaves, rotten dung, or other thoroughly ripe but not too hot fertilizer, and the holes are fitted in firmly with the soil which was taken out. The surface around each is left slightly hollow to facilitate watering, which must be done whenever the weather is dry. The objects of manuring the bottom of the hole are to stimulate the truncheon to send out roots from the lower end, and thus secure a well- and deep-rooted tree, and to help retain moisture where it is most needed. In transplanting rooted trees, the same precaution should be adopted. When the length of stem above ground is great, the soil is sometimes heaped around it, to mitigate the drying influence of the air before the plant has rooted; a hole is then made on one side, and kept open by a wisp of straw, for the purpose of watering. The advantages of planting by truncheons in this manner is that a year is saved, and that the tree commences with a good straight stem.