Arboriculture

Although polycropping, growing trees with arable crops in between, has regularly been practised in the recent past in the Mediterranean, it may have been less common in classical antiquity, at least on the plots of wealthy farmers, because of the habit of trenching around trees, discussed above. Theophrastos certainly understood that repeated digging around trees throughout the year to direct water to the roots retained soil moisture and eliminated weed growth, improving the productivity of the tree. In consequence he did not generally recommend polycropping.

Digging benefits all [trees], since it removes the things which block and intercept the food supply and makes the earth itself damper and lighter. Moreover, air gets mixed in with the soil, as it must when the earth is turned up, and gives some moisture and so provides food. This is why one must dig even dry and waterless ground and turn it up frequently (as said earlier). However, digging is also good for land that is marshy and has surface water. (Theophrastos De Causis Plantarum 3.10.1)

Indeed, plants also that are planted or sown as neighbours are all of them injurious for this reason, some actually destroying a tree, except where they serve a curative purpose, for example when people sow barley or some other dry plant among vine cuttings to reduce the moisture, or sow bitter vetch (orobos) among radishes (raphaneis) so that they are not devoured [by caterpillars], and the like. (Theophrastos De Causis Plantarum 3.10.3)

Olives, vines and figs, like most fruit trees, do not grow true to type from seed. The Greeks propagated them vegetatively using cuttings, ovules (growths at the bases of old olive trees) and grafting. Theophrastos (De Causis Plantarum 1.6.1-10) has a long and detailed discussion of grafting techniques, which farmers clearly used with considerable sophistication (Figure 13.15, top).

It is rightly recommended to keep the bud and bark from getting torn and to trim the inserted scion so that no core wood is exposed at the join. This is why people also first bandage the join with layers of lime bark, then plaster mud over it mixed with hair, to keep it moist and to prevent damage from sun, rain and cold. So too after slitting the stock and making the scion wedge-shaped, they drive it in with a mallet to make the fit as tight as possible. (Theophrastos De Causis Plantarum 1.6.7-8)

Sometimes farmers used the wild forms of olives, figs or pears as rootstock because they were so vigorous, and grafted choice domestic varieties onto them.

It is also reasonable that trees so grafted should bear finer fruit, especially when the scion is from a cultivated tree and the rootstock from a wild tree of the same bark, since the scion is better fed because the stock is strong (this is why it is recommended to plant the wild olives first and later graft them with cultivated buds or twigs). (Theophrastos De Causis Plantarum 1.6.10)

Of course, tree crops were cultivated primarily for their fruit. However, there were many important by-products of arboriculture. Branches pruned from olives, vines, almonds and other fruit trees were an important source of fodder for animals. When all the leaves had been eaten, the branches could then be cut and stored for fuel. Vine prunings in particular made excellent fuel for kilns and ovens. Fallen fruit (e. g., maggot-infested olives and figs) and almond husks were also important supplements for animals in late summer when grazing was scarce. The residue from the pressing of grapes made nutritious fodder, and the residue from olive pressing could be used for either fodder or fuel.