Olives generally prefer a free draining soil with reasonable moisture retention, but some cultivars are more tolerant of heavy soils. Local rainfall patterns tend to simplify or compound problems associated with difficult soil conditions. Overseas heavier soils are usually associated with Mediterranean climates which suit the Olive better. This results in the moisture patterns required for optimum production. These heavy soils also tend to hold trace elements better than many of New Zealand's lighter soils, so trace element requirements need to be considered on a site by site basis in New Zealand. Olives require the full range of soil nutrients but not too much nitrogen. Careful selection of seaweed fertilizers will address the trace element requirements as well as the general nutrient needs.

Microclimate

Every area of the country is often considered to have it's own general set of growing conditions but within these areas there are localized microclimates. Even within the average garden there are microclimates that will suit some plants better than others. When choosing a spot for Olives, the basic requirement is warm dry summers and cool winters, that are not too wet. If high rainfall is to be expected, then good drainage becomes more important. Most of the country experiences enough chill to satisfy Olives, but late frosts at flowering time can be a problem.

Shelter is important so that trees can establish well and do not damage as they mature. Some air movement is needed for pollination as well as to dissipate frost pockets during winter.

It is difficult to accurately make recommendations for any areas without some local experience.

Pollination and fruiting

Olive trees are wind pollinated, with the pollen moving 20 - 30 metres from tree to tree. Some varieties are self fertile, but all will benefit from a pollinator. If planting specifically for pickling the fruit, choose a series of varieties that are all suitable for pickling so that harvesting is simplified.

Fruit size is determined by a combination of variety selection, soil type, nutrition, timing of water availability, tree training and crop load. The main aspect to keep in mind in the garden is water availability since there is often root competition in the garden, even if it is only with the lawn. Spring to mid summer water stress will limit the size of fruit. Dry conditions later in the summer will assist maturing of the fruit. Larger fruit are preferred for pickling, so supplementary water in summer (similar to the requirements of citrus trees) combined with some fruit thinning will be an advantage.

Harvesting

Olives for oil production are harvested when black, but for pickling, some varieties are picked when changing from green to greenish yellow, and others are picked when turning black. Dual purpose varieties such as MANZANILLO and BARNEA are picked green or black. KORONEIKI, although a small fruited variety is sometimes used for pickling. Note that Barnea is large growing.

Spraying for disease

A winter spray program combining at least one oil/copper spray in winter as for citrus is advisable. Also a copper spray in spring before flowering commences should be adequate to control any fungus problems. Leafroller caterpillar can be a problem so watch for this throughout summer, especially on young plants.

Trimming for a more open canopy will assist pollination, air movement, spray penetration and fruit color.

Varieties

Olive Barnea
Olive El Greco
Olive Frantoio
Olive J2
Olive J5
Olive Koroneiki
Olive Manzanillo
Olive Picual
Olive Verdale