These graceful trees are wind, salt and frost-hardy and will grow almost anywhere in New Zealand. They are not that fussy of the soil they are to be grown in, but prefer a well-prepared hole with lots of compost, especially if heavy clay soil is where they are to be grown. Olives are highly-ornamental trees, as well as good fruit producers. They are very tolerant but do best in a sheltered position. It is important that your Olive does not dry out when the fruit is developing, and they do well with an annual application of general slow-release fertilizer. One tree can provide up to 30kg of fruit.
Size matters when it comes to deciding what variety you are going to grow. For pickling, large olives are a better choice. If you are going to press your olives for oil, size is not so important. How much oil they contain as a percentage is more important. You can still pickle 'oil' olives - all going well, they will taste great. Just understand they may be smaller, so there is less flesh relative to stone than with a larger pickling olive.
A lot of the olive varieties need to be pollinated with a different variety. Olives pollinate by wind from trees located within 20–30 meters so it is ideal to plant at least one other variety as a pollinator.
Here are a few of the varieties that are more commonly available:
Ascolano
If size matters, then this variety is perfect for you. The attractive very large fruit that ripen green are great for pickling. Ascolano are fairly disease-resistant. Pollinate with other varieties, such as Frantoio and Leccino.
El Greco
El Greco is an attractive tree even if just grown for its silvery green foliage. It has a compact mature size of just 3mx3m, making it the perfect-sized tree for a smaller urban section. El Greco are self-fertile but are not known to fruit easily in New Zealand. This may be to your advantage as you don't end up with lots of very hard olive stones flying around when you mow under your tree. Good oil content.
Olives J5
J5 is a well-shaped tree that is perfect for the Northern gardener. J5 can be used both for pickling and for oil when the fruit ripens mid-season. Grows to 4X3M
Frantoio
This is a tidy and compact sized tree at 4mx3m, with an early, heavy crop of medium-sized fruit. The oil from these olives has a peppery fresh pressed taste and is great for using for dressings and dipping. They pickle well as an eating olive and are an all-round easy-to-grow variety. Very high in oil content.
Koroneiki
An attractive smaller growing olive tree bearing large crops of small fruit. Well suited to coastal areas. Ideal for hedging and screening. Very high yields of high-quality oil or can be pickled. Hardy. 6M
Leccino
Superb Tuscan oil selection that performs well in most parts of New Zealand. Healthy and vigorous, and tolerant of the cold once established. A medium-sized olive used for both pickling and oil. Very strong grower getting up to 10M tall, so needs more pruning. Pollinate with Frantoio. A good pollinator for other varieties.
Rakino
Olea Rakino is a shapely, small, open, tree suitable for both inland and coastal situations. A prolific summer fruiter, its flavoursome fruit is ideal for pickling. Suitable for warmer areas, including Auckland/Northland. 3X3M
Mission
A vigorous upright grower. Bears a heavy crop of smaller sized Olives which are best pickled. Grows well in the cooler regions. Self-Fertile 5M
Carolea
Carolea Olives are medium to large-sized olives grown both for oil and pickling. It has a good oil yield and small nut. The oil is considered to be a good quality one. Will need a pollinator. 4X4M