If your olive trees are cropping well, the size of the fruit is usually more to do with the variety than anything else.

In an ideal olive season - for example, with early rainfall followed by a hot, dry late summer and an early autumn - fruit size may improve slightly. But in most cases, larger olives come down to growing a naturally larger-fruiting variety.

If your trees fruit heavily and regularly, it is often worth keeping them, even if the fruit is on the smaller side. Not all olive varieties perform equally well in different parts of New Zealand, so there is no guarantee that a larger-fruiting type will crop just as reliably in your area.

If you would like to experiment, talk to other olive growers or a garden centre in your area and see which varieties perform well locally. You could also try planting one or two additional trees of different varieties to compare fruit size and cropping.

It is also worth noting that extra fertiliser will not usually make olive fruit larger. Instead, it is more likely to encourage excessive leafy growth rather than fleshier fruit.