Olea europaea (olive)

There are numerous guides on the internet with contradictory information on how to grow olive trees as a bonsai, likely due to the differences in climate between its native Mediterranean region and colder, wetter areas.

This species has a peculiar fine root system that grows slowly and doesn't require frequent repotting. As a result, the substrate must be very stable to avoid compacting over time. It also needs to be highly draining because these trees do not tolerate the combination of cold and wet soil. Therefore, a mix of pumice and lava is well-suited.

There is less consensus regarding the best time for repotting. Some guides recommend doing it just before spring begins, while others prefer the end of spring or early summer when the trees are already growing. The latter opinion seems to be more common in colder climates.

Pruning can happen in spring prior to the push of growth and after post-flush hardening to induce a second flush of growth in early to mid-summer, which is later than on deciduous trees due to the thicker cuticle and more durable leaf mass which making them slower to respond to environmental conditions (similar to conifers). As a broadleaf evergreen there's no leaf drop in fall and no pruning at this time.