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.

Varieties

• Sylvestris (wild olive)

Links

• https://www.bonsaiempire.com/tree-species/olive
  • strong pruning in late winter
  • cut back long shoots to one or two pairs of leaves
  • healthy specimen can be defoliated
  • young branches can be wired
  • repot in spring before the buds begin to swell, every two or three years and remove about a third of the roots
  • use a well draining soil mix
• https://www.mistralbonsai.com/en/olive-bonsai-care-guide-the-secret-to-take-care-of-your-olea-bonsai-step-by-step (based in Spain)
  • can be wired throughout the year
  • pruning in early March (before spring begins)
  • pinching can be done between April and October
  • can be re-potted every 3 or 4 years
  • use 70% Akadama and 30% Pomice
  • fertilise them from March to October
• https://www.kaizenbonsai.com/bonsai-tree-care-information/heart-of-the-mediterranean-the-olive-tree-as-bonsai (based in the UK)
  • cold is not our worst enemy
  • the big problem is the combination of cold and wet
  • trees that are overwintered in the dry will grow much more strongly in summer
  • if you do have to re-pot an olive the ONLY time to do this is mid-summer
  • olives re-potted in spring tend to produce poor subsequent growth in that year and then return to normal in the following year
  • choose a hot period between mid June and mid July
  • don't prune growth prior to re-potting the tree needs all the leaf mass it can get
  • growing media should be alkaline, olives naturally grow on limestone
  • 80% graded Pumice - 10% Moler clay - 10% clean chipped pine bark
  • use any high quality organic fertiliser so long as it incorporates multiple nutrient sources
  • when pruning an olive to build ramification it is important to cut all new shoots at the same time