Introduction

This post specifically deals with the aftercare of wild olives or Olea europaea subsp. Africana which is widely available across South Africa. It is undoubtedly their proliferation around the country and the fact that many people have been able to gain access to the farms or tracts of land where they can be found, which has led to so many of these trees being collected. 

In this post I do not wish to go into any details about choosing material or how to collect wild olives, perhaps that can be dealt with in a future article. The focus of this post will be what you do with trees which you have collected and have brought home.

Tip #1 Preparing the tree for a container

This is a step which is often overlooked but which is critical to ensuring you can one day pot the tree you have collected into a bonsai container.

Collected olives, assuming you are collecting fairly large material, will have a rather large base which extends into the soil as well. When collecting your main aim is to simply get the tree out of the ground with as little effort as possible. No consideration, at least in my experience, is given to preserving any roots as there usually aren't any which are usable for us anyways. However after collecting the tree you are most likely left with a large bulbous shaped trunk.

Collected wild olive bonsai

Image caption. A collected olive flat-cut with a chainsaw. Ideally the tree should be able to stand, on its own, at roughly the angle it will be styled in.

Where the base of the tree tapers down into what was the root ball, or if your tree does not have that shape then just below the old soil line, you should cut this off. This can be done manually with a large-toothed saw or a chainsaw. The term "flat-cutting" is used to refer to this step. 

Performing this step will ensure that new roots emerge from the base of the tree at an even height, ideal for good future nebari and for maximizing the volume of the future bonsai container. Failure to perform this step will result in new roots being issued at the cut ends of the old roots, which may render the tree impossible to pot in the future leading to you having to flat-cut the tree later after it has already expended much of its energy reserves. Ultimately this may lead to the demise of the tree.

Tip #2 Soaking the tree

Usually you would want to seal the cut branches as soon as possible. However don't do that just yet. Fill a vessel large enough to accommodate the immersed base of your tree with water. Dissolve some Disprin in the water; one for a small tree more for larger trees. This is precisely the same as using so-called "Willow water" as it is from the bark of Willow trees that Aspirin or more specifically salicylic acid is derived (My wife's pharmaceutical knowledge came in handy here!). Salicylic acid is said to negate the effects of a plants naturally occuring stress hormone, abscisic acid. The latter acid promotes healing of wounded or damaged plant tissue effectively amputating it. However salicylic acid is stated to counteract this and aid the plant in absorbing water and rooting. (If you'd like a more detailed read on this then take a look at Harry Harrington's site)

Allow the tree to soak in this solution until you see that the ends of the cut branches are moist. This means the tree has soaked up a lot of water and will help it to survive. You can now go ahead and seal the ends with a good sealer as this will prevent infection and loss of moisture.

Tip #3 Apply rooting hormone

Now the verdict on whether rooting hormone is compulsory or not is still out, so I cannot back this up with irrefutable evidence. However, working on the assumption that any help you can give the tree to issue new roots is worth the effort then I believe applying rooting hormone is beneficial.

Although the liquid rooting hormone is very effective its not easily applied to these large trees so powder types are what I use and would recommend.

Collected wild olive bonsai with rooting hormone

Image caption. Liberal quantities of Dynaroot 3 has been dusted onto the wet trunk.

Using a paintbrush apply liberal quantities of rooting hormone (formulated for hardwood cuttings as this is the strongest formulation of the hormones available) to the edges of the flat-cut tree.

You can make an angled cut all around the edge of the cut base and apply the hormone to this broader area if you prefer however I cannot state definitively that this makes a difference. 

Tip #4 Use a fast draining rooting medium

For a growing medium to be fast draining, it must do precisely that; it must allow water to rapidly pass through the medium you have planted the tree into.

Why? It is a fact that roots develop better in an oxygen rich environment. In contrast they rot in one which is deprived of oxygen (I must wonder why I am so frequently asked for a treatment for olives with root rot if people are so emphatic about how good their growing medium is. Mmmm). Typically a growing medium in which the environment is low in oxygen you will find fine particles, lots of organic material and it takes for ever to dry out {and drying is everything but uniform in the container}

Collected wild olive bonsai fast draining medium

Image caption. My mix of choice is equal parts of Pumice, crushed Leca and crushed stone. No organic, no garden loam (whatever that is), no compost and no sand.

There are many components which can be used to successfully root trees in, these may include or be mixtures of the following:

  • Pumice
  • Leca (Crushed or Whole particles)
  • Stone

You might wish to add some moisture retentive material such as coarse fibered peat but this should not be more that 20% of the mix at most. 

Just remember that once roots have begun to grow they are very tender and if they are allowed to dry out even for a short while they will suffer and perhaps die.

If you want to read an in depth commentary on growing mediums then read this free e-book I wrote on the subject.

Tip #5 Use Sphagnum moss on the surface

Actually this is the first year I have used sphagnum moss as a form of ground cover on top of my growing medium but what I observed has been very exciting and encouraging. The idea was sparked by the common practice, which I learnt in Japan, of placing grated sphagnum moss around a repotted tree.

Sphagnum moss is generally used as the preferred rooting medium when doing air-layers. It is claimed that it has antibacterial properties too. What it is highly effective at is water retention and generating root growth.

Collected wild olive bonsai with sphagnum moss

Image caption. Collected olive potted into a wooden box purpose made for it and then sphagnum moss applied to the surface of the growing medium all around.

When you are using very free draining growing mediums they can dry out rapidly on the top but not so in the middle and bottom of the container. A possible solution for this is to use coarser material at the bottom and fine material on the top (this increases the surface area and thus area for moisture to cling to closing the gap between drying at the surface versus the bottom). We usually water when we see the top drying but in fact as the bottom might still be wet we might be negating the benefits of using the fast draining medium to begin with. By applying a layer of sphagnum moss on top we:

  1. increase the moisture at this level which encourages surface rooting
  2. oxygen penetration is not reduced
  3. the growing medium is stabilized and is not disturbed when you water

Collected wild olive bonsai rooting

Image caption. Within weeks, roots can be seen emerging even from the side of the trunk and into the sphagnum moss.

Tip #6 Place in bright shade

I have personally not experienced the need to put a bag over a tree in order to encourage it to bud, although your experience might be different to mine. If you do use a bag you may need to place your tree differently, but without a bag I place my collected trees in a position where they will get morning sun and be as sheltered from the wind as possible, although I also firmly wire my collected trees into the container as well.

Collected wild olive bonsai in shade

Image caption. A collected olive doing well in a protected, lightly shaded environment exposed to morning sun only.

As the tree gains in strength you can progressively move it to more sun if you think it necessary. Too much shade usually results in overly large leaves and excessively long internodes between leaves and thus dormant buds.

Tip #7 Foliar feed

I do not see the purpose of applying any fertilizer immediately after collecting a tree which has been stripped of most of its branches and all or most of its leaves. There are also no roots to take up nutrients, so any nutrients applied will be wasted.

Video depicts the fine spray from the two independently adjustable nozzles of the Koshin, battery operated sprayer. A fine spray is ideal for foliar feeding.

However, once the tree has begun to develop new foliage I do begin applying a weekly, weak solution of either Seagro or Sea Secret combined with Kelpak as a foliar feed making sure I also get some onto the sphagnum moss which will absorb it and release it slowly. The fertilizer containing fishmeal and other sources of high quality nutrients support this new growth and helps to replenish those which have been expended. The Kelpak provides valuable auxins which promote root development.

Tip #8 Be patient

Assuming you do all the above and your tree responds well to the treatment you will be rewarded with healthy new growth all over the olive. It is at this point that you must practice some restraint.

Collected wild olive bonsai healthy growth

Image caption. Same olive as shown above, 6 months later and growing well.

It is easy to forget the ordeal you have put this tree through so you should really allow it to recover fully before begin work on it. I would recommend at least one full growing season or even two, not cutting a thing during this time. After that, you can begin removing unwanted growth and perhaps a do little basic wiring. The last thing you want to do is heavy bending and or carving work immediately. This will disturb the very young and immature root system and may result in broken or damaged roots.

So there you have them, 8 tips which I am sure will help you to achieve success. If you have any additional tips to share with other readers be sure to leave them below in the comments. I'd also like to thank those who shared their experiences with me, leading to me trying them, contributing my own knowledge and sharing it all with you now. Special mention to Freddie Bisschoff, Stephen Le Roux of Stonelantern.co.za, Brett Simon, Gary Howes from New Age Bonsai and lastly Darren Kelly.


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