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.
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)
I also add Kelpak to this solution as it contains auxins which encourage root development. In fact when I repot a tree I always water it every few weeks with a solution of Kelpak to assist with "post potting" stress and to stimulate the development of new roots. (Kelpak is NOT a fertilizer)
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.
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 high in oxygen you will find ample fine particles.
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: