Remarkable Premna Mooiensis. Part II

The following article is part II of a two part series written by my good friend and fellow bonsai artist Gary Howes. To read part I click here. Gary is an enthusiastic bonsai artist and collector of yamadori living in Durban, South Africa. To my knowledge he has the most extensive local experience on an underutilized species which also happens to be indigenous to South Africa.

Preamble

Hi everyone, before I start with the follow up on my first article. I would like to go just one step back. Regarding soil composition the mix that I now use is not the soil mix that I used before. Before pumice, Leca and akadama became available I used course, washed river sand and that still makes up the majority of the soil that I use on most of my trees. Hopefully I will cover some of the cultivation techniques that I am currently experimenting with and at the same time answer some of the burning questions you might have. This is by no means a completed guide in any form. If we look at the time frame, I have only really started to touch on certain aspects of cultivation. Over time I will hopefully be able to add to it.

Reflection

Once I was happy with the collection and aftercare. I started to ask myself many questions and the one’s that really popped up often is after all the years of just getting them to grow properly:

• How would Premna react to be grown in bonsai conditions?
• How would Premna react to pruning, wiring, watering, being placed in a container and diseases to name a few? Most of the experiments I conducted ran simultaneously and also in conjunction with other growers who have Premna in their collections.

Cultivation and growth management

Premna grow in very rocky arid regions and it is where they have less competition from other species. This does however not mean that they necessary like being dry it’s just the place they thrive in. Much like a juniper which also grows predominantly in dry areas it loves being watered and Premna are no different. I have found that they like to be kept moist and thrive better in those conditions than when kept on the dry side. Well drained soil as explained in the previous article is essential to your Premna’s health, together with a proper fertilizing program. I have experienced up to 1.5m of growth in length during the active growing season and I cannot give you an example of another specie that has such vigorous growth in a bonsai container. If I would make a comparison to say a Celtis, with a Premna you are going to have much more work because it is such a quick growing species. That’s just one of the many reasons that I am so fascinated and attracted to this particular specie. Growth management is vital on a Premna as one can lose the design very easily if this is not managed correctly. I have also found that they perform better under 40% shade cloth than in direct sunlight.

Defoliation

I have so far come across two distinct leaf patterns (serrated and smooth edge) and two colours in the leaves (dark green and luminous green) see fig 1 and 2.

Figure 1.

Figure 2.

Some of the remarkable features of Premna is that the leaves reduce very easily. I would not recommend that you try this out on trees that are not healthy and strong in every aspect. In Durban my growing season starts around July so if I were to defoliate I would start in that month. I take my cue from my tree itself (See Fig 3).

Figure 3.

Figure 3-1

The leaves turn a very pale green to yellow colour with browning occurring on the outside of the leaves. This will happen twice a year between the months of June/July and December/January. Which just so happens to coincide with the two periods of dormancy your trees will go through. On the other end of the scale there are the two periods of growth occurring between the months of Sept/October and March/April. In the months that I’ve mentioned above I defoliated FOUR times in a growing season. That is extreme to say the least but I had to do this to determine what the specie could or could not handle. Keep in mind if you do try this you have to have a proper fertilizing program in place. No experiments were carried out on weak trees. For most of the newer growers that question of how do I know if my tree is healthy or not. Look at the condition of your tree and if there is an abundance of new growth all over with even back budding occurring on old wood, it is for me a clear indication that my tree is in a healthy condition and can be worked on. Premna leaves can grow up to about 7cm and over a period of 3 years I have managed to reduce them down to about 10mm. I know that I will be able to reduce them further with time. See Fig 4.

Figure 4.

You might ask the question why I bothered with leaf reduction when my trees were still in development. I only did the above as an experiment to see how Premna would react to defoliation, the leaf reduction was just a reaction to my defoliation. So it was a bonus that they reduced so easily whilst I was developing my Premna. Once I established how easily they reduce and that they would shoot new growth from almost every place on the old and new wood I was happy that, that part of the experiment was finished. So yes I backed off from the 4 times a year to just twice a year with defoliation. My friends in Cape Town and Johannesburg from our conversations cannot defoliate safely after December for fear of die back on some branches so this is just one thing to keep in mind for the various regions in South Africa. I have also experienced a small portion of die back on very small branches. So this is something I have to work around to determine if it’s me that’s working my tree to hard or is there another underlying problem that I’m not aware of at this stage. One of the most rewarding features for me is the fact that Premna will flower after every defoliation. This is not something that I would want to take place quite yet. As the flowers are not what I want at this stage of my trees development.

Remember flowers and fruit deplete your tree of vital energy. So if you don’t want them to flower it is best to pick them when you see them unfold. I will use a tweezers to remove all unwanted flowers and I will cut all the leaves off when I defoliate.

Wiring

When I first started wiring my Premna I was very frustrated as the new growth within a few weeks developed a hard layer around the cambium. The branches split fibers as you bend them and they are so brittle at this stage. At one point I thought I would have to continue by only using the clip and grow method. Any branch under 5mm would just snap the minute a tried to bend it and I thought well that’s not great at all. I left other branches to grow thicker and then found that between about 6mm to about 15mm I could bend the branch almost 360 degrees without the branch snapping or even showing a tear in it. WOW that’s what my reaction was after I discovered this (See Fig 5).

The branches will set within a month so watch for wire biting into the wood. Scars heel up very quickly after cuts are made and I will always seal all cuts after I’ve worked my Premna. I mainly use cut paste and Kiyonal tree sealer. I have almost snapped branches in half and they have all healed over. Remarkable it’s just one word to explain it. Once my trees are free of wire and near completion I will resort to the clip and grow method to maintain my trees.

Watering and diseases

Premna occur mainly in the North Eastern sides of South Africa where we experience summer rainfalls. They grow in dry rocky areas which does not mean it likes being dry. So with that in mind I went about watering my Premna like I would with all my trees in my collection every second day and it has so far worked for me. Everyday watering in summer will occur only when temperatures exceed 35 degrees. I reduce that over the winter period. So how do you take a species that occurs in a summer rainfall area and get it to grow in a region that experiences winter rainfalls? I sent a few down to friends for them to experiment with and it took just over a year for the Premna too acclimatize. They have acclimatized and now there’s no problem with cultivating them there.

As previously stated once my Premna are growing properly I assume normal watering as per the requirements of my Premna. Yes one of my many experiments was to push a Premna so far with not giving it water to again see what it could handle. I found that if you push it and the leaves begin to wilt that would be the time to water it. So yes some went without water for a week with no visible harm to the tree. I won’t try the NO watering routine again this was just for experimental purposes. It did however give me an indication as to the hardiness of the specie and that’s very important to know. For most of us bonsai enthusiast’s we have full time jobs so we are not always able to give a trees the water when they require them.

For the most part I have only found two pests that have attacked my Premna. Red spider mite is the one problem I have encountered on my Premna and the second is a yet to be identified larva that eats the wood of the tree. It looks like it could be some form of a moth but I am yet to determine the exact name of it. Both of the above can be treated with Koinor systemic poison. For red spider mite I spray the entire tree, sometimes depending on the severity of infestation I might defoliate and then apply as directed. With the larva I inject directly into the hole where the larva occurs see fig 6-a.

Editor note. To use Koinor optimally it should be applied as a soil drench only. SK Eco Oil can be sprayed; is a fungicide, wetting agent and very effective against red spider mite.

Figure 6-a

The larva itself spins a web on the outside of the area where it lives. They can be quite difficult to detect as the web it creates is the same colour as the bark of the tree (see fig 6-b).

Figure 6-b

In fig 6-c, I have circled an area where you will see an almost wire type damage. A worm has ring barked the entire trunk yet the tree continues to grow. I have seen this damage on many of my Premna, yet it is able to survive. That is truly a remarkable adaptation.

Figure 6-c.

Fertilization

Regarding fertilization I usually use a combination of fertilizer. I use bounce back, worm tea and bonsai boost. I mainly use solids during the wetter parts of the year and liquid during the drier months. Being from a sub-tropical area I am able to feed even during the winter months but then I use a very low dosage.

Conclusion

There are still many things I need to learn of the species itself and that will hopefully come from the other growers in South Africa. If we continue with our methods and continually exchange ideas, foster a better understanding and then continue to pass the information forward I think within the next 5 yrs we are truly going to see this species more frequently being displayed throughout the country. I truly believe that it has the potential to be one if, if not the best indigenous deciduous trees for bonsai cultivation in South Africa.

My last words before I end. Please pass on information regarding the cultivation of bonsai regardless of species. In order for our community to grow we need to seriously pass the correct information on to other growers. I truly believe that this will propel bonsai within South Africa to another level. Hope you enjoyed the read.