Wednesday, 14 February 2018

Grafting new branches on Clerodendrum

Our club Clero has really developed some vigor, a perfect time to get on and do the intended branch grafting.

Here is the tree at the start of the process. I've tip pruned all the branches to slow them down and give new new branches a chance to catch-up. Most of the branches that have emerged have come on the left-hand side. Even with that there is a bit of a gap which needs to be filled as well as on the right hand-side.

 
First thing to do is to select locations for the new branches. I have 7 scions ready to go. I've placed some nails in the locations I want to sett he scions to check the general arrangement. The tree produced 8 branches to start with and more recently produced another at the right rear. So that will add up to 8 plus one plus 7 more. 16 branches will be a good place to start with this tree.

I've prepared 7 hairpin scions from a number of cutting that I have struck. Each scion is in itself a small rooted plant. The grafting process using rooted scions makes success less dependent on accuracy and not subject to challenges with dehydration of the scion. They will survive quite happily while incorporation proceeds.

This is one of the scion plants ready to use.

The young plants were not easy to bend into the 180 degree hairpins and as you can see from this closeup the bend was a bit snappy. However even if they do snap as long as some bark remains sound they will mend and survive. After a few weeks they callus over and are ready to use.

Here is one with the wire removed. Fairly lumpy but quite workable.

The next step is to drill a hole where the branch is to be placed. I start with two small pilot holes and then follow with a larger diameter drill, drilling down into the inner sapwood just past the cambium.This is to ensure contact between the cambium in the rootstock and the scion.

Scratching off a section of bark on the scion is the second part of bringing the cambiums into contact. This only need to be done of the arm which will be the new branch.

The hairpin scion is then placed into position.


A piece of wire with a twist in it is prepared to slip between the arms of the hairpin and hold it in position. As the hairpin grows unless it is held in position it could push its way out of the hole.


Here the retaining wire is secured to hold the scion in place.

It is then sealed with sealing paste to assist healing and incorporation.


This process is repeated another 6 times until all the hairpins have been placed.

If they grow as hoped and expected, within 6 to 8 weeks it might be possible to separate the scions from their pots for an independent life as part of the tree.




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