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  • Tom Lau

Kathy Benson Japanese Black Pine Fall Repotting


I hope everybody had a great Thanksgiving! I got around to sit down and update and fix my phone and computer. This report has been over due, but here it is!

Kathy Benson was our guest demonstrator at our last club meeting. She brought tons of detailed information about fall repotting. I know many of you out there would say "repotting" is for beginners, but honestly its a great refresher course right before the "major" window for repotting begans. Thank you Kathy for bring this subject back into the lime light right before the major push for repotting begins in January.

So Kathy Benson had a busy season with organizing and managing the 2015 GSBF Convention in Riverside and planning a "short" course on elms at the Shohin convention in Santa Nella this February. But, she had time come down and demostrate some techniques in repotting Japanese Black Pines in the Fall.

This is one of the original photos almost 20 years ago. John Naka suggested to Kathy to cut the tree down to the first branch shown in this picture. Kinda scary to just cut back to that single branch. But, you have to say the trees is a worthy speciem years later. John was correct to make that drastic cut back in the days.

Kathy had a short discussion about soil mixture. I have to say that soil mixture is really personal and differs from micro-climate to micro-climate. With that said, she got this mixture from Cheryl Manning when she went to study in Japan. The mixture she had lots of sucess is 4-5 parts Akadama, 1 part pumice, 1 part decomposed granite, and 1 part scoria (lava rocks). Other discussion came up and you have to experiment with figure what works best with your location with success. There really isn't a single magic bullet for this one.

Kathy was lucky enough to find a similar pot but just one size larger to transplant into. She started with setting up the new pot with a screen and a single wooden plug for the attachement wires. She mention that that anchor wire is important are of the transplant because it secures down the tree while new feeder roots are formed.

This pot being a single drainage hole will require an attachment plug for the anchor wires. So a simple wooden dowel or thick piece of wire will work with the anchor wires wrapped around the dowel showen in the picture above.

The anchor wires should be treaded through the drainage hole, also through the mesh screen and should like the picture above. Next Kathy got her potting mixture pre-screened and pre-mixed before the demostration.

Next, Kathy scores the edge of the pot with a sickle to slice any roots that have attached themselves to the side of the old pot. Remember you will need to cut the perimeter of the pot if the pot has a hidden lip below the soil level.

Kathy starts to remove about 80%-90% of the old soil around the root mass of the Japanese Black Pine. She makes a comment that we do not remove enough of the old soil in comparsion to our Japanese counter parts. She works to pick out old soil that sits right below the trunk.

Mrs. Benson sits down an examines the pot from all side to pick the "prettiest" side. She states, "You do have 4 sides!" pick the best front possible. I usually repot in crappy pots so this was a first for me!

Next, Kathy starts to layer larger mix at the bottom near the drainage hole. She also starts mounding a small hill of potting mixture where the center of the tree will be sitting. You will have to think how the center gravity of the tree will sit in its new location.

Kathy does a final adjustment of placement having the 1st branch hanging over one side of the pot. She made several adjustments, making sure each time the front of the tree is square to the new pot.

Kathy starts to anchor the tree to the pot with the 4 anchor wire she placed at the beginning of the setup. She made a mockup how the wire should work in the photo below.

If you notice the wires are anchored to each other while pulling and tightning each of the wires to the next piece. The goal is to have the wire as tight as possible sitting on top of the tree.

Kathy finally starts topping off the potting mixture by tapping, poking and any method you like to push in as much potting mix as possible. She is trying to eliminate all possible air pockets that was trapped under the tree and the soil mixture.

After 2 hours of hard work the Japanese Black Pine is in its new home. Thank you Kathy Benson for sharing your knowledge on repotting with us!

#KathyBenson #Repotting #BlackPine

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