Nursery stock 4' Japanese Black Pine Yatsubusa pre bonsai development

[Bubsamecium]

Hi everyone, new to the forum but have enjoyed following the conversations here for some time!

I picked up a couple JBP 'yatsubusa' about 4' in 10 g pots from one of my local nurseries, for those local to BC, I think they might be from Pacific Northwest Propagators (at least the tag looks like it could be). We've been redoing our front yard into a Japanese dry rock garden style and at first, I was planning on growing these as niwaki in the yard, but I became curious if I could grow them as pre-bonsai in the yard before potting them in the next 3-6 years. They are the ‘yatsubusa’ cultivar (I had a hard time finding standard Japanese black pines locally, but I might not be looking in the right places!), and unfortunately have extensive branches at each internode and some (hopefully correctable/minimizable) inverse taper.
I was thinking of up-potting them into 15 g grow bags preserving the root ball and adding some pumice/bark mix, and putting that in the ground, à la Telperion Farms. I've been trying to solicit advice locally and online on what best to do for next steps and timing, like developing and pruning branches from stock to pre-bonsai with an eventual design in mind (the green line I drew on the photos is my first thought) (now, vs next fall?), when to put them in the ground (maybe this coming early spring?), and if it's worth trying to air layer the robust apical trunk/branches (maybe in late spring) and get another piece out of these trees.

I'm in the PNW, in a relatively temperate but windy coastal zone 9a area. I'd appreciate any thoughts or suggestions!

 

[snowman04]

I am in Michigan, so I can't comment on your weather conditions, but I like your idea of using the grow bags and letting them go a bit. I did one three years ago but left it in the ground and now it is Niwaki in a small Japanese garden I started with it...

 

[Bubsamecium]

I am in Michigan, so I can't comment on your weather conditions, but I like your idea of using the grow bags and letting them go a bit. I did one three years ago but left it in the ground and now it is Niwaki in a small Japanese garden I started with it...

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Thanks for the advice and example! That's great to see, I think my front yard sunlight conditions are similar to yours, it's reasonably sunny but there's still a lot of shade this time of year. My backyard, where those photos were taken, is very very full sun, and where I'd keep potted plants and bonsai, but not great for planting in the ground. I wonder how much that would affect development, growing them in the north facing front yard...

 

[Brian Van Fleet]

Yatsubusa is a tough cultivar for bonsai. They have thick stems and like to grow in whorls. They also tend to hold the needles out to the tips, and shed needles inside readily. Plan accordingly as you go; you’ll be making a bigger tree with fairly angular branching.

 

[Bubsamecium]

Yatsubusa is a tough cultivar for bonsai. They have thick stems and like to grow in whorls. They also tend to hold the needles out to the tips, and shed needles inside readily. Plan accordingly as you go; you’ll be making a bigger tree with fairly angular branching.

Thanks Brian, really appreciate your thoughts from a position of experience, I've learned a lot lurking through your posts! Definitely would have gone for the standard species if I could find a good example, but now hoping to work with what I have! I'm hopeful I can mitigate some of those challenges you mentioned with good design/branch selection, for example, a bunjin or semi-cascade style that has few proximal branches. On the bright side, I did hear Yatsubusa has some positive qualities, like a propensity for backbudding https://www.bonsainut.com/threads/other-jbp-varieties.30385/post-508333
Do you have any more advice on next planned steps for how I might be able to handle these guys?

 

[Shibui]

One of the characteristics of Yatsubusa is lots of buds at each node. That makes them good for landscape but harder to manage as bonsai. They need rigorous bud removal to prevent clusters of shoots and overthickening.