Nice tree, I would love to have that sitting on my bench.
You repotted in 2017. I would not remove any foliage, or do any bud management in 2018. It is good you wired it out, this allows light to get into the interior of the tree.
This is a Lodgepole Pine, P contorta. It is a single flush pine, like P, sylvestris, & P. mugo. It is closely related to its eastern cousin, P. banksiana - The Jack pine. They will hybridize in the eastern Rockies where their ranges overlap. Key is being a single flush pine the horticulture is as for P. sylvestris or P. mugo or P. banksiana. Read up the how and when techniques are applied to Scott's pines and or Mugo pines. I personally am using Vance Wood's schedule for when you do what as the guide for my Jack pines. My climate and Vance's are very similar, so I feel comfortable with the ''Mugo calendar''. This means no work, no pruning, no repotting, until after the Summer Solstice. Also no routine removal of old needles. Old needles are kept and cherished, especially if they are in an area a back bud is desired. Only remove needles from areas you never want to have a back bud sprout in.
I am 4 years in on owning Jack pines, 3 named cultivars and several seedlings. Everything is in development, or early phases of refinement. My P. banksiana 'Cherokee' was a 25 or 30 year old piece of grafted nursery stock. It had lost all its interior foliage. Here is what I did
#1 - year one - repotted into Anderson flat. This was done in August. Had to remove more than 50% of the roots to get the tree into the flat. This was major root work. remaining growing season had zero further growth. New buds set only at the ends of branches.
#2 - year 2 - flush of spring growth was lack luster, mainly at the ends of branches, did not get a lot of growth. Just fertilized and kept watered, allowed tree to recover. End of year, wired the branches and brought them down, laid them out more or less flat, allowing light to get into interior. Removed branches that were clearly not going to be needed, total less than 25% of the foliage. That is all. No official styling, just letting it get vigorous. I did thin branch clusters generally to 2 branches at each point. If there was a whorl of more than 3 branches, I reduced it to a trunk and 1 sometimes 2 branches to allow future choices.
#3 year 3 - spring the tree had its first ''normal'' or healthy flush of growth. Still mostly at branch tips. Very few buds in the interior, at most two or three. Did zero pruning, Fertilized and watered, End of summer - early autumn evaluation - I had many, many more buds showing. Maybe a couple dozen buds had formed on bare branches in the interior. Adjusted the wiring in autumn. Pruned out downward growing new growth, Thinned the few locations where I had clusters of more than 2 or 3 branches. Put it away for the winter.
#4 - Fourth growing season - maybe 6 of the dozen interior buds actually extended into new growth, Nice reasonably normal budding in the regions with needles at the ends of branches. In time this tree will get dense again. I allowed the tree to grow out all summer. No bud pruning, no shoot removal just fertilizer and let it grow. This autumn I looked and I have at least 2 dozen buds that have formed on old wood, bare of needles. Jack Pines will form buds on old wood!!! Will these buds grow? It seems that they don't necessarily start the year they form, it seems it is the second year they activate.
#5 - the fifth growing season will be 2018. The 6 or so new shoots on old wood are a start, They are still too small (weak) to prune a branch back to. My hope is summer of 2018 more of the buds on old branches will activate and elongate. Sometime after summer solstice of 2018 I will decide if the tree is vigorous enough to prune off shoots at the ends of the long branches. This will be the pruning that will hopefully activate the several dozen buds that have been sitting there without actually growing. I might wait one more season if the spring flush of growth is not at least as good as the previous year. I'm trying to let the actual health of the tree govern what I do, not some book or internet blog somewhere. I re-evaluate the health of the tree before I do anything, each time I do something. It has now been in the Anderson Flat for 3 1/2 growing seasons, (August repot) I won't repot for several more years, unless there is a change in drainage. Right now, drainage is excellent. Next repotting will likely be the post styling move to a bonsai pot. This tree is still not ready to be officially ''styled''. I am not limiting myself to a specific design, I am keeping the majority of branches so I have options down the road. I have 2 different plans in mind as a possibility, one is to more or less preserve the majority of its current height (about 30 inches) the other is to bring it down about half. Either way, I'm keeping all the branches required for either option. I have only removed those which have no use in any of the several alternatives I have thought of.
So that is how I have handled my Jack Pine. I imagine your Lodgepole pine would respond well to similar treatment. I realize you are in the Pacific Northwest, your climate is very different than mine. So read the different treatments for Scotts pine and for Mugo pine, and consider how you would handle your tree, I think you need to let it grow, as I have, to get back budding. And I think you will get back buds if you do so. You can see by my tree, getting back buds is not a ''one summer wonder''. It takes time to get the tree strong and vigorous.
Attached photos are the Jack Pine 'Chippewa' that I used as this example.
as purchased
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2017
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graft union nearly invisible
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healthy ''normal'' flush of growth, good sign it is getting more vigor, roots have finally recovered. 2017
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