large tripletrunk or clump style mugo pine!?

Hi...

I would like to present a large mugo, which I resently purchased from a garden nursery . It was first fieldgrown, later on grown in plastic continers. At present it has spend a couple of years in this 60l/15gallon container. The base above soil level is apr. 13cm/5inches across and girth continues to expand beneith soil level. I'd like to style this pine as a clump or triple trunk with the third trunk (first from the left) slanting towards a han kengai position and styled with an individual cone shaped apex. The second trunk (towards the back) will be part of the left apex. The main trunk will form another cone shaped apex leaning over the secondary and tertiary trunk (needs a lot of budding, though). There will be a negative space between the main trunk and the other trunks.

This plan depends on were the roots begin on the sub level part of the trunk. I haven't seen the nebari yet, because the surface is quite full of roots (some of the smaller roots apparently are sprouting from the trunk at soil level and the rest is probably part of a very entangled root ball. I don't know. Before I do any further work I would like se the nebari, but I have never handled this much pine in one tree. I simply don't know how a field grown/container grown root ball this size would look like and what to expect?

Yesterday I removed about 40-50% of the original foliage and pinched the candles down to one thirds of the original length. The tree is very healthy, so I am concidering to prune out the candles and feed heavely to promote strong back budding. Another option would be to wire the main branches into position and a third would be to just let the tree rest until transplanting time later this august/september.

So please, does any of you guys have any experienced advise on how to best start training this kind of large material? I would apreciate learning from you all. And how many % root mass is safe to prune out on this (healthy and relatively hard pruned) tree if transplanted in late summer this year).

for any thoughts and advise, thanks in advance ;-)
/Loke Emil

I would be inclined to to do a partial repot now and a full repot in the spring. For a partial I would cut about 5 cm off the bottom of the root ball, comb out some of the surface roots, loosen the circling roots, and plant in a container that is about 10 cm larger in diameter using a fairly coarse soil that contains a fair bit of the same type of nursery mix as in the current root ball. This will encourage the new roots to grow outwards instead of around the bottom of the pot making it easier to get it into a flatter box next spring. In the spring I have then completely root washed a variety of pines for repotting into good bonsai soil in a large moderate depth box. I lose a few, but if they are nursery stock I feel that getting the roots started in the right direction is worth the risk. I would take a more conservative approach for high quality yamadori or prebonsai stock. If you do a preliminary repotting this year, I think you can easily remove 1/2 to 2/3 of the soil in two pie shaped segments with near zero risk in the spring. Remove the rest in two years.

For this type of mugho nursery stock I tend to cut back even harder than you have based upon the picture. I work my way in by removing the strongest branches from a whorl leaving two branches. However, if you have already taken 40-50% of the foliage, you might only take out the strong leaders that don't appear to be part of the future design.

Hi Marty W

Hm! thanks for the good advise...I tend to take the more conservative approach regarding any trees. So what you suggest is pretty scary to me ;-)

I don't want to screw this pine up and I have never tryed with a pie-section root pruning. But it does make perfect sense to start out correcting the roots. I did also prune out all but two branches from all the whorls. I only took out one primary branch and a smaller secondary branch that wasn't going into the future design. So for now all pruning is done. I like the idea of a bare root repotting. However a root wash would bring me out of my myccorhiza comfort zone quite a bit

Best regards from Loke Emil

I wouldn't do a partial repot now. Its a bit too late in my opinion. I would excavate and lower the soil level to investigate the trunk and nebari. I would also reduce last years growth by half and feed well.

will baddeley wrote:I wouldn't do a partial repot now. Its a bit too late in my opinion. I would excavate and lower the soil level to investigate the trunk and nebari. I would also reduce last years growth by half and feed well.

Yes, Will. I was wondering how to excavate the top soil now to be able to investigate everything: I was thinking, maybe use a chop stick and carefully dig/stab down into the root ball - especially close to the trunk - and refill with some pumice after inspection, to encourage new root formation where they are needed instead of at the end of the root tips (the root ball is quite dense with pure spaghnum and I do suspect that this condition will eventually lead to root rot or just no roots back budding from the trunk). Then in the spring 2012 make a repot/transplant - and if the inspection reveals a better nebari/radial roots, I will lower the soil level as suggested.

Thanks Will, I'll feed well ;-)