Nursery pot pines: how to reduce roots?

Atom#28

Shohin
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I have several of these Pinus nigra in big nursery pots. The pots are filled with lots of circling roots, and I want to get these trees into bonsai soil as soon as I can. However, the rootball is so deep (tall?) that I'll likely need to reduce them just to get them into a training pot or grow box. Roots appear healthy, new fleshy white growth tips are visible throughout the mass of roots. Foliage seems healthy as well. I do not plan on performing a full bare root on them, since I hear that's not best for pines. However, these pots seem to be about 90% root and 10% soil right now. The pots are about 15" tall.

Can someone give me some advice? would you just slice the entire rootball horizontally to reduce the height? or comb it all out and trim?

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PiñonJ

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Sounds like you're still OK on timing. The trouble with slicing through the root ball (and I think there are many who would do it that way) is that you won't know what you're cutting through until you've already done it. Though it's unlikely coming out of a can like that, what if there's a big looping root that you don't want to cut through? If there's a heavy mat of roots at the bottom, you can certainly slice that off in one go.
 
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If the entire root mass comes up with the roots/soil entact with visible roots circling the bottom: using a saw I would completely cut off the bottom mat of roots, then on only the bottom half of what remains, get to work on cutting back the largest lignified perrenial roots back to a junction where a smaller root branches off horizontally, gently disentangling as I go in order to remove the soil. When the lower half of the remaining root mass is free of soil and roughly level you could chose to repot there into a smaller pot and continue "chasing the roots" next year to be on the safe side, or (using the same process) continue this year by "half bare rooting" one whole side in order to expose the root flare. To safely take this step, It really depends on how the roots have been treated in the past. I personally would do more than half bare rooting but I don't want to give you advice that would potentially harm your tree. The process of chasing the roots back is simply cutting back to where a smaller root branches off (similar to back budding), with some conifers this can take years to do it safely but it's not difficult, and in the end you will have a main root flare (nebari) with all small roots that branch horizontally from it base.
 
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Potawatomi13

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FIRST see where your surface roots emerge from trunk! This can be 2"-4" below surface. Blindly cutting off root ball without knowing this is huge stupid mistake! If lots of roots in pot BELOW that line then cut off bottom half or so as suggested above. Always determine surface nebari before rest of drastic root reduction;).
 

Wires_Guy_wires

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Consider that you don't have to cut anything off if your grow box is big enough.
Knock some of the dirt out and keep everything in place. You can always cut those fat ropes later, and the more roots you leave, the more feeder roots it can produce.
This is how I approach it for the past couple of years. Haven't lost a pine since.

I see plenty of new roots being made closer to the base, enough to cut back to later. That might not be the case with old trees though.
 

sorce

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Aye ..

I wouldn't do anything until they are as healthy as they were when purchased.

Sorce
 
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