Pine repot critique

[maroun.c]

This is the last from 3 pines I got from same vendor. All in bad soil and roots matting below a screen he puts below the soil. Last 2 trees I repotted died from repot. Last one I repotted had black dry roots mat below screen which all broke up as I removed and tree had few roots in soil and died immediately after repot. Hence I was very careful and disturbed roots as little as possible in this first repot hoping it'll make it till a second repot to take down the roots and nursery soil further. Weirdly trees always did well despite the nursery soil blocking drainage.
Tree before repot.

The typical black matt of roots below the screen yet less dry than previous tree and I see some white roots which I presume are growing... also a load of gravel taking space in the pot and sea stones in the soil also taking root space. Broke down rootball with care not to damage them and didn't cut down any of the roots even the long ones with no hairy ends.


Left this area untouched but did tease roots from it out just a bit more to go into the new soil


Anything I could have made better ? Again my whole concern is because of the history with pines in this soil

 

[River's Edge]

It was wise to limit the root pruning in this case. If I can, I would suggest consideration of other aspects.

Observation reveals. 1. that root work was not completed properly during development, ( crossing roots, aerial root, uneven nebari)
2. The tree is planted too high, feeder roots will be primarily at the base rather than throughout the root ball. ( further evidence on incorrect repotting technique)
3. The tree has been historically repotted on the bottom and sides rather than the best approach of 1/2 HBR for pines. ( all the feeder roots are on the bottom and sides, none or few evident throughout the root ball itself. ( compacted soil near the trunk and above, particles below contribute to this)

I would have used the following approach.
Slowly and carefully comb out sides and bottom. Only the edge of the sides, all of the bottom below the screen.
Then I would choose the weakest side with the fewest feeder roots and comb out that side ( 1/2 HBR) Remove all old soil, dead roots and the thicker roots that have few feeder roots on that one side.
leaving the other side of the root ball intact with just the edge of the side combed out and the bottom trimmed.
I would then plant in a bit larger and deeper container to begin root recovery. If the tree responds well during this growing season, I would perform the other 1/2 HBR this coming fall to complete the removal of old soil and change out for Bonsai mix. I would then begin to reduce the root ball over time as the root ball condenses and rejuvenates at a higher level closer to the nebari.
The goal would be to correct nebari and be able to plant the tree lower in relation to the rim of the pot. In order for this to happen feeder roots need to be established closer to the trunk base rather than just on the outside edges and bottom of the root ball. More frequent repotting and root trimming will result in more feeder roots within the root ball. The better mix of soil will promote that as well.
Correction of the nebari should occur in stages with some progress each successive repotting rather than attempting to remove all the problems at once.

Realistically I would plan on putting the healthier tree with a root ball consisting of primarily feeder roots back in a suitable size bonsai pots within three to four years. In the meantime the health would have improved and design and ramification could have continued due to the slower stage approach of repotting. Also less risk of harm to the tree.
Hope the comments help!

 

[RKatzin]

Exactly what I was thinking, but couldn't possibly have stated as well.

 

[maroun.c]

Thanks for taking the time and the excellent info. Was wondering about the aerial root cause.
I kept the tree in a bonsai pot so it looks nicer on the bench but oversized the pot.
The combing the roots and taking out 1/2 on one side would have been safer i guess which I did that.
As said tree is in a larger pot and way deeper but didn't plant it too low in soil. Should I add soil and to which level. Should I shave tree higher side if I will add more soil ?

Thanks again for the help

 

[River's Edge]

Thanks for taking the time and the excellent info. Was wondering about the aerial root cause.
I kept the tree in a bonsai pot so it looks nicer on the bench but oversized the pot.
The combing the roots and taking out 1/2 on one side would have been safer i guess which I did that.
As said tree is in a larger pot and way deeper but didn't plant it too low in soil. Should I add soil and to which level. Should I shave tree higher side if I will add more soil ?
View attachment 423351View attachment 423352View attachment 423353View attachment 423354
Thanks again for the help

based on the current circumstances I would not cut anything further. I would increase the soil level until it is just 1/4 inch or .5 cm below the lip of the pot. Let the tree recover this growing season. If the trees recovers strongly with new growth this year you can do the 1/2 HBR early fall. Allow six weeks before expected frost in your local climate. If the tree stalls or has trouble with recovery then wait until the following year.. Strong new candle growth is the signal you are waiting for before any further work. I would advise that you do not, wire the tree, thin needles, decandle or prune branches until this new growth is evident.
Hope that makes sense. Root recovery is based on photosynthesis and the more foliage the more photosynthesis.

 

[maroun.c]

Thanks again. Sure will hold off any further work on the tree this year till fall. We don't get frost here, maybe a few nights at +2+3 degrees is the coldest we get in winter so will delay second bare root till late autumn or maybe just leave it till next spring. Won't fertilize as well till i see new candle growth as well?