[Plan of Action] Growing for Size in Containers

[AnacortesSteve]

First off, thanks for the reply and info.

What is meant by "containerization"? Are you suggesting I leave my trees in their nursery containers until the trunk is ready? What about the nursery soil? Shouldn't that be replaced with something better draining? Or is this referring to bonsai pots?

Does that mean the whole open-structured container technique is solely for ramification? Does fine root network not contribute to faster overall growth?

Again, this is where there appears to be little to no consensus. A lot of folks like yourself say I should use a proper bonsai mix while others say I should maintain a fair amount of organics (e.g. 50% draining aggregate such as perlite or pumice, 50% organic such as peat moss, potting mix, or coco coir) for the growing phase. This brings me back to my initial thought of equal parts pumice, scoria and bark as it fits somewhere in the middle (pumice and scoria is dirt cheap here in SoCal).

No need to reinvent the wheel, Listen to this interview, maybe more than once https://bonsaimirai.podbean.com/e/telperion-farms/ they use pumice/pine bark/composted manure, tree is in the ground but in a grow bag. If you don't use a bag, your success of that tree living after being dug up is the same as yamadori, which isn't very good.
I grow hundreds of JBP & JRP and Italian Stone Pines, I grow them in mass on heat mats and grow lights Perlite/Peat, I cut them for radial root development, when they have a good head of real needles, I put them in 4" pots using left over Perlite/Peat and not try not to disturb the roots. I don't use the 72 pots anymore, too much heat gets to the bottom and kills them if you miss a watering. After 1 year I up pot to 1 gal, year 2 work on the roots and go to a #3 air pot. I just repotted a 3 year old Doug Fir I grew from seed, big trunk and massive fine radial roots, it was no fun digging out the substrate from this.

 

[AnacortesSteve]

Can you speak to this a little further. For trees in grow boxes, for example, do you recommend that the tree grows out for a number of years and then replanted? That seems intuitive, but there is a good deal of advice out there encouraging yearly repots to further nebari development. I try not to repot yearly for the reasons you stated, but am always concerned that doing so is allowing my nebari to get away from me. (An irrational fear as I am doing this for too short a time to have any evidence of this).

The point is to work on the roots every time you repot, you shouldn't have to repot that often. My repot from 1 gal to #3 air pot is when I arrange the roots as best I can. Roots are pretty pliable if you are careful, unwind them so you don't damage a lot of fine roots, then I arrange them and cover with my grow mix and let them go another 2 years. I am in a rental house so I can't plant in the ground or I would.