Need help finding resources pls

[u/ObjectEquivalent1155]

I’m trying my hand at growing some northern catalpa from seed. They are all about 6 months old currently. I’ve gone from cell trays , to 1 gallons, to 3gal/5 gals currently. Looking back I didn’t address the flare when they were repotted into the pots they are currently in. Now i’m looking at them develop ,and i’m a little worried i’m girdling some of them ! I tried finding resources on how the root flare develops but I can’t find much. Can a tree wizard muster his beautiful words into the comment section please 🙏

Yes I know they’re packed in tight, they’ll be moved soon lol

[u/spiceydog]

I tried finding resources on how the root flare develops but I can’t find much.

A root flare will eventually develop at the point in the soil in which a seed germinates (see the excerpt below top of the third page of this ISA article). The key is to re-pot at that same depth, to avoid the things we're seeing in pic 2.

Tree root development in a natural forest environment differs markedly from that in a nursery production environment. When a seed falls to the ground and germinates, the primary root emerges from the seed and grows down in response to gravity. Growth of the primary root slows when it encounters the denser, less aerated conditions of deeper soil regions. Such growth cessation may occur quite close to the surface in compacted or poorly drained soils, especially in species with weak primary roots. Roots may grow somewhat deeper in strong taprooted species and on well-drained sites. As growth of the primary root slows, small lateral roots form near the soil surface (Eshel and Waisel 1996; Stokes 2000), eventually forming the root flare or collar.

Though many nursery trees and rootstocks are also propagated by seed, the rooting environment is utterly different from most natural ecosystems. The common production process is to manipulate the root system repeatedly by successive pruning and transplanting events in order to produce a more compact and thus more easily transplanted tree.

Cutting grown trees are a whole different thing and thankfully there is some flexibility with that process, but eventually a root flare will develop at the point in which the cuttings are grown in the soil.

[u/ObjectEquivalent1155 → u/spiceydog]

Thank you so much 🙏