Nebari at germination experiment: success or failure?

[Desert O'Piñon]

I ended up with a pile of bricks. I was storing them, laid out in (mostly) a single layer under the north edge of my carport (for use as a floor if I ever assemble a greenhouse) and over a few years, pecan leaf litter and dirt/dust accumulated in the tiny gaps between them.

Last spring, I noticed a couple mulberry seedlings sprouting, and it occurred to me to test a theory that popped into my coconutso. With concrete below, how well would the roots spread if I kept them moist enough?

Well, like this:

 

[Desert O'Piñon]

So, my procrastination paid off! By not putting up a greenhouse a few years ago, I now have several trees with head start on their nebari. I am considering this to be about a 70% success. I don't know how to explain the large majority to be rootless on one side, but I'm otherwise pretty satisfied. However, I do wish I had considered there would be the significant straight section of trunk for the first 4 inches, where I couldn't do anything to shape it. But it seems a less involved task to add movement than to develop nebari.

I had a rare brilliant moment and thought it would be a good time to do two new things at once, so I took four smaller seedlings and arranged them into a clump, where the roots are more evenly spread around the group. Since mulberry is in the same family as ficus, maybe these trunks will fuse well and I can work on a first tree in this style for me.

I also planted a few seeds intentionally when I noticed the mulberries. Apparently, I failed to get a photo of the pomegranate, but here's the Catclaw Mimosa:

The results were significantly less impressive in this species. The pomegranate was also not as successful, so it appears that these yields are species-dependent.

I really hope I didn't trim the roots too much. The buds just started pushing, and even though it's barely a month after single-digit temperatures, it seems spring may have sprung. Any suggestions or experience with mulberry would be appreciated. Thank you.

 

[Nevilla]

huh! So cool. Might have to experiment with this. I'm wondring if a 3d printed disc that is irregularly shaped would add more character...

 

[Desert O'Piñon]

huh! So cool. Might have to experiment with this. I'm wondring if a 3d printed disc that is irregularly shaped would add more character...

Very possibly. This idea comes from the popular process of placing tiles, discs, flat stones, etc, under the root ball in order to force the roots to grow in a horizontal plane, rather than the predominant natural deep vertical growth. The idea is to achieve mostly uniform radial roots, so I can see how a manufactured "root flare device" could work. For me, though, it's much simpler and cheaper to use concrete (in this case), stone, tile, or some other readily available item. But if you test it out, post a picture here, or even start a progression thread that details your process. I'd be interested to see what happens.

 

[JoeWilson]

I wonder if the roots tending to one side are an indicator of that side being wetter, and if the moisture levels were more constant, you would get better radial growth? Did they consistently point in the same direction?

Excited to see how well they fuse.

 

[Desert O'Piñon]

I wonder if the roots tending to one side are an indicator of that side being wetter, and if the moisture levels were more constant, you would get better radial growth? Did they consistently point in the same direction?

Excited to see how well they fuse.

That's a very good question. The photos in the opening post were all taken facing east. It was my initial question as well, but the moisture was more or less consistent, and none of the "empty" sides of the nebari seem to have been toward any certain compass direction, so that is one mystery yet to be solved.

Another thing I failed to consider was that if a tree grew especially strongly in its first season, there would be a slight flattening of the trunk between the bricks. Well, the tree that was farthest north (only by about a foot, but that would give it about an hour more sun in the summer, and more than a week in the season), grew exceptionally well, and it was my favorite one.
Until it was unbricked. Three inches of flat, straight trunk was especially disappointing, especially since it grew naturally with such impressive but subtle movement above the brick. We'll see if it grows out in the next few years.