AusBonsai

Any one able to tell my what purpose this piece of plastic serves?
It appears to be an “upper” section of a pot to contain soil. My thoughts were it’s to help with producing good nebari or to ensure good watering?
Iv seen it on quite a few larger trees from overseas and keep wondering what it does.

Perhaps it's like a cone of shame? Maybe it's got fleas or just be neutered? Haha.

Better guess, to raise the nebari? In preparation of a root trim and shallower repot?

To retain soil. Not sure why but the tree has been potted higher in the pot and the ring holds the soil above pot level from washing away.
We sometimes use that when layering close above existing roots but this one already clearly has good roots so not for layering in this case.

Okay thanks guys
I thought as much

I would suggest is that it is to retain water.
Mirai uses this technique.
When the tree needs repotting, and the soil becomes a little compacted and less permeable, the water can run off the surface before penetrating the soil, and fail to penetrate the root ball.
You can see there has been soil "filler" placed around the inside of the plastic ring - this is to force the water to the centre of the pot, rather than just accumulate at the edges and run down the inside edge of the pot - again to force water to penetrate the root ball closer to the trunk.

Exactly what @wrcmad said.

Great idea!

Could also be that the tree has produced a lot of roots that has pushed it up out of the pot and it is not a good time for repotting and so having something to retain moisture until it can be repotted.

dansai wrote: ↑May 29th, 2022, 6:33 pm Could also be that the tree has produced a lot of roots that has pushed it up out of the pot and it is not a good time for repotting and so having something to retain moisture until it can be repotted.

This is kinda what I thought it was for, all the other information also makes a lot of sense