I saw a nursery how a nursery man repotted a Japonese maple I wanted to buy from him that that was still loose in the pot.

He decided that the tree's roots did not like the potting soil and was not sending out root growth to attach to the potting soil.

It was very early spring and the tree had been in good shade. He put the tree in a deeper pot and pushed away alot of the his original potting soil from the roots. at that time he immediately put the tree in what he considered a better potting soil that he custom mixed. He made sure to push the new soil up beneath the tree's meager root system. He packed the soil with his hands as he filled the pot to the right height. Then he watered every thing well and releveled with enough more soil to finish off with the right height.

Yesterday, I visited the nursery again to purchase two other trees, and while there I observed that same Japanese maple he was holding and tending for me was healthy looking, growing in shade, and it was secure in the pot. Every thing indicated that the tree had produced enough roots to secure it in the new potted soil.

The nursey man did this early in the spring, well before the summer heat arrived, and he might have poured root stimulator on it but he did not wash the roots before repotting.