About 4 years ago this 4 foot tall, 35 year old cotoneaster hedge had problems and died off. Over the last 3 years it has started to come back and the new growth looks very healthy. I am going to harvest one of the plants to some day turn into a bonsai. When i cut it down i left the bottom of the trunks about 12 inches wide 8 deep and 6 inches tall. Of course the root ball is larger and it has some exposed roots. My questions are how large and deep should the pot be. What type of soil mix should i use. How much of the garden soil surrounding the root ball should i leave with the plant for now. Should i cut back the roots when potting or leave as much as I can dig out with the root ball. I live in southern Alberta, Canada. Temperature ranges from - 35 to +90. Thanks. M

Muckle wrote:

Over the last 3 years it has started to come back and the new growth looks very healthy.

It has some potential, but most of the new growth are suckers. Try do define a main trunk (with a primary branch perhaps?) and get rid of the others.

Muckle wrote:

What type of soil mix should i use. How much of the garden soil surrounding the root ball should i leave with the plant for now.

I would prepare a bonsai mix with non-organic components and good drainage, like leatherback explains HERE .

Muckle wrote:

Should i cut back the roots when potting or leave as much as I can dig out with the root ball.

I would take as much roots as possible from the ground, comb them, and prune the largest ones, the ones going straight down and the longer ones, with good bonsai shears, but leaving some original soil. Try not to harm the finer roots during this process.