Maples grown in different propagation containers

Large roots circled the periphery of the container.

Root circling is evident in this photograph.

Roots deflected in many different directions once they met the plastic side of the container.

Many roots grew up toward the surface. These can develop into stem girdling roots as they grow across the top surface or around the container periphery.

Roots grew mostly down on some trees.

Many roots grew down, and others grew up.

Close up showing how roots that grow up the side of the container can become circling and stem girdling roots.

Main roots on most trees were deflected down the sides. Active root tips were mostly on the bottom of the root ball. Secondary roots can be seen growing up to the surface. We don't know how many of these turn into potential stem girdling roots.

Many roots grew up when deflected by the container wall in the top portion of the container. These should be removed. Some roots in the middle and lower levels deflected down.

Many roots growing down at an angle. Some grew through the paper and did not deflect. No circling roots were found in this container type.

Large main roots deflected down. Most trees in this pot produced roots right at the surface. Trees in other pots were less likely to grow roots from the stem this close to the surface.

Square containers produced the largest trees.

Main roots were deflected down the container sides. Some roots were turned upward after deflection by container bottom.

Many roots deflected down container sides.

All main roots were deflected down container sides.