Posted: 01/12/2015 at 08:23
for me the roots were thick and "pushing". From a 3 litre plant the roots prob grew to exceed rootball by 40 cm at a guess in one season ....deep and wide.
the soil there is good and rich. In other parts of my garden....esp the front garden the soil is different,,viz., sandy but I decided sgainst planting it there.
others may have different experiences with this plant.
I have an aversion to planting anything that could invade. I grow rudbeckias that spread but these roots are surface and easy to control. Just worry about roots I cant see that wander.