Page 103 - Tài liệu cây cảnh Bonsai4me Bonsai Basics

Although the tree had been planted in quite an 'open' organic mix consisting
of compost and grit, the tree had not been bare-rooted. This meant that the
majority of the rootball was encased in thick, heavy London ground clay (from
which they make the infamous London brick!). Not only is this clay incredibly
heavy, it is also an extremely difficult medium for roots to grow in, particularly
in a container.
I decided that for the long-term health and vigour of the tree, the best course

of action would be to bare-root the tree, removing all traces of the ground-clay
and replacing it with a lightweight inorganic soil mix.