Since they have a relatively small root zone, you
can help to upgrade the soil with some organic
amendments in an area about a couple of feet in
diameter and 6 to 8 inches deeper than the root
ball.
Of course, you need
to plant the clematis close to whatever you are
using as a support system. If you must plant more
than a few inches away, you might need to anchor a
string near the transplant leading to the support.
The clematis can climb up the string and begin going
up the trellis.
In order to keep the
roots cool, clematis are often planted with a
"mother plant" nearby to provide shade to the roots.
A small shrub or groundcovers may be used for this
purpose.
Keep the soil moist
but not waterlogged for the coming season or two.
Clematis fall into the category of plants that
"creep, crawl and run" meaning that the first year,
there may be little growth. The second year, the
vine will begin to spread out and in the third year,
it will be off and running.