Janet,
I would think that burlap would be too heavy for adequate light to filter
through but of course there are many factors that need to be considered such
as the distance of the screen to the plants, how much light is allowed in
from the sides, etc. You could, however, position the burlap sections so
that plants are shaded at peak sunlight hours. The other matter that may be
of concern is the structure required to support the burlap, especially if
you are trying to screen a number of plants. Unless you have places where
you can tie the burlap securely, by creating what in effect is a sail, you
run the risk of a gust of wind causing serious damage to your plants . All
this is not to say that it can't be done, because of course it can. It just
may be more effort than it's worth.
Marc Riva
www.riva.ca