On Mar 27, 10:45 am, " wrote:
On Mar 26, 1:27 pm, "Harold" wrote:

First step is to decide how large an area we need for the garden frame
and what preparations are necessary to make the spot ready such as
removal of existing grass or weeds . . .http://www.raised-garden-bed.com/install.html

If I want to install a raised garden bed for vegetables and some
flowers on top of an asphalt patio, what do I need to do to that
asphalt layer, presumably to contain the dirt? Would it be enough to
lay some landscape fabric and staple it to the edges of the garden
frame?

Thanks for your question. I am just starting my second season planting
a garden located on a cement driveway. This particular on is
constructed using cedar decking material. The top frame is joined to
the bottom frame with three dowels in a triangulation. The corners are
re-enforced with metal angles. Coated decking screws bisect the
mitered corners so that they enter the wood going across the grain.
This is done to avoid inserting the screws into the ends of the boards
as they would easily pull out. Once the frame is placed on the hard
surface, whether it be a cement driveway or asphalt patio or even an
apartment or condo roof top, it is filled with bags of topsoil which
is purchased at the local garden center. This particular garden
measures 4 ft. by 4 ft. and is about eleven inches tall. This size
requires half a cubic yard of soil which translates into 14 forty
pound bags. Cost per bag is currently anywhere from 85 cents to $1.25
each depending where it is purchased. I did not experience any leakage
out the bottom of the garden so the soil went directly onto the
concrete surface. Only risk I can see is that it may stain the surface
beneath the soil.