On 10/16/11 5:44 AM, The Soul Patch wrote:
hello all, had such an epic day yesterday up at the soul patch but was
going to see if anyone had any canny and most importantly cheap ideas of
how to create large raised beds. i am thinking 2 20ftx10ft beds so quite
a lot of material needed. any thoughts well appreciated!

Till the ground to the same depth that the raised bed will be above the
natural level. That is, if the raised bed will be 1 foot high, till to
a depth of 1 ft. While tilling, add bone meal or superphosphate;
phosphorus does not readily dissolve and so must be placed where roots
will find it. Also add some organic matter (e.g.: peat moss, compost)
but not much; until you frame the bed, you do not want to raise the soil
level significantly.

Choose framing materials (e.g.: old railroad crossties, concrete
(cinder) blocks, 2x12 boards). Your choice should balance cost versus
how long you plan to maintain the bed. Also, your choice might depend
on whether or not you are planning "organic" gardening since some
framing materials are chemically treated to resist rot.

Frame the bed. For a bed 20x10, you will want to anchor the framing
material even if you frame with something heavy such as a single course
of concrete blocks. I would not use wooden stakes. Instead, consider
scrap water pipes or steel rebar. You should use lengths at least twice
as long as the frame will be high. Pound the anchors into the ground so
that the top of each is about 1 inch below the top of the frame; this is
to reduce the risk of tripping on the anchor.

When the bed is framed, pile enough soild amendment inside the frame to
about 2-3 inches higher than the frame. Till this into the top half of
what you already tilled. Mixed with your native soil, this will quickly
settle down to the level of the frame.

Plant.

No, I have not recommended specific framing materials or soil
amendments. I do not know what is available in your area or -- for what
is available -- what the costs are.

--
David E. Ross
Climate: California Mediterranean, see
http://www.rossde.com/garden/climate.html
Gardening diary at http://www.rossde.com/garden/diary