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Elgin Freeman's on raised beds

Hi, Elgin.  Welcome to the list; I haven't been here long either, but I just
had a professional design-and-build firm create two raised beds for me, so
I'll share some thoughts on you questions.

> I am building raised beds from some lumber I have on hand.

Exactly what sort of wood to use in building raised beds is a hotly
discussed topic.  Railroad ties, most of which have been treated with either
creosote or cuprinol (copper-based preservative), are definitely a BAD idea.
Plain lumber rots fairly fast in contact with the ground, though, so "just
wood" isn't a very good solution either.

My builder used pressure-treated lumber that's shaped pretty much like RR
ties but is blond and looks just like uncured wood to the naked eye. (The
blond color was an unexpected bonus; we have a blond house....)  The label
on each board says "wolmanized," but other than recognizing this word as a
derivative of the Wolman Co., which makes deck sealers and finishes, I have
no info on what it means to be wolmanized.

Our lot is pie shaped, which put some restraints on just how long and wide
the beds could be and still stay on the sunny south side of the house and
remain within our lot lines.  My beds are 24 x 6 feet and 16 x 6 feet.

The lumber comes in 12-foot or 8-foot lengths.  On a 6-foot point-to-point
layout, though, because of overlap with lengthwise members at the corners,
we're getting about 5 feet of actual gardening territory crosswise in each bed.

Some sources recommend narrower width than this, but I can't figure out why.
An adult can easily bend over just a little and reach clear into the center
of a 6-foot-wide bed from either side to harvest produce.  I definitely
wouldn't go past that width, however, because you don't want to be tempted
by unharvestable goodies to walk on the soil and compact it.

>2.  The weeds we have are the mother of all weeds!  With that I was
>thinking of putting heavy black plastic under the bed before I put the
>boards down.  We are planning to fill the bed with compost.  ------ Will
>the 12" depth be enough for all the plant varieties that I might later
>want?  Will the plastic allow enough drainage?  Should I bother with the
>plastic?

I asked my builder this exact question, too.  Our dirt is almost
impenetrable red clay with a fair amount of small rocks.  We are long on weeds.

The builder denied that weed-blocking matting would be needed, but he did
tack some similar material to the inside walls of the beds below the soil
line before dropping the topsoil into position.  I thought this might be
about making a barrier to chemicals that might leach out into the bed after
rain, but he said it was about helping the soil stay inside the bed and not
weep out through the cracks where the timbers meet.  (Actually, he did such
a close fitting job that I don't believe soil loss would have been a problem
anyway.)

The question of height has been brought up several times recently, too.  I
told our guy that as we are only getting older, an both of us have had some
tender back situations, we were looking forward less and less to the bending
necessitated by working at ground level.

What he built for us (because we have a gentle slope in the mix) is two
beds, each of which is flat (not tilted; what an interesting idea from
another thread...) but has a step-down at about the third-of-the-way point
from the high end.  There are five courses of timbers at the high end,
putting the soil line at hipbone height there and at a bit above knee height
on the lower sides.  Three courses of timbers show on the low side.

These beds are gorgeous!  The price was astronomical, but the quality of
workmanship was very good.  (For listers in the greater Washington, DC,
area, I'll be glad to supply my guy's name and number.)

Another correspondent (possibly over in rec.gardens rather than here) had a
very bad result (deformed produce and very little successful growth) from
chemical leaching out of pressure-treated wood.  She talked a little about
the result of her lawsuit against, I believe, the wood source, which
established that the chemicals from the company's timbers did in fact leach
into her soil in the raised beds and poison the plants.

I sincerely hope the timber she used was not what I ended up with!  But just
to be on the safe(r) side, I am taking samples from each bed and setting
them aside to be baseline evidence in case of any trouble down the line.

It'll be a couple more weeks before I can actually plant anything, but I'm
very excited about the whole prospect for the '97 gardening season.

Best wishes to all square footers--Janet Wintermute (USDA zone 7)
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Janet Wintermute             jwintermute@ids2.idsonline.com
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