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  • From: "TradingPostPaul" <tradingpost@riseup.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Raised Bed Gardening
  • Date: Tue, 25 Dec 2007 00:14:13 -0700


Ohio State University Extension Fact Sheet
Horticulture and Crop Science
2021 Coffey Rd., Columbus, Ohio 43210-1086
Raised Bed Gardening
HYG-1641-92
http://ohioline.osu.edu/hyg-fact/1000/1641.html
Pete Lane

Gardening in raised beds, a common practice before colonial times, is
enjoying a resurgence of popularity among home vegetable growers. In parts
of the world with greater population densities or less tillable land,
gardening in beds is still the norm.
What are "raised beds"?

The "raised" part means that the soil level in the bed is higher than the
surrounding soil, and "bed" implies a size small enough to work without
actually stepping onto the bed. A bed should be no wider than 4 feet, but
length can be whatever suits the site or gardener's needs. Wider beds can
be subdivided into sections accessible from planks or stepping stones. The
bed does not have to be enclosed or framed, but if unframed, the use of
power tillers is feasible. Framing offers several other opportunities,
however; and a properly maintained bed will not need powercultivation.
Higher Yields

There are many reasons for the raised bed revival, but probably the most
important is more production per square foot of garden. In a traditional
home garden, good management may yield about .6 pounds of vegetables per
square foot. Records of production over three years in a raised bed at
Dawes Arboretum near Newark, Ohio, indicate an average of 1.24 pounds per
square foot, more than double the conventional yield. Raised beds do not
require the usual space between rows because no walking is done in the bed
to cultivate or harvest. Hence, vegetables are planted in beds at higher
densities - ideally spaced just far enough apart to avoid crowding but
close enough to shade weeds.
Improved Soil Conditions

Another reason for greater production in a given space is the improvement
of soil conditions. Soil compaction can reduce crop yields up to 50
percent. Water, air and roots all have difficulty moving through soil
compressed by tractors, tillers or human feet. Plows, tillers or spades
have been the usual answer to this problem, but gardeners can avoid the
problem completely by creating beds narrow enough to work from the sides.
Soil organic matter content can be increased greatly without getting bogged
down.

Raised beds also help in situations where compaction is not the only
culprit. Homeowners may have low spots unsuited for conventional gardens
because of ponding or excessive erosion from runoff. Raised beds rise above
these, with frames as a foundation. Gravity becomes an ally, not only in
avoiding soggy soils but in reducing a problem common to western Ohio -
alkaline soils. Saturated soils get a dose of lime every spring via
percolation. In a raised bed, gravity reduces percolation to a trickle from
capillary action. Soil acidity can be maintained in the 5.8 to 6.8 pH range
that vegetables prefer.
Ease of Working

The gardener shares some benefits from raised beds as well. The first, and
most important, is the increased ease of timely planting and harvesting.
Most people avoid working traditional gardens in rainy weather to avoid
compaction and muddy feet. Because raised beds are designed for walking
around, not in, there is no reason for mud to delay operation. Spaces
between beds may be left in sod, mulched or even paved with stone or brick.
Ease of Pest Control

Pest control becomes less difficult in raised beds. If burrowing rodents
are abundant, the bottom of the bed can be lined with poultry wire or
hardware cloth. Rabbits and groundhogs can be discouraged by placing their
favorite foods in a framed bed with a low fence. The narrow dimensions of
beds even make bird netting suspended on flexible conduit frames practical.
Weed control with plastic mulch can be achieved economically, as the width
of the bed can be spanned by one roll.
Water Conservation

The narrow dimensions of beds are advantageous for water conservation.
There are several watering systems that ensure the water gets only where it
is needed. Canvas soaker hoses, perforated plastic sprinkle hoses and
drip-type irrigation disperse water in a long, narrow pattern well-suited
to beds. They also reduce disease by directing water to the soil instead of
wetting leaf surfaces as with overhead irrigation.

For those who are producing for more than just family or friends, raised
beds may not be the answer. Certain vegetables, such as squash, melons and
sweet corn might do as well on ground level due to the extensive space they
shade.
Construction Tips

There are only a few guidelines to remember in raised bed construction:
Keep the beds narrow and match their length to the site and the watering
system. A north-south orientation is best for low-growing crops, allowing
direct sunlight to both sides of the bed. Beds that will contain taller
crops such as pole beans, trellised peas or caged tomatoes might do better
on an east-west axis. Thus, lower-growing crops could be planted on the
south side of the bed and still get full sun.

Avoid the use of creosote or pentachlorophenol-treated lumber for bed
frames. These chemicals can leach out and injure plants. Use
pressure-treated lumber, redwood, cement block or brick, and be aware that
the cement in block will raise soil pH over time.

Even if the soil is heavy clay, at least one-third of the volume of the
bed's root zone should consist of existing soil. There are a lot of good
minerals in clay and by loosening it up with one-third compost or peat and
one-third coarse sand, it will make a good growing medium. Add a little
garden fertilizer and test the soil after the first crop year.

Raised bed possibilities are endless. Beds elevated 2 feet or more offer
the promise of gardening without bending and can have benches built on the
sides for even more convenience. Because a bed warms up quicker than the
ground, it can easily double as a cold frame by covering it with a
lightweight clear plastic cover. Imagine being able to start plants early
in beds with covers and never having to transplant them! Supports for
poles, cages and trellises can be mounted to the frame for longer life and
ease of installation and removal.

Many of the same principles used in raised beds are being adopted on a
larger scale in field crops. Ridge tillage, solid seeding and controlled
traffic are all new techniques designed to deal with drainage, weed or
compaction problems and to increase productivity. Traditional gardens with
orderly rows on wide intervals have mimicked their larger farm counterparts
for years. Maybe it is time for them to change their role model to the new
farm, or the ancient garden.






  • [Livingontheland] Raised Bed Gardening, TradingPostPaul, 12/25/2007

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