of Rhode Island GreenShare Factsheets
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.
"Raised" 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 area used. 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. The use of power
tillers is feasible, for example, in unframed beds, although
a properly maintained bed should not need power-cultivation.
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 0.6 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, as 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
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 problem soil 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. Soil acidity can thus be more
easily maintained in the 5.8 to 6.8 pH range, which is preferable
for most vegetable culture.
The first, and most important, benefit of gardening with
raised beds is the increased ease of timely planting and harvesting.
Many 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 mulched
or even paved with stone or brick.
Pest control also 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 simply 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
The narrow dimensions of beds are advantageous for water
conservation. Canvas soaker hoses, perforated plastic sprinkle
hoses and drip-type irrigation disperse water in a long, narrow
pattern well-suited to beds. Directing water to the soil helps
to reduce disease problems which can result from wetting the
foliage with overhead sprinklers.
There are only a few guidelines to remember in raised
1. 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--lower-growing crops could be planted
on the south side of the bed and still get full sun.
2. Avoid the use of creosote or pentachlorophenol-treated
lumber for bed frames, as 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. Framing materials can also be large
stones, untreated lumber, sapling trees or straight logs. Obviously,
colonial farmers did not have all these materials available.
You could just hill up the bed and maintain it regularly. In
recent years, recycled plastic lumber has become readily available
to build a more permanent bed. Depending on the product, it
may have 50% sawdust and plastic. Some are nearly 100% plastic.
They never need staining or painting and come in lengths similar
3. At least one-third of the volume of the bed's root
zone should consist of existing soil. Add one-third compost
or peat and one-third coarse sand to create a well drained
soil. 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.
Adapted from Pete Lane,
Ohio State University Extension, 2000
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
of Rhode Island Cooperative Extension provides equal program