University of Vermont Extension
Department of Plant and Soil Science
Dr. Leonard Perry, Extension
University of Vermont
Raised beds can be any shape and form, from a simple
mound of soil to elaborate ones a foot or more high with wooden
elaborate and large, generally non-mobile containers. They make
gardening much easier, especially
for those less agile or with physical challenges. The off season,
fall or early spring, when
garden chores are less (like weeding and watering), is a good time
raised beds are above ground, they heat up sooner in the spring.
But, on the flip side, they cool down more
quickly in fall and can get quite cold in winter so are not suitable
plants nor most perennials. Many
gardeners with clay or poorly draining soil find these beds make
gardening possible. If for vegetables
and most flowers, site in full sun or with at least 6 hours of sun
the simplest raised bed has straw bales for the sides, the center
soil. The straw will eventually break
down, leaving a mounded berm of soil unless you reconstruct them
use lumber for the sides, either 2-inch by 8-inch or wider boards.
You can connect the ends with lag screws
(nails tend to pull out), or buy corners just for this purpose.
These corners, available from some garden
retailers and online, are often sturdy plastic, push in the ground,
slots to hold the boards. Make sure the
soil where the boards will rest is level.
An advantage of lumber is that you can affix hoops, such as from
flexible plastic piping or sturdy wire,
on the sides to hold shade and frost cloth.
have at least decent soil, you can usually get by with a 6- to
poor soil, you’ll want at least a 12-inch depth for
rooting of most vegetables. Don’t make
beds more than about 24 to 30 inches wide, if accessible by
only one side, or twice that if you can reach from both sides. If
you want to
sit, particularly on taller beds, make sure you have a board or
width on top of
sides for this.
choosing lumber, avoid creosote treated railroad ties. Many
gardeners also avoid pressure-treated wood so any chemicals won’t
leach into the soil, particularly if vegetables are to be grown.
You can spend a bit more money for composite
materials such as made from sawdust and recycled plastics, which
will last for
many years. If you have a local lumber
mill, check for natural woods such as cedar. Some home and garden
raised bed kits in the spring with all the supplies you’ll need, or
even already built.
If you’ll have more than one raised bed, you
can get quite creative with shapes if you time and skills allow.
Otherwise, a simple rectangular bed is
easiest to construct. Allow plenty of
room between beds for movement. I have 3
feet between mine for carts, and for me to maneuver while weeding
harvesting. This also might be good for
wheelchairs and mobility carts. For
these, also plan space for turning around, hard surfaces, and no
more than 5 to
8 percent grade.
paths between beds, I use a thick layer of newspapers covered with
straw. The newspapers help with weed control, and
decompose after a year. Weed control
fabrics could be used instead for longer control The straw is the
same that I’ve recycled
from covering garlic or other winter crops in the beds. Or, you
might use bark,
wood chips, or similar.
you’ve constructed the bed sides, fill with a good quality topsoil
plenty of compost or composted manure. Especially
if your beds are large, you may want to buy bulk soil or have it
delivered. Make sure you mix these together well with a
garden fork or hoe, or by turning.
Particularly if the native soil beneath the beds is poor, break it
somewhat first with a fork.
beds will dry out faster than field soils since they are raised and
exposed. Use mulches on crops, soaker
hoses, and check frequently for watering.
the season is done, I clean up my beds so they are ready for
spring. Test the soil
every few years, and add lime if needed in fall. I also add an inch
of compost on beds in fall
after they’re cleaned so they’re ready in spring when I’m much
busier. But you can add compost just before planting
instead. I wait until spring, or before
planting, to mix in some organic, dry fertilizer.