Gardening in Raised Beds
At the Botanical Garden we grow all our vegetables in raised beds.
A raised bed is a prepared area with a soil level that is higher
than the surrounding soil. We love our raised beds and here are the
reasons why:
Improved soil conditions
Compaction of the soil can reduce crop yields dramatically. Water,
air and roots have trouble moving through soil that has been packed
down by implements and human feet. You can avoid this problem by
constructing beds that are four feet maximum in width and narrow
enough so that you never have to walk on the soil. Raising the soil
depth makes it easier to grow root crops such as carrots and beets.
Raised beds are the answer for areas that have poorly drained
soils. Building up the soil level allows plant roots to develop in
soil above the soggy zone. The small area of a 4' x10' bed is
easier to manage in regards to soil structure, nutrient- holding
capacity and drainage.
Expanded season
When the soil is elevated it
dries more quickly and warms up faster. You can plant earlier in
the spring and harvest later into the fall. In wet seasons, the
soil will dry out faster, allowing for planting between rainfalls.
Raised beds can increase soil temperatures by 4-6 degrees over
ground level soil temperatures.
Maintenance
Once constructed, raised beds are
easier to prepare and care for during the growing season. With all
your crops in their own little space you can manage the soil in
each bed to suit each crop. Intensively planted raised beds provide
dense foliage cover which shades out much of the weed growth. The
narrow linear shape of the bed makes the use of row covers and
plastic mulches easy. Slug traps can be placed on walkways to
‘head ‘em off at the pass"before they reach the
beds.
Higher yields
Better root growth from improved,
deeper soils means more production per square foot of garden.
Raised beds do not need the usual space between rows as no walking
is done in the bed. Vegetables can be planted in raised beds at
higher densities- hopefully spaced just far enough to not be
crowded and close enough to shade out weeds.
Disadvantages
Like many other gardening
techniques, raised beds have a couple of disadvantages. The close
spacings can promote plant diseases by reducing air circulation and
allowing plants to remain damp longer after rain or watering.
Normally, with the amount of wind we have here, air circulation is
not a problem. Another problem might be the watering requirements.
Raised beds will dry out faster than in-ground beds. It is not
uncommon for us to water the vegetable garden every day during hot
sunny weather. Soaker hoses and mulches can cut down on the time
and amount of water you use.
Construction and layout
Our beds are
constructed of 2'x12' planks, on edge. We have painted the outsides
and left the insides untreated. We don't want nasty chemicals
leaching into the soil to be taken up by our veggies. Avoid
pressure-treated lumber and stay away from creosote coated beams.
The life span of an untreated plank is 6-8 years, not bad
considering all the advantages of this system. Layout follows
general vegetable garden guidelines. Orient beds in North- South
lines to take advantage of maximum sunlight. Plant taller crops on
the eastern side to avoid shading lower crops.
One final note and my favorite reason for using raised beds. You
don't have to bend over so far! Yes, 1 foot higher makes it a lot
easier if you are doing it all day.
Carl White
Head Gardener
