are unwanted plants in gardens that reduce available moisture, nutrients,
sunlight and growing space needed by crop plants. Their presence
can reduce crop growth, quality and yield. In addition, they can
make harvest difficult. Weeds also provide cover for diseases, insects
and animals (rodents, box turtles, snakes, etc.). Garden weeds are
hard to control because they grow rapidly, produce vast numbers
of seeds, and spread aggressively by vegetative structures and/or
seeds. A combination of cultural and mechanical weed control methods
can be quite effective in controlling weeds. There are several methods
that can be used in a combined, coordinated effort to control weeds.
Fast growing vegetable crops can effectively suppress
weeds by shading. One method of weed control is to select a crop
that is capable of suppressing (shading) weeds. The following vegetable
crops are listed according to their ability to suppress weeds.
of Crops to Suppress Weeds:
||Peas, garden (English)
||Broccoli and Cabbage
of weeds by crops works best when the crop germinates quickly and
gets a head-start on weeds. To achieve this, plant crops at the
proper depth, with adequate moisture and fertilizer. It is equally
important to purchase high quality vegetable seeds or transplants
that are free of weed seeds or seedlings. Garden soils should be
tested and soil test recommendations followed to stimulate rapid
crop growth capable of weed suppression. See GreenShare
Factsheet on soil testing for more information.
Fast growing 'smother' crops can be used to reduce weed germination
in succeeding crops. For this purpose, smother crops are usually
planted in the fall and killed by tillage the following spring prior
to planting vegetables. The straw residue from smother crops (i.e.
rye, ryegrass, etc.) can inhibit early season germination of weeds
such as common lambsquarters, common purslane and redroot pigweed
by 75% or more.
NOTE: Avoid planting smother crops where small seeded crops
such as lettuce will be seeded the following year or reduction in
germination can occur. Smother crops are also effective in suppression
of many winter annual weeds such as henbit and chickweed.
Rotate crops to different areas of the garden so that a specific
crop is never planted in one area for two years in a row.
Mulches can be used to prevent weed germination and growth and ultimately
reduce time and labor required to remove weeds. Mulches fall into
two categories -- organic mulches, which are derived from plant
material, decompose naturally in the soil, and inorganic mulches,
which do not decompose, must be removed from the soil. Mulches help
to increase soil moisture retention, enhance soil warming and reduce
Mulches: Some of the most commonly used organic mulching materials
are manures, bark chips, ground corncobs, sawdust, grass clippings,
leaves, newspapers (shredded or in layers) and straw. Organic
mulches allow some flexibility in fertilizing and watering, since
they can be raked back from the plants. They should normally be
applied in a uniform layer three to four inches deep around the
base of the vegetable plant. Do not mulch with straw containing
weed seeds. If straw does contain weed seeds, it should be moistened
throughout, kept moist until the weed seeds germinate and then
air dried several times to kill germinating seedlings.
Inorganic Mulches: Black plastic is the most frequently
used inorganic mulch. Clear plastic is not recommended because
it does not exclude the light that weed seeds need to germinate.
Verify that there is adequate moisture in the soil before any
mulch is applied, especially plastic films. It is also necessary
to apply most of the fertilizer required by the plants before
the plastic is installed. There are also several durable weed
fabrics that are very effective in weed suppression. They are
capable of lasting up to 20 years or more when covered with soil.
decision of whether to use an organic or inorganic mulch really
depends on the season of the year and what the gardener is trying
to accomplish. Organic mulches should be applied after the soil
temperature has warmed in the spring. If applied to cold soils,
the soil will warm slowly and the growth rate of most vegetables
will be reduced. Inorganic mulches can increase the soil temperature
by at least 6 to 8 degrees F, making their greatest value early
in the growing season when soils are naturally cool.
emerged weeds present at seeding or transplanting are capable of
growing rapidly, it is important to kill all weeds prior to planting.
Weeds that emerge after planting should be removed before they are
more than 3 inches tall. Large weeds are difficult to remove without
uprooting vegetable plants. Early season competition between vegetables
and weeds may reduce crop growth, yield and quality. Removal by
hand or cultivation can be used to manually rid the garden of weeds.
can be hand pulled or removed using hand tools. Several small hand
tools are available that are very effective on small weeds and for
working near garden plants. They include the springtooth hand cultivator
and the trowel. These tools limit the gardener to working solely
on their knees.
are a variety of effective tools that allow the gardener to stand
while removing weeds. They include the scuffle hoe, the Warren hoe,
the onion hoe, and the Garden Weasel. Scuffle hoes come in
several shapes and are "push-pull" weeders that require no lifting.
One of the most popular is the Dutch version, which is an open stirrup
with a blade. Others consist of triangular plates. Most scuffle
hoes are lightweight and are effective on small weeds. The Warren
hoe has an arrowhead shape and can be used to scratch a furrow
with one end; when turned upside down the two shoulder points fill
in the furrow. The onion hoe is a thin bladed hoe that is
recommended when removing weeds near vegetable plants, as it is
easier to handle than large, heavy hoes. Onion hoes can be made
by grinding a common hoe so that the blade is thin, allowing more
precise maneuvering near vegetable plants. The Garden Weasel
has three sets of wheels with spikes that you "push-pull" to cultivate
weeds. It is recommended where numerous small weeds are present.
The Garden Weasel is also useful in breaking soil crust to aid vegetable
Several implements can be used to cultivate weeds. Push plows, also
called push cultivators, are inexpensive and also very effective
in killing small weeds. The large wheel versions are usually easiest
to push. For large weeds, a garden tiller or small tractor is most
effective. Regardless of the implement, cultivate no deeper than
2 inches deep to prevent root damage to vegetable plants. Cultivators
should normally be adjusted to throw soil around the base of crop
plants and over any emerged weeds that are present in the row. Row
spacing can be adjusted to allow close mowing near the soil surface
to control weeds. Self-propelled rotary or sicklebar mowers and/or
mowers with large rear wheels are easiest to maneuver. Weedeaters
fitted with plastic string can also be used to cut weeds near the
soil surface. Extreme care should be used for crop and personal
safety. See manufacturer's warnings prior to operating all equipment.
from David W. Monks and Larry Bass, North Carolina Cooperative Extension