be growing in a lawn or natural area appear
to spring up as if by magic when the soil is cultivated. Weed seeds may remain viable for
those 7 (or more) years when conditions are not right for their growth. Then, brought to
the surface by tilling, and uninhibited by sod, shade, or other factors, they germinate
and become the pests that take water, nutrients, sunlight, and space from vegetable
plants.
Beneficial weeds
Many plants considered weeds in the garden have positive attributes. Some, such as the
morning glory, and even thistles, have flowers that rival those intentionally planted in
flower beds. In fact, seeds of some weeds are sold by seed companies as flowering plants.
Weeds are often a habitat for various insects, some of which are beneficial to the garden.
They provide shelter, pollen, and nectar for such insects as bees and predators of garden
pests, such as praying mantids.
Wild plants also have other virtues. Parts of some plants are used in natural dyes and
other home-made products. Weeds can be a good source of nitrogenous materials for the
compost pile if pulled before flowering. Many have long roots which bring elements from
the subsoil into their above-ground tissues; when the weeds are pulled or tilled and
allowed to decay in the garden, these elements are made available to other plants.
Finally, the presence of some native plants can indicate certain soil problems, e.g.,
deficiencies, pH changes, soil compaction, etc.
Control methods
Despite all this goodness, most gardeners won't tolerate weeds in their vegetable plots.
Perhaps it is an overreaction to the first garden he or she allowed to go completely to
weeds or perhaps it's the unruly appearance of weeds. This may be a sensible approach. If
one doesn't have time to ruthlessly destroy morning glory vines after enjoying the first
few flowers and before they go to seed, the garden will soon become one glorious display
of morning glories and little else.
Cultivation:
There are several ways to rid the garden of most problem plants. Since mature weeds
extract large quantities of moisture and nutrients from the soil, it is more beneficial
(and easier) to remove weeds when they are young and tender. Hand-pulling and digging are
okay for small gardens and raised beds. Those with larger spaces usually prefer at least a
hoe. There are manual-powered rotary cultivators that do a good job on long rows and
pathways as long as the soil is not too wet or dry and the weeds are small. In large
gardens, a rotary tiller of appropriate size makes the work easy and fast, but it is not
the most pleasant chore to get behind a smoky, noisy engine on a hot summer day. Manual
and powered rotary cultivators are usually unable to turn under weeds very close to
vegetable plants without damaging the vegetables. Hand-pulling or hoeing with a light
touch are best for removing weeds near vegetable plants. Deep cultivation with any
instrument is likely to damage roots or stems of crop plants.
Turning under weeds, especially before they flower, provides organic matter to the soil.
Hand-pulled weeds, except for rhizomatous grasses, may be laid on top of the soil to dry
out and will eventually have the same effect. However, if rain is predicted in the area
within a day or two, it's best to collect the weeds and add them to the compost pile; rain
will wash soil around the roots and some weeds will survive. If weeds have started to go
to seed, leaving them in the garden is not a good idea. Composting may not destroy weed
seeds if the pile doesn't heat up enough after the weeds are added. Grasses that spread by
rhizomes or stolons also present a problem if not completely dried up. In these cases,
despite their potential value as organic material, it's better to let the trash collectors
take the weeds, or burn them and spread the ashes in the garden (if local ordinances
permit). Reducing weed growth around the garden by mowing or other means will also help
prevent the spread of weeds and seeds to the garden area.
Cultivation is best done when the soil is somewhat moist, but not wet. Working wet soil
will change the structure, especially of heavy soils. When it is too dry, weeds are
difficult to pull and hoeing is also hard. A day or two after a rain or irrigation is
probably the best time to cultivate. If you have a choice, remember that the work will be
much more pleasant in the cool temperatures of early morning or evening. On hot summer
afternoons, you are likely to fatigue more easily, get a sunburn, or suffer from sun
poisoning, heat exhaustion, or sunstroke. Wear protective clothing if you must work when
it's sunny, and stop frequently for rest and refreshment.
Mulching
Mulching can be an alternative to weeding if you have a reliable source of mulching
materials. Thick layers of organic mulch will not allow most annual weeds to poke through,
and those that do are usually easily pulled. Weeds with runners are often not so easily
controlled, and black plastic may be a better choice where these prevail. For paths,
newspaper, old carpeting, or other such materials, covered with sawdust, will provide
excellent weed suppression. However, sawdust is not recommended for use right around
plants because of its tendency to crust. The bacteria that breaks down sawdust takes
nitrogen from the soil, and thus from vegetables. Mulch can also be used to modify soil
temperatures. Inorganic mulches (plastic sheeting, weed mats, etc.) warm up the soil,
while organic mulches (sawdust, compost, straw, newspaper, grass clippings, etc.) cool the
soil. Plant growth can be enhanced by matching the right mulch to the type of crop and
weather. Inorganic mulch can be used early in the season to heat up the soil then an
organic mulch can be applied later on to cool the soil as summer temperatures raise.
Close Spacing:
Once vegetable plants are established, if they have been planted close enough to each
other, they will shade the soil and prevent the growth of many weed seedlings. This is the
effect achieved by a well-planned raised bed, in which plants are spaced so that the
foliage of adjacent plants touches and forms a closed canopy at a mature growth stage.
Other Practices:
Some gardeners are experimenting with various types of no-till gardening to reduce weed
problems and prevent erosion and moisture loss. The standard farm no-till practice of
sowing a fall cover crop and then killing it with a herbicide, and planting vegetables in
the dead sod, after a recommended waiting period, is one method. However, there are no
herbicides recommended for use in established home vegetable gardens to kill emerged weeds
at the present time. Use of weed-killers normally recommended for lawns or other areas is
not advised, and until a safe herbicide is available for growing weeds, this type of
no-till practice is unsafe for growing vegetables in the home garden. One alternative is
the use of a living sod, mowed regularly, which has many of the benefits of no-till and
does not necessitate the use of herbicides. This practice works best with raised beds, so
that only the paths need to be mowed.
The use of cover crops over several seasons or years in a particularly weedy section can
also reduce weed problems. However, this method requires leaving that part uncultivated,
reducing gardening space. Cover crops must also be mown or harvested regularly, which can
be time-consuming and/or difficult without appropriate tools. Investigate crop rotations
thoroughly before using them to control weeds. All of the above techniques are still in
the experimental stage for home gardeners. Try them in small sections of the garden to
determine their effectiveness.
Herbicides:
As mentioned before, herbicides may be used in and around the home garden, but special
care must be used to insure it is applied safely. They should always be used according to
label instructions and only for crops listed on the label. The wrong herbicide can destroy
a garden's productivity for years. Even when used properly, drift from herbicide sprays
used on lawns or in areas surrounding the garden can cause damage to vegetable plants, so
take care to spray on windless days and erect barriers to protect plants if necessary.
Drift from pre-emergence herbicides does not damage growing plants, but may prevent seeds
from germinating. Be aware that treatment with an herbicide for one type of weed may
result in the area being colonized by other weeds which are tolerant to the chemical.
Finally, never use a herbicide in the same sprayer used for insect and disease control.
Keep a separate sprayer for plant-killers only. |
