By Mark Czarnota
University of Georgia
Many people don’t like to use synthetic herbicides in the
landscape. But weeds can be a big problem with any gardening
practices. With organic gardening, prevention is one of the most
essential ways to keep weeds out.
Many horticultural and agricultural practices are allowed with
organic agriculture. But if any chemicals are used, they should
come only from plant or animal sources.
Follow these tips
Here are a few tips to help keep weeds out of the landscape and
garden and do so organically.
Prepare the site to be planted. Plowing,
rotary tilling and other
means of soil cultivation are still very good methods of weed
control. Prepare the site to be planted with at least one good
tilling.
If you’re not in a hurry to establish your plantings, several
cultivations three or four weeks apart will eliminate many
difficult weeds.
These continual tillings disturb weed growth and help eliminate
weeds. Weeds like nut sedges (Cyperus species)
and Bermuda grass
(Cynodon dactylon) primarily come from vegetative
structures such
as rhizomes and tubers, and plants coming from vegetative
structures won’t survive continual cultivation.
Get them early. It’s much easier to hoe or
pull out those weeds
when they’re small. The bigger weeds are allowed to grow, the
more they will compete with desirable plants for light, water and
nutrients.
Get to them before they flower
At the least, try to remove the weeds before they flower and
produce seeds. Some fully grown weed plants, such as
lamb’s-quarters (Chenopodium album), pigweed
(Amaranthus species) and
spurge (Euphorbia species), can produce thousands of
seeds.
Removing these weeds while they’re small removes a lot of seeds
you and your future generations will otherwise be fighting.
Mulch! Bare-ground planting is very hard to
keep weed-free and is
usually left for large-scale row-crop or vegetable production.
Besides smothering weeds and preventing their germination,
mulches help to maintain soil moisture and temperature and add
organic matter to the soil.
If the landscape is to be permanently planted and no bulbs or
annuals will be planted, consider using a landscape fabric under
the mulch. The fabric will help smother those tough perennial
weeds.
Wash your equipment when you complete a job.
Soil stuck on
equipment can easily transfer weed seeds from one site to
another.
Don’t bring in weeds. Weeds, such as nut
sedge, often rear their
ugly heads when they’re brought in with nursery plants. To avoid
bringing these weeds into the landscape, carefully select nursery
stock.
Organic products available
Only a few organic herbicides are available. One, pelargonic
acid, is popular with organic growers. It’s sold under several
trade names, such as Scythe and Quik II, and is basically a
concentrated soap you mix with water and spray over the top of
weeds.
Pelargonic acid causes plant cells to fall apart. It kills most
weeds, as long as they don’t have extensive underground rhizome
or tuber systems.
Vinegar (acetic acid) is marketed in several products, such as
Garden-Ville Natural Weed Control, and also works at burning down
emerged weeds. Common table salt, one of the first herbicides, is
still used to control weeds in driveway and sidewalk cracks.
Some plants are adept at making their own herbicides. One good
example is black walnut (Juglans nigra), which produces
juglone.
Produced in many parts of black walnut trees, juglone kills or
reduces the growth of plants growing under and around tree
canopies.
In the future, we may be able to take the genes that produce
juglone and transfer them into a plant like corn. Imagine that: a
plant that can make its own herbicide.
