CORVALLIS, Ore. – Weeds compete with vegetables for water, light and nutrients. Some also harbor pests or diseases. If you control weeds, your vegetables have a better chance to grow and produce.
More information is available from the Oregon State University Extension publication, "Growing Your Own," a practical guide to gardening for first-time gardeners. It can be found online and printed copies are at county Extension offices. Here are a few guidelines:
- Mulching: Organic mulches, such as leaves, hay and grass clippings, keep weeds under control and improve soil as they break down. Apply a layer of organic mulch two to four inches deep to your vegetable garden. Avoid the leaves of black walnut trees or tree-of-heaven, which can inhibit growth of plants and seeds. Avoid using grass or lawn clippings if the lawn was mowed when weeds were in seed.
- Plastic sheeting may also be used to control weeds. Black plastic reduces light and prevents weed growth. If you're using drip irrigation, put the hoses in place before laying down the plastic. Make slits in the plastic, and if weeds appear in the planting slits, immediately remove them.
- Water Management: Sprinklers water a large area, but encourage weed growth over the same area. Drip irrigation delivers water only where you want it.
- Cultivation: Weed seedlings are vulnerable to hoeing, hand pulling or rototilling. Mature weeds are more difficult to remove. Weed early and often.
- Rototillers are practical only in large, open areas. They can damage roots or stems if used close to plants. In addition, too much tilling tends to destroy the structural qualities of soil, and eventually your soil will be better suited to making bricks than garden produce. Never till soil when it is wet. Doing so will leave you with cloddy, compacted soil.
- Hand pulling works well in small gardens and raised beds. A scuffle hoe is better for larger areas. Pull or hoe weeds when the soil is damp, but not wet.
- Several hoe styles are available. The lightweight Warren hoe has a heart-shaped blade and is useful for cultivating between plants. The hula, or action, hoe is a lightweight scuffle hoe. Pushing and pulling it just under the soil surface eliminates newly emerging weeds. It is less effective against well-established weeds.
- Small hand cultivators are good for weeding small areas and between closely spaced plants. Another useful tool is the dandelion digger (also known as a weeder, cultivator or asparagus knife). It is a 10- to 14-inch metal rod with a two-pronged blade and works well for digging long taproots.
- Rotation: Crop rotation can reduce weed problems. Plant fast-germinating, spreading vegetables (such as squash, cucumbers or melons) where noncompetitive crops (such as carrots and onions) grew the year before. Keeping part of the garden in a summer cover crop can help reduce weed problems for the next season.
- Close Spacing: Closely spaced vegetables shade the soil and suppress weeds. Remember, however, that weeding must be done by hand when plants are close together.
- Cover Crops: Cover crops grown on annual beds in the winter can smother much winter weed growth. The cover crop can be a winter-hardy grain, a legume or a combination of the two.