By Richard Jauron, Greg Wallace
Weeds can cause trouble for asparagus, raspberries and strawberries. Here are some tips from Iowa State University Extension and Outreach horticulturists on the proper way to control weeds in home gardens. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or hortline@iastate.edu.
How do I control weeds in my asparagus planting?
Weeds can become a serious problem in asparagus plantings. Cultivation and hand pulling are the most practical weed control measures for home gardeners. Hoeing and hand pulling should be done on a regular basis in spring and early summer. Cultivate lightly to avoid damaging emerging asparagus spears. The application of four to 4 to 6 inches of straw in summer also is effective in controlling weeds.
Herbicides are not a good weed control option for gardeners, as few herbicides are available for use in home gardens. Products containing the pre-emergent herbicide trifluralin can be applied in early spring before the asparagus spears begin to emerge. Glyphosate (Roundup) can be used on difficult-to-control perennial weeds. Spot treat weed-infested areas in early spring before the asparagus spears begin to emerge or immediately after the last harvest when all asparagus spears have been cut off just below ground level. Do not allow Roundup to get on asparagus spears or ferns, as serious plant injury may occur.
How do I control weeds in my raspberries?
Cultivation and mulches are the most practical weed control measures for home gardeners. Cultivate the raspberry planting frequently during the spring and summer months. Small weed seedlings are easily destroyed. Large weeds are more difficult to control. To prevent injury to the raspberry plant roots, do not cultivate deeper than two to three inches.
Possible mulching materials include straw, crushed corncobs, chopped cornstalks, sawdust, wood chips, dried grass clippings and shredded leaves. The depth of mulch needed depends on the material used. Optimum depth ranges from 3 to 4 inches for fine materials, such as sawdust, to 8 to 10 inches for straw on well-drained soils.
Avoid deep mulches on poorly drained soils to discourage root diseases. When mulching red raspberries, apply the full depth of material between rows. Within rows, apply only enough material to control weeds, allowing new canes to emerge in spring. Since organic mulches gradually decompose, apply additional material each year.
How do I control weeds in my strawberries?
Cultivation is the most practical control measure for home gardeners. Cultivate often, but shallow, to control weeds. Hand pulling also may be necessary.
When removing the straw mulch on strawberries in spring, rake the material to the aisles between plant rows. A straw mulch will help control weeds between the rows of strawberries.