Weed control in raspberries is necessary to reduce competition for water, nutrients, and sunlight. Cultivation and mulches are the most practical control measures for home gardeners. Cultivate the raspberry planting frequently during the spring and summer months. Small weed seedlings are relatively easy to destroy. Large weeds are more difficult. To prevent injury to the roots of the raspberry plants, don't cultivate deeper than 2 or 3 inches. Also, maintain a clean, weed-free border around the raspberry planting to prevent perennial weeds, such as ground ivy, from growing into the raspberries from adjacent areas.
Possible mulching materials include straw, crushed corncobs, chopped cornstalks, sawdust, wood chips, grass clippings, and shredded leaves. The depth of mulch needed depends upon the material. The depth ranges from 3 to 4 inches for sawdust to 8 to 10 inches for straw. (When mulching red raspberries, apply the full depth between the rows. Within the rows, apply only enough mulch to control the weeds so new canes can emerge in the spring.) Since mulches gradually decompose, apply additional material each year.
This article originally appeared in the May 5, 1995 issue, p. 54.