CORVALLIS - In western Oregon, late fall or early winter is the time to apply manure to fertilize your established red or black raspberries and blackberries, including marionberries, boysenberries and loganberries, according to Bernadine Strik, berry specialist with the Oregon State University Extension Service.
East of the Cascades and in other colder regions of the state, spring is the best time to apply manure to caneberries, she said.
Either spread manure over the surface of the soil in the row, or dig a three- to four-inch trench a foot away from each side of the row and apply the manure in the trench.
If you use chemical or inorganic fertilizers, wait until early spring. Then apply four to six pounds of 10-20-20 (or equivalent) per 100 feet of row.
In the spring and summer, the foliage of new caneberry canes should be a healthy green color. A pale green or yellow color may indicate nitrogen deficiency. If the plants seem to lack vigor, apply an additional one to one-and-a-half pounds of ammonium nitrate per 100 feet of row when the berries are blooming.
Weed the berries periodically and mulch with any sawdust or bark except cedar to help prevent future weed infestations. The plants will need approximately one inch of water per week (rainfall or irrigation) during the growing season.