The Purple Flowering Raspberry makes a very desirable shrub. Pruning Red Raspberries. The best time to prune reds is in fall after they are done producing. The clusters of purple flowers with nice maple-shaped leaves make this an an attractive plant, found along roadsides and the edges of fertile … This plant is very beautiful though and looks good in our flower garden. Remedy: Avoid … Purple raspberries are the offspring of a red and a black raspberry … The raspberry spectrum doesn’t end with a mere two colors, of course. The rose purple flowers appear in the late spring on the upper portion of the branches. The large 3 to 5 lobed leaves are attractive lime green during the growing … Other advantages follow here: cooler picking conditions, far less berry mold, and a fuller sweetness in the fruit itself in the drier fall window. Flowers are fairly large, 1 to 2 inches across. We find these things wild all over Vermont. Cut out the dead canes. Raspberry spur blight: This is a fungal disease causing purple patches on canes. The raspberries taste soooo good! It rarely kills raspberries, but can reduce yield severely by weakening the canes and killing buds. Pruning Everbearing Raspberries… In fall cut back all canes that have fruited. Pruning Black and Purple Raspberries. Rubus odoratus - Purple-flowering Raspberry, Thimbleberry. Positive: On Sep 3, 2004, MShelly from Jackson, NJ wrote: I have plants growing … I had to prune this plant constantly. Cut the primocanes down to 12 inches.