Distances between rows of 51/2, 7 and 81/2 feet, spacings between stools within the rows of 2, 21/2 and 3 feet and heights of winter tipping of the canes of generally 4, 41/2 and 5 feet were tested in factorial combination with the raspberry varieties Malling Promise, Lloyd George and Norfolk Giant in a 7-year field experiment. Increase either of inter-row distance or of stool spacing produced an improvement in performance per stool, because of the growth or survival of more canes per stool and a higher fruit yield per cane, but this failed to balance the reduction in cane population per unit area caused by the wider separation of the stools. Extension of planting distances therefore resulted in smaller yields per acre. The effect of the inter-row distances on yield per acre exceeded that of the stool spacings.
Increase of tipping height within the range of heights tested produced large increases of yield. Harder (i.e. lower) tipping of the canes slightly delayed ripening.
The productivity of raspberries planted at practicable distances and maintained as permanent stools is approximately proportional to the number of fruiting canes present. The varieties used in this experiment reacted very similarly to the cultural treatments tested, although some minor interactions were recorded. Close planting resulted in some years in greater losses of canes and buds associated with infections by fungi, chiefly Botrytis cinerea and Didymella applanata.