Two
weeks ago, I pinched off the tops of the
black raspberry canes. Left to their own devices, black raspberry
primocanes will grow so long they bend down and root a new plant at
their tip. This trait is useful if you're looking to expand your
berry patch, but is less useful if you actually want to be able to get
into the patch to pick berries.
If you choose to keep
your plants contained, you can pinch off the tips
when the brambles reach waist high. In most plants, apical
dominance tells the plant to put all of its energy into growing the
main shoot, but if that main shoot is gone, the side buds are allowed
to grow. The bottom photo shows what one plant looks like two
weeks after pinching. Notice how the side shoots have grown out
--- these will all be coated with fruits next year when the primocane
becomes a floricane.
I've
similarly pruned our cultivated
blackberries.
Blackberries usually aren't tip-rooters, but
mine are, and I've also found that they will grow primocanes a dozen
feet long if left to their own devices. I prefer the plants to
stay contained in my obsessive rows, so I take a few minutes to summer
prune.