Triple Crown Blackberry Pruning

I planted a one year old bare root cane Triple Crown Blackberry plant in the spring. It grew several new canes that I topped when they reached my upper trellis wire which is about 4’ off the ground and tied them to it. Each of the canes grew a single side shoot which I have run along the top wire. These side chutes seem like they would grow forever if I didn’t also prune them. I’ve been letting them grow pretty long and only prune them when they reach the end of my trellis. Is there any advantage to letting them get this long? How will fruit grow off of these side shoots next year? If I keep them as long as possible does that mean I will get more fruit?

I, too, grow Triple Crown along lateral wires. In the fall I prune them the same way I prune raspberries, i.e., prune all flowering canes back to ground and non-flowering canes to 4 ft. (If you left the flowering canes long and unpruned, you would get diminished production from them and competition from new vigorous fruiting canes …eventually a mess of canes!)
The following year the 4ft canes quickly take off and fruit along frame.
Alternately, you can let the tips of long canes root to start daughter plants, pruning out the mother cane in the spring. I’ve done this once and now have another bed of plants.
These Triple Crown plants are super vigorous!

I let the TC laterals grow until October and prune them. Pruning the laterals earlier will just result in sub-laterals, although you can keep those pruned off every couple of weeks.
So unless you are tripping over them, just wait until autumn. Triple crown has very long fruiting spurs, 18 to 24 inches, and sometimes 36 to 48 inches off the main cane.

The laterals, regardless of length, will fruit to the very end of the pruned lateral.

If I understand you correctly, you are saying that the laterals of first year canes will grow fruit all along their length in the second year?

Yes. I have had laterals run around the trellis structure for 15 feet and fruit production per foot remained constant. Every leaf node is a potential fruiting spur.

On the other hand, weaker main canes (1/4 or 3/8" diameter with spindly laterals) can form undersized fruit. If your growth is vigorous, the sky’s the limit. I suspect your canes will increase in thickness over the next couple of years in such a young planting.

Okay, that is very helpful. Thanks!

I am wondering about new canes in the second year though. If my trellis is covered with the second year laterals and new first year canes are emerging, I won’t have a trellis available to do the same thing for the new first year cane laterals. I don’t have the space to put a trellis on the other side. Any recommendations?

For erect varieties such as TC, you just have to let the protocanes grow up through last years material, prune out all of last year’s stuff after harvest, and untangle and train the current year’s growth. Keep an eye on the new protocanes and keep them vertical by tying to the top board when they are a foot taller than that. Keep an eye on the protocane tips and adjust position if they are growing up against something and could deform. Any laterals that start out perpendicular to the row may need to be removed or kept short. The 2-year TC cycle gets to be a jungle, but I have managed fine for 25 years. I typically prune out 1/3 to 1/2 of the new laterals (by total or partial removal of laterals) every year otherwise TC just outgrows everything–trellis and that whole part of the yard.

Okay, thanks again!