very aggressive, but it is much better if you do it in the fall. you
should not do it in the spring under any circumstances. Pruning in the
summer is OK, but a waste of resources, specially before they have
started fruiting. When you prune them, you can take out 2/3 of the
vines, but of course leave the main branches alone. Make a big pergola,
and do not count your chickens yet, my kiwis took 7 years to fruit.