Answer: There are different types of hardy kiwis, but they all need a highly fertile soil and ample water during the growing season, meaning an evenly moist soil(although they will not tolerate flooding). Low fertility and/or drought would certainly limit their productivity.
Pruning methods depend on the type of kiwi you have and could also make a huge difference. The hardiest type, Actinidia kolomikta, does not need much pruning and will bloom and fruit the length of the vine. If you prune it back every winter, you will be removing the fruiting wood.
Actinidia arguta is also sold as a hardy kiwifruit vine. This one is slightly less hardy and may die back to the ground in hard winters, thus losing all the flower buds for the current year. (It should regrow from the roots.)
If however it survives the winter intact, it needs to be pruned carefully in the late winter to maximize blooming and fruiting. The vines that are already a full year old will bloom and fruit so should be preserved, the other younger stems from last summer's new growth can be trimmed back to just a few buds. These will bloom (and fruit) next spring.
I hope this helps you trouble shoot.
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