I was wondering if any one prunes their kniphofia(torch lily)? would it be a good idea?
You could cut out the flowering stems once they are done...not sure about shaping the foliage. Different Knips have different foliage. If you are unhappy with the plant's appearance, I don't think it would hurt to experiment one year but plants with swordshaped foliage might not look so nice with the tips cut back. They will get a brown edge to them.
Here is a quote from Paghat's Garden about pruning Kniphofia:
"The only other care it needs is yearly "under-pruning" as the old saber-leaves dry out & are mashed down by new growth, so that eventually the under-edges of the clump can be unsightly. If the clump becomes overall too floppy, it can be sheered very short, & will pop back tidily."
So it looks like you can from their experience.