Just moved to a new house, and now have room for a garden. Bad news is that
there is a huge mole problem, so I was thinking about trenching around the
garden area and burying hardware cloth (metal screen with holes too small
for the moles to get through). However, I'm worried about how fast it will
rust out- I can't afford to re-trench every year or two. Soil condition is
very moist.

Does anyone have experience with burying hardware cloth, and how long it
takes before it starts rusting away?

Depending on what widths are available, I'd bury it as deep as possible to
still leave about 9-12 inches above ground to keep them from just coming up
and going over the top.

Thanks!
Keith