What kind of mulch should I use?

Any type of mulch will work, but unfortunately some mulches contain active weed seeds that can germinate into weeds. The best type of mulch to use is bark chips — the larger the better. Shredded bark is OK, but it will deteriorate more quickly and will more easily allow weed seeds to germinate. Pine straw is excellent, and is our personal favorite. If some weeds do come through soon after the installation of fabric and mulch, they can be completely eliminated by spraying with Roundup or other post-emergent systemic weed killer. You should have no further weed penetration problems after the first few weeks.