"Brian" wrote in
:

You will find they are very similar in many ways. Effectiveness is
proportional to depth. If any grass does grow through it will be easy
enough to pull out. Tap rooted weeds will push through and will
thrive, so remove them before the mulch. Pine needles tend to be more
acidic.
Best Wishes.
Thank you for your response. The areas in question have mostly hydrangeas
and camillias. So I think I will opt for pine needles. Thanks