My grandma Rose passed away last March and this year I
want to do a nice planting of flowers around her headstone.

I'm sure you've talked to the cemetary caretakers about this,
right? Most of the cemeteries I've known don't allow the planting
of flowers because it makes it more difficult to do grass
maintenance. Because of that, my mother had two shepherd
hooks placed at my sister's and grandparents' graves and has
huge baskets of flowers that she rotates through there. She
will plant some small plants in early spring then, by the time
it gets *really* hot in the summer, they're getting too big to
be able to get by with only being watered once a week so she'll
bring them to her house and, after it's cooled down a bit,
she places more baskets out there with smaller plants in them
again.

Tracey