I just planted a Nelly Moser on the back of my house about a foot away from the foundation, next to a downspout, and about 3 feet away from my septic tank. Not the drainfield, but the tank, very close to one of those ugly green lids in the ground. Will this prove to be a bad idea in regards to the foundation or septic? I thought I read somewhere that planting at the tank is ok, just shouldn't at the drainfield.