I am something of a gardening novice as most of you know - - only been at it about 5 years, 2 of them in earnest. I was wondering about planting groundcover in garden beds here in NE. What does well here without being so invasive as to crowd out other plants? Does one consider the type of plants already in the bed (i.e. shrubs versus perennials) with respect to the aggressive nature of the ground cover? When is it a good idea to plant ground cover versus just mulching under everything?

Thanks for any input!