Question
Our house has a two-tiered back yard with a sharp drop right between them.  We are trying to identify an appropriate ground cover that would successfully block the weeds we get in this yard.  The top tier is very sunny and we can grow flowers (annuals, some bulbs in the spring, nice).  Back farther there are hedges.  But there is no grass, only weeds, everywhere else.  We really need help with this.  The house is in the suburbs in Virginia.

Answer
The multi-Zoned state of Virginia has weather everywhere between USDA Zone 6a and 8b.  There is no sure way to know what the climate is and what will survive without knowing exactly your plants will be growing most of the time.  Right now, where I am, it is exactly 31 degrees F outside; in Williamsburg, Virginia, it is 46 degrees F.  So I am going out on a limb here making recommendations for the kinds of groundcover that would completely block weeds and everything else from growing, with minimal care.

Lysimachia nummularia Aurea (aka Golden Moneywort, Creeping Charlie, Creeping Jenny) is a dense, low-maintenance, low- growing groundcover.  It needs adequate moisture through the summer, but is otherwise undemanding.  In full sun, the leaves become a bright, vivid lemon.  If you have Clay soil, even better -- this plant thrives on it.

White Phlox subulata spreads quickly across all your sunny, open spots.  In rich soil, it spreads out in patches up to 2 feet wide.

Sedum Ruby Glow is another short, low-maintenance plant with ruby red flowers and delicate, tiny green, red-accented leaves.  Watering the first season is important, but later Sedums are less demanding.

You can also put in some low shrubbery -- first season watering is critical and you may need to amend the soil to lower the pH, but it is lower maintenance as well.  Siberian Cypress (also called "Russian Cypress") gets 1 foot high and spreads.  This shrub is famous for its performance on slopes.

Bluestone Perennials (www.bluestoneperennials.com/) offers several outstanding groundcovers.  Some, you can even walk on; others would make that very difficult.  Do a Custom Search on their website and see what looks good.  Thanks for writing.