I have a fairly large area, ~1000 square feet, that I would like to plant with ground cover that looks good, is low to the ground, and is zero maintenance. The area gets full sun the first half of the day. The soil is moderately clay.
Because it's such a big area and it's on a slope, I'm concerned that it will be difficult to establish.
What are my best options for establishing ground cover in this situation?
I see a problem with the size of the area. No groundcover will be so thick it will choke out grass or other wind borne seeds. After a while you will be looking at weeding and with the size of the area this means wading in. Tough...
White clover is an excellent idea from @woodchips. I have used it to open up and enrich thick clay soil. There are other groundcovers that can compete with grass like creeping thyme although it prefers hot and dry areas.
Another idea which will cost you more in the short term but be very effective is to use Rhus aromatica cultivar 'Gro-low'. This cultivar of this shrub spreads six feet and grows three feet tall. It is great low maintenance plant for mass beds or bank control with fragrant leaves. I see that some kinds of sumac grow where you live so check your local nursery for availability.
To use this you would sow white clover and plant the rhus on five or six feet spacing. If your area was fifty feet by twenty feet you could buy thirty plants and have the job done. The clover would enrich the soil and keep out weeds while the sumac establishes.
I had a very similar problem, on a steep enough slope I had to climb a ladder placed against the hillside. I transplanted a few pieces of crown vetch from another spot where it was growing, but it did not take well. Then I bought a flat of pachysandra. While it is taking acceptably, it will also take some time to fill in as it was still pretty sparse. So I over-seeded with clover, which worked nicely to fill in the holes while staying moderately low.
