The advice you received was correct, despite the claims made by grass seed companies and their "shade mix" products: Grasses are definitely not going to do well with that little sun exposure. Mazus, Ajuga, and Green-and-Gold (Chrysogonum virginianum) come to mind as alternatives, but there are more options. Moisture will be the biggest concern as many shade groundcovers really cannot thrive if they are dry. There are some though, like barrenwort, that will do fine dry. Also, you need to specify how high you want the groundcover to be -- plants up to 1 ft. high are often considered groundcovers, but some people really prefer something that is only a few inches high. Personally, I really like U.S. native viola walteri var. 'Silver Gem' as a shade groundcover. Uploaded with ImageShack.us Click the link below, fill in your information about exposure, etc. and you will get some more choices. The conditions you list seem to leave you with many good possibilities. Good luck! Here is a link that might be useful: Groundcover Selector

Aka Ivy Leaved Toadflax which is the more usual common name over here.

Landscape roses are considered groundcover roses. They are low growing shrub roses (typically not exceeding 3') that spread much wider than they grow tall. Drift, Knock Out, Flower Carpet are all readily available landscape groundcover-type roses. It is not a defined category, but the roses are bred specifically for these attributes. They also tend to be very free flowering and low maintenance compared to other rose types. The issue with most groundcover clematis is that they behave exactly as do their vining cousins....except they don't vine :-) So for the most part, they are not tidy little clumping things but large rambling plants that can easily grow several meters a season. Combining the two - the wide, sprawling landscape roses and the long, rambling clematis - may not be as simple as it sounds without very careful cultivar selections.

thank you Flora for responding to another inaccurate ”invasive” label with short substantive information based on research. Unlike vinca, g. macrorizzum can be easily removed . The rhizomes are largely on the ground’s surface. It offers no resistence and can be pulled up in big handfuls, unlike vinca which has multiple stems, each rooting where itouches the ground , making, in my experience, mats that are difficult to penetrate with a shovel or remove efficiently by hand. i know because ive done both. Also periwinkle , unless if it is variegated, is a periwinkle , is a periwinkle. Without looking at a book i can think of 15 perennial getaniums with different height., leaf texture leaf color, some strongly scented leaves, with no scent, flower form with markings, no markings white, white with stripes and freckles, soft pink, tinted pink, hot pink,magenta, purple, , light blue, deep blue, eyes, no eye. Some hardy to minus 15 or lower, others not hardy below zone 7. i readily acknowledged6 my hillside doesn't reflect the variety of the species. i have a sea of periwinkle in one location i dont want to replace it with geraniums. But in honesty vinca is a 2 note groundcover. Geraniums are a huge varied family. . My scrappy hillside planting doesn't begin to do them justice. An online purveyer of geraniums is ”Geranacea” in California, The little on line catalogue has about 200 different hardy geraniums. it is still in business