Ground Cover Recommendations

I am thinking about replacing the grass on some slopes around my property and need some recommendation. I live a little south of Ottawa, Ontario (zone 5). The slopes all face south or west. The soil seems to be a thin layer of top soil covering sand and gravel fill used for building. The sweep around my garages is about two hundred feet long and the stretch by the road is about a hundred feet. Both are about eight to ten feet high. I am looking for recomendation on variety and quantities ( both seed and plug tray). Most likely I will do this section by section.

There are quite a few herbs that would do well once established on the slopes around your garages. Most herbs like good drainage and a good number are not bothered by a bit of drought. If you don't mind a height of 15 inches (40 cm), common marjoram (S3890) would be an excellent choice that will reward you with masses of purple flowers in mid-summer. Sow it at the rate of three grams per one thousand square feet. Of somewhat lower height is crown vetch (S2040): sow at the rate of 3 grams per ten square feet. Once established it will be covered with pale pink and white flowers all summer long.
If you want a ground hugging carpet, some of the best plants would be thymes or rupturewort. Wild thyme can be grown from seed. Sow it at the rate of one gram per ten square feet. More ground hugging choices would be creeping thyme (P6463), woolly thyme (P6472), orange spice thyme (P6465-800). Use one plug tray per thirteen square feet of area spacing plants about ten centimeters apart and weeding the area until the thyme plants have grown together to form a solid mat. Rupturewort also makes a very low mat, but has no scent and the flowers are not showy. Sow at the rate of one gram per thirty square feet and weed as for thymes.
There is an article on herbal ground covers from seeds by Conrad Richter in the Magazine Rack section of this web site.