We have a very steep, sunny slope that has been covered in weeds and bushes for years. Cleared it, put down landscape cloth over the winter. Looks like a good, inexpensive way to cover the ground would be to grow purple sage. But the plants would be too expensive (about 5000 sq ft). Could we plant sage seeds and cover with the straw mats used to cover new grass seed (need something to hold the soil while seed grows) or would they be too thick?