There are many different types of erosion control blankets. Some are entirely made of natural materials and some have various proportions of non-natural materials. Some have a type of plastic in them that eventually degrades with exposure to sunlight. I used a North American Green blanket. There are many brands, etc. Ernst Conservation seeds and other companies sell them by mail order. I picked one up in person from All Pro Horticulure in Long Island to save on shipping costs (call in advance). To prepare my hillside I cut the weeds, used herbicide planted rye grain over the winter and then cut and herbicided the rye grain before it went to seed in the spring and put down native grass seed covered by the blanket.

What are you trying to accomplish??? Sounds like you already have errosion control with the existing plants/weeds. How steep is the hill?

You might be better off just planting into the weeds, as and the shrubs grow, slowly moving the weeds back from the desired plants.