The weeds don't stand a chance in this dense green mass of garden vetch and hairy vetch, accented with lacy phacelia. The plants in the mix don't overwinter; they die back and form a protective cover that can either be tilled into the soil in the spring or left as mulch. Vetches are nitrogen-fixing legumes and are best grown before more nutrient-demanding crops. The mix produces beautiful flowers in blue, pink, and purple. Annual.