The only exception is the pre-emergent herbicide siduron, which is actually used to assist in seed germination. 4 to13 plants per yard2 can reduce yields of direct-seeded tomatoes by 26 to 71 and soybeans by 15 to 45. In particular, we love their limited-edition Pink Berry feminized seeds.  Source: <a href=https://lkc.hp.com/member/weedseeds>https://lkc.hp.com/member/weedseeds</a>