How do I get a soil amendment registered to sell in different states?

Most U.S. states require fertilizer or soil-amendment registration following AAPFCO labeling, with a guaranteed analysis and supporting lab data. California (CDFA) and Washington (WSDA) are the strictest, often requiring heavy-metal testing. A good manufacturer assists with this paperwork. On AJ Cosmo Labs you can filter for co-packers experienced in multi-state registration so you avoid being blocked from your target market.