Question: What are the best native ornamental grasses to plant on a septic drainage field in zone 5a/4b? Answer: Jonathan Foster, Home Horticulture Outreach Professional As you may know, leach fields are specially engineered structures and care must be taken with anything planted on top of them, as deep root systems can clog, damage, or otherwise read more What are the best native ornamental grasses to plant on a septic drainage field in zone 5a/4b?