Hi, Well lavender plants require very good drainage so if they are sitting in heavy, clay-like soil they may not thrive. These plants need hot, dry conditions and don't like to be overfed. When I hear of lavender problems in the Midwest, I first think it's a soil problem because they prefer a sandy soil and some Midwest soils are heavy. I grow mine in Iowa along a limestone wall where there is sand mixed in with the loam for quick drainage. I also never feed mine. I would never give lavender Miracle Gro.