McKinney sits at the heart of the Blackland Prairie, where Houston Black clay dominates every yard from the historic downtown out to the newer subdivisions pushing toward Prosper and Celina. That clay cracks wide open during summer heat, then swells and shifts after autumn rains, making proper mulch and soil amendment essential for any landscape here. The 41 inches of annual rainfall sounds generous but arrives unevenly, leaving beds parched and exposed through the worst of July and August. Gardeners in Princeton and Anna face the same clay-driven challenges, and layered organic material is the only reliable buffer against those extremes. The naturalistic plantings near the Heard Natural Science Museum offer a model for what adapted McKinney landscapes can look like when the right foundation is in place beneath them.