Clay soil can be challenging for gardening due to its dense, heavy texture and poor drainage. However, many plants thrive in these conditions, making them perfect for an outdoor plant box. Here are some of the best options:

1. Daylilies (Hemerocallis) – These hardy perennials tolerate clay soil well and produce vibrant blooms throughout summer.

2. Russian Sage (Perovskia atriplicifolia) – A drought-tolerant plant with silvery foliage and purple flowers, ideal for clay soil.

3. Black-Eyed Susan (Rudbeckia hirta) – A cheerful, low-maintenance flower that adapts well to heavy soil.

4. Switchgrass (Panicum virgatum) – An ornamental grass that adds texture and thrives in clay.

5. Sedum (Stonecrop) – Succulents like Sedum are excellent for clay soil, requiring minimal care and offering seasonal color.

For best results, amend the clay soil with organic matter to improve drainage before planting. These selections ensure a lush, thriving outdoor plant box despite clay’s challenges.