When designing an outdoor plant box with copper-rich soil, selecting the right plants is crucial for a thriving garden. Copper-accumulating plants not only tolerate high metal concentrations but also benefit from them. Here are some top choices for your copper-accumulating plant box:

1. Alyssum (Lobularia maritima) – This hardy, low-growing plant thrives in copper-rich environments and adds delicate white or purple blooms.

2. Sunflower (Helianthus annuus) – Known for its resilience, sunflowers can absorb copper while adding vibrant color to your space.

3. Thyme (Thymus vulgaris) – Aromatic and adaptable, thyme grows well in metal-enriched soils and requires minimal maintenance.

4. Lamb’s Ear (Stachys byzantina) – With its soft, silvery foliage, this plant is both decorative and tolerant of copper-heavy conditions.

5. Sedum (Stonecrop) – Drought-resistant and versatile, sedum varieties flourish in challenging soils, including those with high copper content.

For optimal growth, ensure proper drainage and monitor soil pH. Pairing these plants with organic mulch can further enhance their health. Whether you're a seasoned gardener or a beginner, these copper-tolerant species will transform your outdoor plant box into a lush, vibrant oasis.