Volcanic eruptions leave behind nutrient-rich but challenging soil, making it ideal for certain resilient plants. If you're creating an outdoor plant box in post-volcanic soil, selecting the right species is key. Here are the best plants to thrive in these unique conditions:

1. Lupines: These hardy perennials fix nitrogen in the soil, improving fertility while adding vibrant colors.

2. Ferns: Species like bracken ferns adapt well to volcanic ash, preferring moist, well-drained soil.

3. Sedges: Tough grasses like Carex thrive in volcanic substrates, offering erosion control.

4. Alpine Aster: This drought-tolerant flower blooms beautifully in mineral-rich volcanic soil.

5. Fireweed: A pioneer species, it colonizes disturbed soils quickly with striking pink flowers.

For best results, mix organic compost to enhance moisture retention. Avoid overly sensitive plants, as volcanic soil can be abrasive. With these choices, your outdoor plant box will flourish in post-volcanic conditions!