In a post-nuclear environment, cultivating plants in contaminated soil requires careful selection of resilient species. Certain plants have demonstrated remarkable tolerance to radiation and heavy metals, making them ideal for an outdoor plant box in such conditions.

1. Sunflowers (Helianthus annuus): Known for their phytoremediation abilities, sunflowers absorb radioactive isotopes like cesium and strontium from the soil. Their deep roots and rapid growth make them a top choice.

2. Mustard Greens (Brassica juncea): These plants excel at extracting heavy metals and radionuclides. Their fast growth and adaptability to harsh conditions are invaluable for post-nuclear gardening.

3. Willow Trees (Salix spp.): While larger, dwarf willow varieties can thrive in plant boxes. Willows are hyperaccumulators, drawing toxins from the soil efficiently.

4. Mushrooms (Pleurotus ostreatus): Certain fungi, like oyster mushrooms, break down radioactive material and can be grown in shaded areas of the plant box.

5. Ferns (Pteris vittata): Specifically the brake fern, which absorbs arsenic and other toxins, is a hardy option for contaminated soils.

To maximize success, use raised plant boxes with clean soil layers and monitor radiation levels. These plants not only survive but also help detoxify the environment, offering hope for sustainable gardening in challenging conditions.