Creating a black hole final state-themed outdoor plant box is a unique way to bring cosmic inspiration into your garden. This dark and mysterious theme calls for plants with deep hues, unusual textures, and a touch of otherworldly charm. Here are the best plants to achieve this striking look:

1. Black Mondo Grass (Ophiopogon planiscapus 'Nigrescens') – With its nearly black foliage, this grass mimics the inky darkness of a black hole, adding depth and contrast.

2. Black Coral Elephant Ear (Colocasia 'Black Coral') – Its large, dark leaves create a dramatic focal point, evoking the vastness of space.

3. Dark Opal Basil (Ocimum basilicum 'Dark Opal') – This edible plant offers deep purple leaves, blending beauty with functionality.

4. Aeonium 'Zwartkop' (Black Rose) – Its rosettes of dark, glossy leaves resemble celestial bodies, perfect for a cosmic theme.

5. Heuchera 'Obsidian' (Coral Bells) – The near-black foliage provides a stunning contrast to lighter plants or decorative elements.

For added intrigue, incorporate silvery or metallic accents like Dusty Miller (Senecio cineraria) or Lamb's Ear (Stachys byzantina) to mimic starlight. Low-light tolerant plants like Snake Plant (Sansevieria) or ZZ Plant (Zamioculcas zamiifolia) can also thrive in shaded areas, enhancing the mysterious vibe.

Pair these plants with dark mulch or charcoal-colored stones to complete the black hole aesthetic. This theme is not only visually striking but also a conversation starter, blending gardening with cosmic wonder.