Creating a gravastar-themed outdoor plant box is a fantastic way to blend cosmic inspiration with nature. To achieve this celestial aesthetic, choose plants that evoke the mystery and beauty of the universe. Here are the best options:

1. Silver Dust (Senecio cineraria) – Its silvery foliage mimics the shimmer of distant stars, perfect for a cosmic vibe.

2. Black Mondo Grass (Ophiopogon planiscapus 'Nigrescens') – Deep purple-black blades resemble the dark expanse of space.

3. Moonflower (Ipomoea alba) – These luminous white blooms open at night, echoing the glow of a gravastar.

4. Blue Star Fern (Phlebodium aureum) – Its blue-green fronds add an otherworldly touch.

5. Echeveria 'Black Prince' – This dark succulent contrasts beautifully with lighter plants, creating a stellar effect.

Pair these plants with decorative elements like glow-in-the-dark pebbles or metallic accents to enhance the theme. A gravastar-themed plant box is not just a garden—it’s a portal to the cosmos!