Creating a cosmic censorship-themed outdoor plant box is a stellar way to blend gardening with celestial inspiration. To achieve this otherworldly aesthetic, consider plants that evoke the mystery and beauty of the cosmos. Here are the best plants to include:

1. Silver Dust (Jacobaea maritima): With its shimmering silver foliage, this plant mimics the glow of distant stars, perfect for a cosmic theme.

2. Black Mondo Grass (Ophiopogon planiscapus 'Nigrescens'): Its dark, almost black leaves resemble the void of space, adding depth to your plant box.

3. Moonflower (Ipomoea alba): These luminous white flowers bloom at night, echoing the ethereal glow of the moon.

4. Blue Star Creeper (Isotoma fluviatilis): Its tiny blue flowers create a starry effect, as if a galaxy is sprouting from your garden.

5. Dusty Miller (Senecio cineraria): The silvery-gray leaves of this plant add a metallic, futuristic touch, reminiscent of cosmic dust.

For added celestial flair, incorporate decorative elements like small LED lights to mimic twinkling stars or metallic accents to represent asteroids. This unique garden setup will transform your outdoor space into a cosmic oasis, blending horticulture with the wonders of the universe.