When it comes to gardening on slopes or in sloped outdoor plant boxes, choosing the right plants is crucial for preventing soil erosion and maintaining stability. Here are some of the best plants for stabilizing soil in such conditions:

1. Creeping Juniper (Juniperus horizontalis) – This low-growing evergreen spreads quickly, forming a dense mat that holds soil in place. It’s drought-tolerant and thrives in full sun.

2. Periwinkle (Vinca minor) – A hardy ground cover with vibrant flowers, periwinkle roots deeply, preventing soil washout while adding color to your garden.

3. Liriope (Liriope muscari) – Also known as lilyturf, this grass-like plant has strong roots that anchor soil effectively. It’s ideal for both sunny and shaded slopes.

4. Sedum (Stonecrop) – Succulent sedums are excellent for dry, sloped areas. Their shallow roots help bind soil, and they require minimal maintenance.

5. Daylilies (Hemerocallis) – With deep, fibrous roots, daylilies prevent erosion while producing beautiful blooms throughout the summer.

For optimal results, combine these plants with mulch or rocks to further reduce erosion. By selecting the right species, you can create a lush, stable garden even on challenging slopes.