Answer: Salvia is not a reliable self-sower. The seeds are fragile and short-lived so you'd have best results if you purchased new seed each year. Annuals that freely self-sow include sweet alyssum (Lobularia maritima) and pot marigolds (Calendula officinalis).
Self-sowing perennials include purple coneflowers (Echinacea purpurea), Virginia spiderworts (Tradescantia virginiana), gloriosa daisies (Rudbeckia hirta), and garden phlox (Phlox paniculata).
Good luck with your new landscaping project!
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