Often, snails and slugs will avoid plants that are likely to irritate their disgusting, slimy little bodies—this would include plants with hairy or rough surfaces, plants with dental floss-like fibers (e.g., grasses), plants with icky sap (e.g., euphorbias), plants that are very aromatic (rosemary, catnip, yarrow), plants with thick, leathery leaves (e.g. agapanthus). The following list of snail and slug-resistant plants has been gleaned from books, websites, experience and hearsay, and is subject to change in response to your very welcome feedback.

Annuals
Sweet alyssum, baby blue eyes (nemophila), bachelor’s buttons, borage, clarkia, coleus, cosmos, dianthus, echium, impatiens, linaria, lobelia, nicotiana, nigella, poppies, forget-me-not, snapdragons, sweet William.

Biennials & Perennials
Agapanthus, allium, alstroemeria, armeria, artemisia, astilbe, cerastium, columbine, daylily (hemerocallis), diascia, dicentra, echinacea, echinops, epimedium, euphorbia, ferns, feverfew (matricaria), foxglove, geum, grasses, hardy geraniums, hellebore, heuchera, iberis, lady’s mantle (alchemilla mollis), lamb’s ears (stachys), lamium, lavender, marguerites, mint, mullein (verbascum), oregano, penstemon, polemonium, potentilla, pulmonaria, rudbeckia, salvia, santolina, saxifrage, scabiosa, Shasta daisy, valerian, veronica, vinca minor, wallflowers (erysimum & cheiranthus).

Shrubs & Vines
Azaleas, camellias (new leaves may be vulnerable), ceanothus, fuchsia, grapes, hebe, holly, hops, hydrangea, ivy, manzanita, rock rose (cistus), rhododendrons, rosemary, viburnum.

If your observations contradict or support the above, please let me know.

–Margaret