Slug Resistant Plants
If you do not want to kill slugs but you do not want them eating your garden either, why not fill your garden with plants that are slug resistant?
If a plant becomes squashy and slimy when it dies then slugs will probably want to eat them. Slug resistant plants can simply be plants that slugs don't like eating. These include plants with woody branches and evergreen leaves. Some might withstand a slug attack simply because they grow faster than they can be eaten or contain sap that slugs don't like.
The following is a list of plants that would likely survive a slug invasion. Google them to see what they look like if you are unsure.
Ajuja
Dianthus
Dicentra
Alyssum
Japanese Anemone
Armeria
Ferns
Hydrangea
Fuchsia
Pelargonium
Iris
Bergenia
Narcissus
Crocosmia
Paeona
Artemesia
Arabis
Lavandula
Grasses (Ornamental)
Astilbe
Periwinkle
Potentilla
Alchemilla
Mollis
Eryngium
Astrantia
Tulipa
Euphorbia
Aubretia
Geranium (Cranesbill)
Penstemon
Heuchera
Foeniculum vulgare
Phlox
Tropaelum species
Hemerocallis cultivars
Sedum spectabile
Saxifraga x urbium
Rosa
Stachys macrantha
Pulmonaria
Sempervivum
Anemone x hybrida