Daintily, a deer sniffs and tastes the flowers in a garden. Although no plant is deer-proof, some plants do not normally attract the four-legged herbivores. The aroma, thorns or sap of these plants repels deer, encouraging them to forage in a neighboring deer-friendly garden. When deer's food sources dwindle, however, no plant is truly deer-resistant. A hungry deer will eat nearly anything, including plants that it normally would avoid.
Deer tend to avoid aromatic foliage, flowers and herbs. The oils in many ornamental and culinary herbs repel most deer. Those herb plants include common sage (Salvia officinalis) and Russian oregano (Origanum vulgare subspecies gracile), both of which are hardy in U.S. Department of Agriculture plant hardiness zones 4 through 8, rosemary (Rosmarinus officinalis, USDA zones 8 through 10) and English thyme (Thymus vulgaris, USDA zones 5 through 9).
Certain flowering plants that are annuals also discourage deer from browsing in a garden. For example, pot marigold (Calendula spp.), French marigold (Tagetes patula), anise (Pimpinalla anisum) and flowering tobacco (Nicotiana spp.) all have strong aromas that encourage deer to forage in another garden.
Thorns and More
Although not all thorny, spiny or prickly plants discourage deer from browsing, native plants, such as Oregon grape (Mahonia repens, USDA zones 5 through 8 ), American holly (Ilex opaca, USDA zones 5 through 9) and Adam's needle yucca (Yucca filamentosa, USDA zones 5 through 10) are avoided by deer. When planted along a yard's perimeter, these North American natives discourage deer from searching deeper into the property and discovering its more palatable plants.
The caustic sap of swamp milkweed (Asclepias incarnata, USDA zones 3 through 6) and Euphorbia species such as spurge (Euphorbia myrsinites, USDA zones 5 through 9) and snow-on-the-mountain (Euphorbia marginata), discourage deer browsing. Deer tend to seek out tastier tidbits in the garden or the neighbor's yard before resorting to eating these sap-filled species. Swamp milkweed thrives in wet soil while spurge grows best in dry, well-drained locations. Snow-on-the-mountain is an annual plant cultivated by gardeners during the warm months of the growing season.