Deer like plants that will give them moisture, protein, minerals and salts. They usually prefer new growth and may be attracted by certain smells. Unfortunately, you have no way of knowing what smells appeal to your local deer.
Generally, deer avoid prickly plants and trees, and so will usually not eat spruce, holly, juniper, pine, and fir trees. Other trees that deer usually avoid include bottlebrush buckeye (Aesculus parviflora), mimosa (Albizia julibrissin) and paper birch (Betula papyrifera).
If you'd like to include some shrubs with the trees, roses with lots of thorns may be left alone by deer. Yucca (Yucca spp), with its sharp pointy leaves, is another that deer tend to shy away from. However, deer seem to like tea roses, so either protect them or avoid planting them. Here are some other shrubs that deer often avoid:
Russian Cypress (Microbiota decussata
Russian Olive (Elaeagnus angustifolia
Red Elderberry (Sambucus racemosa)
Evergreen Sumac (Rhus virens)
Japanese Yew (Cephalotaxus harringtonia)
Japanese Boxwood (Buxus microphylla)
Oleander (Nerium oleander)
Viburnum (Viburnum spp.)
Butterfly Bush (Buddleja spp.)
Deer also don't like plants that taste bitter and they tend to avoid plants with strong smells. For this reason, some gardeners plant wormwood (Artemisia absinthium), catmint, chives, lavender, sage, rosemary and thyme. It may help to plant these among the plants that are currently being snacked on in your landscape. It may help and it can't hurt.
Perennials that are commonly avoided by deer include hardy amaryllis (Hippeastrum x johnsonii), angel trumpets (Datura spp.), bearded iris (Iris spp.), dusty miller (Senecio cineraria), elephant ears (Alocasia spp./Colocasia spp.), lantana (Lantana spp.), oxeye daisy (Chrysanthemum leucanthemum), prickly pears (Opuntia spp) and Russian sage (Perovskia atriplicifolia). But these aren't all. Some gardeners report success when planting these perennials:
Candytuft (Iberis sempervirens)
Gold moss sedum (Sedum acre)
'Indigo Spires' Salvia
Mallow hibiscus (Hibiscus moscheutos)
Mexican hat (Ratibida columnaris)
Jerusalem cherry (Solanum pseudocapsicum)
Other flowers that seem to grow under the deer's radar include marigolds (Tagetes spp), larkspur (Delphinium consolida), periwinkles (Catharanthus roseus), zinnias, spider flowers (Cleome hasslerana), forget-me-nots (Myosotis) and mealy cup sage (Salvia farinacea).
So far, it looks like you have lots of options, but you can even add some ornamental grasses to the list. Try some pampas grass (Cortaderia selloana) or purple fountain grass (Pennisetum setaceum). You can also try inland sea oats (Chasmanthium latifolium), maiden grass (Miscanthus sinensis) or gulf muhley (Muhlenbergia capillaris). Clump bamboo (Fargesia) is another good choice for a deer resistant ornamental grass.
After reading such a long list, it may seem that there are lots of options for deer resistant landscaping, and there are. Keep in mind, however, that different deer like different things. A plant that deer won't touch in one region may be a favorite in another region. After a long winter, anything green will be on the must-eat list for most deer, even if they just take a nibble. Also, the degree of damage to some plants may be relatively minor, while other plants may get chewed to the ground.
Landscaping can be quite an investment and no one wants to see their hard earned dollars become a deer dinner buffet. Ask your neighbors which plants they have success with and then talk to your county Extension Agent. They will be able to give you tips on what plants in your area seem to do best around deer.
Then, be prepared to engage in a bit of trial an error. Even with the best advice, you may still end up with plants that your deer love. Then it's up to you to decide if you can tolerate it or if you won't plant that particular plant anymore. Hopefully you can come up with a happy medium with deer that you can watch out your window and a beautiful landscape to boot.
What deer resistant plants have you had the most success with?