One of the scourges of gardens throughout the eastern US are the deer. I've heard and read so many horror stories about them, but my home garden is in a densely populated area so they are not a problem there. But things are different where my school is, deer freely roam around the school at night, and I find their footprints in my slope garden, and occasionally other signs of their presence, like a double flowered helianthis stripped of foliage, or missing branches on my Anisodontea julii plants that I had in the slope garden last year. They seem not to bother the garden near the wall, perhaps it feeks to enclosed for them to feel safe, but they do check out the slope garden. I have found that they never touch certain plants, especially ones known to be toxic or herb type plants that emit odors from their foliage. They don't like most salvias, nor marigolds, and only took one chomp of a young Shirley poppy before they decided that wasn't so good either. I started several perennials from seed last year from a "Zone 6 mix" that was offered a couple of years ago by Gardens North (an amazing resource for seeds). I love surprises, and indeed I couldn't figure out what some of the plants were until they bloomed. Some did bloom the first year, most notably some salvias and an agastache, both of which the deer refused to touch. A large leaved plant also was untouched, but only when the shaggy yellow daisies appeared this year did I realize it was Telekia speciosa. Telekia is definitely a space hog, but the foliage is attractive and the flowers quite nice. Surpisingly I could not identify Sweet Rocket (Hesperis matronalis) before it bloomed this spring, even though it grows in the woods around here. It is an invasive species, but one of the better ones, I suppose, since it has lovely fragrant flowers and is not as aggressive as its ugly cousin garlic mustard. I did cut it back after blooming to prevent it from further seeding in my garden so as to enjoy it in strictly limited quantity in the future. A pink silene also came out of the mix, I think it is Silene dioica. It started blooming in May and is still blooming right now. Some bearded Iris cultivars were also planted among the perennials, and they were not bothered either, but I admit to putting down some homemade repellent (hot pepper, milk, eggs, garlic powder with my own added special touch of a bit of lime sulfur to worsen the already repulsive odor) when their buds got close to opening. Iris are toxic, but I have read accounts of deer "testing" the flower buds. Achillea (yarrow) is avoided, and is so easy to grow from plants or seeds. The pink forms are especially pretty in a cottage style garden.
The local deer also have plenty of other things to eat around Chappaqua, so that may also be a factor in preventing really serious damage to my garden. Still I think it is prudent to plant things that make them feel unwelcome so as not to encourage them in any way. The real answer to the deer problem lies in reducing their numbers, since we killed off their natural predator (wolf) and created much more of the "edge" habitats that they prefer. Its not just gardens that they terrorize, but also increasingly threatened native wildflowers, particularly cypripediums and trilliums, among many others. And don't get me started on Lyme disease, that's a whole 'nother discussion!