The best method to protect your garden is a fence. It’s expensive and time consuming, but it’s the only way to guarantee that deer won’t eat up all of your hard work. Plant pungent smelling perennials like garlic, chives, and lavender to mask the appealing aromas of nearby annuals. (Here’s some more deer-resistant plants: http://njaes.rutgers.edu/deerresistance/). Use a scarecrow.
Back in the day we used to use mothballs (before environmental concerns were raised). A couple of new tricks include bundling up hair (dog, cat, even human) in bags and hanging it up; rubbing highly scented soap on the bark of vulnerable trees, or hanging bags of soap in branches; spraying with a hot-pepper spray -- the competing smells confuse the deer. There are also some products on the market including Deer Away and Deer Off.
Here are some tips generated from local residents:
1) Plantskyd-liquid deer blood. It has proved effective on my hostas and fruit trees. Do not follow instructions on the container to spray it on your plants and trees. Rather, put the liquid in a yogurt container and paint it on the bark and branches of fruit trees with a brush, or else brush the liquid on stakes and place them in the ground around valuable plants. Use a container that has a secure fitting lid for storage. It stinks, so keep it somewhere you do not have to smell it. Also it cannot freeze, so must be stored inside in cold weather. It will last, even in rain, for a few weeks.
2) Creating deer lines. I use fly fishing line to string a “fence” at chest height around a tricky spot across a deer run behind my garden. Deer walk into it and quickly shy away as they touch something they cannot see--it’s a defense mechanism. Fishing line is cheaper than sprays. I use fly line because it is stronger. You do need to remember where your lines are strung; you could even hang prayer flags along the same spot to define (with deer line below). The key is, you are building a “fence” so unless you enclose the space, eventually the deer will figure it out.
3) Lighting: since deer like to feed at dusk and dawn, motion sensitive floodlights/outdoor lights will scare deer away. Similarly, motion-sensitive lawn sprinklers will also send them running.