Do store bought snake repellents work? NO
I'm sure you've seen them at every garden center. A number of products like Snake Away & other packaged snake repellents. Most of these products contain sulfur or naphthalene (moth balls) and a host of other, inert ingredients. The bottles will be covered in appealing lettering, and images and promises about how the product will repel snakes. Unfortunately, none of these remedies work. Studies have shown snakes are not bothered by these smells & have been seen crawling right over them. They can cause more harm than good if a family pet or child gets into them. So best to ditch the store bought over priced repellents.
Do moth balls work?: NO
Again like store bought repellents, moth balls do not effect snakes. They can be toxic if a family pet or child gets ahold of them, so it's best not to risk it.
Are there plants that repel snakes? NO
I've read a few people claim some plants like lemongrass & marigolds repel snakes. I can say that there is no proof that snakes would be bothered at all by these plants. It's true marigolds do repel some mammals like cats, so it's possible they repel rodents, and in by that you might see fewer snakes. But I have found no information on if rodents are bothered by marigolds. I've grown both of these plants in the past & have seen snakes right where these plants where.
How do I repel snakes then?
If you want to "get rid" of snakes on your property, you need to look first at why the snakes are there. Do you have a rodent problem? Lots of tall grass & brush piles? Cleaning up your property is the only real way to have any kind of control over the snake population. Snakes are there looking for food. So by removing the rodents, normally the snakes will move on. Keep grass cut short, clean up brush pills & keep animal food in rodent proof containers. If you have livestock like chickens make sure your coop is snake proof.