Will i get tetanus - last shot 3 years ago - puncture wound - rusty nail in garden?

Unlikely to happen: The vaccine is good protection for simple wounds for up to 10 years. It will not protect you from the other germs in the wound so proper care of the wound is important.

Ok: Tetanus up to date get tdap form next shot in 7 years.

Puncture wound care: If your last tetanus shot was a booster then you are covered. If not then you need to get vaccinated and treated. Besides tetanus the concern with rusty garden nail puncture wound is getting a bacterial infection so the wound needs to be cleansed and treated with topical antibiotics. Sometimes antibiotics by mouth are indicated as well. See your pcp.

Have it evaluated: Such injuries can potentially be dangerous as one may develop tetanus, or a number of other types of deep infections. If the wound was deep enough they may lead to bone infections. Have the wound properly evaluated and treated to avoid preventable complications.

Up to date: On tetanus since the last tetanus shot is op to date.But clean the wound and watch for any signs of infection or damage to the foot ( pain, redness, swelling, indurartion......See your doctor. There are many other infections you can get besides tetanus, see doctor if you have symptoms or are unsure.