The first thing to consider is location. Martin do like being near humans (perhaps because they know that humans keep away predators) but not too near. A good estimate for placing a Martin house in proximity to your own home or barn is no further than 100 feet but no closer than 30 feet. Martins also like open areas so you should pick the area of your yard with fewest trees and try to provide 40-60 feet of open air space in at least a couple directions.
After choosing a good location, it’s time to choose the right Martin house. There are two main types of houses, the multi-room house and the gourd system (both can be combined on the same pole). When choosing a multi-room house, it’s advisable to get a light-colored aluminum house because it will stay cooler on hot sunny days. An advantage of hanging gourd houses is that they sway in the wind, which does not bother Martins but will discourage Starlings and House Sparrows from nesting.
Once you have installed your Purple Martin housing you can leave it alone until fall cleaning. However, with more active maintenance, you can increase the nesting success and number of Martins.
Mid-afternoon on warm and calm days, check houses for pests like unwanted nesters, predators, and blowfly infestations. It is VERY IMPORTANT to return the house to the same height and orientation after each inspection; mark the pole with permanent marker so you can return the house to the same vertical and horizontal position. The house should never be tilted after nesting has started in order to avoid damaging eggs and young. Keep in mind that it is normal for not all eggs to hatch or all nestlings to fledge. You can, however, aid nesting success by placing crushed eggshell and mealworms on platforms near the Martin houses. The eggshells facilitate calcium and egg production, and the meal worms are a tasty snack.