We're lucky to have Purple Finches in our yard all summer, and the last few years have been banner years for them. They'll move on soon from my yard, but that means that other folks in eastern New York might be seeing them soon.
1. Feed them safflower seed
While Purple Finches eat some black oil sunflower as well as niger seed, at our house they prefer straight safflower seed. The advantage to this is that squirrels don't typically bother safflower seed so you have more flexibility in where you locate their feeders.
2. Give them their own space
We find that Purple Finches, like goldfinches, seem to prefer a feeding area that is mostly just for them. For the Purple Finches, we place three feeders filled with safflower seed under the hemlock tree on the shady west side of the house. It's a cozy location and is very wooded with coniferous trees. We have another feeder filled with safflower seed in the wide open of the front yard, but they seem to prefer their special feeding area and only go to the front yard feeders for overflow.
Enjoying Safflower Seed from WBU Tube Feeder
3. Provide lots of perches
I describe finches as "sitters" - they will sit at a feeder and open seed after seed right there on the perch, unlike chickadees, titmice, and nuthatches who take a seed and go. This means you could have many Purple Finches on the feeder at one time. So give them many perches on multiple feeders and you will open up the possibility of seeing lots of Purple Finches at once.
In the area of our yard that is dominated by Purple Finches, the feeders offer over 20 perches, and sometimes there are still birds waiting in the nearby trees for a perch to open up. Sometimes a dominant Purple Finch will force another one off the feeder, so give them lots of perches!
As always, keep your birdfeeders clean, make sure the seed is fresh, and enjoy the beautiful Purple Finch!