The past two summers I had a huge problem with bird seed germinating in pachysandra. Fortunately,  depending on one's perspective, the tree I was using for the feeders had to be removed last summer so that problem was eliminated.  I still had a lot of the mixed seed left over and was hesitant to use it because of the germinating problem.  I found a solution to that problem on the the internet I think it was--roast the bird seed before putting out for the birds.  I did this once or twice and decided it was "for the birds" and too much trouble.  I've been buying the black oil sunflower seeds and the birds love it, especially the zillion cardinals that are around this wiinter and I have to refill the feeder every two or three days.  I can't get to any other feeder spot because of deep snow and by the time it's gone the birds can find their own food.  I don't feed them in summer.

I don't believe there would be the same germination problem with the black oil sunflower seeds.  By the looks of the ground under the feeder the birds take the seed-also the part that would germinate--and leave the husk behind.

II guess is a matter of perspective.

My feeders hang from a the rail of what is essentially a second-story deck.  The area beneath the deck has riverstones, and a large part of the area is used for firewood storage. 

So the few non-hybrid reverted sunflowers that spring up through the stones are nice surprises.  Some summers I get a couple, sometimes I don't.   Last yuear I had a couple of wild mint plants appear.  Unexpected gifts.

Well, the bears are up and roaming, so, with some sadness, I have taken the feeder down for the season.
It was great fun.
The yard is alive with birds now. Lots of nesting behavior underway.

LOL !