Better Than Wolves Forum

I've decided to automate the Wither Skeleton Skull collection so I made a Nether Fortress mob trap.
The design is pretty straightforward, mobs should spawn on Nether Brick covered by a pressure plate, which then activates a piston which pushes them to their doom.
But I wonder if I messed it up? Do mobs spawn on pressure plates or not?

Also, do Zombie Pigmen spawn on Nether Bricks or only on Netherrack?

Mobs can spawn on pressure plates and netherrack and netherbrick have the same spawn properties. Are you far enought from the farm for mobs to be able to spawn in it?

Yes, I'm at least 50 blocks away from the farm. I also planted Nether Groth to nearby Netherrack and covered the Fortress with slabs, so there are no other mobs spawning, except for Ghasts.

There's actually another thread on this exact topic on the front page from when I had the same issue, as well as several others over the past several years. I suggest you check those threads out for advice. Two things I will say though are that spawn rates are frustratingly slow, even with highly developed groth in your nether, and you should research spawning requirements/restrictions for all nether mobs, especially ghasts. You really should do a search on these things before you ask about them though, I doubt there's very much information on the topic that hasn't been discussed on these forums already.