Trim fat from ribs. For rub, in a small bowl combine paprika, garlic salt, onion powder, sage, celery seeds, and cayenne pepper. Sprinkle rub evenly over both sides of the ribs; rub in with your fingers.
Prepare grill for indirect grilling. Test for medium heat above the drip pan. Place ribs, bone sides down, on the grill rack over the drip pan. (Or place ribs in a rib rack; place on the grill rack over the drip pan.) Cover and grill for 1 1/2 to 1 3/4 hours or until ribs are tender, brushing occasionally with apple juice after the first 45 minutes of grilling. Makes 8 servings.