Arikmai

I am currently running the harvester and planter for a tree farm. I don't know exactly how it is supposed to work, but at the moment, it is not picking up all of the saplings, it is just spewing half of them on the ground. If this is intentional, is there a better way to pick them up besides using the item collector? Because I would need like 30 of them and they wouldn't pick up the ones in the middle.