I have planted a mix of orchard grass and perennial rye grass as 18 foot wide rows between mulched rows of apple trees.  Both of these grasses are I believe "bunch" grasses and not turf grasses.  They appear to be healthy and are about 5 years old and much denser planting than if in a pasture.  I mow them about a half dozen times a year using a tractor and flail mower.  I have some concern about compaction from the tractor and mowing.  My question is about the benefits, or harm perhaps, from running a plug aerator down the grass rows.

I assume spring would be the correct timing, but not being turf grass I was wondering if I might cause more harm than good with plug aeration.

Thanks, John