:o Well I think if it was me, & it had 5yrs of weed growth I would start with the weed killer first, while the weather is dry (if it is with you) Then when died back clear all the dead top growth then rotovate if poss to take out initial back breaking digging, & keep that up until nice tilth achieved & as many weeds as poss removed. You may need to weedkiller a few times, but if you want to stay organic if you are only going to go that way then I think you may have lots of digging to do, I rotovated & weedkillered ,with great success a patch a few years ago ;D