Hi Shannon,
I personally would never leave my buns outside by themselves, even in a covered pen. I’m not sure about your climate? I have taken our two outside a couple of times in the just the perfect weather (mid 60’s, low 70’s) in an xpen connected to a play pen and a cover on top. The cover is SO IMPORTANT. Even if you dont think there are flying predators, trust me, there are! I never once saw a hawk until after I took my buns out in this safe enclosure. They are out there! So anyways, fulling enclosed and covered with supervision. Your bunny might dig his way out while you are not around!
The other thing i did was make sure I set them up on an area free of leaves and weeds so that they wouldn’t eat anything that would make them sick. You have to be aware of bugs that could bite him and cause infections as well.
The other thing is that if your bunny is not used to fresh grass, all that munching can cause digestive issues. When I brought mine out we brought out tons of hay and their daily veggies too. They literally did not stop eating for an hour! Pumpkin loved the grass!
Anyways, yes, most members are going to say its a bad idea…it really might be. Are the risks worth the rewards? Like I said, we have done it a couple times, but it’s not something we make a habit of and honestly, I’m nervous the whole time, lol!!