I have a fairly large backyard with grass that's fenced but has recently been taken over with weeds. Questions:

1. Should I treat the yard first before letting Sir Rupert out into the yard? Not with chemical weedkillers, obviously, but are weeds bad or unsafe for rabbits?

2. Would yard grass be okay for rabbits to eat in place of hay? Does it matter if it's fresh (green) or dry?

3. Sir Rupert isn't trained yet, but even if he were well-trained, would it be advised to keep him in an x-pen instead of letting him roam free? He won't be able to get into the street but he might get into some other trouble. Or, would a harness be a good middle ground, assuming he's okay with them?

4. Can he catch anything even if there aren't any other animals he can come in contact with in the yard?

Sorry about all the questions, and thanks

To my knowledge, common grass weeds are not dangerous for bunnies. Pesticides are not recommended in areas where bunnies are playing.

Fresh grass is not an alternative for hay. It needs to be fed in a small amount, eating too much can make a bunny sick.

Harnesses are dangerous because a bunny can injure themselves if they get startled and try to escape. Some may break a leg or even their back.
I would recommend an xpen for the bunny's safety. Even with a fenced in backyard, you don't know where the fence may have a small hole that the bun could slip out of. And if any animal gets into your backyard, the xpen adds an extra measure of security. With that said, never leave your bunny unattended in the yard.

Parasites and fleas are a risk anytime your rabbit is outside.

Parasites and fleas including cutebara are huge risks for your rabbit. Cutebara is a terrible thing - happened to one of my good friend's rabbit luckily the vet was able to save her. She had good intentions as well but never ever let her rabbits out again after this incident.

Any time ours are outside we always have them in an Xpen, even though our yard is fenced. For one thing they're incredibly fast and sneaky and I can so totally see them quickly digging under the fence. But it also lessens the chance of some other predator (cat, owl, hawk etc) getting at them. We have taken them for "walks" on harnesses before, although not for a while. I'd never just leave them outside on a harness though (not that you'd leave them unattended) but when you're walking them you're right there with thm all the time.
Oh, and ours love dandylions. Apparently they're quite tasty.
- Annette

Thanks all. I think I'd prefer Rupert to be an indoor-only rabbit, if he can still catch diseases just by being outside. Seems like it's just not worth the trouble especially since I can't exactly walk him and it doesn't seem to have too many advantages over the risks.

I feel the same way. It's not worth the risk. My buns are indoor only.