When first reading and learning about rabbits I was amazed to find that they are actually very smart. And much like our cat they can be litter box trained! As funny as it sounds rabbits love to eat and poop at the same time and they are also BIG creatures of habit. Once they find a corner they like to "go" in, it's much easier to just make that the bathroom corner than trying to get them to go somewhere else. But first things first you need a litter box. You can use many things but ideally you want it to be removable and easy to clean. We find that the high side cat litter boxes work best. But much like everything else it all comes down to personal preference. So you've got your box, now you need to line it with something. We use kiln-dried pine shavings, they are cheap and we buy them in bulk from tractor supply because we use them for so many things but there are other options. There is a myth going around the internet that pine shavings are toxic to rabbits, they aren't. Especially if they are kiln-dried. They are also the cheapest litter you can buy and they stack up pretty well with order control and absorption. We've been using this type of litter for our rabbits for years and have never had any issues with it. But this is only one option. You can also use paper based litters, hay/straw (although not as absorbent) compressed sawdust or wheatgrass-based litters. Some to avoid would be clumping, clay or corn cob based litters. These types of litter can cause a heap of health issues if ingested, and if it's going in the rabbit cage you bet some bits of it will probably be ingested. Alright so your box is now ready to be used. Put it in the space you rabbit typically goes the most and add a little bit of dirty bedding to the litter box. You want the box to smell like them a tad so they get the idea that this is where I should go. You can also hang there hay feeder close by the box or just fill one side of the box with hay (we recommend timothy, mixed with some alfalfa for younger buns). In the beginning limit the amount of space she might have to run free. And when she is out of the cage for exercise keep a close eye on her and shoo her back into the cage as soon as she starts to urinate. Be careful not to use her cage as a "time-out", you want your rabbit's cage or house etc. to feel like their safe place. Also keep in mind the younger the rabbit the longer they will take to train so don't give up. When your rabbits is otherwise occupied gently go in the pick up all the loose poops and just plop them into the litter box. If she does have an accident outside the box clean the urine with white vinegar or another animal safe cleaner. You don't want it to stain or continue to have a smell because then it will become a place she will want to keep using. When it comes to poop, rabbits will sometimes mark their territory with scattered poop. This doesn't mean they aren't getting it, a rabbit who isn't using her box will poo in a big pile- not scattered all over the place. As your rabbit starts to use the litter box more you can slowly increase her roaming space. I highly recommend cleaning out the box everyday. If you use an organic litter you can repurpose the mess into fertilizer, mulch or add it to your compost. The nice thing about rabbit waste is that it can go right into the garden, it doesn't need to compost for months like chicken waste does. If you find little drops of urine trailed around your rabbit's cage it could be a sign of a bladder infection and you should check in with your vet. Non spayed and neutered rabbits will spray urine to mark their territory, the best way to fix this is to get your pet fixed.
We hope these tips and tricks help! And remember as your rabbit gets older, it will get easier. Don't give up!