Rabbits are vegetarians who love to eat fresh fruits, grasses, vegetables, a lot of hay and plant materials.They have a unique digestive system with the ability to process fibre and nutrients. Fresh plants and herbs provide your rabbit with a wide range of nutrients, vitamins and minerals.
While most of the herbs are safe, there are several herbs which can be dangerous for your bunny. Some herbs can disrupt the bunny’s digestive system and cause several health issues. Knowing which herbs to offer will assist in keeping the rabbit healthy and free from diseases.There are many herbs which a rabbit can eat safely. You can find most of them in gardens or feed stores.If you are planning to feed herbs, you may feed them directly or dry them and mix with other feed like hay and fruits. Don’t forget to include more hay in your rabbit’s feed.
The safe category of herb includes: 

Basil,coriander,dill,fennel,lavender,mint,tarragon,thyme,watercress,mustard,oregano,parsley,rosemary, sage,cilantro, caraway, peppermint, lemon balm and comfrey. Along with these herbs, they can also eat weeds, flowers and wild herbs like borage, calendula, chamomile, chickweed, clover (leaves and flowers) and more. You can grow most of them in your backyard to get a regular supply.
However, there are several herbs that a rabbit should never eat. Herbs have many components such as roots, leaves, stem etc. Some or all parts of these herbs might cause adverse health effects. They can lead to gut problems and many other diseases. Here is a list of herbs that you should never feed a rabbit:

Chives
Chives can cause blood-related issues and gut problems. They can damage RBC in the blood, which can then lead to haemolytic anaemia. So it is better to avoid plants in the onion family such as chives, leeks, garlic etc.
Ginger
Ginger is not so toxic to rabbits. However, this herb may upset their digestive system. Their strong spicy flavour can cause mouth and throat irritations to your bunny.

Sorrel
Sorrel is a small green herb, which is edible for us, but you should never feed it to the rabbit. Sorrel is highly toxic for them and may even lead to their death. The herb can cause damage to your rabbit’s kidneys.

Other dangerous herbs include aloe, amaryllis, bloodroot, bluebonnet, agave leaves, blue-green algae, buttercup, belladonna, echinacea, mistletoe, nutmeg, oak leaves, eucalyptus, hemlock, hogwort, holly,jasmine, lily of the valley, poppy, ragwort, milkweed, mistletoe etc.
Once the rabbits eat such herbs, they show symptoms like loss of appetite, indigestion and seizure. In such a case, you should immediately take them to the vet.Rabbits have sensitive stomachs, so you should not feed them in excess. After introducing a new feed,examine their health status and stool for at least the next 24 hours. Always check with the vet if you are unsure about the food or the quantity.
A rabbit might not recognize which plant is safe and which is not. So it will often taste a plant even if it is poisonous. So it’s our responsibility to choose and feed the right veggies to our little buddies.