Freezing helps protect the flavor of many herbs. Herbs that freeze well are basil, chervil, chives, dill, fennel, parsley, mint, salad burnet, sweet cicely and tarragon. To freeze herbs put clean dry leaves in freezer bags, press out any air and seal. Make sure you label the bags. You can also puree them with olive oil then put them in freezer safe and bpa free containers. Basil is great to do that with. I published a pesto recipe in the past on this site if you want to make and freeze pesto. When freezing the herbs only place one type of herb in each bag. There are these small containers available on Amazon that are great for freezing pesto. They are bpa free and these are the ones I use and they work well. They are small enough to just thaw out one at a time.