Vermiculture can be the perfect answer for an indoor herb gardener. Vermiculture is a way of composting using earthworms to speed up the process. It is easily done inside the home as it takes only a small amount of room and creates no odor. In fact, if you are an indoor-only herb gardener, you will benefit from having just the right amount of compost to add to your smaller sized garden area. The real problem is not the size of the indoor worm bin, it's trying to find more room in your home for more bins!
Use any bin that is moisture and escape proof. The only tricky part is that if your worms aren't happy, they will try to escape. Signs of this are worms crawling on the top of the lid you cover the bin with. A few are fine, but for the most part, they want to be under the shredded material and out of any chance to have light on them.
Remember to poke holes in the lid of whatever you are using. Of course to provide air to the worms, but also to allow excess moisture to evaporate. This is critical to a healthy bin. I like using styrofoam bins if I can. What else are they going to be used for, right? This way it avoids the styrofoam being thrown away and they do make pretty sturdy bins.
I have successfully started many vermiculture kits for customers. My method that fits easily under the kitchen sink and provides enough compost for a windowsill garden. Your worm bin will not create mess or smell.
As the worms digest the kitchen scraps, their castings (poop), is a rich fertilizer for your herb garden. You can have fresh compost year around for your herb pots. Remember, this stuff is pretty potent. There is no need to use it as thickly as you do regular compost. In fact, I would consider this black gold.
It can be added to water and then that resulting nutrient rich water can feed your plants. Think of how long that will last!
Using Finished Compost
The finished compost will be black and crumbly. This composted material is not to be used straight in your pots, however. Mix it into the top inch of your plant pot as an amendment to what is already there. As you water, you will slowly wash the nutrients down to the roots. You now have an endless supply of organic fertilizer. Finished compost is rich and complete. Your plants will grow well and you will be completing an age old process that helps the earth; right in your kitchen!
A final thought: Buy your worms during the spring/summer/early fall. Any reputable worm farmer will not risk sending delicate worms through the winter where they could easily become frozen.