Many people are worried that a garden, even a tiny little garden will take up loads of time. This can be true as the investment of time often is rewarded with lots of kinds of crops. However there are some plants that are permanent and that will produce food or flowers repeatedly. These are called perennials.
I have lived in my home for the past 13 years and I can attest that I have never planted Campanula. It comes back year after year on the back steps to the delight of all bees and insects. Below is a photo of my cat Max enjoying the Campanula.