The majority of bee species nest in the ground. Sometimes a bee chooses a flower pot as her nesting site, digs a tiny burrow and lays her eggs inside. She doesn’t harm plants in the process. If you are a poor gardener, you still have chance for a potted bee – they often prefer pots without much plants and with bare earth inside. Of course they should also have access to some food plants nearby. In areas with seasonality, a pot inhabited by bees should be left outside for winter because they need low temperatures to develop and time their emergence properly.
In my own balcony flower pots the leafcutter bees (Megachile) have been nesting since a few years. Many members of this genus line their nests with cutted leaf parts, so I can see how they repeatedly come home with leaf pieces in their mandibles.
Non-honey bees 