We have no need to prepare nests since we have so many dead hollow weed stems for them to nest in already. Our high density of native bees is also why I ask the folks keeping honey bees on my property to put them far from our vegetable field so they don't compete as much or share diseases with these solitary bees. He says our place produces the most honey of all his hives. The swarms of native bees are particularly high once the pussy willows start flowering. Its like a fog of bees around these trees each spring.