Keeping bees is more than just cramming a swarm in a box and letting them do their thing. They need food, specifically a floral buffet that will keep them coming back for more.
One challenge is that most of the plants that provide bees with the bulk of their sustenance are…not terribly exciting to gardeners. That, or they’re considered pests. Dandelion, for example, which has inspired an entire agro-chem industry dedicated to its extermination. Or sumac, which causes a lot of rashes but also blooms for a whopping 150 days (at least, in the Piedmont region of NC).
You can certainly plant a pollinator garden; personally, I try to add plants that will attract bees, as well as other beneficial insects. However, here is a quick-and-dirty guide to the plants that will feed your bees even if you decide not to do a damn thing:
1.) Maple (Acer), which starts blooming early in the season, kick-starting Spring foraging activities.
2.) Dandelion (Taraxacum), which, as I’ve explained, are one of the most useful “weeds” in existence; also, SO CHEERFUL AND PRETTY.
3.) Clover (Trifolium), a mainstay of honeybees — probably because, between all the different varieties (alsike, ladino, crimson, etc.), something is always in bloom.
4.) Sumac (Rhus), which is good for bees but often bad for people.
5.) Goldenrod (Solidago), an all-around useful pollinator plant — hardy, versatile, colorful.
6.) Asters (Aster), of which there are infinite varietals; makes for good late season foraging.
A lot of these will just grow of their own accord — that is, if you can restrain yourself from shearing your lawn down to the ground or trying to turn it into living astroturf.
That can be tough, even if you don’t have a HOA to worry about; every spring I put off mowing the grass for as long as I possibly can just so the bees won’t starve — which ultimately results in a neighbor-generated nastygram, but whatever. By the time the city gets around to issuing an official, rather toothless* warning, my delaying tactics have bought our bees several additional weeks of prime foraging.
tl;dr — Rule of thumb: mow your lawn, kill your bees.