A key to creating a refuge for bees is to avoid using pesticides, these chemical substances don't discriminate between good and bad insects and they're lethal for bees. Some commonly used pesticides called neonicitinoids are "systemic," which means once they're applied to plants the chemicals remain active over time so there is no safe time.
Bees need water and if you have a bird bath, remember that bees need stepping stones. Refresh the water regularly, and especially on very hot days to avoid evaporation.
While honeybees attract a lot of attention, native wild bees are very important to our food system and environment. Local bees forage on native plant species, and we can plan gardens that provide pollen and nectar for native pollinators throughout the growing season.
Below is a chart with some suggestions for bee-friendly plants (source: NW Edible).
The Bee Haven at UC Davis has created this list of plants that includes info on which ones are best for pollen and nectar (many have both).
Swarm is a fan of herb gardens that can attract pollinators when you let some plants flower. Herbs are easy to grow and often can thrive in partial shade. We like to cut some herbs for our kitchen use, and let some of the plants go to flower. Many herbs such as mint, rosemary and lavender have blue/purple flowers, which research has shown is the bees' favorite color!
Additional online pollinator garden resources:
NASA Honey Bee Forage Guide for Oregon
Pollinator Conservation in Portland metro area