As much as possible! Okay, that’s not much of an answer.
First, which kinds of pollinators do you want to attract?
Hummingbirds – red tubular Penstemon and Acanthus flowers work great.
Bees – sunflowers are your best bet.
Butterflies and moths aren’t so picky, but you’ll want to provide host plants, like milkweed for Monarchs.
Left: Male longhorn bees (genus Melissodes) shelter overnight on sunflowers (Helianthus)
Right: Spiny goldenweed (Xanthisma spinulosum) volunteers in author’s yard
Where can I buy these plants? Check out our new page here: pollinatorweb.com/host-plants/native-plant-nurseries/
Also, don’t kill all the “weeds” in your yard. Many native plants are dispersed by wind and birds and will grow on their own if given a chance.