Spring: treesBirch, oak, ash, elm, cedar, mesquite, olive and mulberry. In Texas and the Southwest, mountain cedar and juniper pollinate through winter.
Summer: grassBermuda, timothy and northern grasses. Mowing, sports fields and warm windy days are the worst.
Fall: ragweedEarly August to mid-October. One plant sheds a billion grains, and they have been found 400 miles out to sea.
A Moderate Freeze, 25 To 28 Degrees, Ends The Season