Pollen Seasons
Trees in Central Oklahoma trees begin pollinating from mid-September (mountain cedar from the Arbuckle Mountains) through early May (pecan) and late June (pine). There is a second elm season in the fall (late August to October) due to the introduction of lacebark elms and cedar elms to this area. Each of the common tree species (elm, oak, maple/box elder, pecan/hickory, birch, mulberry, juniper, sycamore, pine, cottonwood/poplar, willow) usually pollinate for only a few weeks but added together the season is quite long.
Grasses
Central Oklahoma has two grass seasons. Cool season grasses (blue, fescue, timothy, rye, orchard, and redtop) can begin as early as late February or March but after a month or two they stop pollinating totally. The warm season grasses (which do not cross-react with cool season grasses) such as Bermuda, Bahia, crabgrass, and Johnson begin when the weather becomes warm and do not always stop until a good hard freeze in November.
Weeds
Some weeds pollinate in late spring or summer (dock and plantain), but most begin in late summer and fall. Ragweed pollination begins based on hours of daylight and almost always begin when the days shorten around the middle of August. However, the weeds often continue to pollinate until there is a hard freeze, often in late November.
Molds
We find molds in Central Oklahoma every day of the year unless there is a very hard freeze and/or the ground is covered with snow.
The Oklahoma Allergy & Asthma Clinic is a certified counting station for pollen and mold. We are associated with the National Allergy Bureau and the AAAAI. You can find our counts on the internet at www.oklahomaallergy.com. We supply the local media (TV stations, newspaper and radio) with our counts every day they are done. To learn more about the National Allergy Bureau (NAB) you can go to www.aaaai.org.