Which Pollens Strike When?

At least one in five Americans has some kind of allergy. Common allergy triggers include food, dust, mold, pet dander, and, of course, the dreaded pollen. Pollens tend to take brief breaks during extreme temperatures (such as the peak of summer and dead of winter), but more often than not, there’s some kind of pollen granule floating around in the air to afflict allergy sufferers.

Pollens Strike

(Pixabay / anaterate)

It’s nearly impossible to avoid pollen, but you can minimize your exposure to them if you understand more about when certain pollens are in bloom.

Here’s a closer look at the timeframes of different types of pollen:


Tree pollens usually kick up around February and die down in May, though some trees, such as black walnut, tend to pollinate later into the summer. Cedar, acacia (southwest region), alder (northern states), olive (southwest region), and pine usually pollinate first. Ash, birch, cottonwood, elm, maple, mulberry, mesquite, oak, pecan, sycamore, and willow (northwest region) join in in March or April. Some trees take a break during summer but start pollinating again in fall. This includes cedar and elm.


Grasses usually pick up the gauntlet as tree pollens are dying down. They can start pollinating as early as April, and some grasses (such as Bermuda) continue pollinating into August and September. Brome and orchard grass (common in the northwest), Bermuda, Kentucky bluegrass, meadow fescue, rye, and Timothy grass produce the most allergenic pollens.


Ragweed is one of the heaviest pollinators. A single ragweed plant can release one billion grains of pollen in a single season, and the light, powdery pollens can be carried for hundreds of miles on the wind. Ragweed pollen often gets started around August and continues through October, give or take a month depending on the weather. Other common weeds include Kochia, marsh elder, plantain, Russian thistle, sage, and scales. Weeds generally pollinate during the summer months, starting in May and dropping off in September.

As a general rule, if you suffer from pollen allergies for a couple of months of the year, you may be able to get by with temporary relief from medications like antihistamines. If your allergies make you miserable for more than three or four months of the year, though, you may want to consider allergy immunotherapy (either through allergy shots or sublingual immunotherapy). Allergy immunotherapy provides a natural allergy treatment free of the side effects common to allergy drugs.

About The Author

Stuart H. Agren, M.D.

Stuart H. Agren, M.D. completed his undergraduate studies at the University of Utah and went on to earn his Doctor of Medicine from Tulane University School of Medicine in 1974. He completed additional training at L.D.S. Hospital in Salt Lake City, Utah and then established his private medical practice starting in 1975. Dr. Agren completed a mini-residency in Industrial Medicine at the Robert Johnson School of Medicine at Rutgers University and also completed training to become a certified Medical Review Officer.

Dr. Agren was the Medical Director at TRW and McDonnell Douglas in Mesa, Arizona and at Stauffer Chemical and Kennecott Copper in Salt Lake City, Utah. He also served as an adjunct faculty member at Arizona State University.

In his private medical practice, Dr. Agren specialized in family practice and allergy. In his work as a private practice allergist, he was one of the first doctors in the country to prescribe sublingual immunotherapy to his patients as an alternative to subcutaneous immunotherapy (allergy shots). He has also been a trailblazer in the field of food allergy treatment and research, developing a program to treat multiple food allergies simultaneously using sublingual immunotherapy. Dr. Agren has been featured on local CBS, NBC, and ABC news affiliates and won the peer-nominated “Top Doc” award from Phoenix Magazine.

After 20 years in private practice, Dr. Agren became the Founder and President of AllergyEasy, which helps primary care physicians around the country offer allergy testing and sublingual immunotherapy treatment to their patients. Over 200 physicians in over 32 states use the AllergyEasy program to help their patients overcome environmental and food allergies and asthma.