Which grasses cause the most allergies?

The usual suspects are Timothy, Kentucky bluegrass, ryegrass, fescue, orchard, Bermuda, Bahia, and Johnson grass. Timothy carries an especially heavy allergen load.

Why is grass pollen so hard to avoid?

Grains run about 16 to 77 microns and the wind carries them with ease. Even a neighbor’s lawn can set off symptoms.

If I react to one grass, am I allergic to all of them?

Not automatically, yet many grasses contain the shared pan-allergen profilin, so cross-reactions happen. Timothy packs roughly 4.8 times the group-5 allergen per grain compared with Kentucky bluegrass.

Can grass pollen cause food reactions?

Yes, mild ones. Grass-linked oral allergy syndrome can prompt mouth itching after raw melon, tomato, orange, or peach. The itch is brief and cooking the food normally prevents it.

How do I reduce grass-pollen symptoms?

Stay indoors when counts spike, skip mowing during peak weeks or wear a mask, keep windows closed, run AC, and shower after yard work.

Grass Pollen Allergy: Season, Triggers, and Relief

Late-spring and summer hay fever owes most of its misery to grass pollen. The real offenders are everyday turf and pasture grasses, not fancy ornamentals: Timothy, Kentucky bluegrass, orchard, ryegrass, fescue, sweet vernal, Bermuda, Bahia, and Johnson grass (per AAFA).

Each grain is small and light, about 16 to 77 microns across with most grassland types landing near 31 microns, so the breeze sweeps them up. A single neighbor’s lawn can launch your symptoms, which is why grass pollen is so hard to dodge.

Grass owns late spring and summer

On the national calendar grass (highlighted) bridges the spring tree season and the fall ragweed season.

Tree

Grass

Ragweed

Season windows are the deterministic seasonal-estimate model (see methodology); the tick marks each type’s peak month. Not measured counts.

When is grass pollen season?

Grasses release their pollen after trees finish. Across the North, Timothy, Kentucky bluegrass, ryegrass, fescue, and Johnson grass peak from April through June. In the South, warm-season Bermuda and Bahia stretch far longer, and in the Deep South and Southwest some grasses pollinate most of the year (per Allergy & Asthma Network and ACAAI).

That geographic split shapes planning. A northern sufferer faces a short, sharp window and can sync meds to it. In the South, where the season can run almost year-round, daily vigilance and following the local count matter more, and a longer treatment plan is often worth discussing with an allergist.

Not all grasses are equal

Species differ in how much allergen they pack. Timothy delivers roughly 4.8 times the key group-5 allergen per grain compared with Kentucky bluegrass (per Schmidt et al.). Reacting to one grass does not guarantee a reaction to every grass, yet many share the pan-allergen profilin, so cross-reactions between Timothy and orchard grass are common.

Because of that overlap, a standard skin or blood screen tests several grasses together. If your strongest response lands on northern pasture types, your hardest weeks will cluster in late spring; if Bermuda is the driver, expect a longer, milder season. Pinpointing the culprit lets an allergist fine-tune both timing and, if needed, immunotherapy.

Cutting grass-pollen exposure

Pollen counts jump on warm, windy days, so check the forecast and skip prolonged outdoor time when numbers climb. Let someone else mow during peak weeks, or mask up if you must handle it. Shut the windows, use AC, and rinse off after yard chores.

Grass-linked oral allergy syndrome can make raw melon, tomato, orange, or peach tickle or itch inside the mouth; the feeling fades quickly and cooking the food usually ends it (per AAAAI). When meds fall short, allergy immunotherapy aimed at your specific grasses is the only option that retrains the immune system over time.

Why "High" grass is a low number

It takes far fewer grass grains per cubic meter to reach High than tree pollen — grass is potent.

GrassModerate 5 grains/m³High 20 grains/m³Very High 200 grains/m³

TreeModerate 15 grains/m³High 90 grains/m³Very High 1,500 grains/m³

RagweedModerate 10 grains/m³High 50 grains/m³Very High 500 grains/m³

Thresholds in grains/m³ per the AAAAI National Allergy Bureau scale.

Grass pollen, by the numbers

16–77µm

grass pollen grain diameter

palynology

4.8×

more allergen in timothy vs. Kentucky bluegrass

NIH/PMC

31µm

typical grass grain size

palynology

Check your local grass pollen forecast

Pollen seasons vary sharply by region. These metros see some of the worst grass pollen pressure — check the current forecast for each, or look up any US city on the pollen count hub:

Oklahoma City, OK pollen count — Southern Plains warm-season grasses (Bermuda, Johnson) pollinate for months.
Dallas, TX pollen count — Bermuda and Johnson grass run a long warm-season stretch across North Texas.
Wichita, KS pollen count — Plains grassland on every edge of town keeps grass counts high all summer.
Memphis, TN pollen count — Mid-South heat and humidity extend the warm-season grass period.
Fresno, CA pollen count — San Joaquin Valley agriculture surrounds the city with heavy grass pollen.
San Antonio, TX pollen count — South Texas warmth gives Bermuda and Johnson grass a long pollination window.

Frequently asked

When is grass pollen season?: Northern grasses release pollen mainly from April through June, after tree season. In the South, warm-season types like Bermuda pollinate much longer, sometimes nearly year-round.
Which grasses cause the most allergies?: The usual suspects are Timothy, Kentucky bluegrass, ryegrass, fescue, orchard, Bermuda, Bahia, and Johnson grass. Timothy carries an especially heavy allergen load.
Why is grass pollen so hard to avoid?: Grains run about 16 to 77 microns and the wind carries them with ease. Even a neighbor’s lawn can set off symptoms.
If I react to one grass, am I allergic to all of them?: Not automatically, yet many grasses contain the shared pan-allergen profilin, so cross-reactions happen. Timothy packs roughly 4.8 times the group-5 allergen per grain compared with Kentucky bluegrass.
Can grass pollen cause food reactions?: Yes, mild ones. Grass-linked oral allergy syndrome can prompt mouth itching after raw melon, tomato, orange, or peach. The itch is brief and cooking the food normally prevents it.
How do I reduce grass-pollen symptoms?: Stay indoors when counts spike, skip mowing during peak weeks or wear a mask, keep windows closed, run AC, and shower after yard work.