Grass pollen is the most common cause of seasonal allergic rhinitis, also known as hay fever, both worldwide and in Slovenia. Of all the pollen types we track, it affects the largest share of allergy sufferers — many people who don't react to any other pollen at all have noticeable symptoms specifically during grass season.
Biology — why grasses are tracked as a single category
Grasses (the Poaceae family) are wind-pollinated plants: their pollen is carried by wind rather than insects, which is why it appears in the air in large quantities during flowering. Dozens of species contribute to the overall load — among the most common are timothy (Phleum pratense), ryegrass (Lolium perenne), cocksfoot (Dactylis glomerata), and meadow grass (Poa pratensis) — but pelud.net, like most European pollen services, tracks them under a single combined category, "Grasses". The reason is the high cross-reactivity within the family: the proteins in the pollen of different grass species are similar enough that the immune system of a sensitive person generally reacts to all of them alike, so breaking the count down by individual species wouldn't give an allergy sufferer any additional useful information.
The season in Slovenia — the longest of the tracked species
The grass season is the longest of all six pollen types tracked by pelud.net in Slovenia. It runs roughly from May to July, typically peaking in late May and June. After the main peak, concentrations gradually decline, but because of mowing and the later regrowth of young grass, a lower level of exposure often persists into August — freshly cut grass can release a short but noticeable burst of pollen, even after the main peak of the season has passed.
Mowing is therefore an important local factor. Regular mowing before flowering significantly reduces the amount of pollen a meadow or lawn can release in the first place — meadows that are mown early contribute less to the overall load than unmown roadside verges, abandoned plots, or neglected meadows where grasses are left to mature and flower undisturbed. As the grass season winds down toward the end of summer, it's often followed in eastern Slovenia by ragweed, which starts flowering in mid-August.
Where grasses are most widespread
Grasses grow almost anywhere there is even a small patch of unpaved ground, so they're widespread across all of Slovenia — in meadows, along roads, on uncultivated plots, and on home lawns. They flower most intensively on agricultural land in Prekmurje, Dolenjska, and Posavje, where meadows and pastures cover a large share of the landscape, as well as in the Ljubljana basin and Podravje (see also our overview of the pollen season by Slovenian region). Anyone living near an unmown meadow, a roadside verge, or agricultural land with tall grass is likely more exposed during the season than someone living in a dense urban center.
For Slovenian cities, pelud.net does not measure pollen directly but estimates it from the European CAMS model (Copernicus Atmosphere Monitoring Service), accessed via the Open-Meteo service — the same approach used for the other pollen types we track for Slovenian cities (more detail in our article on how the risk score is calculated). It's a useful, scientifically grounded estimate, but not a measured value from a local monitoring station.
Symptoms
Symptoms of grass pollen allergy are the classic signs of hay fever:
- sneezing and watery nasal discharge
- nasal congestion
- itchy, watery, and red eyes
- itching of the palate and throat
- worsening asthma in more sensitive individuals
- fatigue and reduced concentration due to disturbed sleep
Because the season is long, symptoms from grass pollen can be more wearing than those from shorter seasons — some allergy sufferers are exposed almost continuously for three months.
Cross-reactivity
Grass pollen cross-reacts across nearly all grass species, which is exactly why it's tracked as a single category — someone allergic to one type of grass is generally sensitive to others as well.
A minority of patients also experience cross-reactivity with food, although oral allergy syndrome is less pronounced with grasses than with some tree pollens (birch, for example). Possible triggers include melon, tomato, peanut, and orange. Reactions are usually mild — itching or slight swelling of the mouth — but it's worth paying attention if unusual symptoms appear after eating these foods during grass season.
Treatment
- Second-generation antihistamines are the first choice for relieving sneezing, itching, and nasal discharge.
- Nasal corticosteroid sprays work best when started before the season begins, not only once symptoms appear.
- Eye drops help with allergic conjunctivitis.
- Specific immunotherapy (SLIT or SCIT) for grass pollen is one of the best-studied and most effective treatments for pollen allergies — in many patients it reduces symptoms and medication needs over the long term. Treatment lasts several years and is started by an allergist.
Practical tips
- Follow daily pollen levels on pelud.net and, where possible, plan outdoor activities outside the peak concentration hours.
- Grass pollen often reaches its highest levels in the morning and around midday — where possible, push running, gardening, or longer walks to late afternoon or evening.
- If you mow your own lawn, wear a mask and protective glasses if possible, since mowing throws a lot of pollen and grass particles into the air; shower and change clothes afterward.
- During the season, keep windows closed in the morning and ventilate in the evening instead, when concentrations are lower.
- After time outdoors, rinse your face and hair and wash clothing that was exposed to tall grass.
Note
This is not medical advice. For an individual assessment of symptoms, treatment, or immunotherapy, consult your family physician or an allergist.