Pollenservice Wien

Currently the tree of heaven is flowering in Vienna. It is an invasive neophyte introduced to Europe as an ornamental plant in the 18th century and now also part of the flora in Austria. These trees are well adapted in urban climates as they are relatively resistant to salt, drought, and herbicides, and can tolerate air pollution in cities better than other plants. Despite being insect-pollinated, the tree of heaven releases large amounts of pollen, which can be detected in significant quantities in pollen traps as well. Recent scientific publications from Germany have highlighted sensitization to Tree of Heaven pollen and identified the plant as an additional allergen source in the context of climate change.

Photo: Flowering ryegrass

Mid- and long-term forecast for Vienna
This forecast gives you an overview for a longer time period so that you can improve your planning.

Thunderstorms and precipitation over Pentecost can restrict the pollen release - high levels from grasses still possible!

The grass pollen season continues its peak flowering period. In the urban area itself, orchard grass, false-oat grass, brome grasses, couch grasses and reed grasses are in flower. In addition, two highly allergenic grass species, the fescue grasses and ryegrass, are in flower as well. Around Vienna, cereals (cultivated rye and wheat) are flowering which can exacerbate the symptoms of grass pollen allergies. 

In the meadows, dock and plantain are also flowering. Both can trigger cross-reactions in individuals allergic to grass pollen.

The tree of heaven has started to flower in Vienna and is also causing pollination. Increasing pollen concentrations are already being measured, particularly in urban areas where the trees are more common. 

Nettle plants such as the stinging nettle and pellitory also flower and are releasing their pollen. 

Fungal spores also benefit from the higher temperatures and precipitation. The concentrations of Cladosporium and Alternaria can rise quite quickly to high levels in the Vienna area due to the current weather situation. 

Under suitable weather conditions, the grasses continue to reach high levels. Over the weekend, the pollen release is limited at times due to the increased likelihood of thunderstorms and precipitation. On sunny and dry days, the pollen concentrations of the grasses will reach high levels again. The tree of heaven also causes pollination. Fungal spores are also gaining in importance and high concentrations are already possible, especially after precipitation. Nettle plants can also cause pollination.

Pollination profile

Grasses:
State of the flower: main flowering period/high pollination
trend: constant
time of the start of the flower: earlier than average

Fungal spores:
State of the season: main season/high concentrations
trend: constant
time of the start of the season: average 

Tree of heaven:
State of the season: start of the flower/pollination
trend: constant
time of the start of the season: average 

Nettle plants:
State of the flower: start of flower/pollination
trend: constant
time of the start of the flower: average

You can find the typical pollen seasons in our pollen calendar.

Tip of the season: It is advisable to wear sunglasses and headgear when going for a walk outside. These mechanical barriers ensure that your eyes and hair come into less contact with pollen, thus minimizing direct physical contact with the allergen.

Pollen spectrum:
Pollen from elderberry, privet, linden and wine is also detected at our monitoring station.

Current main allergen: Grasses

Grass pollen allergy is the most prevalent pollen allergy in Vienna!
Pollination time in Vienna: April to September; decorative grasses extend the pollination time into autumn!

Occurrence in Vienna: The sweet grass family (Poaceae) is prevalent and found nearly everywhere. Natural monuments, parks, the banks of the Danube and obviously all areas (meadows/lawns), that are mowed infrequently, are hot spots.

Who are “the grasses“?
There are many genera and species of relevance for persons concerned, especially because reactions to different taxa of the family are individual. Those grasses, that are of highest relevance for a grass pollen allergy, are mentioned in the following.
Bluegrass (Poa pratensis): flowers from April to June. It is sowed frequently for lawns and pastures.
Orchard grass (Dactylis glomerata): flowers from May to June. It occurs frequently (especially on meadows, roadsides, ruderal areas).
Falseoat-grass (Arrhenatherum elatius): flowers from May to July. Falseoat-grass prefers pastures and clearings.
Fescue grass (Festuca sp.): flowers from May to July. This genus is species-rich and prefers marshes like fine lawns, but also alluvial forests and roadsides.
Perennial rye grass (Lolium perenne): flowers from June to July. Perennial rye grass grows frequently on meadows and pastures and is used as pasture grass.
Timothy grass (Phleum pratense): flowers from June to September. Timothy grass is an allergologically famous gras but plays a minor role in Vienna due to its infrequent distribution. It prefers natural areas.
Bermuda grass (Cynodon dactylon): flowers from July to August. Bermuda grass is a neophyte in Europa and a light and heat indicator.
Cereals (cultivated rye, wheat and maize): Cereals belong as well to the sweet grass family. Grain fields in vicinity of Vienna may cause locally increased pollination, although cereal pollen is in general larger and thus not transported as far. Cultivated rye flowers usually from May to June, wheat from June to July and maize from July to August.

Cross-reactivity to pollen of other plants: Grass pollen is highly cross-reactive among pollen of other grasses

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The first birch trees reached its readiness to flower in Vienna in the week of March 24, 2025 and went into bloom shortly afterwards (Video ©Katharina Bastl (MedUni Vienna/Pollenservice Vienna)). Accordingly, pollen release takes place under favorable conditions.

Here you can see birch catkins that are already dusting in a macro video. Pollen is released into the air as yellowish dust when touched.