Fighting annual meadow grass

Annual meadow grass, the nightmare of every greenkeeper and field manager. Annual meadow grass (Poa annua) is one of the most common grass species, but also one of the weakest. It is an annual, sometimes biennial and occasionally perennial meadow grass (Poa) with seed production up to eight times per year. It is the only surviving mechanism of this species. The plant has few roots, has no wear tolerance, is sensitive to diseases and has poor winter and summer hardiness. By making smart choices in your grass seed selection for over seeding or new seeding, you can compete against this weak plant!

How to recognise annual meadow grass

Annual meadow grass is usually easy to identify. The youngest leaf will appear in a folded shape. There are no auricles at the base of the leaf, and the underside of the unribbed leaf is matte and often pale green in colour. This color difference is often clearly visible in a field. Furthermore, Poa annua has a long and milky-white ligule. In a field, annual meadow grass can easily be identified by its abundant seed formation. After all, it flowers year-round. The leaves are unribbed, which means that they are soft and wavy.


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Figure 1: The surviving mechanism of Poa annua

3 ways to fight annual meadow grass

1. Early germination of strong grasses

Annual meadow grass germinates at soil temperatures as low as 7 - 8 °C. When the fields have been played bare after winter, annual meadow grass will often be the first to appear as most grass mixtures germinate at higher temperatures. This means that the bare patches are filled in fast and the field is green, which is always better than nothing. However, this benefit does not outweigh the disadvantages. Annual meadow grass can be tackled by, for example, SOS® technology from Barenbrug. SOS® germinates at approx. 4 °C where normal Lolium perenne needs at least 7 - 8 °C. If the wear tolerant SOS® plants have a position on the bare patches, there is no space for annual meadow grass to establish itself.

Figure 2: Beat Poa annua on speed of germination

2. Faster recovery by strong and creeping grasses

The wear tolerance of annual meadow grass is moderate to low, partly due to its shallow roots. This means that the grass is easily kicked or hit away, which may result in many bare spots that will significantly reduce the quality of play on a sports field or golf course. If these bare spots aren’t re-covered by strong grasses, Poa annua will come back and will take over because of the always present seed bed.


The easiest way to compete against annual meadow grass within the growing season is to use a grass technology that is able to recover the pitch by itself. Normal Lolium perenne is a bunch-type plant with no stolons nor rhizomes and is not able to repair bare spots. Poa pratensis, smooth stock meadow grass, which is also often used for this purpose, does make rhizomes, but is very slow in recovery and by that habit can’t compete against Poa annua.


The fastest solution to recover bare spots by good plants is using so called creeping perennial Rye grass. Barenbrug created the RPR®-grass technology, Regenerating Perennial Rye grass, in 2012 and so far there is no cool season plant on the sport market that has such a fast recovering habit. With every seed of RPR® that you plant, you  can potentially create more than ten new plants in the future that help you to recover bare spots. Normal perennial Rye grass will only produce one plant by one seed and is not able to help you!

Figure 3: RPR® (l) regenerating perennial  versus normal Lolium perenne(r)

3. Beat the Poa annua in extreme cirumstances

Prolonged drought and heat, high disease pressure and long-term low nutritional levels, are all factors that can be fatal for your turf and cause many greenkeepers and fieldmanagers headaches. Recently introduced Barenbrug grass technology Resilient Blue® is the solution for these conditions. Unlike normal smooth-stalked meadow grasses, Resilient Blue® keeps a 'cool head' under these conditions and it tolerates a wide range of stress factors. By recovering at the right time, Resilient Blue® can fight back and achieve optimal grass coverage. This makes Resilient Blue® a unique solution in the battle against Poa annua.

Figure 3: Resilient Blue® versus normal Poa pratensis in stress situation

The solution is tailor-made

Poa annua has a lot of weaknesses. If you know them, you can use them to your advantage. Early in the season after winter, or late in autumn before winter, when temperatures are low, SOS® grass technology offers the fastest solution to beat annual meadow grass. If you need faster recovery from wear during the season, so bare spots are filled with strong wear tolerant grasses, the RPR® grass technology offers the best solution. With the changing climate, the unique Resilient Blue® grass technology is the most future-proof solution and will help you to prevent a weak pitch or fairway. All these solutions will help you to save money in the long term, because ultimately Poa annua is the most expensive grass to maintain.


SOS® - Super Over Seeding

SOS® is an excellent product, especially in the winter months as it germinates at a temperature as low as 4 °C. This is sooner than annual meadow grass, which germinates at around 8 °C. SOS® is therefore another serious challenger of annual meadow grass. 


RPR® – Regenerating Perennial Ryegrass

Most grass mixtures lose the battle against annual meadow grass. This is due to the very fast germination of annual meadow grass. It germinates and establishes itself faster than most grass mixtures. However, at Barenbrug we have mixtures that are even faster. 


Resilient Blue - Grass that fights back!

Resilient Blue® keeps a 'cool head' under extreme conditions and tolerates a wide range of stress factors. By recovering at the right time, Resilient Blue® can fight back and achieve optimal grass coverage. This makes Resilient Blue® a unique solution in the battle against Poa annua.