Annual meadow grass is a nightmare for lawn owners. The tufts of grass, which are up to 30 centimeters high, not only stand out because of their light colour, they are also not sturdy and dry out quickly. Unfortunately, Poa annua is difficult to control because the species easily reproduces by wind and self-pollination. Luckily, there are effective ways to control weeds.
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Caution: risk of confusion
Before you use any prevention or control methods, you should definitely know whether it is really annual meadow grass or one of the following types of millet:
- Kulturhirse (bot. Panicum miliaceum subsp. miliaceum)
- Unhealthy weed (bot. Panicum miliaceum subsp. Agricolum)
- Unkrauthirse (bot. Panicum miliaceum subsp. ruderale)
The reason for the assumption is often the light color of the grasses, the similar shape of the inflorescences and the growth habit, which begins in short clumps. As the growth progresses, however, the shape changes significantly, as millet develops long and thin stems up to 100 centimeters high, while annual meadow grasses stop at around 30 centimeters. In addition, the flowering time of the grasses must be compared here, since Poa annua can be seen much earlier in the year:
- Annual meadow grass: February to September
- Millets: mid-July to September
Millet only sprout from a permanent temperature of 20°C, i.e. normally only from the middle or end of May, when the ice saints are over. However, the annual can already be seen at the end of winter or the onset of spring and can even break through thin layers of snow. Thus, the annual is even the earliest and at the same time the most common of the genus Poa, since it can easily spread over several months. If the first flowers of the tufts do not appear until mid-summer, it is millet, which you have to fight in a different way. The following characteristics describe the annual meadow grasses in detail:
- leaf-blade: folded, soft, unscored, wavy
- missing leaf auricles
- Underside of leaf blades dull
- Colour: light green
- ligule: long, white
- inflorescence: panicles
- numerous flowers are formed
- Flower color: green, rarely a light violet
Prevent
The best way to avoid suffering from a persistent bluegrass infestation is prevention. If you prevent the weeds, they can’t spread in your lawn and you don’t have to do any tedious work to get rid of them. This will also help prevent the following diseases that are commonly associated with Poa annua when it is trampled on and dies:
- Anthraknose
- Fusariose
- brown spots up to 50 centimeters in diameter
- snow mold
- Typhula-Fäule
- dollar spot disease
When preventing, it is important to deprive the annual meadow grasses of their basis for spreading. That means you have to bet on one of the following methods:
- Perennial Ryegrass (bot. Lolium perenne): Perennial ryegrass is a species of grass that is considered an effective competitor to Poa annua. It sprout so strongly and even faster than annual bluegrass that it cannot take root. For this reason, lawn seed from perennial ryegrass is often used for sports fields or golf courses, as these areas are particularly badly affected by meadow grasses. In English it is abbreviated to RPR for “regenerating Perennial Ryegrass”.
- Fertilize effectively: Adjust the amount of fertilizer to make life difficult for the annual meadow grasses. If the lawn is used heavily, give a little more fertilizer throughout the year to keep the area nice and dense.
- Overseed: In many cases it is sufficient if you overseed more throughout the year. This is especially important on bald patches, which can come up from time to time. As already described, a dense lawn protects against the spread of annoying grasses and so it is advisable to scatter a little seed again, especially in autumn.
The better you take care of your lawn, the more effectively you prevent Poa annua.
Combating annual bluegrass: 3 methods
When prevention isn’t enough or you’re dealing with a sudden infestation, you should take immediate action. It’s important that you don’t take too long when you notice annual bluegrass in your lawn, as it spreads faster than other types of grass over a short period of time. In this case, you should use one of the three methods below to get the weeds under control.
cut the lawn
Mow the lawn as soon as you spot Poa annua in the lawn. The earlier you do this, the less chance the grasses have of forming seeds and thus spreading. You will achieve the greatest effect if you leave the lawn at a height of four to eight centimeters and reach for the lawnmower at regular intervals. It is important that the blades of the lawn mower are always sharp, as annual meadow grass is quite robust.
scarify
Scarifying helps to render most of the seeds contained in the soil unable to germinate. Since you reach deep into the soil layers of the lawn when scarifying, the seeds are transported to the lower layers. The seeds of the Poa annua cannot sprout there because they germinate in the light. So grab your scarifier or lawn aerator shoes and dig deep into the lawn. Then sow new seeds and after a few weeks the lawn will be back. Then scarify at regular intervals to prevent annual meadow grass.
cut out
Cutting out the individual Poa annua specimens is even more complex in terms of time. With this method, you use a weed puller, with which you remove the individual tufts from the soil one by one, thus ridding the lawn of unwanted grass. Weeders are available either as simple hand shovels for around ten euros or versions with a telescopic rod or long handles, which are particularly recommended for people with back or knee pain. Such devices are offered for around 50 euros. In addition to the weed puller, you will also need the following materials:
- Earth
- seed
Then proceed as follows:
- Choose a dry day for this method. The drier the soil, the easier it is to dig out the soil that is otherwise too heavy. The time of day doesn’t matter, it just depends on the weather in general.
- Next, begin by locating individual tufts in the lawn and poking them out one at a time. To do this, insert the weed puller into the ground right next to the tuft and lift the entire plant, including the roots, out of the ground. Continue doing this until all specimens have been removed from the lawn.
- You then dispose of the plants in the household waste, otherwise you will have to struggle with the seeds again.
- Fill in the holes with fresh soil and spread seeds on the now bare spots. Wait a few weeks until a dense lawn has formed. You should take care of them as well as possible.
