Especially after hot periods crabgrass often spreads in the lawn and causes problems there. Newly established and still patchy lawns provide ideal breeding grounds for the various species of crabgrass. As a result, its mass appearance can not only hinder the growth of the young grasses in the lawn but almost completely displace them. How to properly combat finger crabgrass, we have summarized for you in this article.
Table of Content
Crabgrass, a small spelled cereal, is one of the oldest cereals we know. It belongs to the sweet grass family and probably originated in Asia. Many species of the annual, herbaceous plant are used as food for their grains. The feral crabgrass species commonly referred to as weeds are viewed in a somewhat more nuanced way from a botanical perspective. However, whether species of Digitaria, Setaria or even finger crabgrass (Eleusine) are spreading in the lawn should interest few garden owners.
As an annual plant, crabgrass reproduces by seed. A single plant can produce several thousand seeds. The unpleasant part is that, unlike most other grasses, almost every species of crabgrass can also form its flower spikes flat above the ground – and thus below the cutting height of the lawnmower. As the days get shorter and temperatures drop in the fall, the crabgrass dies. Unfortunately, this does not solve the problem in the lawn by itself, because the numerous seeds remain germinable in the soil for decades after the mother plant dies. For the seeds to germinate, at least two conditions must be met.
- warm, dry weather with temperatures above 20 degrees Celsius
- the sunnier the location, the better
- open areas in the lawn
If you discover scattered crabgrass in the lawn from the end of May, you should pull it out by hand as early as possible, or even prick it out. Finger crabgrass does not root particularly deep, so it is not difficult to remove it from the soil. Since the sweetgrass is in a hurry to reproduce, the first seeds appear after only a few weeks. Their formation must be prevented at all costs. If you manage to stop the dispersal of seeds, in many cases you have already succeeded and the next year you will have peace from the annoying herb.
Other environmentally-friendly measures
To control crabgrass in the lawn, the following measures have proven effective.
An effective way to control sweetgrass is to dethatch the lawn flat. This involves adjusting the machine so that the blades do not touch the ground. Instead, the stalks of the sweetgrass plants, which lie flat, are lifted and can then be captured by the lawnmower, which should be set very flat. This action is far less strenuous than weeding each plant by hand. It is best to scarify the lawn already in the fall. This allows a denser lawn cover to form the following spring.
- Start mowing already in March (from 10 degrees).
- If temperatures rise above 20 degrees for a longer period of time: scarify
- Depending on the weather, for the first time from the end of May
- Scarify the area twice
- Once lengthwise
- Once crosswise
- Then mow flat
Form dense turf
Finger crabgrass spreads mainly in patchy, thin lawns. Therefore, it is effective for its control if the lawn is always kept nice and dense by reseeding. If the turf has closed sufficiently by the following year, the unwanted sweetgrass can hardly develop.
Fertilizing and mowing
If the lawn is fertilized, the otherwise rather flat growing crabgrass straightens up. This makes it easier to grasp with a low-set lawnmower. In addition, fertilizing also strengthens the lawn grasses so that they grow more vigorously and densely.
- Time: May to August
- Best directly after scarifying
- In spring fertilize with Lawn Soil Activator
- Use potassium-rich fertilizer in the fall
- Cut short frequently
- Water during drought
- Avoid waterlogging
Since the various species of crabgrass prefer to thrive in soil that has an acidic pH, liming the lawn may be useful in controlling the invasive plant. To check what the pH of the garden soil is, simple tests are commercially available. If the result is below the ideal pH of 6 to 7, it is recommended to treat with algal lime, which can be easily used throughout the growing season.
Control weed crabgrass biologically
It is recommended to use corn starch meal, which acts similarly to a herbicide. The proteins in the corn starch prevent the formation of roots in the seedlings, thus causing the young crabgrass plant to die. Whether this measure actually has the desired effect must be tested. In this country, there is a lack of empirical values in this regard.
- The clear lawn of leaves in advance
- Apply corn starch with fertilizer wagons
- Sprinkle on rainy days or alternatively water well
Even weeds like the crabgrass plant only thrive under good conditions. To grow, it needs light, space, and above all, warmth. A densely grown sward makes it difficult for crabgrass to establish itself. Therefore, fill in bare spots with new grass seed and provide the lawn with sufficient water and nutrients.
Laying new lawn
Those who establish a new lawn should do it in the fall, to create from the very beginning unfavorable conditions for the spread of various species of crabgrass. At this time of year, it is too cool, so it can not germinate. Then, early in the spring, check whether there are patches where the lawn is poorly grown. In this case, reseed as soon as possible. It is best to fertilize immediately with a slow-release fertilizer. This also strengthens the weeds, but even more important is a dense turf.
Especially when new lawns are established, finger crabgrass may spread to such an extent under unfavorable conditions that it overgrows almost the entire area. In this case, the following measures are recommended:
If the crabgrass has spread over the entire lawn, the only solution is to remove the entire turf. In the fall, the lawn is then reseeded.
If all measures do not help, because there are already countless seeds in the soil, a rolled lawn is the last option to cope with crabgrass. A rolled lawn can also be laid in the summer. In this case, a beautiful, dense lawn is guaranteed right from the start.