Berlin (dpa / tmn) – In the garden, aspiration and reality sometimes diverge – especially when it comes to lawn care. Unfortunately, it is not enough to just leave it to itself, to the rain and the sun. In spring, the lawn needs a makeover and a four-course meal.
March to April: Fertilize
Fertilizing the lawn is now the first task. The important nutrients for grasses include nitrogen (N), phosphorus (P) and potassium (K). Nitrogen ensures growth and a nice green colour, the energy carrier phosphorus (P) for root growth and as an energy carrier. Potassium makes the lawn resilient and strengthens it against drought, cold and diseases. Magnesium (M) completes the four-course spring menu. It helps in the formation of chlorophyll, which is needed for photosynthesis.
These terms or letters can be found in various combinations in commercial lawn mixtures. For example, in long-term mixtures, these nutrients are put together in such a way that the lawn gets everything it needs throughout spring and summer. The German Lawn Society recommends the first fertilization around mid-April.
A map for the optimal fertilizer day
However, the weather is not the same every year. Sometimes the winter weather lasts longer, sometimes spring temperatures come earlier. A good time for fertilization is therefore the beginning of the growing season in a region. And that can be determined much more precisely.
For example, with the grassland temperature sum (GTS), which farmers use to determine the beginning their field work is used. The positive daily mean temperatures from January 1st are added together. The values in January are multiplied by a factor of 0.5, those in February by 0.75. From March, the full daily values are used.
If you reach a total of 200 degrees, the soil is considered warm enough to grow. And so fertilization makes sense, since the grasses can absorb the nitrogen in the fertilizer without losses. But even from a value of 170 can be fertilized.
Keeping statistics on a daily basis is too time-consuming for you? The federal states and chambers of agriculture in Germany have joined forces in the Information System Integrated Plant Production Association (ISIP). ISIP maintains a map with the values. Green dots in one place stand for a value of 200 or more. If you click on them, you can read the specific values.
Up to three fertilizer applications per year
A second fertilization of pure ornamental lawns takes place in July. If the lawn is subject to more stress, for example from children playing, recommends the Rasengesellschaft three rounds of fertilizing – in April, June and August. For grasses in the shade of trees, there should also be at least three fertilizations.
April to May: Scarifying
The lawn can be scarified a good two to three weeks after fertilizing and shortly after the second cut – this is the second part of the lawn treatment in spring.
At first, scarifying looks like destroying the area, which is slowly becoming green again, because dead or superfluous material such as moss is removed from between the grasses. What remains is a thinned out lawn.
But the measure is important, otherwise the surface will become matted. This would have consequences for water and fertilizer absorption and air exchange. It can also happen that the roots then grow flatter and the grasses are more susceptible to diseases.
Borrow a scarifier from a hardware store
For this you use a scarifier – a type of mower with vertically rotating blades or wires. If you don’t have one, you can borrow one from a hardware store. Some lawnmowers also have a special setting for this. And if you only have a small lawn area, you can simply do the work with a hand scarifier, a kind of rake or rake.
the Saxon Garden Academy recommends shortening the lawn to a cutting height of about two centimeters before scarifying. Then it is best to scarify the surface once lengthways and once across. If the lawn is very battered afterwards and has large bare spots, overseeding is worthwhile.
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