Last updated on October 23rd, 2023 at 08:44 pm
Algae in the lawn close soil pores and thus prevent grass roots from absorbing sufficient water, air and nutrients. They must be selectively removed during the next dry period, otherwise infested lawns will die.
Contents
Three types of algae as pests
It is mostly blue-green algae (Cyanobacteria), green algae (Chlorophyta) or diatoms (Bacillariophyceae) that spread on permanent garden areas. Lawn grasses do not harm them directly, but they take away their livelihood because they seal the soil and act as competitors.
- grasses can absorb less nutrients
- they suffer from lack of oxygen
- get less light
- they become weaker and weaker
- as a result they die out completely
When the grass dies, unsightly bare patches remain that do not regenerate on their own. To avoid this scenario and a costly lawn renovation, all visible traces of algae should be removed promptly.
Tip: After a dry period, the algae problem seems to have taken care of itself. But this is deceptive! Algae survive long dry periods and continue to grow as soon as they get more moisture. So under no circumstances should you refrain from combating them!
The ideal time for control
Even if the green-black, slippery and often fibrous mass is spotted after rainy periods. For its elimination, a dry period is ideal. A few sunny days will cause it to shrivel up and crust over, making it easier to remove from the lawn.
Instructions for algae removal
The algae has the ability to multiply from the smallest remnants under favorable conditions. That is why it is necessary to be very thorough in the fight against it. This is usually done manually and is time consuming.
Remove the entire crust of algae. For this you can use a rake or remove the
mass with a flat-bladed, sharp spade.
Then, poke the cleaned areas deeply several times with a digging fork to loosen the soil.
Mix coarse-grained sand and sifted compost to replace the removed soil.
Immediately scatter new lawn seed on bare spots.
Spread a thin layer of lawn soil over them.
Tip: Do not put the algae residue in the compost, because it can spread again from there. Instead, put them in a plastic bag, which you seal when the job is done and throw in the residual waste garbage can.
Chemical control
The hassle of removing algae by hand just calls for a chemical solution. In fact, some moss preparations help in this case as well. But since the algae is only dried out, this quick solution only lasts until the next wet period. In the long run, there is no way around the root cause, especially if the problem recurs regularly.
Causes of persistent algae infestation
Blue and green algae occur naturally in the soil. They only become a visible problem when they multiply explosively. If algae infestation occurs repeatedly, the cause cannot be found in large amounts of precipitation alone. It is possible that compacted
compacted soil may contribute to the fact that the water cannot seep away well. Inadequate lawn care, in turn, is responsible for weak turf that can hardly resist algae infestation.
Renovate compacted lawns
Large, badly damaged lawns on compacted soil should be comprehensively renovated in the spring or fall. This includes the following steps:
- Mowing down to the shortest level
- Scarifying until all weeds are removed
- Spreading of a seed mixture (without gaps with a spreader)
- Fertilizing with a special starter fertilizer
- Watering with sprinkler hose
Also, cover the sod with a two-inch layer of construction sand. Repeat the procedure several years in a row, so the soil will become much more permeable.
Preventive maintenance
To prevent a new or general algae infestation, you should take specific helpful care measures every year. But do not start too early in the year. Even if the days are warm, the ground will remain cold for a long time. Do not start lawn care until April/May.
- Regularly scarify the lawn and aerify if necessary
- preferably several times a year
- mow grass regularly (not deeper than 4 cm)
- Fertilize selectively and as needed
- if necessary, check nutrient content with soil sample
- strengthen turf with autumn fertilization
- Water without causing waterlogging
- Match lawn type to site conditions
Tip: Shady lawns stay wet longer and are therefore more affected by algae infestation. Sow robust shade turf here or use ground-covering plants. In the spirit of nature, a pure rock garden is not a good alternative.
Nostoc commune
Nostoc commune is one of the cyanobacteria. Outside of a garden pond, they can be found mainly on flagstones and paths. But even the lawn is not completely safe from them. In dry periods, the colony is only paper-thin, barely visible. After a heavy downpour, the bacteria form small green and slimy balls. The bacterium is not only harmless, but also helpful. It secretes ammonium, which can serve as a good fertilizer for the grass plants. The balls “disappear” as soon as it becomes dry. However, they come back with the next rain. Despite their harmlessness, many people find them disgusting. That is why they are also fought.
Eliminate nostoc commune
Often recommended to sprinkle lime. But it only ensures that the balls are deprived of water. The alga lives and comes back in the next wet period. Instead of drying them out, it is better to effectively combat them. Depending on what area of the garden was colonized, the procedure is somewhat different:
- remove from lawns with a rake
- on slabs use hard broom or high-pressure cleaner
- from open soil areas remove the top layer of soil by a few centimeters
- always dispose of as residual waste
It is hardly possible to remove all Nestoc balls completely from the garden. Therefore, it is also important to immediately cover cleared areas with grass or other plants. Otherwise, a new colony will soon emerge.