It is undisputed that mowing is an essential part of lawn care. What is less known, however, is that liming the green area is just as important: without lime, the grasses may not be able to benefit from the nutrients present in the soil or added through fertilization.
Why and when should you lime the lawn?
Limeing the lawn is important to compensate for acidic soil and improve nutrient availability for the grasses. It is best to lime the lawn in spring or autumn, with the pH of the soil determining whether lime should be applied. An overdose of lime can damage the lawn.
Only if you know why and when your lawn needs lime and how the product helps, the green area can remain he althy and free of unwanted growth such as moss, wood sorrel and other weeds. In the following article we provide you with well-founded answers to the most important questions regarding the optimal supply of lime to the lawn.
What is the best way to apply lime?
Lawn lime is available in stores either in powder form or as pellets (€9.00 on Amazon). Lime powder is a white, very fine powder that is simply sprinkled over the lawn. When purchasing, choose a variety that is as finely ground as possible, as it reacts more quickly with the soil due to the larger surface area. Wear a face mask during application to avoid inhaling the fine dust. Under no circumstances should lime powder be spread in windy and/or heavy rain. Furthermore, it is not advisable to lime in hot weather or when the sun is intense, as this can cause burns to the turf. Lime pellets, on the other hand, cause significantly less dirt and are simply distributed evenly over the lawn. After liming - especially if the drought continues - you should water the lawn vigorously so that the calcium carbonate can penetrate the soil and do its work.
How much lime should I apply?
How many grams of lime per square meter (g/m2) of lime you need to apply depends on the results of the previously carried out soil tests. These are based on the soil type and the current pH value and thus provide you with the amount you actually need. Follow these recommendations carefully as allowable amounts can vary significantly depending on soil type. Clay soil requires much more lime than sandy soil to achieve the same results.
How much lime should be applied depends on the pH of the soil
When is the best time to apply the lime?
Spring, summer, autumn or winter – which month is best for liming the lawn? In principle, you can apply lime to the green area in spring or autumn, but the late summer/autumn months of August and September are considered the best time for this project - after all, the product has plenty of time for the rather slow chemical reaction until the following spring which results in the neutralization of the soil. However, avoid liming in high heat and sub-zero temperatures, as this will significantly reduce the effect.
Which product is best for liming the lawn?
There are different types of lime that are more or less suitable for lawn care. The best solution is simple calcium carbonate, which is very mild and gentle and can be applied to almost any soil. With this product, overliming is virtually impossible because it is only effective in acidic soils. If, on the other hand, the substrate is neutral, it no longer dissolves as well and is instead gradually broken down by soil organisms. You can recognize lawn lime made from calcium carbonate by the chemical formula CaCO3 printed on the package. High-quality dolomite lime is also very suitable.
Less suitable, however, is quicklime, which is not without reason also called quicklime. It is normally used as a mortar admixture and is not suitable for lawn care due to its corrosive effects on plants. You can recognize its use in lawn lime mixtures by the chemical symbol CaO - if this is printed on the package, it's best to stay away from it. Special lime mixtures such as magnesium lime or so-called slag lime are only useful in special cases - for example because your lawn is already deficient in magnesium - and are otherwise a waste of money. Even algae lime, which is sold at a high price, offers no further advantages over simple calcium carbonate, even if many manufacturers advertise it flowerily.
Why should you lime the lawn?
Moss in the lawn indicates acidic soil that can be treated with lime
Lawns need lime when low soil pH affects nutrient availability. The preferences of the different types of grass with regard to the pH value vary, but are in a neutral to slightly acidic range between 5.8 and 7.2. In the warm season, lawn grasses tolerate a slightly lower pH value, while in the cool season they tolerate a slightly lower pH value Season should be a little higher. If the pH value deviates too much, the absorption of even abundant nutrients is restricted. Lime restores balance in overly acidic soils to bring the pH back to an optimal growth level for the lawn.
When do you have to sand the lawn?
Even if the pH value of the soil is in a he althy range, other measures to improve the soil may be necessary in addition to liming. This includes sanding the soil, where heavy, clayey subsoils are made looser and more permeable by adding sand. Please note that sand also contains lime - depending on the type and variety used - and sanding also changes the pH value.
Excursus
Indicator plants
You can quickly tell whether the substrate is becoming too acidic for your lawn: In this case, the grasses are displaced by plants that prefer to grow in acidic soil. For example, the presence of moss or wood sorrel signals that the pH value of the soil has long since become too low for he althy grass growth. Other warning signs include increased growth of weeds, diseases (which manifest themselves in the yellowing of the blades of grass) and the increased occurrence of pests. Grass mites in particular, which prefer to live in mossy lawns, are a sure and unpleasant sign of this for both humans and animals. That's why liming also helps
- against (sour) clover
- against moss
- against weeds
- against grass mites
- and against fungi
Be sure to apply the lime first and then any herbicides and insecticides, as a low pH value also reduces the effectiveness of these products. Another indication of acidic soil is the fact that even the grasses do not react to high-quality lawn fertilizer with the usual or expected he althy and vigorous growth.
Clover is an indicator plant for acidic soil
Should you lime or fertilize first?
Balanced fertilization is just as much a part of good lawn care as liming. In general, experts recommend not applying fertilizer and lime at the same time - only in some cases this may be advisable. Otherwise, which action you should take first depends on various factors.
Basically, the pH value of the soil determines whether lime or fertilizer is applied first. An example: If this is too low, the lime must first be applied and take effect, otherwise the grass cannot absorb nutrients. Therefore, it is also important to clarify this question what pH value the substrate actually has.
When do you have to lime first?
If the soil has a high acid content, it must be limed first and only fertilized after a certain waiting period. Since the deacidification process is slow, there must be a waiting period of several weeks between liming and fertilization. However, you can shorten this by using particularly finely ground lime - this reacts more quickly with the soil so that fertilization can take place more quickly.
When should you fertilize first?
The recommendation is the other way around if you want to sow new lawn or reseed: In this case, fertilize first and then lime. The reason lies in the germination ability of the seeds, because they can only germinate and grow into a magnificent lawn if there are enough nutrients in the soil. Before sowing, prepare the area, fertilize according to the recommendations, sow - and then wait about seven to ten days before liming. The waiting time is necessary so that the soil can absorb the nutrients from the fertilizer. The lime, in turn, increases its effectiveness and ensures that the roots of the seedlings can absorb it and benefit from the additional boost.
In which cases can lime and fertilizer be applied at the same time?
However, applying lime and fertilizer at the same time is possible if the pH value of the soil is already neutral and it is therefore only a maintenance lime. In this case, the task of the lime is to continuously maintain the pH value, while the fertilizer supplies the grasses with immediately available nutrients. However, you should not apply both together, otherwise an uneven distribution may result. First spread the fertilizer on the lawn and only then the lime.
Background
What is lime?
Lime is a natural soil conditioner made from ground limestone. The mineral contains the compounds calcium carbonate and magnesium carbonate, which are intended to increase the pH of the soil so that it becomes less acidic and more alkaline. Although lime naturally contains important nutrients such as calcium and magnesium, it is not a suitable fertilizer replacement. The main task of lime is to change the pH of the soil and balance its constantly fluctuating acidity. In this way you improve the availability of plant nutrients.
Why is soil testing important?
However, you should not rely on a visual diagnosis alone. A soil test at a government or private institute provides a more accurate measurement of your soil's current pH as well as other factors such as soil type. This knowledge is necessary because this also affects the amount of lime required and possible other treatments of the soil. Applying unnecessary or excessive amounts of lime can harm the lawn rather than help it. If your soil is too acidic, test again every year until balance is restored. Established lawns, on the other hand, only need to be checked every three to four years.
Neudorff Tipps: Rasen kalken – oder nicht?
Why does soil pH keep changing?
Soil pH changes for many reasons, including lime or other products applied. For example, in areas with heavy rainfall, calcium is naturally leached from the soil as rainwater flows through the soil. The loss of calcium causes the pH value to drop, so that the substrate becomes acidic over time. In these regions, applying lime is a necessity for he althy lawns. In areas with very little rainfall, however, no calcium is released, so lawns can even become too alkaline. Furthermore, lawn care also lowers the pH value of the soil. Regular fertilization, proper irrigation, and increased activity of beneficial soil microorganisms all contribute to the gradual, normal declines in pH.
How does fertilizing affect the pH value of the soil?
An acidic soil contains a lot of hydrogen and becomes more alkaline the more you feed it with a nitrogen-based fertilizer. For this reason, you should definitely avoid over-fertilizing the lawn, as this will definitely lead to acidification of the subsoil. A lot doesn't help much - instead, plant nutrition that is tailored precisely to your specific needs is so important. Through a thorough soil analysis you will find out which nutrients the lawn actually needs and in what quantities.
Why does mowing the lawn also have an influence on the pH value?
In addition, regular lawn mowing also leads to acidification of the soil. The reason for this is simply that by mowing you are interrupting the natural cycle - and this of course has an impact on the wider environment. The grasses are alkaline and always have a higher pH value than the substrate on which they grow. In nature, plants eventually die and decompose in the soil, thus restoring balance. However, if you mow the grass, this process is interrupted and the ground cannot be leveled.
What are the consequences for the lawn if there is an overdose of lime?
Not only a deficiency, but also an overdose can have serious consequences for lawn he alth: An excess of calcium carbonate usually results in iron chlorosis, in which the grass ultimately suffers from an iron deficiency. Because of this, the stalks eventually turn yellow or even die. Furthermore, overliming results in chemical burns (especially if quicklime was used!) and, due to the weakening, an increased occurrence of diseases (which manifest themselves in increased growth of fungi) or pests (e.g. ants).
Tip
Mature garden compost also raises the pH value of the soil, which is why many experienced gardeners swear by self-produced compost instead of lime to neutralize it. Dog urine, on the other hand - as sometimes recommended in forums - is not a suitable remedy at all. Instead, urine damages the turf due to the pungent substances it contains.
