Lawn lime is considered a proven and inexpensive means of keeping the lawn he althy and green and keeping moss away. In this article you will find out why this assumption is not always correct and when it actually makes sense to lime the lawn.
What is lawn lime good for and when should you use it?
Lawn lime is used to neutralize acidic soil by increasing the pH. For a he althy lawn, the ideal pH value is between 6.2 and 7. Before use, the actual need should be determined using a rapid pH test and lime should only be used if necessary.
- Lawn lime should only be used to neutralize acidic soil.
- A rapid pH test is essential to determine an actual need. The optimal pH value for lawns is between 6, 2 and 7, depending on the type of soil.
- Use carbonated lime if possible, as it is less problematic than quicklime or quicklime.
- It is best to lime in autumn, but at the latest in early spring.
What is lawn lime?
Lawn lime is available in powder or granular form
Lawn lime is by no means a special lime for the lawn - instead you use conventional calcium carbonate (the chemical formula is CaCO3). This is also known as carbonated lime. Lawn lime is basically just the trade name for it, especially since there are usually no differences to garden lime, for example. However, this only applies if it is a product without any additives - i.e. made from pure calcium carbonate.
Lawn lime is sold in powder or granular form and is white in color. It is a natural material that occurs in various sedimentary rocks (such as limestone or marble) as well as in organic materials such as mussel shells, snail shells, eggshells, etc. Strictly speaking, limestone is just fossilization of organic, calcareous material - mussel shells or snail shells.
Tip
Calcium carbonate should not be confused with the strongly alkaline quicklime (also known as quicklime or calcium oxide). Although this is also suitable for neutralizing the garden soil, it is dangerous and, above all, it leaves unsightly burns on the lawn.
What does lawn lime do?
If moss and other typical indicator plants such as sorrel, meadow sorrel, field sorrel and daisies develop splendidly on the lawn, then the pH value of the soil is probably too acidic. With a commercially available pH rapid test (€320.00 at Amazon) or - if the soil composition needs to be analyzed more intensively - a soil test, you can check whether your lawn actually needs lime. This is the case if the measured pH value is below 5.5.
Advantages and disadvantages of lawn lime
Lime is immensely important for the fertility of the soil because it revitalizes the microbial soil life, improves the crumb structure and ensures better root development in plants. The mineral is also important for he althy and firm plant cell walls. But be careful: Don't be too wasteful with lawn lime, because overliming inhibits the absorption of nutrients, especially iron and various trace elements.
PH measurement takes place before liming
That's why prior pH measurement is so important so that you don't just start liming on suspicion. The presence of the indicator plants mentioned above, such as moss or daisies, does not necessarily mean that the soil is acidic. In the case of moss, too much moisture or heavily compacted soil promotes growth - in these cases, liming does not help and you have to take other care measures instead.
Excursus
Lawn lime against moss? How to get the moss out of your lawn
Moss often grows in acidic soil and can therefore be controlled by liming. However, this doesn't always help, because lawns that are heavily compacted, moist and/or not fertilized enough with nitrogen are also susceptible to moss growth. Therefore, you should scarify the lawn, remove thatch and mow regularly - but never too short! In addition, balanced fertilization with nitrogen-containing fertilizer makes sense. Liming, however, should only be carried out after a pH test that confirms the necessity of the measure.
Types of lawn lime
Some gardeners only know quicklime and garden lime - but the range of lawn lime is much larger. We have clearly summarized the most important types for you in this table.
| Kalkart | Description | Special features |
|---|---|---|
| Algae limestone | Rock powder with 80% lime content, carbonated lime from fossilized coral and algae deposits | also contains important trace elements and magnesium |
| Caustic Lime | slaked lime | delete before use, see quicklime |
| Brightlime | slaked lime, works very quickly | is only suitable for heavy soils, unfavorable influence on soil life |
| Dolomite limestone | Carbonated lime with high magnesium content | well suited for light soils, use with simultaneous magnesium deficiency |
| Fertilizer lime | Mixture of different types of limestone | Collective name, no particular use |
| Rock flour | finely ground rock powder | depending on the variety, it also contains many minerals and trace elements, prefer products made from lava stones |
| Limestone powder | finely ground limestone, carbonated lime | well suited for use in autumn |
| Slaked lime | see quicklime | see quicklime |
| Thomasmehl | Ore smelting waste product | contains a lot of phosphorus, manganese and other trace elements, very good for acidic soils |
| Vital lime | Carbonated lime with proportions of magnesium, trace elements, soil-active Azotobacter bacteria and peat | developed specifically for lawns – 10 kilograms per 100 square meters |
Lawn lime or dolomite lime? Which is better?
Which lawn lime is best depends on various factors
Which type of lime you use depends primarily on these factors:
- Soil type and its humus content
- Soil pH value
- other existing deficiencies in nutrients or minerals
- Time of liming
You can find out when which lime is best suited in the table above. In principle, if there are mineral deficiencies - which can occur in addition to the acidic pH value - an appropriate rock powder should be used instead of pure calcium carbonate. Please note, however, that these work very slowly and are therefore not suitable for quickly eliminating the existing defect.
In addition, quicklime (and other types of quicklime) should generally only be used on heavy soils, if at all. These types of lime are problematic for other reasons, for example, unlike carbonated lime, they do not have a positive effect on soil life. Therefore, it is better to avoid these types.
Algae lime - in contrast to pure calcium carbonate - can generally be used all year round. The product is therefore very suitable for liming in between.
Alternatives to lawn lime
Instead of lime, which is problematic in many cases, you can simply spread mature compost, possibly mixed with a little primary rock powder, on the lawn in autumn. This measure not only raises the pH value of the soil, but also adds valuable humus to it - instead of consuming it, as pure calcium carbonate does. This way you kill two birds with one stone and also avoid overcalcification.
Application and spreading of lawn lime – This is how it’s done
“In most cases, liming is completely unnecessary and even harmful! Always determine the pH value of the soil first.”
Before any liming, the soil must first be tested to determine the actual need. In principle, liming only needs to be done if this value is below 6.5 for light, sandy soils and below 5.5 for heavier soils - the optimal value for a lawn is exactly within this range. If the pH value is above this, you must not lime under any circumstances! In this case, there is a risk of over-calcification, with the result that the plants then only absorb nutrients poorly - there is a risk of deficiency symptoms and lawn diseases.
Apply lawn lime
Lawn lime is applied after scarifying
Once the pH value has been determined and the soil's need for lime has been determined, first do the preparatory work. To do this, you should mow the lawn to a cutting height of approx. four centimeters so that the lime actually ends up on the ground and not on the grass. It is also important to scarify the lawn and remove thatch. This is best done in early spring, before the grass really starts to grow. You can either use a scarifier or simply a rake.
By scarifying, you not only remove the felt, but also a lot of foreign growth - such as moss, which has grown diligently over the winter months. This measure ensures that the lawn is ventilated and the grass has enough space, light and air for new growth. Only now apply the lawn lime. For this purpose, it is recommended to spread the product with a spreader for a more even distribution. When applying by hand, there is a risk that too much or too little of the product will end up on the lawn in some places.
When spreading the spreader, it is best to proceed as follows:
- Mow the lawn to a height of four centimeters.
- Thorify the lawn thoroughly (this works best with a rake).
- First run along the length of the lawn with the spreader.
- It is best to mark expired strips, for example with stones or a string.
- Then spread the lime on the horizontal strips.
- This ensures better and more even coverage.
After liming, the lawn must be watered thoroughly so that the product quickly penetrates the soil and reaches where it can be effective. It therefore makes sense to apply lime shortly before an expected downpour. Then let the lawn rest for about four weeks, which means: do not fertilize or mow!
Excursus
How to determine the pH of the soil
The pH value of the soil can easily be tested yourself, for example with the help of a soil test or quick test from a gardening store. These pH tests are easy to use. They are available in different price ranges from different manufacturers, although you can also choose a cheap no-name product from a discounter without hesitation. Alternatively, a professional soil test in a specialized laboratory makes sense, especially as this will provide you with precise instructions for the correct fertilization tailored to your garden soil.
Lawn lime – when to sprinkle?
Lawn lime is usually applied in autumn, but at least four weeks before the first fertilization in spring. The main reason for this early fertilization is simply that carbonate of lime only develops its effect very slowly and therefore needs sufficient time.
Can you apply lawn lime and fertilizer at the same time?
Since lime should only be applied to acidic soils for neutralization, supplying the lawn with fertilizer at the same time makes little sense - especially if it is a nitrogen-containing fertilizer. On acidic soils, plants' nutrient absorption is inhibited, meaning they cannot benefit from the nutrients provided. Liming should therefore be carried out first and the first fertilization should be carried out at least four weeks apart. However, you should definitely not forget these, as lime removes nutrients from the soil - of course these have to be added back. Compost or humus soil are very suitable for this purpose.
How much lawn lime is needed?
How much lime you need to apply depends on various factors. The most important determining factor for the dosage is the soil type:
| Soil type | Dosage |
|---|---|
| Light soil | 6 to 8 kilograms per 100 square meters |
| Middle ground | 8 to 13 kilograms per 100 square meters |
| Heavy soil | 12 to 18 kilograms per 100 square meters |
If that seems like too much - after all, such amounts involve quite serious interference with the life of the soil - you can spread the liming over several dates and use less lime. For example, you can lime in both spring and autumn. However, if the soil is only slightly acidic and only needs to be raised from a pH value of 5 to 6, distribute around 400 grams of carbonated lime per square meter of lawn. The values given refer to the amount of lime required per year.
Excursus
Be careful with neighboring plants that do not tolerate lime
Not all garden plants tolerate lime - and some of them grow in close proximity to the lawn. To ensure that these plants are not damaged by the lime and the resulting higher pH value, you should maintain an appropriate safety distance and also pay close attention to where the rainwater flows - this can also wash the lime into the bed with the conifers or ericaceous plants.
Frequently asked questions
Is lawn lime poisonous?
Lawn lime can lead to allergic reactions in humans and animals
Whether lime is toxic or not depends on the type of lime used and any additives it may contain. In any case, the material is questionable and can cause skin irritation - for example when a small child runs barefoot across the lawn. The same applies to pets such as dogs and cats. Furthermore, it is better not to inhale the fine lime dust as it can settle in the respiratory organs. Limescale is therefore definitely harmful to children and animals. The limed area should not be walked on again at least until the next heavy rain shower so that the material seeps into the ground.
Does moss actually only grow on acidic soil?
Many gardeners are quick to use lawn lime as soon as moss grows in the lawn. Moss is often viewed as an indicator of soil that is too acidic (pH value below 5), but growth can also have completely different reasons. For example, soil that is compacted or too moist and a lack of nutrients (especially if too little nitrogen has been fertilized!) lead to increased moss growth. The rule also applies here: don't start liming straight away, but first determine the pH value.
Does lime also help with clover in the lawn?
Most types of clover such as red and white clover prefer to grow in neutral to alkaline soil, which is why liming against clover is of no use - the soil already contains too much lime. The measure would therefore be counterproductive and would only promote the growth of clover plants. However, there is one exception: as the name suggests, sorrel prefers an acidic environment. It is therefore worth determining the specific type of clover or simply determining the pH value of the soil.
Tip
You can buy both fine dust and granular lawn lime in stores. While the former is more easily absorbed into the ground, the latter is easier to distribute. However, be sure to wear long clothing as well as safety glasses and a respiratory mask - the fine flour easily penetrates the respiratory organs and causes irritation.
