Lime fertilizer is an important material in the garden because it counteracts acidification of the garden soil and ensures that your plants can always absorb enough nutrients. There are different types of lime, but the versatile garden lime is best suited for hobby and home gardening.
What is garden lime good for and which plants should it be used on?
Garden lime is an important helper against acidic soils as it raises the pH value and supplies plants with calcium. It improves nutrient availability, soil structure and promotes soil organisms. However, plants that prefer acidic soils should not be limed.
What is garden lime?
Basically, lime is a form of the chemical element calcium (Ca), which is one of the most important mineral building blocks in humans, animals and plants. Bones and teeth consist largely of calcium, while the mineral is an elementary component of the cell walls in plants.
In nature, calcium occurs in various types of rocks and sediments, mostly in its form as calcium carbonate (CaCO3, also called carbonate of lime). This raw material is also the basis of most lime fertilizers. As a rule, lime is obtained from so-called lime deposits, which are sediment deposits from the ancient seas. Many millions of years ago, the calcareous remains of sea creatures such as snails, mussels, crabs and others formed the basis of these rock layers. Today, limestone makes up a large part of the earth's crust and serves as an important raw material for all kinds of uses in industry, home and garden.
Garden lime against moss
Moss loves acidic soil. If you have a lot of moss in your lawn, this is a sure sign that your soil is acidic. Garden lime can help here because it is alkaline and therefore raises the pH value in the soil. It is best to apply the lime in spring and work it into the soil with a scarifier. Scarifying brings additional oxygen into the soil, which moss also can't stand.
What do you need garden lime for?
Every soil naturally has a different pH value, which is a measure of the amount of hydrogen present in the soil. The pH value is shown on a scale between 0 and 14, with a neutral soil having a value of 7. Acidic soils lie below, alkaline (also called basic) above. Most plants thrive best at values between 6 and 7, although there are of course also extreme acid lovers (moorland plants) or sand plants. The plants have their own preferences in this regard, which should be taken into account when choosing a location as well as when fertilizing and liming.
However, the pH value of the soil is not static, but can be influenced both unfavorably and favorably. Mowing the lawn and harvesting the vegetable patch naturally leads to slow acidification, which must be counteracted by targeted liming. Over-fertilizing the soil with nitrogen-based fertilizers also leads to acidification. If the pH value of the soil is too acidic, this has many disadvantages for the plants:
- Availability of nutrients: In acidic soil, plants cannot absorb vital nutrients such as nitrogen, phosphorus and potassium. Growth inhibition occurs.
- Activity of microorganisms: Bacteria and fungi cannot break down organic matter in acidic soil conditions, so the nutrient cycle in the soil collapses.
- Aluminum poisoning: At low pH values, aluminum dissolves, which limits root growth and thus the availability of nutrients and water.
By liming you counteract acidification and thus deficiency symptoms.
When does the floor need to be limed?
Garden lime improves the soil and helps with acidification
Garden lime is an effective soil improvement agent as it supplies the plants with calcium and also makes other nutrients available in the soil. At the same time, the pH value in the soil is increased so that you can counteract acidification by liming.
Benefits of garden lime:
- raises soil pH and neutralizes acidity
- provides plants with lime
- improves the availability of nutrients
- improves the soil structure, creates fine, crumbly soil
- This is important for keeping the plants in the soil and for their nutrient absorption
- promotes the activity of soil organisms
- strengthens the resistance of plants to diseases
- makes it difficult for many acid-loving weeds and mosses to grow
However, garden lime not only has advantages, but also tangible disadvantages. These occur when the product is used incorrectly or excessively and reverse the positive consequences of liming. An oversupply of lime also leads to a faster breakdown of the humus layer, which initially makes more nutrients available - but in the long term it depletes the soil. It is not without reason that an old saying goes:
“Kalk first makes rich fathers and then poor sons.” (author unknown)
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Not all plants like lime
When fertilizing with lime, pay attention to the fact that some plants rely on an acidic environment to thrive. Rhododendrons, azaleas and blue hydrangeas must under no circumstances be fertilized with lime.
When is the right time to apply lime?
Garden lime should be applied either in early spring or autumn, although autumn is preferable. The slow-acting lime fertilizer then has enough time to develop its effect over the winter months. Finally, in spring you give your plants a starter fertilizer, which leads to he althier and faster growth due to the better availability. Never apply lime fertilizer at the same time as fertilizers containing nitrogen, as this reduces the nitrogen content.
Instructions for applying lime
Apply the garden lime either freehand or with the help of a special spreader. The latter helps to achieve a more even distribution over larger areas. Make sure there is a wide and even distribution and these instructions should also be followed:
- lime on dry ground
- Do not sprinkle over plant parts, but apply directly to the ground
- Contact with plant parts can lead to burns on leaves etc.
- work deeply into beds and borders
- Water the lawn well afterwards
When and why you should lime your lawn (and when not) is clearly explained in this video:
Rasen kalken - Warum und wann Rasen kalken - Rasenkalk Kalk für den Rasen
What lime fertilizers are there?
Background
Composition of garden lime
Garden lime is available commercially under very different names, with more or less similar basic ingredients hidden behind the different brand names. However, not every type of lime is suitable for every soil. The following table clearly shows which soil you should use which lime on:
| Soil type | Features | Kalkart | Features |
|---|---|---|---|
| humus-rich | dead and decomposed organic material, nutrient-rich, fine-crumbly, dark | carbonated lime | natural calcium carbonate, gentle and long-lasting |
| humus-rich | dead and decomposed organic material, nutrient-rich, fine-crumbly, dark | Algae limestone | natural lime fertilizer made from red algae, contains additional nutrients, gentle and long-lasting |
| easy to moderately difficult | sandy to loamy | Garden lime | natural calcium carbonate, versatile |
| sandy | sandy, very light, permeable, low in nutrients | lime marl | contains calcium carbonate and clay, improves soil quality in the long term |
Carbonated lime
This is lime fertilizer that is obtained from natural lime deposits. These include, for example, these types:
- Chalk stone or chalk limestone
- Limestone
- lime marl
- Dolomite limestone
These rocks consist mainly of calcium carbonate, which is also known as carbonate of lime. The ground limestone is particularly suitable for the garden because it dissolves slowly and therefore has a gentle and long-lasting effect. Dolomite lime is a type of lime that also contains magnesium and is therefore particularly suitable for plants with a higher magnesium content.
Tip
When liming regularly, make sure not to use lime fertilizers with a magnesium content of more than ten percent. Otherwise there will be an oversupply.
Algae limestone
Algae lime is obtained from the dead deposits of red algae and is therefore also a natural type of lime. The product contains around 70 percent calcium carbonate, up to ten percent magnesium and, in contrast to other lime fertilizers, other trace elements.
lime marl
This natural lime fertilizer contributes significantly to improving sandy soils, as the clay it contains improves its storage capacity. With regular use, water and nutrients no longer “just run through”, but are retained in the soil and can be absorbed by the plants. High-quality lime marl consists of 60 to 70 percent calcium carbonate and 30 to 40 percent clay.
Garden lime
Garden lime is not a type of rock, but the general name for various types of lime fertilizer. As a rule, it is ground natural lime with or without magnesium content. Sometimes garden lime also contains additives such as additional fertilizers or weed killers. Garden lime is difficult to dissolve, which is why its effect only develops slowly and gently.
Caustic lime / quicklime
Caustic lime or quicklime (calcium oxide) was widely used in home gardens a few decades ago, but today it can only be found in agriculture. The substance can be mixed with water, where it reacts to form calcium hydroxide - the so-called slaked lime. Both forms are quickly effective, but also highly aggressive. They burn skin and mucous membranes, and if used improperly, they can cause serious damage to plants and the environment. These products are absolutely not recommended for garden liming!
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Is there a difference between lawn lime and garden lime?
There are basically no differences between lawn lime and garden lime. Instead, it is actually a description of the variety, because not every garden lime fertilizer is suitable for sensitive lawns. For a he althy, green lawn, it is best to use so-called dolomite lime, which is a natural fertilizer made from calcium and magnesium. Many commercially available types of lawn lime are also mixed with long-term fertilizers for he althy grass growth, which, however, does not always make sense. Depending on the pH value of the soil, fertilization and liming should not be done at the same time.
- high pH value: lime first (preferably in autumn), fertilize in spring
- Planting a new lawn: when sowing grass seeds, both fertilize and lime
- neutral pH value: even with maintenance liming you can lime and fertilize at the same time
Testing the lime content of the soil
For this reason, you should always check the pH value of your garden soil before applying lime fertilizer. To do this, you can take soil samples and send them to a specialized laboratory (and get exact fertilizer recommendations back at the same time), but you can also carry out the test at home. There are special limescale tester sets available from specialist retailers (€14.00 on Amazon), which you can use even without basic chemical knowledge. The disadvantage of using it at home, however, is that you don't have to fertilize or fertilize it. Receive liming recommendations. Instead, you have to calculate the correct amount of lime yourself.
Indicator plants
Certain plants – so-called indicator plants – also give you a clear indication of whether your soil is acidic or alkaline. These plants feel comfortable in very specific soil conditions and therefore show what the pH value is like at their location without any test. The following table lists some of the most common species in the home garden.
| These indicator plants indicate acidic soil | These indicator plants like lime |
|---|---|
| Moose | Fieldbellflower |
| Rabbit Clover | Meadow button |
| Field chamomile | Waiting away |
| Small sorrel | Stinging Nettle |
| Field Horsetail | Gamander |
| Sand Pansies | goose thistle |
| Sorrel | Adonis Roses |
| Farmer's mustard | Coltsfoot |
| Yellow growth flower | Dandelions |
| Honorary Award | Deadnettle |
| Daisies | Storkbill |
Deficiency symptoms are an indication of hyperacidity
Yellowed leaves, dried shoot tips or brownish spots on the flesh: all of these deficiency symptoms often indicate excessive acidification of the soil. But not only, because these phenomena also occur when there is waterlogging or a general lack of nutrients (e.g. as a result of inadequate fertilization).
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Are rock dust and garden lime the same thing?
Garden lime is pure calcium carbonate, which is sometimes enriched with magnesium. Meanwhile, rock dust is exactly what the name suggests: finely ground rock. Depending on the type of rock, this is more or less calcareous, but also contains a number of other minerals and trace elements. For this reason, rock powder can hardly be overdosed, while fertilization with garden lime must be measured precisely - overfertilization can have drastic consequences for the fertility of the soil.
Frequently asked questions
Does lime also help against snails?
In fact, a ring of carbonated lime or garden lime around an endangered plant can protect it from voracious snails. The animals generally avoid crawling over material that they find sharp and drying out.
Is lime actually poisonous for dogs?
Don't let your pets - not just dogs, but also cats and rodents such as guinea pigs and rabbits as well as turtles - walk across freshly limed ground or lawn. The product may have a corrosive effect and can lead to injuries. If you eat limed grass, poisoning is very likely, especially for small animals.
Tip
Although eggshells contain lime, they are not suitable as a substitute for garden lime. Nevertheless, you can use it as an inexpensive fertilizer for house and balcony plants and of course in the garden. To do this, let crushed eggshells steep in tap water for a few days and then water your plants with them. Allow two to three eggshells per liter of water.
