Lime is a valuable, natural fertilizer that ensures excellent harvests of vegetables and fruit. However, lime should be used carefully, because in the long term the agent leaches the soil. Algae lime is often used in ecological gardening in particular. The following article reveals the advantages and disadvantages of this compared to conventional garden lime and how to use it.

Algae lime has many uses in the garden

Table of Contents

Show all
  1. the essentials in brief
  2. What is algae lime?
  3. application
  4. mode of action
  5. When does fertilization with algae lime make sense?
  6. When should lime fertilization be avoided?
  7. Usage and Dosage
  8. Advantages over other lime fertilizers
  9. Algae lime against pests and plant diseases
  10. ecological problem
  11. frequently asked Questions
  12. Is algae lime poisonous?
  13. Does algae lime also help against moss?
  14. Is algae lime also suitable for roses?
  15. What are the differences between garden lime and algae lime?

    16. the essentials in brief

    • Algae lime is a long-term fertilizer made from dead coral deposits of red algae
    • In addition to calcium carbonate, algae lime contains many valuable minerals and trace elements.
    • The algae lime is used in the garden for soil improvement, plant protection and fertilization.
    • It neutralizes acidic soils and thus prevents the growth of unwanted weeds.

    What is algae lime?

    Algae lime is a slow-acting lime fertilizer (€9.70) that is obtained from the coral deposits of red algae that died millions of years ago. On the other hand, dolomite lime, which is often used to fertilize lawns, consists of sedimented mussel shells and the remains of other marine animals. Algae lime is therefore a purely biological substance that, in addition to calcium carbonate (just the lime), also contains other minerals and trace elements.

    Primarily in ecological horticulture, but also in hobby gardens, algae lime is used to improve the soil, for plant protection purposes and for fertilization. Like all types of lime, the powder neutralizes soil acids and counteracts the gradual acidification of the soil, which occurs involuntarily in the course of gardening. Algae lime is mainly used on light to medium-heavy soils.

    ingredients

    In contrast to other lime fertilizers, algae lime not only contains calcium carbonate (chemical formula: CaCO3), but also other minerals and trace elements essential for plant nutrition. The proportion of calcium carbonate, which is also known as carbonate of lime, is around 80 percent. In addition, algae lime also contains the following ingredients:

    ingredients Average portion per kilogram
    magnesium carbonate 130 grams (13%)
    iron 2150 milligrams
    boron 416 milligrams
    manganese 160 milligrams
    iodine 40 milligrams
    copper 28 milligrams
    zinc 16 milligrams
    molybdenum 3 milligrams
    cobalt 1.1 milligrams
    selenium 0.16 milligrams

    Furthermore, algae lime contains tiny traces of aluminium, bromine, fluorine, indium, nickel, silver, titanium and tin, which can hardly be detected and are therefore negligible.

    The most important difference to other lime fertilizers is the high proportion of magnesium. In addition, algae lime works very slowly due to the calcium carbonate it contains, since the substance is not water-soluble and is therefore only gradually absorbed.

    What is Calcium Carbonate?

    Calcium carbonate or carbonate of lime is one of the most common chemical compounds on earth. These are mainly found on sedimentary rocks and sediments that form over millions of years from organic and mineral remains of mussels, corals, red algae and other sea creatures. The deposits are not necessarily in the sea, because where there was sea water a few million years ago, there is now solid land.

    application

    Algae lime neutralizes acidic soil

    No garden can do without fertilizer, because it contains nutrients that are essential for the plants to survive. A balanced fertilization adapted to the respective soil also ensures that the plants remain healthy and can defend themselves against pathogens and pests. Many clinical pictures are caused by an incorrect or insufficient composition of the soil and/or the fertilizer. A lack of calcium carbonate - i.e. lime - is shown in many plants, such as boxwood, by brown discoloration of the leaves. For this reason, algae lime is indispensable in the garden for these areas of application:

    • soil improvement: Raising a pH value that is too low and thus improving the soil structure, plants can better absorb nutrients from fertilization carried out after liming
    • improvement of soil life: Microorganisms living in the soil are essential, because they not only keep the topsoil loose and permeable, but tirelessly produce valuable humus. However, these microorganisms avoid acidic soils, which is why regular liming maintains the balance and thus perfect living conditions.
    • fertilization: In addition, calcium carbonate itself is an important plant nutrient, which, for example, strengthens the immune system of the plants and strengthens them against damaging influences. In addition, some crops have a high lime requirement and therefore benefit from fertilization several times.
    • crop protection: Algae lime can also be used directly as a plant protection product to get rid of fungal or bacterial pathogens or even animal pests in the garden.

    However, the use of algae lime and other lime fertilizers does not always make sense at all times. You can find out when and under what conditions you should lime the garden in the following sections.

    mode of action

    The pH value of the garden soil sinks into the acidic range all by itself over time. There are many reasons for this, including, for example, the continuous washing out of the calcium in the soil by rain and garden irrigation. But harvesting vegetables, clearing beds in autumn and mowing the lawn also lower the pH value.

    As a result, the plants absorb existing and added nutrients more and more poorly, so that over time there can be a nutrient deficiency - even though there are actually enough nutrients in the right composition in the soil. With an acidic pH value, however, these are too firmly attached to the soil particles and are therefore no longer available to the plants. Lime fertilization neutralizes the soil again, which promotes the absorption of nutrients by the garden plants. Algae lime has proven to be a tried and tested aid, especially on acidic sandy soils.

    The soil quality improved by liming is reflected in features such as these:

    • improved soil structure
    • improved activity of soil-dwelling microorganisms
    • Water can be stored better in the soil
    • Substrate contains more air and is therefore looser
    • Heavy metals in the soil are bound by lime

    All of these benefits result in plants growing better and healthier.

    tips

    However, not all plant species tolerate lime fertilization. Some - such as rhododendrons, azaleas and heather plants such as heather - are extremely sensitive to lime and love an acidic pH value. For this reason you should not lime camellias, hydrangeas or summer heather.

    When does fertilization with algae lime make sense?

    In the garden, algae lime can be used very well in the following areas:

    • pot plants: as a preventive fertilization measure against deficiency diseases, which are shown, for example, by the leaves turning light green (the so-called chlorosis).
    • flowering plants: often bloom particularly beautifully and long-lasting after liming, since they can now better absorb the phosphorus that is so important for bloom formation
    • potato cultivation: Potatoes germinate better on a limed cultivation area and are more resistant to many pests, such as nematodes (roundworms)
    • vegetable growing: Crops grow better on limed soil due to the improved uptake of nutrients, and dusting the plants with lime powder also helps against many diseases and pests

    This section of text explains when it is advisable to use algae lime in the garden and how to recognize the need for lime.

    lack of lime in the soil

    A lack of lime in the soil is particularly noticeable in the vegetable patch. Typical signs are for example:

    • growth disorders
    • pale leaf colouration, yellow discolored young foliage
    • dried shoot tips
    • blossom end rot (on tomatoes)
    • brown dots or spots on fruit (especially apples)

    The main signs of growth failure are stunted, slow growth and the characteristic hallmarks of malnutrition resulting from poor nutrient availability in the soil. If a lime deficiency is suspected, a simple pH value from the pharmacy quickly provides certainty, so that you can initiate the appropriate countermeasures immediately.

    Which plants indicate a lime deficiency

    So-called indicator plants are plants that show the condition and composition of the soil quite clearly, even without chemical soil analysis. Grow amplified species like

    • rabbit clover
    • Little sorrel
    • field horsetail
    • Sand Pansies
    • Three Leaf Prize
    • peasant mustard
    • or moss

    in your garden, the lime content of the soil is too low and appropriate countermeasures - namely liming the soil - are urgently needed. The plants mentioned feel very comfortable in acidic soil and therefore indicate a garden soil with too low a pH value.

    Lime-loving plants

    Many of the typical garden plants love lime and need a calcareous soil to grow and thrive. The following species, for example, benefit from regular liming:

    • Lilac (Syringa)
    • Lavender (Lavandula)
    • Christmas rose (Helleborus niger)
    • Boxwood (Buxus)
    • Judas tree (Cercis siliquastrum)
    • Smoke Tree (Cotinus coggygria)
    • Common ash (Fraxinus excelsior)
    • Japanese or Tulip Rose (Eustoma lisianthus)
    • Blackthorn (Prunus spinosa)
    • Sea Buckthorn (Hippophae rhamnoides)
    • Marguerites (Leucanthemum)
    • many herbs such as wild garlic, chives or parsley

    Furthermore, lime is often indispensable for lawn care, especially since regular lawn mowing causes the pH value of the soil to drop again and again. Moss and sorrel in the lawn are sure signs that you should use algae lime.

    However, there are also many plants that are very sensitive to lime and should therefore not be limed. When buying, be sure to pay attention to the relevant information on the plant label and do not place these plants in the immediate vicinity of lime-loving plants.

    When should lime fertilization be avoided?

    "Lime makes rich fathers and poor sons" (peasant wisdom)

    However, in view of all the advantages described, you should not immediately supply your garden with algae lime, because like so many things, excessive use of calcium carbonate has negative effects. Too much lime in the soil leaches it out in the long run, so it is important to follow the manufacturer's exact dosage recommendations. In addition, have a soil test carried out regularly - preferably about every two years - in a specialized laboratory to find out the exact composition and pH value of the topsoil. Together with the chemical analysis, the laboratory also provides you with specific fertilization recommendations so that over-fertilization does not occur.

    You can have the soil analysis carried out in a state or private laboratory, taking the samples yourself and sending them to the selected provider together with the application form (which can be printed out online). When taking the soil samples, follow the instructions exactly to avoid measuring errors.

    How to do a pH test yourself

    The pH value can be determined with a simple paper test

    However, you can easily carry out a simple pH test yourself:

    1. Purchase pH test sticks from a pharmacy or garden center.
    2. Take a soil sample from a depth of ten centimetres.
    3. Crumble the sample into a plastic bucket.
    4. Add distilled water in a 1:1 ratio.
    5. Stir the sample well.
    6. Insert the test stick.
    7. After waiting one minute, read the test result.

    Alternatively, you can also use indicator paper, which shows the pH value of the soil sample based on its colour. A value between 6.5 and 8 is optimal, below that the soil is too acidic and should be limed. A value above 8, on the other hand, speaks against liming, because in this case the soil is already too alkaline.

    Usage and Dosage

    There are often specific dosage recommendations on the packaging of most types of algae lime, but these are mostly general quantities. These do not relate to the concrete garden soil - each type of soil requires different amounts of lime - and are also mostly based on the recommendations for "healthy" soil. This means that the recommendations are only suitable for maintenance liming, as experts call liming to prevent acidification.

    dosage

    For a so-called recovery liming, i. H. for the liming of an already acidic soil, however, completely different guide values are necessary. The following table shows you what quantities of algae lime you need for which soil and pH values.

    soil type PH value Algal lime in grams per square meter
    Light soil less than 5.3 200
    Light soil between 5.3 and 5.7 120 to 180
    Medium soil less than 5.7 300 to 400
    Medium soil between 5.7 and 6.5 180 to 250
    heavy soil less than 6.3 400
    heavy soil between 6.3 and 7.0 250 to 350

    As you can see from the table, a heavy clay soil needs about twice as much lime as a light sandy soil. You should therefore always plan higher amounts for heavy soils than for light ones - this applies to both maintenance and recovery liming.

    How and when is the best time to fertilize with algae lime

    The best period for liming is either early spring - before the first shoots appear - or autumn. The reason for this is the fact that algae lime takes a long time to become effective. In addition, the soil should be provided with the effect at least four weeks before the first fertilization, otherwise the nutrients will not be properly absorbed by the plants. Basically, lime is applied first and then fertilized. Only in exceptional cases - such as when you plant a new lawn or vegetable patch - do you apply algae lime and (organic) fertilizer at the same time to optimize the starting conditions. The soil is loosened before liming so that the powder can penetrate better. Use a spreader or similar hand-held device to spread the material evenly. Do not work in windy and/or rainy weather.

    What advantages does algae lime have over other lime fertilizers?

    In principle, almost any natural lime is a good choice

    Basically, the highly praised algae lime does not have any significant advantages over other types of lime. Calcium carbonate is calcium carbonate, no matter what source it comes from. The effectiveness is always the same. Only the approximately 20 percent additional minerals and trace elements that other lime fertilizers do not have should be emphasized. In particular, the high proportion of magnesium should be emphasized. However, you can also administer these nutrients with normal fertilization, so that they alone do not justify the higher price of algae lime. Especially since the proportion of calcium carbonate is significantly lower due to the additions per 100 grams and you therefore need about 20 percent more algae lime per square meter of area for liming compared to other lime fertilizers.

    background

    What does lime cause in the soil?

    Lime is supposed to deacidify the soil and raise its pH value. Most garden plants need a neutral to slightly alkaline pH level, although many garden activities such as mowing the lawn, raking leaves and harvesting the vegetable patches regularly lower this level. In addition, the activities of the soil organisms are strongly influenced by the degree of acidity of the soil and its physical properties, which is why adding lime improves the soil structure. In this way, the calcium ions combine humus and clay particles in the soil into more stable, larger crumbs and ensure that plants can absorb water and nutrients better.

    Algae lime against pests and plant diseases

    Fungal diseases in the garden are annoying because they threaten the growth of the plants and the harvest, and they are often fatal for the affected plants. With the help of finely powdered algae lime, however, you can put an end to the fungal pathogens: Dust the leaves and shoots of the green plants thinly with the powder, then diseases such as mildew or scab have no chance. However, apply the algae lime only thinly so as not to negatively affect the respiration and photosynthesis of the plants. It is best to use a special powder atomizer to ensure even distribution.

    digression

    Make your own powder atomizer

    If you don't have a powder atomizer, a PET bottle with a plastic lid that you poke a hole in with a needle will do. Fill the bottle with the algae lime powder, screw on the lid and atomize the powder by gently pressing the container.

    Algae against pests

    In the same way as described, algae lime helps against many annoying garden pests such as flea beetles, Colorado potato beetles or leek moths. However, the powder seems to be particularly effective against the dreaded box tree moth, whose voracious caterpillars have been threatening entire box tree plantations for several years. The effect is particularly great here if the caterpillars cannot settle in the box: If you regularly dust box bushes with algae lime from spring to autumn, then no caterpillars can develop there. Start the procedure as soon as you see the first butterflies.

    The following video shows very clearly how this works:

    youtube

    White paint on fruit trees

    Lime or white paint on fruit tree trunks is a tried and tested method of protecting the sensitive bark of still young trees from frost cracks. In addition, such a coating prevents annoying game browsing and the associated damage, especially in natural gardens and meadow orchards. Furthermore, the algae lime in the bark of the trees kills overwintering pests, so that the plague to be expected in the following year is less than feared.

    Mix and apply lime paint

    You can easily mix and apply white paint yourself. However, do not use quicklime, even if some recipes suggest it. This is unslaked lime, which can cause severe burns to the skin, mucous membranes and respiratory tract. It is better to use carbonate of lime such as algae lime.

    And this is how you mix and use a coat of white paint:

    1. Mix ten liters of tap water with one and a half kilograms of algae lime.
    2. Add half a kilogram of wallpaper paste (without additives!).
    3. Stir the mixture thoroughly until all the components have combined.
    4. Now carefully work the bark of the trees with a wire brush.
    5. Remove moss, lichen and loose pieces of bark.
    6. Be careful not to damage the bark!
    7. Paint the trunk and main branches with a thick brush.
    8. Work from bottom to top.
    9. Young shoots are not painted.
    10. Let the first coat dry and paint the wood one more time.

    The ideal time for such a coat of paint is late autumn, although another might be necessary after damp and rainy weather: the lime coat is not waterproof and is washed off by rain.

    Lime protects the tree from frost and voracious visitors

    ecological problem

    Since 2012, algae lime produced in the EU may only be mined from fossil deposits. The reason for this ordinance was the fact that the material was previously often removed from living red algae banks (the so-called "maërl banks") with the help of vacuum cleaner boats. As a result, the algae banks and their ecosystems, including the other sea creatures living in and from them, were permanently destroyed. In contrast, the mining of fossil deposits is considered ecologically harmless.

    Calcareous algae of the species Lithotamnium calcareum grow extremely slowly, so that the build-up of a lime deposit takes a lot of time - comparable to how peat forms in a raised bog. But this is not the only reason why the extraction of algae lime from living banks is problematic: The Maërl banks are home to many rare fish and other sea creatures, so that when the algae disappear, these water creatures also die.

    Although these algae banks have been protected throughout the EU since 2012, retailers can still sell algae lime from living banks. These products come from countries outside the EU and are therefore subject to different legislation. When buying algae lime, make sure that it comes from fossil deposits. Ask your specialist dealer where the desired product comes from and where it was mined.

    frequently asked Questions

    Is algae lime poisonous?

    Algae lime is not toxic to humans or animals, so you can touch it with your hand without any problems. Nevertheless, you should wear a face mask and safety goggles when applying, because the fine dust irritates the mucous membranes. This also applies to pets. Also, do not lime on strong windy days and make sure that you always have the wind at your back while liming. Not only the powdery types, but also the granules produce a lot of dust.

    Does algae lime also help against moss?

    Since moss basically indicates an overly acidic soil, a healing liming is indicated. If there is moss in the lawn, first scarify the area and then apply the recommended amount of algae lime depending on the pH value and the type of soil.

    Is algae lime also suitable for roses?

    Roses prefer neutral to slightly acidic soil, which is why you should only lime the bed if it is too acidic. However, dusting the shrubs with algae lime or rock flour (14.13€) helps against all sorts of diseases and pests, such as the unsightly fungal disease rose rust.

    What are the differences between garden lime and algae lime?

    Algae lime is always calcium carbonate obtained from (fossil) red algae, while garden lime (€9.70) comes from other sources. In addition, algae lime has natural admixtures of minerals and trace elements amounting to around 20 percent, which normal garden lime does not have or which are artificially added to it.

    tips

    A vegetable garden has an optimal pH value of 7, which is why you need between 250 and 500 grams per square meter for liming with algae lime, depending on the soil conditions. For flower beds and lawns, the pH value can be around 6.5, which is why lower amounts are necessary here.

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Garden design