Iron fertilizer for lawns: application & alternatives

Iron fertilizer is said to help reduce moss in the lawn. Read here when you can save the money for iron fertilizer and how a shortage occurs.

That seems to be the case in spring moss in the lawn often to be multiplied again. In search of solutions to this problem, every lawn owner sooner or later hears about the possibility of getting rid of moss with iron fertilizer. We create clarity in the tangled moss carpet of dangerous half-knowledge, well-intentioned advice and real expertise.

Iron is an essential nutrient for all plants. In the following we would like to explain to you why lawns need iron, whether iron fertilizer fights moss in the lawn and how you can recognize an iron deficiency. We then go into how iron deficiency can develop and when iron fertilization is necessary – there are usually much better alternatives.

General information about lawn fertilizer can be found in our special article.

Why does the lawn need iron?

Like any other plant, lawn grasses need the 14 essential nutrient elements to be able to survive and reproduce. In addition to the main nutrient elements nitrogen (N), phosphorus (P) and potassium (K), magnesium (Mg) is also absorbed by the lawn in large quantities. Iron (Fe) is one of the trace nutrients. These are only absorbed in the smallest amounts, but are no less important than the main nutrients. Iron, for example, plays a key role in controlling enzyme activity in plants and thus also enables the formation of proteins and green chlorophyll. The plant also needs it to regulate cell respiration, in which energy is obtained from carbohydrates.

Tip: Many lawn fertilizers contain the trace element iron and advertise its content. In fact, however, iron is the most abundant nutrient in soil. That a deficiency occurs because the turf has stripped the soil of all the iron present is extremely unlikely: after all, iron makes up only about 0.01% of the dry plant mass on average the end.

Iron fertilizer against moss in the lawn

In quite a few heads, as well as in internet forums, there is a rumor that moss in the lawn can be combated with iron fertilizer. In fact, with the application of iron sulfate (FeS0₄) achieve a certain effect: The reaction of FeSO₄ in aqueous solution is acidic. The application can achieve a very rapid pH change in the soil, which is poorly tolerated by the moss plants. As a result, they die and can be raked out. However, this effect is short-lived. Due to the acidification of the soil under the lawn, the moss has an even easier time of it the next time. And the constant application of iron sulphate and lime alternately is not a solution either: one Accumulation of calcium, iron and sulfur in the soil sooner or later leads to excess symptoms at lawn.

A long-term solution to moss displacement is just a change in the contributing factors: waterlogging, soil compaction, shade, missing or wrong fertilization and the choice of one Improper lawn seed mix cannot be remedied by applying large amounts of iron fertilizer - although some sellers of the generous 10 liter bucket would like to think so permit.

Recognize iron deficiency in lawns

An iron deficiency manifests itself as chlorosis (yellowing) of the stalks. What is special about iron deficiency is that the leaf veins remain green longer than the area in between. In addition, the symptom always appears on the youngest culms first - unlike with nitrogen deficiency, which affects the older culms first. In order to differentiate between an iron deficiency and a nitrogen deficiency, you have to look very closely. A severe deficiency can even result in a whitish discoloration.

Reasons for iron deficiency in lawns

The most common reason for iron deficiency is not the absence of iron. If there is no lack of iron, even normal iron fertilization has no significant effect on the nutritional status of the lawn.

Iron is present in the soil as trivalent and bivalent iron ions. Plants usually take iron only as the divalent ion (Fe²⁺) on. The two ion forms are in a chemical equilibrium with each other, which can shift: if the soil is more acidic, there is a lot of Fe²⁺ and there will be no shortage under any circumstances.

At a high pH, ​​on the other hand, there is more Fe³⁺ that normally cannot be recorded. A relative iron deficiency can occur. However, grasses possess a strategy that is unique in the plant kingdom: They form mugeic acids, which have a very strong attraction for Fe³⁺ to have. These mugeic acids are transported out of the roots and into the root space, where they are Fe³⁺ tie. At the same time, special transport channels are built up in the outer cells of the root, which are specialized in absorbing the iron ions together with mugeic acid. Grasses are therefore able to absorb iron when the pH value is actually too high. However, because this physiological adaptation costs a lot of energy, it is only possible if the plant can operate an active metabolism to generate energy. For this reason, anything that inhibits the life processes of the lawn can lead to a relative iron deficiency when the pH of the soil is too high. In the table below we have summarized for you what causes a relative iron deficiency in lawns and what you can do about it.

Which leads to relative iron deficiency	solution
Waterlogged or compacted soil	- Regular scarifying, aerating, sanding (maximum once a year) - Never fertilize with sulphur, as this binds Fe2+ so that it is not available - Long-term: Fertilize organically to keep soil loose and well-aerated through humus formation
Dry soil that does not retain water well	- Long-term: Organic fertilization to improve water storage capacity through humus formation
Calcareous soils with high pH	- Use of acidic fertilizers (eg. B. ammonium sulphate), water only with rainwater, regular spreading of acidic materials - e.g. B. Compost from rhododendron leaves, coffee grounds, softwood and ammonium

As a rule, therefore, only a relative iron deficiency occurs in the lawn. However, in special locations where no iron can form from the parent rock through weathering, there can also be an absolute deficiency. Raised bog soils and peat substrates do not contain any iron reserves. In the rare case that your lawn grows on such a substrate, iron fertilization may be appropriate.

Tip: Difficult living conditions in general can therefore cause a relative iron deficiency in lawn grasses, even though there is iron in the soil. You can prevent an overwhelmed lawn by using a lawn seed mixture that is suitable for your location from the start. Here we have put together for you which lawn type makes sense when is!

Iron fertilizer for lawns: application and application

On a healthy soil with normal pH, iron fertilization can be done with ferrous sulphate. Sulfur and iron ions dissolve in water and can be absorbed by the plants. However, when there is a lack of oxygen due to waterlogging or soil compaction, they also like to come together again and are then difficult to dissolve. Fetrilon® is a compound fertilizer with many micronutrients. It contains several trace nutrients in a special, soluble compound. Radigen® is also a fertilizer with several trace elements, which has a gentle long-term effect. In the case of severe and acute deficiency, iron(II) sulfate, iron chelates or iron citrate can be applied as foliar fertilizer.

Please note: Due to its acidic reaction with water, ferrous sulfate has a corrosive effect on the skin and mucous membranes. Animals as well as humans can be severely damaged if they are touched or even swallowed. A lawn treated with iron (II) sulfate should not be walked on for at least 24 hours and should also be as inaccessible as possible to wild animals and domestic animals. In addition, granules worn on shoes or paws on the pavement lead to rust stains on many materials. These stains can only be removed again with even stronger acid.

Iron fertilizer for lawns: benefits & alternatives

In summary, it can be said that iron fertilization is not necessary in most cases and has no effect. A general improvement of the soil, on the other hand, reliably helps to prevent iron deficiency. With organic lawn fertilization, for example, this is still possible without any problems long after the lawn has been laid. Our Plantura organic lawn fertilizer and ours Plantura Organic Autumn Lawn Fertilizer are certified organic and come with everything you need to keep your soil and lawn healthy and the iron available.

In this special article you will find general information about organic lawn fertilizers. This article will also tell you about Organic Lawn Fertilizer.