Is Iron Fertilizer Good For Your Lawn?

If the lawn no longer looks healthy or weeds are spreading, one of the reasons may be an existing nutrient deficiency. Although lawns in themselves seem very undemanding, it is still important to ensure a sufficient supply of nutrients.

This also applies to iron, among other things. If it is suspected that the lawn is suffering from an iron deficiency, the use of an iron fertilizer could provide relief. Is it safe to use and what do you need to watch out for? Learn here how to safely support your lawn with the iron.

How does iron deficiency manifest itself?

Iron is an essential nutrient for plants. It is needed for them to form enzymes and chlorophyll. Without iron, plants would show symptoms of deficiency after only a short time. This manifests itself, for example, in the lawn turning yellow or plants generally losing their green color. This is because chlorophyll is necessary for them to appear a lush green. If there is a lack of iron, chlorophyll cannot be formed and the deficiency is clearly visible in the plants.

The absorption of iron is difficult for some plants. This is because in order for the iron to reach the soil, organic compounds must first be released into the soil. This is the only way for the plants to absorb the iron.

For some plants, however, this process turns out to be complicated. Citrus plants or rhododendrons are therefore more quickly affected by an iron deficiency. In their case, it can be seen in a relatively short time that there is a lack of iron.

The same applies to other plant species. Affected are for example:

  • Roses
  • Blackberries
  • Tomatoes
  • Petunias

Even plants that are actually considered easy to care for can have their problems with iron supply. To protect your lawn and the plants in your garden, you should urgently pay attention to an adequate supply.

Causes of iron deficiency

The iron deficiency can exist due to two factors. On the one hand, the soil may simply not contain the sufficient amount of iron. However, this circumstance is relatively rare. In addition, as a rule, the complete fertilizers used already contain iron, so a deficiency is unlikely to exist. If you already use a complete fertilizer that contains iron, but the plants still show typical signs of an iron deficiency, this may be due to the nature of the soil. In this case, there is enough iron available but it is simply inaccessible to the plants.

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To understand this, it is important to understand how the soil is constructed. The soil in your garden has a certain pH value. This tells you whether it is more acidic or alkaline.

Iron is best absorbed at a pH between 5 and 6. However, various circumstances can cause the soil to become more alkaline. The pH value therefore increases.


This can happen, for example, because your water in the region is relatively calcareous. The calcareous water manifests itself in an increased pH value. The iron is more strongly bound to the soil and some plants are now no longer able to absorb the iron. This danger exists from a pH value of 7. If a pH value between 7 and 8 is present, however, this does not automatically mean that all plants suffer from an iron deficiency. Particularly sensitive plants are affected, for which the iron remains inaccessible.

One possible solution should therefore be to measure the soil. Check yourself how high the pH value of the soil is. There are several quick testers you can use for this purpose. These immediately show the pH value and decide whether it makes sense to apply an iron fertilizer at all.

If the quick test shows that the pH is above 7, applying an iron fertilizer does not make sense. The cause of the iron deficiency is then not due to a lack of iron in the soil, but to its poor condition.

Therefore, you should take measures so that your plants absorb the iron better and lower the pH value in the soil in the long term. You can achieve this, for example, by no longer applying lime to the lawn and by not using a nitrate fertilizer.

If your irrigation water is very chalky, try using rainwater to water the lawn instead. For example, you can set up a basic water supply with the help of a cistern pump and completely use the natural rainwater. In the household, it is equally preferable to use a domestic water machine and replace, for example, the domestic water with the rainwater. The calciferous water damages the pipes and can cause damage in the long term. Rainwater, on the other hand, is much gentler and cheaper.

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What iron fertilizers are available?

If your soil is in the optimal pH range but the plants still appear yellowish and no longer green, this could be improved by applying an iron fertilizer.

Most complete fertilizers already contain iron as a trace element. If you want to prepare the soil in the spring, it is a good idea to use such a complete fertilizer and provide all the necessary nutrients.

However, if you notice during the season that the plants do not develop as desired and you want to provide the iron specifically, there is the possibility to apply an iron II sulfate. However, care must be taken here, because the iron II sulfate is toxic. You must handle it similarly to a pesticide and store it safely. For example, after fertilizing, the lawn must not be walked on by pets or the small children.

In addition to this dangerous method, however, there are iron fertilizers based on a water-soluble iron chelate. These are much more compatible and gentle on the environment. Therefore, use this less dangerous variant and your garden will also appear in a new green.

The iron fertilizer is available either as granules or liquid fertilizer. You are free to choose which variant is more suitable for your requirements and promises greater success.

The right application of iron in your garden

In order for the iron fertilizer to develop its full effect, there are some tips to follow when applying it. Among them falls that the weather must be suitable. Do not apply the iron fertilizer when the blazing sun is shining on your garden and the temperature is higher than 25°C. Especially the liquid fertilizer would then hardly be absorbed and evaporate on the surface.

If you decide to apply the toxic iron-II sulfalt, special precautions should be taken. If the agent gets into the eyes or on the skin, for example, this causes chemical burns. Therefore, it is urgent to wear protective goggles and long clothing. Make sure that the agent does not get onto other surfaces. Even small drops will cause discoloration and leave an unsightly impression. Due to its hazardous nature, this iron fertilizer must be kept out of reach of children.

If you are struggling with unpleasant weeds in the garden, you can use the iron against moss. It is a popular remedy to get the garden free of moss again. If you use iron-II-sulfate for this purpose, you will have to take care of the lawn for about 3 to 4 days afterwards.

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The iron fertilizer for a green garden

If you notice discoloration in your garden and plants appear increasingly yellow, this may be related to an iron deficiency. Iron is an important element for the formation of leaf green. If the plant does not absorb enough iron, this will have a direct impact on its appearance.

If this is the case, you need to check if there is actually an iron deficiency or if the pH of the soil is not optimal. To do this, use a quick tester and check the condition of the soil. If the pH is above 7, you should first work to lower this value.

Only if the pH is already in a range between 5 and 6 does it seem reasonable to apply the iron fertilizer. If so, there may actually be an iron deficiency in the soil, so targeted fertilizing will help the plants and lawn.

Keep in mind that fertilizing is not an immediate action. It takes a few weeks or even months for the iron to take effect. Therefore, take the opportunity in the spring to already apply a complete fertilizer. This will ensure that the soil has the necessary nutrients and you will not need to take further action later in the season.


  • James Jones

    Meet James Jones, a passionate gardening writer whose words bloom with the wisdom of an experienced horticulturist. With a deep-rooted love for all things green, James has dedicated his life to sharing the art and science of gardening with the world. James's words have found their way into countless publications, and his gardening insights have inspired a new generation of green thumbs. His commitment to sustainability and environmental stewardship shines through in every article he crafts.

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