How To Fight Moss With Iron Fertilizer

Lawns can be pushed back by various weeds and other plants. Whether clover is spreading in the lawn or moss is now found in the lawn. Action should be taken quickly to drive out the unwelcome plants and protect the lawn. Iron fertilizer against moss is a popular product that many gardeners use to remove the moss. But is iron fertilizer really that effective in the fight against moss and what needs to be considered when dealing with it?

Eisendünger gegen Moos

Moss may not yet be as visually noticeable as other weeds and may not have such devastating effects at first. But in the long run, the lawn can be pushed back. In addition, moss indicates that the lawn is not doing well.

Therefore, the indications should be taken seriously and the lawn should be protected. Here you will now learn how iron fertilizer helps against moss and how to make the lawn permanently fit, so that it is more resistant to moss and other weeds.

How does moss get in your garden?

Eisendünger gegen Moos im Rasen

Lawn usually shines green and is tougher than its reputation. A healthy lawn can defend itself against most weeds and plants that want to encroach on its territory.

It is only when the lawn is not in top condition that it becomes easier for weeds to spread and take over the lawn’s space. Therefore, moss is an indication that the lawn is not in the best condition.

A common reason for the spread of moss is a lack of nutrients. Although the lawn is not particularly demanding and it usually only needs water and some light, a fertilizer should also be applied at regular intervals. If the fertilizer is already used up or could not develop its effect, then the lawn can suffer from a nutrient deficiency.

So, in addition to nutrients, light is a second important source of health for the lawn. If the lawn is in the shade, then the moss has an easier time asserting itself against the lawn. This is because moss is much less demanding and can spread well even in low light.

When to use iron fertilizer

In normal soil, iron should be present in sufficient quantities. However, if you are unlucky and your soil does not have enough iron, then this can become noticeable by your lawn losing its green color and appearing more yellowish. The yellowish discoloration is a clear indication that there is not enough iron.

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However, before you start applying the iron fertilizer now, you should discuss other causes that can promote the growth of moss.

After all, moss also spreads when the soil is too acidic. One solution here is to apply lawn lime. This can be used to raise the pH level. A healthy lawn should have a pH of 6 to 7.

If you have not maintained your lawn well and there is still a lot of cuttings on the lawn, then the lawn does not receive enough light and cannot utilize nutrients optimally. Here, scarifying the lawn is a suitable countermeasure.

If there is not enough light and the lawn is in the shade. Then special shade lawn should be sown. This still copes well with more difficult light conditions.

If any of these factors apply, then you do not need to start applying iron fertilizer yet. Rather, try liming or dethatching the lawn first to get it back in shape.

How to apply the iron fertilizer against moss

However, if the lawn is noticeably yellowish in color and no other factors can be identified that could be responsible for its deterioration, then the decision in favor of iron fertilizer should be clear.

Iron fertilizer is available in various forms and designs. On the one hand, it can be applied to the lawn as a liquid, or as granules.

The advantage of granules is that they are easier to spread with a spreader. Thus, a large lawn area can be very evenly strengthened with the iron fertilizer.

However, if only a small area is affected by discoloration, then the granules can be dissolved in water and poured over the lawn. How you proceed is up to you, and the method of application makes little difference to the ultimate effect.

However, if you already have a spreader, then the application of the granules in this form is recommended. Here, however, it should also be noted that after spreading the granules the lawn is still a little watered. Watering allows the granules to penetrate the lawn better.

In addition, the lawn should not be walked on for several days. If necessary, use barrier tape to ensure that the lawn is really not walked on.

After about two weeks, you should see a noticeable effect. The moss is now dead and should be removed. You can use a lawn rake to remove the moss from the top layer of the lawn. Do this carefully, because if too much moss is left, the lawn may again not receive enough light.

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If moss is visible in the lawn again after a few months, then the whole procedure should be repeated a second time. After a second treatment, the soil is sufficiently supplied with iron and the moss has been successfully pushed back for many years.

When to apply the lawn fertilizer

Has your lawn already had problems in previous years and struggled with other weeds? If you suspect that the soil does not contain enough iron, then you should start applying the iron fertilizer in the spring as a precaution.

Here, the spring months around March are a good time to start the first application of the iron fertilizer. The advantage here is that the lawn finds its full strength over the summer and can defy the moss. To apply the iron fertilizer, the temperature should be more than 10 degrees. In addition, the lawn should be mowed to a length of 3 to 4 centimeters.

If the lawn nevertheless struggles with a slight infestation of moss during the summer, then the iron fertilizer should be applied to the lawn a second time during the fall. The months between September and October are recommended.

Iron fertilizer should not be applied in winter. If the ground is frozen, then it cannot absorb the fertilizer at all.

On rainy days, the iron fertilizer should also not be applied. The fertilizer would only be washed out by the rain and not absorbed by the soil.

Risks of iron fertilizer

Iron fertilizer has some positive properties for the lawn and can compensate for a lack of nutrients. At the same time, however, it is important to note that iron is a toxic substance and should therefore only be applied under strict conditions.

For example, if the iron gets on a paved surface, then there will be ugly stains. Therefore, when applying the iron, the adjacent surfaces should be protected with a cover sheet. Even if you think that you will not spill fertilizer already, wind and rain can still cause the fertilizer to get on the paved area. Therefore, generously apply a protective film.

The fact that the lawn should not be walked on for a few days is not only due to the fact that the lawn should be protected, but also because the iron II sulfate is toxic. Special care should be taken if there are children or pets in the household. These could quite carelessly run onto the lawn and come into contact with the toxic substance. Here there is a danger of poisoning, which would have to be avoided or treated urgently. Therefore, block off the lawn completely in case of danger.

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Protective measures should also be taken when applying the iron fertilizer. Contact can irritate mucous membranes and eyes. The iron also forms the toxic sulfuric acid with contact of water.

The iron fertilizer should be applied only with adequate protective clothing. This includes a protective suit, acid-proof gloves and safety glasses.

If you are unsure yourself, then you can also hire a professional to apply the iron fertilizer. However, with the protective measures and a few days of waiting, there is no danger to you.


If moss is spreading in your lawn, it could be for a few reasons. The lawn could be in the shade, suffering from a low pH, or covered in clippings.

However, if there is a clear yellow discoloration, then this is a clear indication that there is an iron deficiency. To correct the iron deficiency, an iron fertilizer should be applied.

The iron fertilizer can either be poured over the lawn as a liquid or spread as granules using a spreader.

The best time to treat the lawn with the iron fertilizer is in spring. When temperatures rise above 10°C then is the time to support the lawn with the iron.

In the following weeks the moss should recede. In particularly severe cases, a second treatment is necessary in the fall. After the second treatment, the soil should be sufficiently strengthened with iron.

In the case of a very light infestation of moss, it may be sufficient to remove the moss with a rake.

In any case, when handling the toxic iron fertilizer, make sure to follow the warnings. It should only be applied with protective goggles and a suit.


  • 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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