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There can be a variety of reasons for the appearance of moss in the lawn. Many hobby gardeners swear by the use of iron sulphate for quick control. Everything you need to know about this can be found below.

In a nutshell

  • Iron sulphate does not work against causes and moss-promoting circumstances, but only against the moss itself
  • Use can lead to pollution of the environment -> pay attention to protective measures
  • Moss will die off in 5-10 days and can be removed by raking
  • our recommendation: Clarify causes, improve soil and optimal lawn care

Clarify the causes before use

Iron sulphate is also known under the names ferrous sulphate, green salt or iron vitriol. As a rule, it is manufactured technically. Indes can be used on lawns to combat moss. Very often it is commercially available in combination with fertilizer and thus ensures good growth at the same time, ultimately for a lush green lawn. When green salt is used, moss dies off in a very short time, in about five to ten days, because it does not tolerate iron. It then turns brown to black and can be easily combed out of the lawn with a rake. After treatment with iron sulphate, moss will not grow back so quickly at this point. However, the use of green salt in the garden is not without its problems.

Especially when fighting moss in the lawn, before using green salt, it should be clarified exactly which causes are responsible for its formation. This can be:

  • waterlogging in the soil
  • heavily compacted, heavy soil
  • pH too low
  • ideal pH between 5 and 7
  • nutrient deficiency
  • irregular mowing
  • too short mowing
  • generally wrong care
  • wrong lawn mixture for the site
  • insufficient preparation of the soil before sowing

It is important that comprehensible causes for the moss infestation are eliminated, even if iron sulphate has been used to combat the moss in the meantime. Otherwise, new formation will always occur and regular use of iron sulphate is not necessarily recommended for the sake of the environment.

Notice: Moss usually forms when the pH of the soil is too low. Lime can easily regulate the value here. However, this can only be measured again after three to four weeks.

consider environmental pollution

The use of iron sulphate in the garden is not really completely harmless. There is an unfavorable influence on the soil, which ultimately also leads to pollution of the environment. Due to the sulfuric acid contained in green salt, it has a caustic effect in connection with liquids. From this it can already be seen that appropriate protective measures are necessary when handling iron sulphate. This includes:

  • Avoid contact with skin and eyes
  • causes skin and eye irritation
  • Wear safety goggles and gloves
  • however, these must be resistant to chemicals
  • recommended long clothing and sturdy shoes
  • do not apply to stone slabs, garden furniture, walls etc
  • there formation of brown spots, not removable
  • Damage to nearby plants possible

In addition, areas that have already been treated should not be walked on, because footprints that appear on paving slabs can no longer be removed.

Attention: Always store ferrous sulphate out of the reach of pets and children.

Use ferrous sulfate correctly

Due to the adverse health effects, careful handling is required. Gr├╝nsalz offers the trade as granules and also in liquid form. The best time to use it is in spring between March and April, but September to October is also possible. However, it should not be used in the winter months. There are a few things to keep in mind when using it, such as:

  • no use in hot weather above 25°C
  • avoid blazing sun
  • ideal slightly damp weather
  • Alternatively, sprinkle the lawn beforehand
  • Floor temperature above 10 °C necessary
  • Mow the lawn a week in advance
  • ideal stem height 3 to 4 cm
  • Moss absorbs remedies better
  • Add green salt to the irrigation water
  • Use a watering can with a shower attachment or a pressure sprayer
  • even application to the lawn
  • Do not walk on the treated area, at least for two days
  • Deny access to children and pets

After about five to ten days the moss will have died off. It is brownish to black in color and can now be easily combed out of the lawn with a rake. Scarifying the entire area is even better.

Notice: The dead plant parts must not be disposed of in the compost as they are contaminated with the chemical. Just put it in the trash.

Alternatively, green salt in the form of granules can also be used. The procedure is as follows:

  • either dissolution in the irrigation water or
  • Application in spreader
  • important to apply evenly
  • Then water the lawn well

Approximately two weeks after the treatment, the resulting gaps in the lawn can be closed with new lawn seeds.

If the moss infestation is very severe, the treatment must be repeated in August or September. It is also advisable here, especially if more than 20 percent of the entire lawn area is affected, to remove most of the moss mechanically in advance by pulling it out or poking it. Then green salt can be used.

Dose ferrous sulphate correctly

The best results are achieved when using green salt in liquid form. However, the dosage is crucial for this. A maximum of 25 grams of green salt should be applied to one square meter. Under no circumstances should this amount be exceeded. For dosing this means:

  • for watering can dissolve 250 grams in 10 liters of water
  • Using lukewarm water
  • therefore better solubility
  • uniform application of 10 liters to 10 square meters

However, for a pressure sprayer, 10 milliliters should be dissolved in 10 liters of water.

Prevention better than cure

For the sake of the environment, the use of chemical agents should be avoided as far as possible. Moss infestation in the lawn does not have to be. This can be prevented by various measures such as:

  • increased care necessary in shady, damp places
  • Culm length should be longer (10 to 12 cm) than in sunny places
  • Avoid waterlogging
  • irrigation in the morning
  • Lawn can dry until evening
  • Loosen soil regularly by scarifying
  • mow once a week
  • not shorter than 5 to 7 cm
  • Spring and autumn application of long-term fertilizer
  • Possibly administration of calcium cyanamide
  • regulate the pH of the soil if necessary
  • giving lime for it
  • optimal pH 5 to 7

Tip: In order not to unnecessarily pollute the environment with chemicals, green salt should be avoided. Instead, moss in the lawn can also be combated by regularly scarifying the soil.

frequently asked Questions

How toxic is ferrous sulfate?

It can cause skin and eye irritation. Ingestion of higher amounts can damage the gastrointestinal tract, the liver and the cardiovascular system. In contact with water it has a corrosive effect. Therefore it should always out of the reach of children and pets be stored.

How long does iron sulfate have to act?

Since it is dissolved in water and you should water the lawn well afterwards, it quickly gets into the ground.

How often should ferrous sulfate be used?

Maximum twice a year. The lawn needs time to regenerate after application. First, moss must be removed and disposed of in the residual waste bin (never throw it in the compost). After that, grass is sown to fill in the patches.

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