The Content Of The Article:
- Why plants need iron
- Iron deficient plants
- Iron deficiency in the garden
- Forms of iron fertilizers
- Apply iron fertilizer correctly
- Iron fertilizer against acute iron deficiency
Why plants need iron
Whether for mass transfer or as a building block for enzymes and chlorophyll: all plants need iron. Although they absorb it only in small amounts, iron deficiency is quickly noticeable: Young leaves fade and turn yellow, the leaf veins remain green. This genuineness or chlorosis has a simple reason - the leaves simply lack the leaf green, the chlorophyll.
Iron deficient plants
Some plants are more susceptible to iron deficiency than others. In order to get nutrients, certain ions simply dissolve from the roots and the plants receive nutrients from the soil. In the case of iron, the plants themselves have to become active and release organic compounds to the soil, for which the iron compounds exist. Some plants, such as citrus or rhododendrons, have more problems with them than other plants and show more rapid deficiency symptoms. This also applies to magnolia, hydrangea, roses and azaleas, blackberries, tomatoes or balcony plants such as petunia.
This apple tree suffers from iron deficiency, recognizable by the yellow leaves
Iron deficiency in the garden
Iron deficiency has two causes: The soil lacks iron or - this is the more common case - there is enough iron there, but so tightly bound that the plants can not pick it up and show deficiency symptoms. Iron in the garden you do not need to fertilize specifically, the whole fertilizer usually contain iron and other trace elements anyway.
Iron is best available in acid soils with a pH between five and six, and moorland plants such as azaleas can be used as they please. If the pH increases with calcareous irrigation water, more and more iron is bound to soil particles and sensitive plants can not absorb it - they show deficiency symptoms. This is called lime chlorosis, which starts at a pH of seven to eight. The plants have the iron right in front of their roots, but they can not do anything with it - it's like being inaccessible behind a pane of glass.
If one notices first deficiency symptoms, one should first of all check the pH value by means of a rapid test, which is an indication of poor iron availability. If the value is in order and the soil is loose, you can start from actual deficiency and sprinkle iron fertilizer,
A pH test tells you if enough iron is available in the soil
On the other hand, if the soil is calcareous, iron fertilizers bring nothing - you have to improve the soil so that the plants can use the existing iron. Because even dense, astonishing soil or permanent lack of water can cause chlorosis - the transport routes for nutrients in the plant are too dry or the sensitive root tips rot in the damp soil. And only then can plants absorb the iron. You've got the following possibilities:
- Do not use lime or nitrate fertilizer, as these also increase the pH.
- If possible, rain with rainwater that does not affect the pH.
- Provide compacted soil with humus and drain in case of waterlogging.
- Fertilize with sulfuric ammonia or rhododendron fertilizer.
- Spread generously peat bed or spruce needles.
Forms of iron fertilizers
Iron is either contained as a trace element in many complete fertilizers or you give special iron fertilizer. These contain water-soluble iron chelate (EDTA) or ferrous sulfate as a nutrient. The starting materials for this are industrially processed iron salts, minerals and rock flour. Iron (II) sulphate is also formed from elemental iron and sulfuric acid. Ferrous sulfate is poisonous, so iron fertilizer should be treated as carefully as a pesticide with this form of iron, and the use of fertilizer should be carefully considered - especially if pets or children have access to the garden and you want to use the fertilizer extensively on the lawn,
Iron fertilizer is available as granules or liquid fertilizer, but also many organic substances contain iron. Common liquid fertilizers are for example Ferramin from Neudoff or Fetrilon from Compo. In addition, granules are also offered as iron fertilizers - mostly for the lawn.
Apply iron fertilizer correctly
As with all fertilizers, it is important to follow the recommended dosage and not fertilize in hot sun or over 25 degrees Celsius on hot days. Fertilizer granules are loosely sprinkled and well watered, liquid fertilizer can either be distributed with the watering can or spread as foliar application with the garden sprayer.
Iron (II) sulphate is corrosive when combined with moisture, so protective goggles and gloves are just as required as long clothing and sturdy shoes. On terraces, paving stones and tiles, iron fertilizer can leave stubborn stains. This is also very small in the instructions for use, but the sellers usually do not point out enough. This is not so dramatic with iron fertilizers with iron chelates, the compound is not toxic.Nevertheless, these fertilizers should also be stored out of the reach of children.
Iron fertilizers are often sold as an anti-moss agent in the lawn because mosses are sensitive to iron regardless of the iron form - they turn black and can easily be shaved off. Anyone who manages fertilizer with ferrous sulphate should not let children or pets on the lawn for at least three to four days afterwards. Remember to not walk directly on stone surfaces after fertilizing, but to clean the soles of the shoe - otherwise clear footprints remain behind.
Iron fertilizer against acute iron deficiency
Even if the causes of iron chlorosis have been remedied in the garden, it takes a few weeks or even months for the measures to take effect and for the plants to be able to use their own iron supply from the soil again. Until then, you can help the plants with liquid iron fertilizer, which you spray as a foliar application on the foliage and so can be directly absorbed by the plants. The yellow leaves are not green again, the new shoots, however, are again in the rich green.
There are liquid or powdered foliar fertilizers consisting of synthetically produced nutrient salts. In order to avoid damage to the leaves, foliar fertilizer is injected with a lot of water and, if possible, in the evening - and preferably on moist leaves. Afterwards it should not rain for a few hours.