Potassium deficiency guide

Potassium deficiency guide

It is necessary for all activities having to do with water transport and the opening and closing of the stomata.

Potassium takes care of the strength and the quality of the plant and controls countless other processes such as the carbohydrate system. 

About potassium in short

What is it and what does it do?
Potassium takes care of the strength and the quality of the plant.
Controls countless other processes such as the carbohydrate system.
What can you see?
Dead edges on the leaves.
What can you do?
In case the EC in the substrate or potting mix is high, you can rinse it with clean water.
Add potassium yourself.

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Symptoms of a deficiency

Evaporation is reduced if there is a shortage of potassium. A consequence is that the temperature in the leaves will increase and the cells will burn. This occurs mostly on the edges of the leaves, where normally, evaporation is highest.

Development of a deficiency

  • Tips of the younger leaves show gray edges.
  • Leaves turn yellow from the edge in the direction of the veins and rusty colored dead spots appear in the leaves.
  • The tips of the leaves curl up radically and whole sections of the leaves begin to rot. The leaves keep on curling and ultimately fall off.
  • An extreme shortage produces meagre, unhealthy-looking plants with strongly reduced flowering.

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Reasons for a deficiency

  • Too little, or the wrong type of fertilizer.
  • Growing in potassium-fixed potting mixes.
  • An excess of sodium (kitchen salt) in the root environment, as sodium slows down potassium intake.

Solutions for a deficiency

  • In case the EC in the substrate or potting mix is high, you can rinse with water.
  • Add potassium yourself, either in inorganic form: Dissolve 5 – 10 grams of potassium nitrate in 2.5 gallons of water. In acidic potting mixes, you can add potassium bicarbonate or potassium hydroxide (5ml in 2.5 gallons of water).
  • Add potassium in organic form: Add a water solution of wood ash, chicken manure or slurry of manure (be careful not to burn the roots). Extracts of the grape family also contain a lot of potassium.

For your information

  • Potassium is absorbed quickly and easily by the plant. In a hydroponic system results get visible within several days. Potassium supplementation by leaf fertilization is not recommended.
  • Too much potassium will cause salt damage, calcium and magnesium deficiencies and acidification of the root environment!

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Manganese deficiency guide

Manganese deficiency guide

Manganese is an essential trace element for all plants. Manganese acts as an activator for different enzyme reactions in the plant, for example in water-splitting during photosynthesis, the synthesis of amino acids and proteins and the build up of plant cell membranes and chloroplasts.

Manganese is generally taken up via the roots. Once inside the plant it is difficult to transport but not as difficult as calcium or iron for example. Silicon and molybdenum improve the transport possibilities for manganese in the plant.

About manganese in short

What is it and what does it do?
The metal manganese is an essential trace nutrient and acts as an activator for different enzyme reactions in the plant.
What can you see?
Yellow stripes appear between the leaf’s side veins.
What can you do?
Using products that contain trace elements (Tracemix).

Manganese deficiency guide

Symptoms of a deficiency

A manganese deficiency causes different physiological changes in the plant due to a decrease in protein production. Among others, this causes less nitrate to be fixed in the plant, which can lead to dangerously high levels of nitrate. Additionally, a lot of chemical reactions in plant cells slow down which may result in a build up of organic acids.

Development of a deficiency

The progression in chronological order:

  • Yellow stripes appear between the leaf’s side veins on the larger leaves at the top of the plant.
  • The yellowing between the side veins spreads further over the leaf and small, yellow/brown necrotic spots can form.
  • The final result is a small plant (-10%) with minimum fruit/flower production.

Manganese deficiency guide

Reasons for a deficiency

In practice, the most common reason is that the pH in the substrate is too high. Like iron, manganese is easily dissolved at a low pH value in the substrate. If the pH is too low, a risk of excess manganese may occur. At high pH values manganese precipitates into manganese oxide (MnO2) which cannot be taken up by the plant which can cause deficiency.

Solutions to resolve a deficiency

  • Check the medium’s pH when the first symptoms are noticed. High pH values mean that there is less manganese available for the plant. By lowering the pH of the nutrition (pH minus (down)) the medium’s pH can be lowered to 5.0 – 5.5.
  • Low substrate temperature can be the cause of reduced manganese absorption. If a deficiency is noticed, check that the substrate temperature is sufficiently high (68 – 77 oC) during the day.
  • Using products that contain trace elements may also help. A manganese deficiency is usually not a problem on its own. To facilitate manganese transportation in the plant, molybdenum is needed. Thus, the problem may well be a molybdenum deficiency. High levels of phosphorus may also result in a reduced availability of trace elements like zinc, copper and (of course) manganese. CANNA advises to use a mix of all needed trace elements. Trace elements can be given to the plant both in the feeding and by spraying the leaves. Spray the plant at the end of the day and spray daily with water after spraying to prevent burning.

Excess Manganese!

When there are high concentrations, manganese precipitates into manganese oxide (MnO2 or black manganese) which causes yellow-brown spots on the leaves. Initially, small spots will appear along the main and side veins of the leaf, following this, the spots will spread out from the veins. Excess manganese can be a result of a low pH in the substrate.

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