Calcium (Ca): Importance for Plants, Addressing Nutrient Deficiencies and Correct Fertilising
Plants affected by calcium deficiency may look similar to those scorched by fertilisers. They have dark green leaves, scorched edges and shoots that die back. Learn to recognise the first symptoms and act in time before the calcium deficiency affects your harvest.
Calcium is an important component of pectins in cell walls and is essential for the formation of new tissues. Calcium also acts as a signalling molecule and contributes to the regulation of stomata – pores through which plants release water vapour. Together with nitrogen, phosphorus, potassium, magnesium and sulphur, calcium is classified as a macronutrient, which plants consume in the greatest quantities. Calcium is important for plants throughout the entire growth cycle and in all growth phases.
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Calcium deficiency in plants
Calcium deficiency is most apparent in young shoots, which turn yellow or purple and begin to dry out. The leaves of plants affected by calcium deficiency are darker and have clearly defined necrotic spots. Older leaves dry out from the edges, similarly to fertiliser burn.
Plants need calcium to produce new root hairs. When calcium is deficient, roots cannot grow properly, begin to rot and become more susceptible to bacterial and fungal attacks. The roots of plants affected by calcium deficiency often have an unhealthy brown colour.
- dying, twisted shoots at the tips
- clearly defined necrotic spots on new and older leaves
- drying leaf edges
- dark green leaves
- stunted plants
- sparse flowers
- rotting roots
Calcium deficiency can occur when growing in soil, in coco substrates and in hydroponic systems. In soil, it is often caused by pH that is too low (acidic soil), which prevents plants from absorbing calcium. Coco fibre has a high cation exchange capacity (CEC) and binds calcium ions. Therefore, when growing in coco, it is important to use CalMag (a supplementary fertiliser containing calcium and magnesium). Calcium and magnesium should likewise be added to water with a low mineral content (distilled water, reverse osmosis water or soft water).
How to provide plants with calcium
When growing in beds, the most common reason for calcium deficiency is soil that is too acidic. To increase the pH of soil in beds, calcium dolomite is usually used. It provides plants with calcium and stabilises soil pH over the long term.
When growing in pots or hydroponically, the quickest way to supplement calcium is with a supplementary CalMag fertiliser, which contains immediately absorbable calcium and magnesium. At Higarden, you will also find a wide range of fertilisers containing calcium intended for different growing methods and systems.
- Plagron Calcium Kick – pH regulator for growing in soil substrates, for both outdoor and indoor use.
- Green House Powder Feeding Calcium – water-soluble single-component fertiliser containing calcium.
- BioNova Ca 15 (calcium) – single-component liquid fertiliser containing calcium, also suitable for irrigation systems.
- Canna Calmag Agent – liquid CalMag for universal use, suitable for all types of substrates.
It is important to realise that nutrient deficiencies in plants can have many causes, and resolving them correctly requires at least a knowledge of the basic principles of plant nutrition. You can find more advice and guides for outdoor and indoor growers on the Higarden blog.