FUNCTION OF THE MACRO AND MICRO NUTRIENTS
| Nutrient | Symbol | Function | Comments | |||
| Boron (Borax or boric acid) | B | Involved in the movement of sugars, part of the cell membrane of growing roots and shoots, influences pollen health. | Deficiency seen first in actively growing tissue (discolouring and death of new leaves and root tips). Toxic if provided at 10X requirement. | |||
| Calcium (can be present in water supply) Calcium Nitrate, Calcium Sulphate | Ca | Structural component of cell walls so a constant supply is necessary for cell strength, growth and division. Activates enzymes, influences water movement in and out of cells. | Deficiency causes stunting of new growths, stems, flowers, roots. Yellow margins may appear. Extra calcium can enhance strength of spikes. | |||
| Carbon | C | Part of a wide range of organic compounds in plants. | Available through air. | |||
| Chlorine | Cl | Helps maintain turgidity of cells through osmosis and balancing positive charges within plant solutions. | Plenty is available through water. Deficiency is rare. Excess is toxic and may cause premature leaf drop and scotching of leaves. | |||
| Cobalt | Co | Beneficial but not essential | ||||
| Copper | Cu | Component of several plant enzymes. Involved in photosynthesis, immune protection, plant respiration, sexual development of flowers. | Deficiency results in darker bluish green leaves. Younger leaves show stunting. | |||
| Iron (iron chelate) | Fe | Catalyst for the production of chlorophyll. | Deficiency seen in young leaves first (pale leaf colour, yellowing of veins). Unavailable to the plant if mix is too alkaline | |||
| Hydrogen | H | Part of a wide range of organic compounds in plants. | Available through water. | |||
| Magnesium (Magnesium Sulphate) | Mg | Part of the chlorophyll molecule. Essential in many chemical reaction systems. Part of enzymes involved in carbohydrate production and fat production. | An excessive potassium or calcium level can create magnesium deficiency which affects older leaves first. They show yellowing between veins. Leaves may drop and show black (dead) spots. Best applied separately. Can inhibit growth at levels 4 times requirements. | |||
| Manganese (manganese sulphate) | Mn | Important in photosynthesis. Activator of important enzymes involved in plant processes. | Deficiency can develop into alkaline mix. Deficiency is seen as yellow mottling on both young and old leaves. Growth of roots and the whole plant is affected. If mix is too acid too much manganese may be absorbed. Excess interferes with the uptake of calcium and magnesium. | |||
| Molybdenum (sodium molybdate) | Mo | Necessary for a cellular enzyme which converts nitrate to nitrite. Involved in production and visibility of pollen. | Required in extremely small quantities. Deficiency is rare. | |||
| Nickel | Ni | Essential trace element | ||||
| Nitrogen (general supplied through fertilisers as ammonium nitrate, Potassium nitrate or Urea) | N | Important for plant life and growth. Major part of proteins, hormones, chlorophyll, vitamins, enzymes, so is involved in a wide range of plant processes. | If deficient you will see poor growth, yellowing of leaves. Older leaves go yellow and drop off quicker than usual. If in excess leaves become very dark green and soft. Ammonium and urea reduce mix pH. | |||
| Oxygen | O | Part of a wide range of organic compounds in plants. | Available through water, air and produced in photosynthesis. | |||
| Phosphorous (Potassium Phosphates) | P | Important for a wide range of plant processes including energy transfer, photosynthesis, root and cell growth and maturity. | Deficiency is purple tinge in leaves, reduced growth and flowering. Excess can promote zinc and iron deficiency. | |||
| Potassium (Potassium Nitrate, Potassium Sulphate or Mono Potassium Phosphate) | K | Involved in a wide range of processes e.g. formation of carbohydrates, proteins, cell division in roots. Helps control the movement of air and gas in and out of plant pores. | Important in maintaining the firm texture of healthy plants and flowers. Promotes strong spikes and flowers. Deficiency shows up in older leaves first, leaves wilt, yellow and then brown along tips and edges. The plant is prone to fungal disease and root rot. Excess can affect uptake and availability of magnesium and calcium. | |||
| Sodium | Na | Essential trace element | ||||
| Silicon | Si | Beneficial but not essential | Found to improve heat tolerance and resistance to insects and fungal infections. | |||
| Sulphur (Sulphates) | S | Structural component of some amino acids (building blocks of proteins), vitamins, enzymes. Essential to produce chlorophyll. | Usually present in water supply. Included in fertilisers. | |||
| Zinc | Zn | Activator and component of several important enzyme systems. Important in the making of the growth hormone auxin in meristematic tissue and new leaves. | Deficiency causes poor growth and stunting, crinkling and mottling of new leaves. |
During winter the lower temperatures, lower light levels and shorter days reduce activity. Many growers do not fertilise at all during winter or if the temperature is below 20 degrees Celsius.
Apply fertiliser when the plant can use it. Fertilising is most beneficial during periods of active growth. This usually corresponds to the warmer months of spring summer and early autumn. Avoid fertilising a dry plant, and/or a cold plant.