Plants need the right combination of nutrients to live, grow and reproduce. When plants suffer from malnutrition, they show symptoms of being unhealthy.
Macronutrients are elements that are needed in relatively large amounts. They include nitrogen, potassium, sulfur, calcium, magnesium and phosphorus.
Micronutrients are elements that plants need in small amounts like iron, boron, manganese, zinc, copper, chlorine and molybdenum.
Both macro- and micronutrients are naturally obtained by the roots from the soil
MACRONUTRIENTS Replace macronutrients regularly (at least 1x per growing season)
(N) Nitrogen – General yellowing of older leaves (bottom of plant). The rest of the plant is often light green. Most plants absorb nitrogen in the form of ammonium or nitrate. These forms readily dissolve in water and leach away. Anything with the words “ammonium,” “nitrate,” or “urea.” Also manures.
(P) Phosphorus – Leaf tips look burnt, followed by older leaves turning a dark green or reddish-purple. Plants absorb phosphorus in the form of phosphate. This form dissolves only slightly in water, but pH strongly affects uptake. Anything with the words “phosphate” or “bone.” Also greensand.
(K) Potassium – Older leaves may wilt, look scorched. Interveinal chlorosis begins at the base, scorching inward from leaf margins. Plants absorb potassium as an ion, which can be readily leached from soil. Anything with the words “potassium” or “potash.”
(Ca) Calcium – New leaves (top of plant) are distorted or irregularly shaped. Causes blossom-end rot. Excessive calcium can limit the availability of other nutrients. Anything with the word “calcium”; also gypsum.
(Mg) Magnesium – Older leaves turn yellow at edge leaving a green arrowhead shape in the center of the leaf. Plants absorb magnesium as an ion (charged particle), which can be readily leached from soil. May be readily leached from soil if calcium is not present. Anything with the word “magnesium”; also Epsom salts (magnesium sulfate).
(S) Sulfur – Younger leaves turn yellow first, sometimes followed by older leaves. Plants absorb sulfur in the form of sulfate. This readily leaches from the soil. Sulfur may acidify the soil (lower the pH). Anything with the word “sulfate.”
MICRONUTRIENTS Replace when deficiency symptoms are evident.
(B) Boron – Terminal buds die, witches’ brooms form. Plants absorb boron in the form of borate. Problems are seen in intensely cropped areas. Anything with the words “borax” or “borate.”
(Cu) Copper – Leaves are dark green, plant is stunted. Plants absorb copper as an ion. Anything with the words “copper,” “cupric,” or “cuprous.”
(Fe) Iron – Yellowing occurs between the veins of young leaves. Plants absorb iron as an ion through their foliage as well as their roots. Uptake is strongly affected by pH. Chelated iron is readily available for use by the plant, other forms of iron may be tied up in the soil. Anything with the word “iron chelate.”
(Mn) Manganese – Yellowing occurs between the veins of young leaves. Pattern is not as distinct as with iron. Reduction in size of plant parts (leaves, shoots, fruit) generally. Dead spots or patches. Plants absorb manganese as an ion through their foliage as well as their roots. Anything with the words “manganese” or “manganous.” Often required with zinc application.
(Mo) Molybdenum – General yellowing of older leaves (bottom of plant). The rest of the plant is often light green. Plants absorb molybdenum in the form of molybdate. Anything with the words “molybdate” or “molybdic.”
(Zn) Zinc – Terminal leaves may be rosetted, and yellowing occurs between the veins of the new leaves. Plants absorb zinc as an ion through their foliage as well as their roots. High pH may limit availability. Anything with the word “zinc.”