Nutrient

Function

Deficiency symptoms

Sources

Nitrogen
(N)

Required for all phases of growth and development

Lower leaves light green or yellowish; plant is stunted.

Blood meal, composted poultry manure, feather meal, worm castings.

Phosphorus
(P)

Strengthens stems, helps in resistance to pests and diseases, fruiting and flowering

Lower leaves and stem are reddish; upper leaves are dull, pale; failure to flower or produce fruit, premature dropping of fruit.

Bone meal & rock phosphate (slow release), colloidal (soft) rock phosphate, fish meal, fish hydrolysate - Other sources

Potassium
(K)

Required for formation of all sugars, starches and proteins; contributes to cold-hardiness; root development.

Lower leaves spotted, mottled or curled; underdeveloped roots, stem tissue may appear weak

Composted manure, wood chips, greensand, seaweed (kelp), wood ashes (use with caution). Beware of excess K

Calcium
(Ca)

Required for cell growth and division, helps plants use nitrogen

Tip burn on lettuce, blossom-end rot in pepper and tomatoes, development of thick woody stems.

Bone meal, gypsum, lime, ground oyster shells. Soluble Ca may be helpful during growth. More

Sulfur (S)

Constituent of protein and certain vitamin complexes.

New leaves are yellowish.

Composted manure, gypsum, Sul-Po-Mag.

Magnesium (Mg)

Constituent of chlorophyll; required for enzyme action.

Whitish patches appear first on older leaves, between leaf veins.

Dolomitic limestone, Sul-Po-Mag, Epsom salts