Nutrient Deficiencies: Characteristics

Nutrient Symptoms Solution
Iron leaves are chlorotic (yellow) between the veins; veins remain green. Necrotic (dead) spots usually absent. May have death of margins and leaf tips, sometimes extending inwards developing large areas. spray plants with a solution of iron chelates, either on the foliage or as a soil drench e.g., Tru-Green: Iron Chelates. As well, Sequestrene may be used.
Phosphate foliage is dark green, growth is retarded. Lower leaves sometimes yellow between veins, but more often purplish. Leaves often dropping early. apply a slow release fertilizer to top of pot, as directed on package e.g., 14-14-14 or 19-6-12, and bonemeal or blood meal.
Nitrogen foliage is light green, growth is stunted, stalks slender. Leaves small, lower ones lighter yellow than upper. Yellowing followed by a drying to a light brown color, usually little dropping. apply fertilizer such as calcium nitrate 17-0-0. Avoid heavy application as leaf tip burn may result. Manure is an excellent source of organic nitrogen.
Potassium usually seen as symptoms on older, lower leaves. Lower leaves mottled, blotchy color, usually with dead areas near the tip and margins. Yellowing begins at the margin and continues towards the centre. Margins later becoming brown and curving under. Older leaves dropping. apply fertilizer such as 0-0-48, Potassium fulfate, wood ashes, or coffee grounds.
Sulfur leaves are light green, veins are lighter than adjoining interveinal areas. Some necrotic spots. Little or no drying of older leaves. Stems often hard and brittle. sprinkle dry powdered sulfur or wood ashes on surface of soil. Ammonium sulfate or Magnesium sulfate may also be used (1 teaspoon/gallon water).
Excess Salt salt damage often seen as slow growth, yellowing of leaves, or wilting. In more serious cases, leaf scorch, shedding of leaves, or even collapse of the entire plant may occur. see below

To avoid the problem of salt buildup in houseplants:

  1. avoid single, heavy applications of fertilizer; try using slow release materials.
  2. water thoroughly and not too often; a thorough watering will leach excess salts down through the pot.
  3. make certain that pots drain well
  4. thoroughly soak old clay pots before reusing them because salts accumulate in the porous walls
  5. when possible, water plants with rainwater

If you discover an excess of salt problem, you should leach out the excess salt by the following process:

  1. flush out the pot using about 2 quarts of water for a 6-inch pot
  2. wait one hour, then repeat
  3. wait another hour, then repeat, for a total of three flushings
  4. fertilize to replace the soil nutrients lost in the leaching process