Common Nutrient Deficiencies in Plants

AlanGardenMaster
Published on December 5th 2019
11
a plant showing signs of nutrient deficiency
Plants are amazingly resilient. They'll muddle along even when they lack an essential nutrient or trace element. But if you want your plants to be at their best, then it's good to know what they might need when symptoms appear.
And what better time to respond to your plant's needs than World Soil Day! Check out the recommended articles at the bottom of the page to learn more about all things soil.

The basics

  • It's more likely that your plant is suffering from nutrient deficiency rather than excess.
  • Plants that grow in fast-draining sandy soils are more likely to suffer from nutrient shortages than those in soils with high clay content.
  • Container grown plants are much more likely to suffer from nutrient deficiencies.
  • Potting composts that contain soil are less likely to suffer from both major and minor element deficiencies and excesses.
  • Symptoms are most likely to appear on fruit and vegetable plants
  • Soil with either a high or low pH - that is very alkaline or acid - are likely to show signs of plant nutrient deficiencies.
  • Generally, poor growing conditions can cause plants to struggle to get the nutrients they need. This might be caused by waterlogging, excessively dry soil, poor soil preparation and many other factors.
a deficient tomato leaf
A deficient tomato plant

Macronutrients

  • These are the major nutrients that plants require to grow.
  • You will usually see major nutrients shortened to their chemical signs. N for nitrogen, P for phosphate and K for potassium.
  • You'll find percentage figures on packs of fertiliser, usually printed within a small box.
  • For human-made fertilisers, this must be displayed on the pack but is often missing on organic fertilisers as they tend to be more variable.

Nitrogen (N)

Plants that lack nitrogen tend to look weak and 'weedy'.
  • They'll have yellow leaves and stems that are sometimes too spindly to hold the plant upright.
Yellow pear leaves
Yellow pear leaves caused by nitrogen deficiency
  • Application of a woody mulch - rather than a composted one - can tie up soil nitrogen temporarily for plants to access.
Nitrogen is rapidly leached out of soils if not taken up by plant roots, to be washed away and wasted. For that reason, nitrogen should be applied in spring and perhaps more frequently than other major nutrients.

Phosphorous (P)

  • Also referred to as phosphate, phosphorus is needed by plants to develop a healthy root and shoot system.
  • Plants lacking is phosphorous have growth is slow and stunted.
  • Foliage and stems become bluish-green and then can become reddish/purple.
  • Phosphorus deficiency is not common but might occur where rainfall is high or in heavy clay soils.

Potassium (K)

  • Also referred to as potash.
  • Leaf tips and edges become brown and curled. Occasionally, purple spots appear on the undersides of leaves.
  • Chlorotic yellow areas might appear between the leaf veins.
  • Potassium deficiency affects growth in roots, shoots, leaves, flowers and fruits.

Intermediate nutrients

Magnesium (Mg)

Interveinal chlorosis of tomato leaves
Interveinal chlorosis of tomato leaves
  • This nutrient is required by plants to produce chlorophyll, which is essential for photosynthesis.
  • When lacking in chlorophyll, leaves become chlorotic (white or pale) and often fall prematurely.
  • Some crops are more likely to show symptoms of magnesium deficiency than others. Keep an eye out for it on tomatoes, raspberries, apples, Camellia, grapevines, roses, azalea, Rhodoendron, Pieris and heathers.
A Potentilla shrub with chlorotic leaves
Potentilla shrub showing chlorotic leaves
  • High applications of potash feeds can lead to magnesium deficiency as plants will take up potassium in preference to magnesium.
  • Magnesium deficiency is more common in soils that are highly alkaline and very sandy.

Calcium

  • Calcium is a crucial nutrient needed by plants for cell wall development.
  • Plants lacking calcium will look necrotic (distorted dying tissue).
  • Shoot tips and the main growing point are the first to show symptoms and die.
A chlorotic blackcurrant leaf
A chlorotic blackcurrant leaf
  • Calcium is the element of lime that alters the pH of soils.
  • Many trace elements become unobtainable or even toxic to plants if the soil pH is too high or too low.

Sulphur (S)

  • Sulphur deficiency, or sulfur as the Americans call it, produces similar symptoms as calcium deficiency.
  • Instead of symptoms primarily occurring on shoot tips, plant growth becomes pale and yellow (necrotic) throughout the whole plant.
  • Inevitably this leads to stunted growth.
  • Fortunately, sulphur deficiency is uncommon.

Minor or Trace Nutrients

Manganese and Iron

  • I've lumped these together because they produce the same symptoms.
  • Interveinal chlorosis is a key symptom. This is when the leaf veins remain green, but the tissue between them bleaches.
  • In members of the Ericaceae family ( Rhododendron, Pieris, Erica, Calluna, blueberries, etc.), the edges of the leaves may also have a brown scorch.
  • These deficiencies are most likely to turn up among plants that like acidic soils.
  • Unless your plants are in very alkaline soils, they are unlikely to suffer from a deficiency of these trace elements.
  • Keep an eye on plants grown in containers that may have poorly prepared potting composts.

Boron (B)

  • There are several different symptoms of boron deficiency.
  • Watch for stunted growth and tip dieback on lettuce. Swedes, turnips and celeriac will rot. Celery stems will have brown cracks and dimples will appear on pear fruits.
  • Fortunately, boron deficiency is rare.
celeriac
Celeriacs will rot when deficient in boron

Molybdenum (Mb)

  • Molybdenum deficiency is something to watch out for when growing the cabbage family (Brassicaceae).
  • Symptoms to look out for are twisted leaf tips and distorted leaves (aphids can also cause this).
  • If you have an alkaline soil with a high pH, then molybdenum deficiency is more likely to occur, but also can't be ruled out in acidic soils.

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