Identifying nutrient deficiency in plants and trees.

DeficiencySymptomsCauseRemedy
Nitrogen (N) Spindly yellow plants or yellow leaves, sometimes with pink tints. Nitrogen promotes green, leafy growth and deficiency results in yellowing and stunted growth. Nitrogen is very soluble, so is easily washed out of the soil in winter rains, leaving the soil deficient in spring, just when plants are putting on new growth. Nitrogen deficiency is a common cause of yellow leaves in spring.In the long term, mulching with organic rotted manure will increase the nitrogen in your compost. . In the short term, applying high nitrogen organic fertilisers such as sulphate of ammonia or organic poultry manure pellets will remedy the problem.
Potassium (K)Yellow or purple leaf-tints with browning at the leaf edge and poor flowering or fruiting.Potassium is needed for controlling both water uptake and the process allowing plants to harness energy from the sun (photosynthesis). Potassium promotes flowering, fruiting and general hardiness. Shortages are more likely on light, sandy or chalky soils where potassium is easily washed away. Clay soils, by contrast, hold potassium within their structure.Apply organic high potassium fertilisers such as sulphate of potash, or certain organic potassium sources derived from sugar beet processing.
Phosphorus (P)Slow growth and dull yellow foliage.Phosphorus is needed for healthy roots and shoot growth. Soil shortages of phosphorus are rare, but may occur in areas with high rainfall and heavy clay soil.Apply organic fertilisers such as superphosphate or bone meal.
Magnesium (Mg)Yellowing between the leaf veins, sometimes with reddish brown tints and early leaf fall. Magnesium deficiency is common in tomatoes, apples, grape vines, raspberries, roses and rhododendrons.Magnesium is needed for healthy leaves and for plants to harness energy from the sun (photosynthesis). Soil shortages of magnesium are more common on light, sandy soils. Over-use of high-potassium fertilisers (such as tomato feed) can cause magnesium deficiency, as plants take up potassium in preference to magnesium.In the short term, apply Epsom salts as a foliar feed in summer. Apply two or three times at fortnightly intervals, spraying in dull weather to avoid leaf scorch. In the long term apply to the soil around the roots either Dolomite limestone (calcium-magnesium carbonate) at 100g per sq m (4oz per sq yd) or Epsom salts (magnesium sulphate) at 30g per sq m (1oz per sq yd). Dolomite limestone will make the soil more alkaline, so should not be used around ericaceous (acid-loving) plants such as tomatoes, rhododendrons or camellias, or where the soil is already alkaline.
Manganese (Mn)Manganese deficiency symptoms, which often look like those of iron deficiency, appear as interveinal chlorosis (yellow leaves with green veins) on the young leaves, and sometimes tan, sunken spots that appear in the chlorotic areas between the veins. Plant growth may also be reduced and stuntedManganese is important for allowing plants to harness the energy of the sun (photosynthesis). Soil shortages are rare, but manganese and iron can be unavailable to plant roots in alkaline conditions. Ericaceous (acid-loving) plants are particularly vulnerable when growing in alkaline soils or potting composts.Apply organic sulphate of potash magnesia.
Iron (Fe)Yellowing between the leaf veins with browning of leaf edges on acid-loving plants.Iron is important for allowing plants to harness the energy of the sun (photosynthesis). Soil shortages are rare, but manganese and iron can be unavailable to plant roots in alkaline conditions. Ericaceous (acid-loving) plants are particularly vulnerable when growing in alkaline soils or potting composts.Apply organic chelated iron treatments, to the soil around the plant roots. Natural chelates can be found in soil organic matter. Well rotted organic manure can give beneficial iron.
Molybdenum (Mo) Elongated twisted leaves on cauliflowers or other brassicas growing in alkaline soil. Molybdenum deficiency is normally seen in cauliflowers and brassicas, particularly when growing in insufficiently alkaline soil.Molybdenum is required for a variety of plant growth processes, but is needed only in tiny quantities. Soil shortages of molybdenum are rare, but it can be less available to plant roots in acid conditions. Liming the soil will help in the long term, as making the soil more alkaline will help to make the molybdenum more available.
Boron (B)Stunted growth and tip dieback on lettuce, brown cracks in celery; rotten swedes, turnips and celeriac; dimples in pears with brown patches underneath.Boron is required for healthy plant cell formation. Soil shortages are rare, but this nutrient can be less available to plant roots in alkaline conditions.Micronutrients can be powerful tools, but a little goes a long way, and you must be careful. One tablespoon household borax dissolved in a gallon of water can rectify the deficiency.
Sulphur (S)A sulfur deficient plant will experience yellowing or pale green colouring throughout the plant. Younger leaves suffer from chlorosis with their tips becoming necrotic. Overall plant development and growth will be stunted without enough sulfur in the soil. After transplanting, seedlings are likely to have higher mortality rates than normal. These symptoms resemble those of a nitrogen deficiency. To distinguish between the two deficiencies look for red pigmentation in the veins of young leaves for nitrogen deficiencies, while sulfur deficiencies will not typically affect the vein patterns on leaves.sulfur deficiencies often occur in areas with heavy rainfall and weathered soils. Since sulfur is water soluble, heavy rain causes the soil to be leached of its sulfur content, leading to sulfur deficiencies in plants. In coastal regions, sea spray can be a substantial source of sulfur, but even islands experience sulfur deficiencies in their soil. Areas with high levels of phosphorus may displace sulfur from the soil, causing higher rates of sulfur deficient plants.Adding sulfur to acidify soil is not a quick fix or even a permanent fix; it’s a slow process, which can take a few months or even a year or two. Bacteria in the soil help transform sulfur to sulfuric acid that plants can utilize, and when soil bacteria have used up the sulfur you’ve added. Naturally mined gypsum can be used as an organic method to add sulphur to your plants.
ZincStunting, reduced height, brown spots on leavesZinc deficiency occurs when plant growth is limited because the plant cannot take up sufficient quantities of this essential micronutrient from its growing medium. Organic zinc sulfate.