They are a shortage or imbalance of the

To grow well, plants need a wide range of nutrients in various amounts, depending on the individual plant and its stage of growth. The three key plant nutrients usually derived from soil are nitrogen, phosphorus and potassium, while carbon, oxygen and hydrogen are absorbed from the air. Other vital soil nutrients include magnesium, calcium and sulphur. Most garden soils contain enough nutrients to promote healthy plant growth.

• The main nutrients (macronutrients) plants need are nitrogen, phosphorus, potassium, calcium, magnesium and sulphur. 
• Trace elements (micronutrients) such as boron, chlorine, copper, iron, manganese, molybdenum and zinc are needed in smaller amounts for healthy plant growth. 

Some deficiencies exhibit similar symptoms, making accurate identification challenging. Analysis of leaf tissue is offered by specialist laboratories, but this is very expensive. 

Deficiencies cause plants to grow poorly and show a range of symptoms. Use this diagram to help you identify which deficiencies you have on your plants.
 

Use the nutrient deficiency shown above to help you match the symptoms to the potential remedies. 

Nitrogen (N) – needed for green and leafy growth

Deficiency symptoms: Spindly, stunted plants with pale yellow leaves and, occasionally, pink tints. Older leaves are affected first, but the yellowing spreads to younger foliage.  

Cause: A lack of nitrogen. This nutrient is easily washed out of the soil by rain and from compost by watering. Soil can be deficient by spring and compost in containers after a few months use. However, poor spring growth of plants in the ground could also stem from winter waterlogging, frost damage or cold weather.

Remedy for containers: Plants need a general-purpose liquid feed, for example – Miracle-Gro® Performance Organics Fruit & Veg Concentrated Liquid Plant Food.

Remedy for the ground: Long-term improvements can be made by mulching with organic matter (such as garden compost, manure or plant-based soil conditioner) to provide a small, steady amount of nitrogen.

A short-term fix is to apply nitrogen-rich fertilisers according to label instructions, such as poultry manure pellets or Miracle-Gro Performance Organics All Purpose Granular Food. 

Problems: Overapplication of nitrogen fertilisers is damaging to plants. Nitrogen toxicity symptoms include dark green leaves and stunted growth. Nitrogen is also prone to being washed away by rain (leaching) presenting a pollution risk.
 

Phosphorus (P) - needed for healthy root and shoot growth

Cause: Phosphorus shortage, but this is uncommon as it doesn't readily wash away. Very acidic or alkaline soils reduce its availability. Wet, heavy clay or waterlogged compost (especially in cool weather) hinders root uptake.

Remedy in containers: Regularly liquid feed containers with a general-purpose liquid fertiliser. Be careful not to overwater containers, especially in cool weather. 

Remedy in the ground: In the long term, improve soil structure and drainage by mulching with organic matter such as homemade garden compost. This boosts root growth and phosphorus uptake. Delay planting out tender crops and ornamentals until the end of May or early June, when soil is drier and warmer.

In the short-term, use general-purpose fertiliser such as Vitax Q4 or fish, blood and bone. Phosphorus shortages in cultivated soils are rare, so application of phosphorus-rich fertilisers such as bonemeal are rarely needed unless identified by results of soil analysis.

Problems: Phosphorus fertilisers can cause water pollution. Although it is not readily leached, phosphorus can be washed away with surface water runoff, particularly on slopes. Some plants, such as those in the Proteaceae family, are sensitive to high levels. 

Potassium (K) – also called potash, needed for flowering, fruiting and general hardiness

Deficiency symptoms: Yellow or purple-red leaf tints with browning that begins at the edges of mature leaves. Also causes poor flowering and fruiting.

Cause:  Shortage of potassium is common on light, sandy or chalky soils where it is easily washed away (leaching). Clay soils, by contrast, hold onto potassium.

Remedy: In the long-term, enrich the soil by applying a mulch of organic matter such as homemade garden compost.

In the short-term, apply potassium-rich fertilisers to soil according to label instructions. Examples include comfrey pellets, Vitax Organic Potato & Vegetable Fertiliser and fish, blood and bone. Crops and plants in containers may need additional feeding with a potassium-rich fertiliser. Use seaweed-based and organic tomato liquid feeds.

Problems: Overapplication of potassium fertilisers reduces magnesium uptake. This leads to magnesium deficiency, particularly in tomatoes. See Magnesium deficiency below.
 

Magnesium (Mg) – needed for green leaves 

Cause: Shortage of magnesium in soil, particularly on light, sandy soils. Over-use of potassium-rich fertilisers (such as tomato feed) can cause magnesium deficiency, as plants take up potassium in preference to magnesium.

Remedy:  For long-term improvement with deficiencies on light, free draining soils, apply magnesium sulphate (Epsom salts or Kieserite) to the soil at 30g per sq m. Avoid overfeeding with high potassium feeds.

On acidic soils consider using naturally occurring Dolomite limestone (calcium-magnesium carbonate) at 100g per sq m. Do not use this around ericaceous (acid-loving) plants.

Short-term, apply Epsom salts as a foliar feed in summer. Dilute at a rate of 20g of Epsom salts per litre of water. Spray on or use a watering can to wet leaves. Repeat two or three times a fortnight. 

Problems: Foliar feeding can cause leaf scorch in sunny weather. Only apply when it’s dull and overcast. 
 

Manganese (Mn) and Iron (Fe) - needed for green leaves 

Cause: Ericaceous plants are vulnerable when growing on alkaline and chalky soils, or in containers where ericaceous compost wasn’t used. These nutrients are less available for plant roots to take up in alkaline conditions. 

Remedy: Long-term, grow plants suited to your soil pH. Where deficiencies occur on slightly acid to neutral soils, up to pH 7, reduce pH with acidifying substances. If gardening on clay or highly alkaline soils, lowering the pH is very difficult. If free lime or chalk is present, acidifying such soils isn’t practically possible. Alternatively, grow ericaceous plants in containers of ericaceous compost.

Short-term, feed plants in containers with liquid seaweed products containing sequestered iron. In soil, apply synthetic chelated (sequestered) iron and manganese fertilisers. For suspected manganese deficiency, foliar feed with products containing manganese sulphate (sulphate of manganese).
 

Calcium (Ca) - needed for cell wall formation

Deficiency symptoms: Variable depending on plants, but mainly affects fruit and vegetables. Examples include blossom end rot in tomatoes, bitter pit and water core in apples. 

Cause: It is very rare for soils, growing bags or potting media to lack calcium. Deficiencies are caused by poor distribution of calcium within the plant following the drying out of the soil or compost.

In crops, deficiency can also occur when plants are pruned hard or when overfed with potassium-rich fertilisers, such as tomato feed.

High air humidity in greenhouses or polytunnels reduces transpiration and roots stop drawing up water that contains calcium. 

Remedy: Ensure fruit and vegetable plants aren’t allowed to dry out. Mulch apple and quince trees to reduce water stress. Avoid overfeeding with fertilisers high in potassium and nitrogen. Refrain from excessive pruning. Where humidity is high, improve ventilation.

Common calcium deficiencies:  

Molybdenum (Mo) – supports a variety of plant growth functions

Deficiency symptoms: Elongated twisted leaves. Occurs in cauliflowers, causing a disorder called whiptail. Also affects other brassicas when grown on acid soil. 

Cause: Molybdenum deficiency is an issue in acid conditions because less is available for plant roots. Molybdenum is needed in tiny quantities, so soil shortages are rare.

Remedy: Long-term, test soil pH where growing brassicas. If it’s less than 6.3, consider liming soil to raise the pH to 7 (neutral). This makes molybdenum more available to plants. See our advice on lime and liming for further details. 

Short-term, treat soil with fritted trace elements that contain molybdenum prior to sowing or planting. See our advice on using fertilisers.

Problems: Avoid excessive liming. This can make the soil too alkaline, potentially leading to other nutrient deficiencies. 
 

Boron (B) – needed for plant cell formation

Deficiency symptoms: Generally stunted growth with browning.
Vegtables: Leaf tip dieback on lettuce. Brown cracks in celery stalks. Discoloured flesh or rotting hearts in swedes, turnips and celeriac. Hollow stems and browning heads in cabbage, cauliflower and calabrese.
Fruit: Dimpled pear skin with corresponding brown patches in flesh. Distorted strawberry fruits. 

Cause: Boron is less available to plant roots in alkaline soils (above pH 7). However, soil shortages tend to be rare. 

Remedy: Test soil pH. Avoid liming on already alkaline soils, since this reduces availability of boron. Consider acidifying soil to lower pH. However, if gardening on clay or highly alkaline soils, lowering the pH is very difficult. If free lime or chalk is present, acidifying such soils isn’t practically possible.

Short-term, treat soil with fritted trace elements that contain boron prior to sowing or planting. See our advice on using fertilisers.

Problems: Over application of fertilisers containing boron is a risk, as the difference between deficiency and damaging excess is narrow. Apply fertilisers carefully according to packaging instructions.
 

Plants struggle to get nutrients for several reasons:

• Container plants quickly deplete compost nutrients (lasting 6-8 weeks), need consistent watering for uptake, and soggy compost hinders absorption. 

• Acid-loving plants need ericaceous compost and acid soils (below pH 7) to take up iron and manganese and extreme soil pH (acidic or alkaline) locks up certain nutrients. 

• In the ground, sandy/stony soils leach nutrients easily.

• Wet or dry soil also limits root function and nutrient absorption. 

• Poor planting practices like rootbound plants or incorrect depth prevent proper establishment and nutrient access.

Choosing plants suited to your soil and good planting care are key to success.