How do you recognize magnesium deficiency in plants?

Magnesium is very common on earth and an estimated 2% of the earth’s crust is magnesium, but only in a bound form. These magnesium compounds mainly occur in seawater, salt basins and in old earth layers. Since magnesium also occurs in tap water, together with calcium it is responsible for the hardness of the water and thus the EC value.

What is the function of magnesium for the plant?

Magnesium is an element that is important for people and animals, but certainly for plants as well. In fact it is a building block for chlorophyll, the leaf green that gives the plant its green color. This chlorophyll plays an important role in photosynthesis and a magnesium deficiency in plants is also reflected in a reduced amount of leaf green granules, which makes the leaves turn yellow. In addition, magnesium fulfills the role of a cofactor in many plant processes, such as leaf formation.

How do you recognize the symptoms of a magnesium deficiency?

A magnesium deficiency in plants is a treacherous deficiency, since it is virtually unrecognizable during the first three to four weeks: the plant grows well and the leaves are healthy and green. The symptoms can only be recognized between weeks 4 and 6 of the growth. These manifest themselves in small rust-brown spots on the leaves under the later flowering part of the plant. This yellowing should not be confused with a nitrogen deficiency.

The striking thing about a magnesium deficiency is that especially the young leaves grow undiminished and stay healthy and green, while the older leaves are increasingly falling prey to the chlorosis and increasingly yellowing between the veins. Only in case of a severe deficiency do the younger leaves also get chlorosis. In a further stage, the spots can turn brown or even red.

Magnesium deficiency is relatively more common than other nutritional deficiencies but less in the culture on soil, since soil contains a relatively large amount of magnesium.

Causes of a magnesium deficiency in plants

The causes of a magnesium deficiency can be of a different nature, but in most cases a magnesium deficiency is the result of an incorrect ratio with other nutrients. An excess of potassium, ammonium and calcium in the substrate or in the nutrient solution ensures a reduced absorption of magnesium.

A low temperature of the substrate can also be a cause. This ensures a reduced metabolism and thus a reduced absorption of magnesium by the roots. An acidic soil environment can also be a cause of magnesium deficiency.

What can you do about a magnesium deficiency?

Fortunately, a magnesium deficiency is easily remedied in many cases. Preventively, measures can already be taken to this end by adding magnesium-based fertilizers to the nutrient water. Curatively, you can make a 2% magnesium sulfate solution with water and spray the plant with it. The fertilization with magnesium salts can be done via the root system.

To prevent a magnesium deficiency in plants, it is wise to opt for high-quality plant nutrition and to provide the plant with the right nutrients in both the growth phase and the flowering phase.

Magnesium deficiency

Magnesium is needed to give leaves their green colour, so when there’s a deficiency, yellow breaks through between the veins and around the leaf edges instead. Other colours, such as purple, brown or red, might also appear. Older leaves suffer first, and will die if they’re not given any treatment. The nutrient can be leached out of light, sandy, acidic soil by high rainfall. Or if there is too much potassium in the soil, the plants absorb that instead of the magnesium.



The absence of magnesium is detected by yellowing between the leaf veins and around the leaf margins. Other colours might break through as the green fades.

Find it on

potatoes, apples, cherries, grape vines, tomatoes, camellias, rhododendrons


For a long-term solution, apply a yearly mulch of home-made compost. This will conserve moisture, prevent the leaching of nutrients during heavy rainfall, and provide the soil with sufficient quantities of magnesium to keep your plants healthy.



Use a magnesium leaf spray, such as Epsom salts, on potatoes for a quick, temporary solution in summer. Apply Epsom salts or calcium-magnesium carbonate to the soil in autumn or winter to remedy the deficiency for next year.

Cures For Plant Nutrient Deficiencies

Have you noticed purplish leaves? What about yellow leaves on the lower parts of your plants? These are all signs of common plant nutrient deficiences. Luckily, your plants are telling you what is wrong with them and their problems are easily identifiable. Here are a few common deficiencies, how to identify them, and what you can do to help return your plants to full health.

Yellow Lower Leaves

Symptoms: Lower leaves turn yellow, shrivel, and may eventually fall off. Plants, especially big ones, normally lose leaves off the bottom as they approach the end of the flowering cycle, but yellowing that moves steadily up the layers of leaves during the vegetative stage indicates a problem. Younger plants are stunted.

Cause: Nitrogen deficiency

Cures: Nitrogen is the nutrient that plants depend on for leaf and stem growth, so it is an essential component of most fertilizers. It is particularly vital during the plants’ vegetative stage (a little less so during flowering). To fix a nitrogen deficiency, first check the label of your fertilizer to be sure that you are using the proper dilution rate—even a small discrepancy could affect your plants.

If the dilution rate is correct, your plants may still suffer from nitrogen deficiency if the nutrient solution has a pH below 5.0 or above 7.5. Use organic fertilizers, which are not high in salts, like synthetic plant foods are, as they lower pH. Choose one that’s formulated for the stage your plants are growing through, whether it is vegetative or flowering.

Very Dark New Leaves

Symptoms: New leaves are very dark green. The leaves begin to curl downward and their edges become very dry, looking a little like they’ve been burnt.

Cause: Nitrogen toxicity

Cures: The urge to turbocharge plants often entices inexperienced growers to give them extra nutrients, which can lead to damaging levels of nitrogen. Resist this impulse and instead feed your plants organic fertilizers, which gradually provide nutrients in the form that is best absorbed. Synthetic fertilizers are like steroids for people, stimulating unnatural growth and in many cases leading to toxicity. Thoroughly flush your hydroponic system or the soil with just water before beginning to feed the plants again.

Purplish Leaves and Stems

Symptoms: Stems and leaf veins have a purplish tint. (Plants with naturally purple stems and leaves have a consistent color rather than a changing color from the base to the top.) Plants’ growth is stunted, and they may lose leaves.

Cause: Phosphorus deficiency

Cures: When the temperature of your indoor garden or the nutrient solution falls below 55 degrees Fahrenheit, plants take up less phosphorus than they need. If you’ve determined that the temperature is not the problem, treat your plants to bone meal, a supplement that’s rich in phosphorus. Affected leaves do not recover, but the new growth will be healthy.

Yellow or Dead Leaf Tips and Edges

Symptoms: The tips and edges of newly matured leaves have yellow or dead areas. Stems and branches are weak and break easily. Older leaves may appear reddish and curl upward.

Cause: Potassium deficiency

Cures: Excess calcium, sodium, or nitrogen in your nutrient solution prevents plants from absorbing potassium. Those conditions can be the result of using water that is high in minerals (aka, hard water) or that’s been treated with water softeners or synthetic fertilizers. Feed your plants organic nutrients for the right stage of the plants’ growth: Potassium needs are higher during the flowering stage when the need for nitrogen is lower.

Mottled Leaves

Symptoms: New top leaves appear mottled, misshapen, or stunted.

Cause: Calcium deficiency

Cures: When the pH of your nutrient solution falls below 6.0, calcium becomes less water-soluble and plants are not able to absorb it efficiently. Adjust the pH so that it is not too acidic. If the pH is in the right range, use a bone-meal supplement, which is rich in calcium, to increase the supply of the mineral for your plants.

Yellow Older Leaves

Symptoms: The older leaves (lowest on the stem) turn yellow or bright green, starting at their edges, and may even become white while veins remain dark green. The leaves begin to curl upward and eventually drop off.

Cause: Magnesium deficiency

Cures: The pH levels of the nutrient solution must be between 6.0 and 6.5 for plants to absorb magnesium, and plants need appropriate levels of calcium to take up and use magnesium, too. When you need to add supplemental magnesium, Epsom salts (magnesium sulfate) are a widely available source. Bear in mind that leaves afflicted by a magnesium deficiency probably won’t recover, but the yellowing and loss of lower leaves should stop when the problem is corrected.

Brown, Mushy Roots

Symptoms: Plants’ roots are brown and mushy rather than white and firm. Leaves droop and are pale green to yellow.

Cause: Oxygen deficiency

Cures: When plants’ roots are immersed in stagnant water, they become oxygen deprived and develop root rot. Hydroponic systems work best when the nutrient solution is oxygenated with an air pump as it’s delivered to the plants. Soil-grown plants suffer from oxygen deficiency when they are over-watered. Give the soil a chance to dry out between watering and give your plants only the amount of water they can absorb in a few hours. Once a plant suffers from root rot, it’s nearly impossible to rescue it.

Bands of Yellow on Leaves

Symptoms: Younger top leaves have yellow between the veins, creating a banded appearance, and they begin to grow closely together in bunches. They may also be gnarled or twisted rather than their normal shape. If the plant is in its flowering stage, the buds may die off.

Cause: Zinc deficiency

Cures: Zinc is vital for plants’ production of chlorophyll and healthy leaf and stem development. As with other minerals, alkaline and acidic conditions (high and low pH) block plants from absorbing zinc. Bone-meal supplements both raise the pH and increase plants’ calcium content, which helps them better absorb zinc.

Stunted Growth

Symptoms: Stunted growth. Plants take up less water or nutrient solution than normal.

Cause: Carbon dioxide deficiency

Cures: When carbon dioxide levels are low, plants are not able to photosynthesize efficiently and their growth slows. Since you exhale carbon dioxide with every breath, talking to (or at least around) your plants can increase the available carbon dioxide. A fan blowing gently in your grow room refreshes the air around plants and brings them a new supply of carbon dioxide. A fan with outside ventilation is even better. For grow rooms with a high concentration of plants, a carbon dioxide generator helps ensure that there’s always enough.

Have These Deficiencies Appeared In Your Garden?

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Phosphorus Deficiency In Cannabis Plants

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One factor that growers must constantly be aware of when cultivating their plants is the risk of nutrient deficiency. Cannabis plants require an array of important nutrients that carry out vital biological functions throughout the grow cycle. If a certain key nutrient is missing during the vegetative or flowering stages, plants will start to display symptoms of deficiencies. These signs can help growers determine what is missing and therefore, what needs to be added to the soil before it is too late. One of these vital nutrients is phosphorus.


Phosphorus plays an important role in the health of all living organisms. Plants require this nutrient in order to achieve normal growth and to reach maturity. Phosphorus contributes to the DNA of the plant, as well as the RNA, which reads the genetic code in order to build proteins and other structures. Phosphorus is also vital in the creation of ATP, the unit of energy that plants use during photosynthesis. Phosphorus helps to stimulate root development, increase the strength of stems, improve flower formation and seed production, improve the quality of crops, boost resistance against diseases and support development throughout the overall growth cycle.


It is obvious that phosphorus deficiency could do some damage to the health of your plants and their potential yields. There are quite a few different symptoms to look out for that could signal phosphorus deficiency within your crop. First of all, the deficiency will usually start to affect the older leaves that are lower down on plants. These leaves may begin to exhibit a shiny appearance and turn to darker shades of green, blue and grey. Along with this change in colour, leaves will also start to develop purple and brown spots. Leaves will also become very dry and begin to thicken. The stems of the plant may also begin to turn bright red or purple.


One cause of a phosphorus deficiency is the pH of the roots. A root pH between 6.2 and 7 is best in order to maximise absorption of the nutrient. Therefore, it is ideal to strive for a soil pH between this range when deficiency symptoms manifest. This can be achieved by using pH up and down products.

An organic fertiliser containing adequate amounts of each vital nutrient can also be used to ensure that your plants are receiving the proper levels of phosphorus that they require. Additionally, other sources of phosphorus can be added to the soil in order to maximise exposure. Good source of phosphorus include warm casting, fish meal, crab shell and soft rock phosphate. Overwatering and compact soil can also be causes of phosphorous deficiency. Be sure to water your plants correctly to avoid this.

Try to remain calm if you notice a phosphorus deficiency setting in. Panicking and adding far too much phosphorus back into the soil could prevent your plants from uptaking other nutrients and end up doing more harm than good.

Temperature is another detail to pay attention to in order to achieve optimum phosphorus levels. Lower and colder temperatures can make it more difficult for your cannabis crop to absorb adequate levels of the nutrient. Temperatures that drop below 15 degrees Celsius may start to cause negative effects.

If your plants have fallen victim to phosphorus deficiency symptoms, you will notice a recovery stage take place if you take the right steps to restore the health of your plants. The spread of brown spots, red and purple stems and other symptoms will stop effecting new leaves. Don’t worry if old leaves do not recover, as this is normal.

Mineral Deficiency

What is a mineral deficiency?

Minerals are specific kinds of nutrients that your body needs in order to function properly. A mineral deficiency occurs when your body doesn’t obtain or absorb the required amount of a mineral.

The human body requires different amounts of each mineral to stay healthy. Specific needs are outlined in recommended daily allowances (RDA).

The RDA is the average amount that meets the needs of about 97 percent of healthy people. They can be obtained from food, mineral supplements, and food products that have been fortified with extra minerals.

A deficiency often happens slowly over time and can be caused by a number of reasons. An increased need for the mineral, lack of the mineral in the diet, or difficulty absorbing the mineral from food are some of the more common reasons.

Mineral deficiencies can lead to a variety of health problems, such as weak bones, fatigue, or a decreased immune system.

What types of mineral deficiency are there?

There are five main categories of mineral deficiency: calcium, iron, magnesium, potassium, and zinc.

Calcium deficiency

Calcium is needed for strong bones and teeth. It also supports proper function of your blood vessels, muscles, nerves, and hormones.

Natural sources of calcium include milk, yogurt, cheese, and small fish with bones, beans, and peas. Vegetables such as broccoli, kale, and Chinese cabbage also provide calcium. Some foods are also fortified with the mineral, including tofu, cereals, and juices.

A calcium deficiency produces few obvious symptoms in the short term. That’s because your body carefully regulates the amount of calcium in the blood. Lack of calcium over the long term can lead to decreased bone mineral density called osteopenia.

If left untreated, osteopenia can turn to osteoporosis. This increases the risk of bone fractures, especially in older adults.

Severe calcium deficiency is usually caused by medical problems or treatments, such as medications (like diuretics), surgery to remove the stomach, or kidney failure. Symptoms of a severe deficiency include:

  • cramping of the muscles
  • numbness
  • tingling in the fingers
  • fatigue
  • poor appetite
  • irregular heart rhythms

Iron deficiency

More than half of the iron in your body is in red blood cells. Iron is an important part of hemoglobin, a protein that carries oxygen to your tissues.

Iron is also a part of other proteins and enzymes that keep your body healthy. The best sources of iron are meat, poultry, or fish. Plant-based foods such as beans or lentils are also good sources.

Iron deficiency develops slowly and can cause anemia. It’s considered uncommon in the United States and in people with healthy diets. But, the World Health Organization estimated in a 2008 report that iron deficiency causes approximately half of all anemia cases worldwide.

The symptoms of iron-deficiency anemia include feeling weak and tired. You may be performing poorly at work or school. Children may exhibit signs through slow social and cognitive development.

The body needs magnesium for hundreds of chemical reactions. These include responses that control blood glucose levels and blood pressure. Proper function of muscles and nerves, brain function, energy metabolism, and protein production are also controlled by magnesium.

Roughly 60 percent of the body’s magnesium resides in the bones while nearly 40 percent resides in muscle and soft tissue cells. Good sources of magnesium include:

  • legumes
  • nuts
  • seeds
  • whole grains
  • green leafy vegetables, such as spinach

Magnesium deficiency is uncommon in healthy people. The kidneys can keep magnesium from leaving the body through the urine. Still, certain medications and chronic health conditions like alcoholism may cause magnesium deficiency.

Magnesium needs are also highly influenced by the presence of disease. In this situation, the RDA for magnesium may not be sufficient for some individuals.

Early signs of magnesium deficiency include:

  • fatigue
  • weakness
  • loss of appetite
  • nausea
  • vomiting

Magnesium deficiency can lead to the following symptoms if left untreated:

  • numbness
  • tingling
  • muscle cramps
  • seizures
  • abnormal rhythms of the heart

Potassium deficiency

Potassium is a mineral that functions as an electrolyte. It’s required for muscle contraction, proper heart function, and the transmission of nerve signals. It’s also needed by a few enzymes, including one that helps your body turn carbohydrates into energy.

The best sources of potassium are fruits and vegetables, such as bananas, avocado, dark leafy greens, beets, potatoes, and plums. Other good sources include orange juice and nuts.

The most common cause of potassium deficiency is excessive fluid loss. Examples can include extended vomiting, kidney disease, or the use of certain medications such as diuretics.

Symptoms of potassium deficiency include muscle cramping and weakness. Other symptoms show up as constipation, bloating, or abdominal pain caused by paralysis of the intestines.

Severe potassium deficiency can cause paralysis of the muscles or irregular heart rhythms that may lead to death.

Zinc deficiency

Zinc plays a role in many aspects of the body’s metabolism. These include:

  • protein synthesis
  • immune system function
  • wound healing
  • DNA synthesis

It’s also important for proper growth and development during pregnancy, childhood, and adolescence. Zinc is found in animal products like oysters, red meat, and poultry. Other good sources of zinc include:

  • beans
  • nuts
  • whole grains
  • dairy products

Zinc deficiency can cause loss of appetite, taste, or smell. Decreased function of the immune system and slowed growth are other symptoms.

Severe deficiency can also cause diarrhea, loss of hair, and impotence. It can also prolong the process that your body takes to heals wounds.

What causes mineral deficiency?

One major cause of mineral deficiency is simply not getting enough essential minerals from food or supplements.

There are different types of diets that might result in this deficiency. A poor diet that relies on junk food, or a diet that lacks adequate fruits and vegetables can be possible causes.

Alternately, a very low-calorie diet may produce this deficiency. This includes people in weight-loss programs or with eating disorders. Older adults with poor appetites may also not get enough calories or nutrients in their diet.

Restricted diets may also cause you to have a mineral deficiency. Vegetarians, vegans, and people with food allergies or lactose intolerance might experience mineral deficiency if they fail to manage their diet effectively.

Difficulty with digestion of food or absorption of nutrients can result in mineral deficiency. Potential causes of these difficulties include:

  • diseases of the liver, gallbladder, intestine, pancreas, or kidney
  • surgery of the digestive tract
  • chronic alcoholism
  • medications such as antacids, antibiotics, laxatives, and diuretics

Mineral deficiency can also result from an increased need for certain minerals. Women, for instance, may encounter this need during pregnancy, heavy menstruation, and post menopause.

What are the symptoms of mineral deficiency?

The symptoms of a mineral deficiency depend upon which nutrient the body lacks. Possible symptoms include:

  • constipation, bloating, or abdominal pain
  • decreased immune system
  • diarrhea
  • irregular heart beat
  • loss of appetite
  • muscle cramping
  • nausea and vomiting
  • numbness or tingling in the extremities
  • poor concentration
  • slow social or mental development in children
  • weakness or tiredness

You may display one or more of these symptoms, and the severity may vary. Some symptoms may be so minor that they go unnoticed and undiagnosed.

Contact your healthcare provider if you experience prolonged fatigue, weakness, or poor concentration. The symptoms may be a sign of a mineral deficiency or another health condition.

How is a mineral deficiency diagnosed?

Your healthcare provider may use one or more of the following diagnostic tools to determine if you have a mineral deficiency:

  • medical history, including symptoms and family history of diseases
  • physical exam
  • review of your diet and eating habits
  • routine blood tests, such as complete blood count (CBC) and a measurement of electrolytes (minerals) in the blood
  • other tests to identify other underlying conditions

How is a mineral deficiency treated?

The treatment for a mineral deficiency depends upon the type and the severity of the deficiency. Underlying conditions are also a factor.

Your doctor may order further tests to identify the amount of damage before deciding on a treatment plan. This can include treatment for other diseases or a change in medication.

Dietary changes

A change in eating habits may help if you have a minor mineral deficiency. People with anemia due to a lack of iron in the diet, may be asked to eat more meat, poultry, eggs, and iron-fortified cereals.

You may be referred to a registered dietitian if your deficiency is more severe. They’ll help you modify your eating habits. This will include guidelines on how to eat a well-balanced diet rich in fruits, vegetables, and whole grains.

The dietitian may also ask you to keep a food diary to track what foods you’re eating and your progress.


Certain mineral deficiencies cannot be treated with diet alone. You may be required to take a multivitamin or mineral supplement.

These may be taken alone or with other supplements that help the body absorb or use the mineral. Vitamin D, for example, is usually taken along with calcium.

Your healthcare provider will decide how much and how often you should take supplements. It’s important to follow your provider’s instructions because excessive intake of certain supplements can be harmful.

Emergency treatment

Hospitalization may be required in very severe cases of mineral deficiency. Minerals and other nutrients can be administered intravenously.

Treatment may be required one or more times a day for several days. This type of treatment can have side effects including fever or chills, swelling of the hands or feet, or changes in heartbeat.

Your healthcare provider will administer additional blood tests to determine whether treatment was successful.

Stunted plant growth

The pests, or parasitic diseases have various effects on plants, in particular on their growth. The disorder can occur at any time of plant ?development. It can occur at an early stage, which is the case for example of a viral infection. Growth of plants infected by a virus is sometimes immediately and completely stopped, and thus plants remain stunted (figure 1). This is the case in particular with TLCV (tobacco leaf curl virus), TStV (tobacco stunt virus) and TYDV (tobacco yellow dwarf virus).
Similar situations also occur in fields heavily contaminated by a soilborne fungus or nematodes. The seedlings which face the inoculum in the soil soon after transplanting suffer from root damage that disrupt their development. See the topics related to Root and Collar abnormalities and lesions.
Sometimes, the plants seem to be perfectly normal, then suddenly the apical bud stops growing. This is the case particularly with a boron deficiency (figure 2).
Slow growth or cessation of vegetation may occur later when the plants have reached a certain size (figures 3 and 4). In this case, we can observe:
– a slowdown in apex development, newly formed leaves are smaller in size and have shorter internodes in the affected stem parts than healthy stems;
– An almost complete cessation of growth, the leaves are smaller, grey/bronze green and tend to curl.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

As you understand from these few examples, the diseases described in this section on abnormal leaf shape change both the shape of tobacco leaves, and the general growth of plants, and thus often give the tobacco plants or their apex (temporarily or permanently) particular appearances which contrast with the surrounding healthy plants (figures 5 and 6). These appearances are sometimes very specific to one or similar to several diseases. It is therefore necessary to be very careful. They reflect the malfunctions of the plants and their cause(s) must be sought in different sub-headings and the following fact sheets.
If you cannot identify the pest problem that affects your crop by consulting the above mentioned symptoms, remember that several parasitic and non-parasitic diseases covered in other sections of this web site can sometimes cause growth cessation and stunting of plants. They also induce more characteristic symptoms, which should be investigated and analysed.

  • A very uncommon condition, referred to as tobacco stunting, has been reported only in Kentucky, USA, on Burley tobacco. This essentially results in a significantly slower plant growth, which causes stunted plants. No symptoms are observed in the roots. In affected plots the yields are low and the quality poor. The development of two mycorrhizal fungi in the tobacco roots, Glomus macrocarpus Tul. & Tul. and Glomus microcarpus (Tul. & Tul.) Gerd. & Tul., disrupts the root growth and consequently that of the plants. This condition may exist in other production areas and other types of tobacco, but it is not easy to identify.

Last change : 04/22/13

  • Author :
  • D Blancard (INRA)

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