Heat stress on marijuana leaves typically shows up by a browning of the edges of marijuana leaves. Nutrient burn and heat burn look very similar, however, heat burn on marijuana leaves will show up only near marijuana plant tops that are nearest to heat lamps. The only way to remedy this situation is by moving your marijuana plants and your light sources away from each other.
Our guess would be the marijuana bud shown here experienced burn from the nutrient solution. You will typically see results like this on your marijuana plants when your concentration of nutrients is a bit too high. You can also see these symptoms if you accidentally get some nutrient solution on your marijuana leaves while you have your HID lamps turned on, burning the marijuana leaves.
This is a common ailment to see on homegrown marijuana plants. Early stage nutrient solution burn indicates your marijuana plants are full to the brim with nutrients and you are still feeding them a bit more. If you lower your concentration within your nutrient solution slightly, most instances of this issue should disappear. If you never see your plant look worse than this example, you will not likely have any issues with your marijuana plants.
Over-fertilization. Giving too much fertilizer will allow the excess nutrients to build up within your marijuana leaves, leaving them dry and burnt. To remedy this issue, flush your marijuana plants with clean and pure water as soon as possible, allowing your roots time to recover, preventing future damage.
With a drip system, continuously pumping the nutrient solution through the growing medium this usually saturates the root system. You may find better success with occasional feedings of around 30 minutes during each 2-3 hour cycle. This change would give your marijuana plants the ability to get air exposure which will help prevent rotting of the roots, among other issues. They are sitting within an H² O² solution that is being used in an attempt to fix the issue of nutrient solution burn. Fish tank air stones can also help add necessary oxygen to your nutrient solution.
Over-fertilization or an imbalanced pH look almost the same. An imbalanced pH arises because of salts that do not dissolve around your marijuana plants, leaving a potentially toxic mixture surrounding your marijuana plants. The concern that usually arises with this issue is the grower's attempt to fix the problem by adding additional fertilizers, continuing the cycle and increasing the salts. Most growers see this problem when using soil mixes because improper mixing left "hot" spots within the soil.
You will typically notice this rare problem near your generator. If you happen to believe your marijuana plants are experiencing the symptoms of this issue, it will often appear looking like a deficiency of Magnesium (Mg) right around your generator. The first sign is a yellowing that usually turns to brown on older marijuana plant leaves, with the second sign being chlorosis on the veins of those same leaves. The problems will begin on the margin or the tip of the leaf and move toward the leaf in between veins.
You will typically only see this happen if your marijuana plants are low in Calcium (Ca) or acid, or if your plants are experiencing a copper or aluminum toxicity. Occasionally you may find a species of marijuana plant that will show this behavior when it is deficient in Boron (B). First you will notice your marijuana plant's roots growing thicker and more peg-like. Then you will typically see the root system discoloring to a grey or brown color.
Occasional plant symptoms localized to shoot growth points:
- Baby leaves becoming distorted, killing off the leaf tips, or a marijuana plant that is pale green in color = a deficiency of Copper (Cu)
- Stem collapse, stunted growth of shoots, dead petiole, collapsed stems or new growth coming out withered = a deficiency of Calcium (Ca)
- Marijuana plants dying back, new growth coming out a yellow or pale green color, or dead leaf tips = a deficiency of Boron (B)
You will typically see the effects of mobile elements in the oldest leaves of your marijuana plants due to the demand that new growth would require.
Organic and Inorganic forms of Nitrate-Ammonium can be found within marijuana plants because it combines with oxygen, hydrogen, carbon and occasionally sulfur (S) in order to create the amino enzymes, amino acids, chlorophyll, purine bases, nucleic acids and alkaloids the marijuana plant requires. This is one of the highest rated proteins as far as molecular weight goes within the tissues of the plant. While you will have to feed quite a bit of Nitrogen to a plant growing vegetation, it is possible to feed it too much. If you have accidentally done this, flushing your growth medium with pure water will help remove any soluble Nitrogen (N) which typically accumulates on or within the shallow layers of the marijuana plant's roots. You do not want to give your plant too much ammonium nitrogen because it can make it to where your marijuana plant cannot get enough of the other necessary nutrients. Excessive Nitrogen (N) will slow flowering of your plants, and withholding Nitrogen (N) before harvesting will increase the flavor of your crop.
A Nitrogen (N) Deficiency
The symptoms of a Nitrogen deficient marijuana plant include weakness, stunted or slow growth, or a lack of vigor for the plant. Overall yield and quality will decline with this issue. A lack of necessary chlorophyll will cause the oldest leaves to turn yellow and eventually die off and drop off of the plant. There will not be a noticeable curling to the leaves, but the discoloration will slowly take over the entire marijuana plant. The last symptoms of this problem include some lower leaves, stems or petioles turning purple.
Nitrogen (N) Toxicity
Early symptoms include dark green marijuana leaves, but if the excess quantity of Nitrogen (N) is great enough, the leaves of your marijuana plant may dry and eventually fall off. You will not have sufficient roots with this issue, and eventually the roots will deteriorate. Once the tissues begin to slow the intake of water and nutrients, the ability of the plant to resist stress is greatly diminished.
This component of plant proteins and enzymes is required for proper genetic formation and energy transfer within the plant. Phosphorus (P) is a major part of these components: deoxyribonucleic acid (DNA), phytin, ribonucleic acid (RNA) and adenosine tri-phosphate (ATP).
A Phosphorus (P) Deficiency
There are numerous symptoms of phosphorus (P) deficiencies. Some examples are leaves that are curled under, browning and dying, fanned marijuana leaves that are purple or yellow, or smaller marijuana buds than a standard crop. You will almost always see weak marijuana plants when you have this issue, along with stunted or slowly growing plants that show a dark pigmentation to the oldest leaves and stems on your marijuana plants.
A bit of deficiency when your marijuana plant is flowering is considered normal, but you do not want this to go too far. This deficiency is difficult to diagnose because some symptoms are normal depending on the variety of marijuana plant you are growing. Excess phosphorus will sometimes lead to an iron (Fe) deficiency as well, leaving your marijuana plants purple, red or even blue. Different species of marijuana plants may show a yellow color to the leaves and stems instead of purple, so you have to make sure you know what you are treating before doing any harm to your plants.
A deficiency of Phosphorus (P) during growth of vegetation is commonly thought to be a fungus, but that is inaccurate. The damage on the end of the leaves, the brittle texture and the discoloration are your cues with this issue.
Potassium (K) is considered a part of what helps your marijuana plants hold their water, open and close their stomata and maintain the pressure within each cell. This element is also required to allow carbohydrates to accumulate and move around the plant's cells. A plant deficient in Potassium (K) will have a lower quality and yield.
A Potassium (K) Deficiency
When your marijuana plants are deficient of potassium (K) then you will first see yellowing of the leaves with a quick change to dead tissues on the leaves. The tips and the margins of your marijuana leaves are affected first, with the weakening of branches and stems coming next. Your marijuana plants will then become more easily diseased or suffer toxicity. You will notice the appearance of an iron (Fe) deficiency with the tips of your leaves curling up and the leaf edges beginning to burn and then die. Typically this issue is caused by a build up of sodium (Na) that is replacing the necessary potassium (K). If you have been using baking soda, excessive manure or a water-softening style of filter (which is a big no-no!) then flush the growing medium to remove the excess salinity. Avoid cold weather for your plants along with excess calcium (Ca) and ammonium Nitrogen (N) because these can all cause this issue.
A Potassium (K) Toxicity
This is not a typical problem for marijuana plants. Too much potassium (K) can influence the uptake of elements such as Manganese (Mn), Magnesium (Mg), Iron (Fe), Zinc (Zn) and Calcium (Ca).
This element is required for necessary plant enzymes and the plant's chlorophyll.
A Magnesium (Mg) Deficiency
Again you will see a yellowing (and possible browning) of the older marijuana leaves along with a chlorosis of the veins first. It will start along the tip or margin of the leaves, slowly moving in toward the veins. You will still see some green on the veins. A simple way to remember this is if you see a curling of the leaves toward a praying position, the marijuana leaves are praying to receive Magnesium (Mg)! Sometimes the tips of the marijuana leaves will twist, but this issue has an easy remedy. Water your marijuana plants with one gallon (3.5 L) of water that has had 1 tablespoon of Epsom salts dissolved in it. Foliage feeding is recommended until you fix whatever is causing the issues with your plants uptake of nutrients. This watering solution will give your marijuana plants the required Magnesium (Mg) and Nitrogen (N).
It is recommended that you feed your plants through their foliage at this point with a diluted Epsom salt solution of � teaspoon of Epsom salt per quart of water. When preparing your growing medium, make sure to add 2 teaspoons of dolomite lime for each gallon (3.5 L) of growing medium you use. If you are using water that has more than 200 parts per million (ppm), it is considered hard water. The negative effects of this is a lock out of some elements (like Magnesium) due to the high concentration of other elements (like Calcium) in the water. Either the Epsom salt mixture or the lime in the growing medium will reduce the effects of the lockout, or you can purchase a water filter that does reverse osmosis. Magnesium gets locked out from too much of one of three main elements: Calcium (Ca), Ammonium Nitrogen (N) or Chloride (Cl), but adding in too much Magnesium will have the same effect on other nutrients.
Magnesium (Mg) Toxicity
Although a toxicity to Magnesium (Mg) is quite rare and hard to detect, it can harm the ion levels within your nutrient solution when it happens.
Manganese (Mn) and Magnesium (Mg) do some of the same functions as Zinc (Zn), especially when you look at the quantity of enzymes that require zinc (Zn) to properly function. Chlorophyll formation and repair is vital to the marijuana plant, and zinc (Zn) is an important element in those processes. Processes such as Carbonic Anhydrate is known to become activated by the use of zinc (Zn).
A Zinc (Zn) Deficiency
A zinc (Zn) deficiency will typically appear as banding around the marijuana leaf, or as chlorosis around the veins of new marijuana growth. The size of marijuana leaves usually declines with this deficiency, and internode length typically shortens. Growers tend to notice wrinkled and/or distorted leaf margins, and if left untreated, branches that bear fruit will begin to die back. Due to how marijuana plants lock out similar elements when the plants get a high pH level, growers will usually see a deficiency of Iron (Fe), Zinc (Zn), and Manganese (Mn) together. Over doing the micro-nutrients can make it to where plants are not able to get the nutrients they otherwise would, so this is not a good option either. Feeding your marijuana plants through their foliage works if they are looking quite sickly by using chelated zinc (Zn). Marijuana plant growers will notice little leaves when their plants are suffering from this deficiency, often producing "rosetting" where the leaves bunch behind each growing tip, resulting in a rose-like appearance of tightly bunched leaves.
Zinc (Zn) Toxicity
Too much zinc (Zn) will quickly kill off your marijuana plants. Too much zinc (Zn) will stop iron (Fe) from being absorbed, causing signs of chlorosis, especially in the more sensitive forms of marijuana plants.
Symptoms from immobile elements typically first appear on new growth and young marijuana plants, later progressing to the rest of your marijuana plant.
Protein synthesis requires sulfate, which is a portion of some amino acids, namely thiamine and cystine. These building blocks are active within the marijuana plant's structure and regulate the metabolism from within the plant. Respiration for the marijuana plant requires sulphur (S), as does the breakdown and synthesis of essential fatty acids.
A Sulphur (S) Deficiency
If you see your marijuana leaves turning yellow, including the veins, especially on new growth, then chances are you are experiencing a sulphur (S) deficiency. The tips of the leaves typically turn yellow and begin to curl down toward the roots due to the lack of nutrients and succulence from the deficiency. Woody stems, extended roots and purple stems tend to also appear with this deficiency. It will usually take over the entire marijuana plant, not just stay right at the top of the marijuana plant.
Sulphur (S) Toxicity
Marijuana plant growers will usually notice yellow leaves, sometimes with scorching around the edges of the leaves, along with stunted growth or a reduced leaf size on the marijuana plant.
Cell membrane permeability and integrity is maintained by Calcium (Ca).
A Calcium (Ca) Deficiency
Marijuana plant growers will usually notice the effects of a calcium (Ca) deficiency on the youngest marijuana plants, showing distortion through irregular spotting, margins or necrotic tissue. The development of marijuana buds will stop, and bud rot will also likely occur from the inside of the plant, out. Roots also tend to remain undeveloped or die because of a lack of calcium (Ca). The main symptoms to watch out for include marginal necrosis, chlorosis, curling of leaf tips and root tips to begin to die back. You will likely also see smaller symptoms like crinkling of the leaves, distortion of the leaves, stopping of shoot growth, a strap-like shape developing on the leaves and a miniaturization of the leaves as they grow.
Calcium (Ca) Toxicity
This form of toxicity is difficult to spot, but it tends to cause a clouding of the nutrient solution. This toxicity is usually a precursor to sulphur (S) showing up in large quantities and will typically cause a deficiency in Magnesium (Mg) or Potassium (K).
The electron transportation within the processes of terminal respiration and photosynthesis require iron to be within marijuana plant's enzymes. This catalyst helps boost the production of chlorophyll and reduces the amounts of nitrates and sulfates within the plant.
An Iron (Fe) Deficiency
Similar to what you'd see if you had a magnesium (Mg) deficiency, an iron (Fe) deficiency will cause chlorosis on the veins of young marijuana plant's leaves. The yellowing that growers will see on their marijuana leaves is usually between the main veins, and usually starts at the bottom of the plant and works its way up. This deficiency is typically caused by anything that would interfere with the plant's ability to absorb iron (Fe) from the roots, like excessive salts, pests, inadequate water drainage, over-irrigation, nematodes or a pH level that is too high. An iron (Fe) supplement added into the next watering of the marijuana plants will usually correct this issue. If the pH is too high, however, iron (Fe) is locked out, so you will need to fix your pH level first. Do not use phosphorus (P) to correct the pH as this will also lock up the marijuana plant's ability to soak up iron (Fe). Chelated iron (Fe), which is usually listed as "iron EDTA", will give the plant the best ability to soak up the necessary iron (Fe). Just keep the amounts of iron and phosphorus close so that you do not allow your marijuana plants to become deficient in different element when trying to correct the first one.
When you add iron (Fe) to your nutrient solution, skip the fertilization treatment for that particular watering to avoid any negative reaction between the iron and other components within the fertilizer. You will avoid any additional form of lockout of elements, and you will avoid any adverse reaction from a combination of the supplement and fertilizer.
Iron (Fe) Toxicity
Bronzing or little brown-colored spots on your marijuana plants leaves could be a sign of excess iron on your marijuana plants.
Reducing oxygen through the transportation of electrons during photosynthesis is the main job that manganese (Mn) has with marijuana plants. This element is crucial for the membrane of chloroplast, plus it serves as a catalyst for many different enzymes.
A Manganese (Mn) Deficiency
Common symptoms of manganese (Mn) deficiencies include necrotic lesions, leaf shredding and chlorosis. Excessive levels can make the chlorophyll distribute unevenly, giving your marijuana plant a blotchy look. Failure to thrive and slowed or stunted growth are also relatively common symptoms. If the pH level is too high or the iron (Fe) levels become excessive, manganese (Mn) will become locked out. To help a deficiency, try using chelated manganese (Mn).
Manganese (Mn) Toxicity
The tissues of marijuana leaves will look blotchy or yellow (chlorosis) if this issue occurs because there is not enough synthesis of chlorophyll happening. The vigor of the marijuana plant will decrease, as will the growth rate.
During photosynthesis, chlorine (Cl) becomes necessary for oxygen to evolve into the essential element each marijuana plant cell requires for healthy roots and leaves. The chlorine (Cl) increases the osmotic pressure within the cell, regulates stomata and also increases the ability of the tissues of the marijuana plant to hydrate. So long as your water has fewer than 140 ppm, your water should be safe for your marijuana plants. If you happen to be growing marijuana plants with a chloride sensitivity, you need to keep the levels below 20 ppm in order to avoid leaf burn around the margins of the leaf or tip burn.
A Chlorine (Cl) Deficiency
A deficiency of chlorine (Cl) will typically cause your marijuana plant leaves to turn a bronze color and have wilted leaves. Root growth is slowed or stunted completely with tip thickening, and the marijuana plant as a whole will be paler with wilting around the plant from this issue.
Chlorine (Cl) Toxicity
Common symptoms of chlorine toxicity include a bronze or yellow color to the leaves, splitting of the marijuana leaves, burnt tips or leaf margins, a decrease in leaf size and a slower rate of growth for the marijuana plant.
The main functions of Boron (B) are largely unknown, but the one guess that most scientists have is it helps synthesize the building blocks for RNA creation. There may be additional cellular activities that it performs, like differentiation, division, respiration and maturation. Boron (B) also aids in pollen germination.
A Boron (B) Deficiency
Brittle shoot tips along with failure for the root tips to grow properly are the two most common symptoms of a Boron (B) deficiency. There is commonly death of the stems and root stems with this deficiency, along with discolored roots that do not allow the internal tissues to thrive properly. There are often times fungal problems that come in after the rot begins as well. The leaves of your marijuana plants will also show symptoms, like thickening, distortion, necrotic spotting, leaves that dry out and chlorosis.
Boron (B) Toxicity
Leaf tips that turn yellow and then die (necrosis), slowly progressing toward the inside of the plant until the entire plant begins to die are common symptoms of a boron (B) toxicity. Occasionally plants are quite sensitive to any excess boron (B).
Copper (Cu) is required for most enzymes and some of the proteins that marijuana plants need. The function of Copper (Cu) is to assist in the metabolism of carbohydrates within the the plant, fixing the nitrogen (N) and reducing the oxygen within the plant.
A Copper (Cu) Deficiency
The first symptoms you will see if your marijuana plants are deficient of copper (Cu) would be stunted growth, with common distortion of new marijuana plant growth, or a dieing of the leaf tips. Growers often notice the dark green, twisted appearance of new growth with this issue. Necrotic spots also can appear from this deficiency. A final yield will be decreased with this deficiency as well.
Copper (Cu) Toxicity
Only minute amounts of copper (Cu) are required for normal marijuana plant growth. This means that just a little copper (Cu) can be toxic to your plants. Excess copper (Cu) can create an iron deficiency, causing a suppression of root growth, stunted plant growth, abnormal darkening of the plant's roots and chlorosis.
The process that turns nitrates into ammonium requires molybdenum (Mb).
A Molybdenum (Mb) Deficiency
The first symptoms of a molybdenum (Mb) deficiency is chlorosis, similar to other deficiencies, but it typically happens in the older marijuana growth. The difference here is that the twisting that follows the chlorosis is severe, eventually killing the marijuana leaves. With as closely as this deficiency looks like a nitrogen (N) deficiency, you have to look at which growth is affected first to differentiate between them.
Molybdenum (Mb) Toxicity
Excess molybdenum (Mb) causes the marijuana leaves to become discolored. Even through this toxicity is quite rare, it can happen simply by a continuous accumulation during application because of how little the plant actually requires. Excess typically will not harm your marijuana plants, but it may not be in your best interest to smoke the crop if the levels were exceedingly high.
Salicylic acid is how most plants come in contact with silicon (Si). The typical use of silicon (Si) is for the epidermal cell walls, but it is also used in other cell walls throughout the marijuana plant. This element is found in both soil and water, and if the levels of the silicon (Si) are too low, yields can suffer a reduction of nearly 50%. Occasionally the symptoms of excess silicon (Si) includes deformed marijuana leaves, but no known toxicity symptoms have been found on a regular basis.
A Silicon (Si) Deficiency
The main effects that a silicon (Si) deficiency can cause include a negative development of stems, roots and leaves, a reduction of photosynthesis and a thicker cell layer on the epidermal cells. The main symptoms a marijuana plant grower would see include: lower resistances to diseases, smaller crop yields and droopy or soft marijuana leaves.
This element is essential the the bacteria that benefit the nitrogen (N) fixation of your marijuana plants. It helps increase the effectiveness of vitamin B12 within your marijuana plants, allowing necessary enzymes to form around the aromatic portions of the marijuana plant. The additional benefits of Cobalt (Co) are not yet known, but the increase that it shows in the health of animals makes it potentially quite beneficial to marijuana plants as well.