Shopping Cart

subtotal


Marijuana nutrient disorders

 

About nutrients

The availability of too much or too little of one or more required nutrients causes nutrient disorders. There is a golden rule for the proper absorption of nutrients namely, the pH standard is between 5 and 7 [healthy ph] and TDS between 800-300 - pmm.

The elements

Marijuana needs more than 20 elements to grow into a healthy plant. There are elements which are regulated by the plant itself such as oxygen, carbon and hydrogen. the plant absorbs this from air and water. The minerals are added by the grower as a nutrient solution.

The primary or macro- nutrients. Nitrogen [N], Phosphorus [P] and Potassium [K] are the elements marijuana plants use the most. Calcium [Ca] and magnesium [Mg] are secondary nutrients and used in smaller amounts. Iron [Fe], sulfur [S], manganese [Mn], boron [B], molybdenum [Mb], zinc [Zn] and copper [Cu] are micro-nutrients or trace elements.

Trace elements are found in most soils. Rockwool [hydroponic] fertilizers must contain these trace elements, as they do not normally exist in sufficient quantities in rockwool or water. Other elements also play a part in marijuana plant growth. Aluminum, chlorine, cobalt, iodine, selenium, silicon, sodium and vanadium are not normally included in nutrient mixes. They are required in very minute amounts that are usually present as impurities in the water supply or mixed along with other nutrients.

Note!

The nutrients must be soluble [able to be dissolved in water] and go into solution.

Macro-nutrients

Nitrogen [N]

Nitrogen [N] is primary to marijuana plant growth. Marijuana plants convert Nitrogen [N] to make proteins essential to new cell growth. Nitrogen [N] is mainly responsible for leaf and stem growth as well as overall size and vigor. Nitrogen [N] moves easily to active young cannabis buds, shoots and leaves and slower to older marijuana leaves. Deficiency signs show first in older marijuana leaves. They turn a pale yellow and may die. New growth becomes weak and spindly. An abundance of Nitrogen [N] will cause soft, weak growth and even delay marijuana production if it is allowed to accumulate.

Phosphorus [P]

Phosphorus [P] is necessary for photosynthesis and works as a catalyst for energy transfer within the marijuana plant. Phosphorus [P] helps build strong roots and is vital for marijuana flower and seed production. Highest levels of Phosphorus [P] are used during marijuana germination, seedling growth and flowering. Deficiencies will show in older marijuana leaves first. Leaves turn deep green on a uniformly smaller, stunted marijuana plant. Leaves show brown or purple spots. Note: Phosphorus [P] flocculates when concentrated and combined with calcium [Ca].

Potassium [K]

Potassium [K] activates the manufacture and movement of sugars and starches, as well as growth by cell division. Potassium [K] increases chlorophyll in foliage and helps regulate stomata openings so marijuana plants make better use of light and air. Potassium [K] encourages strong root growth, water uptake and triggers enzymes that fight disease. Potassium [K] is necessary during all stages of marijuana growth. Deficiency signs of potassium [K] are: Marijuana plants are the tallest and appear healthy. Older cannabis leaves mottle and yellow between veins, followed by whole marijuana leaves that turn dark yellow and die. Potassium [K] is usually locked out by high salinity.

Secondary nutrients

Calcium [Ca]

Calcium [Ca] is fundamental to cell manufacture and growth. Soil gardeners use dolomite lime, which contains calcium [Ca] and magnesium [Mg] , to keep the soil sweet or buffered. Rockwool gardeners use calcium [Ca] to buffer excess nutrients. Calcium [Ca] moves slowly within the marijuana plant and tends to concentrate in roots and older growth. Consequently young growth shows deficiency signs first. Deficient leaf tips, edges and new growth will turn brown and die back. If too much calcium [Ca] is applied early in life, it will stunt growth as well. It will also flocculate when a concentrated form is combined with potassium [K].

Magnesium [Mg]

Magnesium [Mg] is found as a central atom in the chlorophyll molecule and is essential to the absorption of light energy. Magnesium [Mg] aids in the utilization of nutrients, neutralizes acids and toxic compounds produced by the marijuana plant. Deficiency signs of magnesium [Mg] are: Older marijuana leaves yellow from the center outward, while veins remain green on deficient marijuana plants. Leaf tips and edges may discolor and curl upward. Growing tips turn lime green if the deficiency progresses to the top of the marijuana plant.

Trace elements

Boron [B]

Boron [B] is necessary for cells to divide and protein formation. It also plays an active role in pollination and marijuana seed production.

Copper [Cu]

Copper [Cu] is a catalyst for several enzymes. A shortage of copper [Cu] makes new growth wilt and causes irregular growth. Excesses of copper [Cu] causes sudden death. Copper [Cu] is also used as a fungicide and wards off insects and diseases because of this property.

Iron [Fe]

Iron [Fe] is a key catalyst in chlorophyll production and is used in photosynthesis. A lack of Iron [Fe] turns marijuana leaves pale yellow or white while the veins remain green. Iron [Fe] is difficult for marijuana plants to absorb and moves slowly within the marijuana plant. Always use chelated [immediately available to the marijuana plant] iron [Fe] in nutrient mixes.

Manganese [Mn]

Manganese [Mn] works with marijuana plant enzymes to reduce nitrates before producing proteins. A lack of manganese [Mn] turns young marijuana leaves a mottled yellow or brown.

Molybdenum [Mb]

Molybdenum [Mb] helps form proteins and aids the marijuana plant's ability to fix Nitrogen [N] from the air. A deficiency causes marijuana leaves to turn pale and fringes to appear scorched. Irregular marijuana leaf growth may also result.

Sulphur [S]

Sulphur [S] is a component of marijuana plant proteins and plays a role in root growth and chlorophyll supply. Distributed relatively evenly with largest amounts in marijuana leaves which affects the flavour and odor in many marijuana plants. Sulphur [S], like calcium [Ca], moves little within marijuana plant tissue and the first signs of a deficiency are pale young marijuana leaves. Growth is slow but leaves tend to get brittle and stay narrower than normal.

Zinc [Zn]

Zinc [Zn] is a catalyst and must be present in minute amounts for marijuana plant growth. A lack of Zinc [Zn] results in stunting, yellowing and curling of small marijuana leaves. An excess of Zinc [Zn] is uncommon but very toxic and causes wilting or death.

These nutrients are mixed together to form a complete marijuana plant fertilizer. The mix contains all the nutrients in the proper ratios to give marijuana plants all they need for lush, rapid growth. The fertilizer is dissolved in water to make a nutrient solution. Water transports these soluble nutrients into contact with the marijuana plant roots. In the presence of oxygen and water, the nutrients are absorbed through the root hairs.

Solutions to nutrient deficiencies [the nutrients]

Nitrogen [N]

Marijuana plants need lots of Nitrogen [N] during vegetative period, but it's easy to overdo it. Added too much? Flush the soil with plain water. Soluble Nitrogen [N] [especially nitrate] is the form that's the most quickly available to the roots, while insoluble Nitrogen [N] [like urea] first needs to be broken down by microbes in the soil before the roots can absorb it. Avoid excessive ammonium nitrogen, which can interfere with other nutrients. Too much Nitrogen [N] delays marijuana flowering. Marijuana plants should be allowed to become N-deficient late in flowering for best flavour.

Phosphorus [P]

Some deficiency during marijuana flowering is normal, but too much shouldn't be tolerated. Red petioles and stems are a normal, genetic characteristic for many varieties, plus it can also be a co-symptom of Nitrogen [N], Potassium [K] and Magnesium [Mg] deficiencies, so red stems are not a foolproof sign of Phosphorus [P] deficiency. Too much Phosphorus [P] can lead to Iron [Fe] deficiency.

Potassium [K]

Too much sodium [Na] displaces Potassium [K], causing a Potassium K deficiency. Sources of high salinity are: baking soda [sodium bicarbonate "pH-up"], too much manure, and the use of water-softening filters [which should not be used]. If the problem is Sodium [Na], flush the soil. Potassium [K] can get locked up from too much Calcium [Ca] or ammonium nitrogen, and possibly cold weather.

Magnesium [Mg]

Magnesium [Mg] deficiency is pretty common since marijuana uses lots of it and many fertilizers don't have enough of it. Magnesium [Mg] deficiency is easily fixed with ¼ teaspoon per gallon | 3.5 liters of Epsom salts [first powdered and dissolved in some hot water] or foliar feed at ½ teaspoon per 0.25 gallon | 0.8 liter. When mixing up soil, use 2 teaspoons dolomite lime per gallon | 3.5 liter of soil for Magnesium [Mg]. Magnesium [Mg] can get locked-up by too much Calcium [Ca], Cl or ammonium nitrogen. Don't overdo Magnesium [Mg] or you'll lock up other nutrients.

Manganese [Mn]

Manganese [Mn] gets locked out when the pH is too high, and when there's too much Iron [Fe]. Use chelated Manganese [Mn].

Iron [Fe]

Iron [Fe] is unavailable to marijuana plants when the pH of the water or soil is too high. If deficient, lower the pH to about 6.5 [for rockwool, about 5.7], and check that you're not adding too much Phosphorus [P], which can lock up Iron [Fe]. Use Iron [Fe] that's chelated for maximum availability. Read your fertilizer's ingredients - chelated Iron [Fe] might read something like "iron EDTA". To much Iron [Fe] without adding enough Phosphorus [P] can cause a Phosphorus [P] deficiency.

Boron [B]

Growing marijuana shoots turn grey or die. Growing shoots appear burnt. Treat with one teaspoon of Boric acid [sold as eyewash] per gallon | 3.5 liter of water.

Calcium [Ca]

Lack of Calcium [Ca] in the soil results in the soil becoming too acid. This leads to Magnesium [Mg] or Iron [Fe] deficiency or very slow stunted growth. Treat by foliar feeding with one teaspoon of dolomatic lime per 0.25 gallons | 0.8 liter of water until condition improves.

Zinc [Zn]

Also gets locked out due to high pH. Zinc [Zn], Iron [Fe], and Manganese [Mn] deficiencies often occur together, and are usually from a high pH. Don't overdo the micro nutrients lower the pH if that's the problem so the nutrients become available. Foliar feed if the marijuana plant looks real bad. Use chelated Zinc [Zn].

Check your water

Crusty faucets and shower heads mean your water is "hard", usually due to too many minerals. Tap water with a TDS [total dissolved solids] level of more than around 200ppm [parts per million] is "hard" and should be looked into, especially if your marijuana plants have a chronic problem. Ask your water company for an analysis listing, which will usually list the pH, TDS, and mineral levels [as well as the pollutants, carcinogens, etc] for the tap water in your area. This is a common request, especially in this day and age, so it shouldn't raise an eyebrow. Regular water filters will not reduce a high TDS level, but the costlier reverse-osmosis units, distillers, and de-ionizers will. A digital TDS meter [or EC = electrical conductivity meter] is an incredibly useful tool for monitoring the nutrient levels of nutrient solution, and will pay for itself before you know it.

pH

The pH of water after adding any nutrients should be around 5.9 to 6.5 [in rockwool, 5.5 to 6.1] . Generally speaking, the micro nutrients Iron [Fe], Zinc [Zn], Manganese [Mn], Copper [Cu] get locked out at a high pH [alkaline] above 7.0, while the major nutrients Nitrogen [N], Phosphorus [P], Potassium [K], Magnesium [Mg] can be less available in acidic soil or water [below 5.0]. Tap water is often too alkaline. Soils with lots of peat or other organic matter in them tend to get too acidic, which some dolomite lime will help fix. Soil test kits vary in accuracy, and generally the more you pay the better the accuracy. For the water, color-based pH test kits from aquarium stores are inexpensive, but inaccurate. Invest in a digital pH meter, preferably a waterproof one. You won't regret it.

Over fertilization

Causes marijuana leaf tips to appear yellow or burnt. To correct soil should be flushed with 3 gallons | 10 liters of water per one gallon | 3.5 liter of soil.

General feeding tips

Marijuana pot plants are very adaptable, but a general rule of thumb is to use more Nitrogen [N] and less Phosphorus [P] during the vegetative period, and the exact opposite during the flowering period. For the vegetative period try a N.P.K ratio of about 10.7.8 [which of course is the same ratio as 20.14.16], and for flowering marijuana plants, 4.8.8. Check the pH after adding nutrients. If you use a reservoir, keep it circulating and change it every two weeks. A general guideline for TDS levels is as follows: marijuana seedlings = 50 to 150 ppm [parts per million]; unrooted marijuana clones = 100 to 350 ppm [parts per million]; small marijuana plants = 400 to 800 ppm [parts per million]; large marijuana plants = 900 to 1800 ppm [parts per million]; last week of flowering = taper off to plain water. These numbers are just a guideline, and many factors can change the actual level the marijuana plants will need. Certain nutrients are "invisible" to TDS meters, especially organics, so use TDS level only as an estimate of actual nutrient levels. When in doubt about a new fertilizer, follow the fertilizer's directions for feeding tomatoes. Grow a few tomato or radish plants nearby for comparison.

Other things

Cold

Cold weather [below 50°F | 10°C] can lock up Phosphorus [P]. Some marijuana varieties, like equatorial sativa's, don't take well to cold weather. If you can keep the roots warmer, the marijuana plant will be able to take cooler temperatures than it otherwise could.

Heat

If the grow lights are too close to the marijuana plant, the tops may be curled, dry, and look burnt, mimicking a nutrient problem. Your hand should not feel hot after a minute when you hold it at the top of the marijuana plants. Raise the lights and/or aim a fan at the hot zone. Room temperatures should be kept under 85°F | 29°C or 90°F | 32°C if you add additional CO².

Humidity

Thin, shriveled marijuana leaves can be from low humidity. 40 to 80% is usually fine.

Mold and fungus

Dark patchy areas on marijuana leaves and marijuana buds can be mold. Lower the humidity and increase the ventilation if mold is a problem. Remove any dead marijuana leaves, wherever they are. Keep your marijuana garden clean.

Insects

White spots on the tops of leaves can mean spider mites underneath.

Sprays

Foliar sprays can have a "magnifying glass" effect under bright lights, causing small white, yellow or burnt spots which can be confused with a nutrient problem. Some sprays can also cause chemical reactions.

Insufficient light

Tall, stretching marijuana plants are usually from using the wrong kind of light. Don't use regular incandescent bulbs ["grow bulbs"] or halogens to grow marijuana. Invest in fluorescent lighting [good] or HID lighting [much better] which supply the high-intensity light that marijuana needs for good growth and tight marijuana buds. Even better, grow in sunlight.

Clones

Yellowing marijuana leaves on unrooted clones can be from too much light, or the stem may not be firmly touching the rooting medium. Turn off any CO² until they root. Too much fertilizer can shrivel or wilt marijuana clones. Plain tap water is fine.

Symptoms

Yellow upper leaves

Suspected element

Iron [Fe]

Symptoms: Marijuana leaves on growing shoots turn pale and veins remain dark green. pH imbalances make iron insoluble.

Solution: Foliar feed with chemical fertilizer containing Iron [Fe] or rusty water.

Sulfur [S]

Symptoms: Marijuana plants suffering from Sulfur [S] deficiencies exhibit yellowing of new growth.

Solution: Mix one tablespoon of Epsom salts per gallon | 3.5 liter of water until condition improves.

Yellowing of middle leaves

Suspected element

Molybdenum [Mb]

Symptoms: Yellowing of middle marijuana leaves.

Solution: Foliar feed with chemical fertilizer containing Molybdenum [Mb].

Yellowing of lower leaves

Suspected element

Nitrogen [N]

Symptoms: Pale marijuana plants, red stems, smaller growth. Rapid yellowing of lower leaves progressing up the marijuana plant.

Solution: Add any chemical fertilizer containing Nitrogen [N]. Treated marijuana plants will recover in about a week.

Pottasium [K]

Symptoms: Affected marijuana plants are usually tallest and appear to be most vigorous. Necrotic spots form on lower marijuana leaves. Red stems. Leaves appear pale or yellow.

Solution: Add chemical fertilizer containing Potassium [K].

Red stems

Suspected element

Nitrogen [N]

Symptoms: Pale marijuana plants, red stems, smaller growth. Rapid yellowing of lower leaves progressing up the marijuana plant.

Solution: Add any chemical fertilizer containing Nitrogen [N]. Treated marijuana plants will recover in about a week.

Pottasium [K]

Symptoms: Affected marijuana plants are usually tallest and appear to be most vigorous. Necrotic spots form on lower marijuana leaves. Red stems. Leaves appear pale or yellow.

Solution: Add chemical fertilizer containing Potassium [K].

Necrosis

Suspected element

Magnesium [Mg]

Symptoms: Lower cannabis leaves yellow and may even turn white while veins remain dark green. Blades die and curl upward.

Solution: This can be quickly resolved by watering with one tablespoon Epsom salts per gallon | 3.5 of water. Until you can correct nutrient lockout, try foliar feeding.

Iron [Fe]

Symptoms: Marijuana leaves on growing shoots turn pale and veins remain dark green. pH imbalances make iron insoluble.

Solution: Foliar feed with chemical fertilizer containing Iron [Fe] or rusty water.

Pottasium [K]

Symptoms: Affected marijuana plants are usually tallest and appear to be most vigorous. Necrotic spots form on lower marijuana leaves. Red stems. Leaves appear pale or yellow.

Solution: Add chemical fertilizer containing Potassium [K].

Zinc [Zn]

Symptoms: White areas form at the marijuana leaf tips and between veins. Occurs in alkaline soils.

Solution: Zinc [Zn] deficiency can be treated by burying galvanized nails in the soil. Chemical fertilizer containing Zinc [Zn] can also be used.

Manganese [Mn]

Symptoms: Necrotic and yellow spots form on top marijuana leaves. Magnese [Mn] deficiency occurs when large amounts of Magnesium [Mg] are present in the soil.

Solution: Foliar feed with any chemical fertilizer containing Magnese [Mn].

Spots

Suspected element

Manganese [Mn]

Symptoms: Necrotic and yellow spots form on top marijuana leaves. Magnese [Mn] deficiency occurs when large amounts of Magnesium [Mg] are present in the soil.

Solution: Foliar feed with any chemical fertilizer containing Magnese [Mn].

Growing shoots die

Suspected element

Boron [B]

Symptoms: Growing marijuana shoots turn grey or die. Growing shoots appear burnt.

Solution: Treat with one teaspoon of Boric acid [sold as eyewash] per gallon | 3.5 liter of water.

White leaf tips

Suspected element

Magnesium [Mg]

Symptoms: Lower cannabis leaves yellow and may even turn white while veins remain dark green. Blades die and curl upward.

Solution: This can be quickly resolved by watering with one tablespoon Epsom salts per gallon | 3.5 of water. Until you can correct nutrient lockout, try foliar feeding.

Zinc [Zn]

Symptoms: White areas form at the marijuana leaf tips and between veins. Occurs in alkaline soils.

Solution: Zinc [Zn] deficiency can be treated by burying galvanized nails in the soil. Chemical fertilizer containing Zinc [Zn] can also be used.

Stunded growth

Suspected element

Nitrogen [N]

Symptoms: Pale marijuana plants, red stems, smaller growth. Rapid yellowing of lower leaves progressing up the marijuana plant.

Solution: Add any chemical fertilizer containing Nitrogen [N]. Treated marijuana plants will recover in about a week.

Phosphorus [P]

Symptoms: Slow or stunted growth, red stems. Smaller marijuana leaves that are dark green. Lower marijuana leaves are yellow and die.

Solution: Add chemical fertilizer containing Phosphorus [P]. Affected marijuana leaves will not show recovery but new growth will appear normal.

Deformed new growth

Suspected element

Phosphorus [P]

Symptoms: Slow or stunted growth, red stems. Smaller marijuana leaves that are dark green. Lower marijuana leaves are yellow and die.

Solution: Add chemical fertilizer containing Phosphorus [P]. Affected marijuana leaves will not show recovery but new growth will appear normal.

Yellow leaf tips

Suspected element

Over fertilization

Symptoms: Causes marijuana leaf tips to appear yellow or burnt.

Solution: To correct soil should be flushed with three gallons | 10 liters of water per one gallon | 3.5 liter of soil.

Twisted growth

Suspected element

Boron [B]

Symptoms: Growing marijuana shoots turn grey or die. Growing shoots appear burnt.

Solution: Treat with one teaspoon of Boric acid [sold as eyewash] per gallon | 3.5 liter of water.