Marijuana growers new to the game will spend hours researching the 'secret' to growing the biggest and the best crops. In reality, as any veteran cultivator will know, there’s no single answer.
Instead, there are several basic principles similar to growing any other plant. Your marijuana plants need the appropriate climate, temperature, and humidity. Light exposure, pH levels, watering, and an adequate diet of nutrients are also crucial for the health of your weed.
Without these, your pot will become stressed and unhealthy. It’ll also be more susceptible to molds, disease, and cannabis deficiencies. As a result, the quality of the terpenes and cannabinoids will be affected, alongside the size of your yield.
If you want your pot to thrive, you must understand cannabis nutrient deficiencies and acquire the skills to identify and fix the problem quickly.
Continue reading to learn everything there is to know about common marijuana nutrient deficiencies and how you can overcome them.
Prevention is always better than the cure, so we've shared our expert tips to keep weed deficiencies at bay from the get-go.
What are cannabis deficiencies?
Cannabis deficiencies begin when vital minerals and nutrients are lacking in the weed plants' environments.
The absence of just one key nutrient can have a detrimental effect on the health of your plant. The processes that particular nutrient is responsible for are likely linked to several others, which often causes a domino effect of cannabis deficiencies and ill health.
If your marijuana can't access the things it needs to grow, it’ll quickly become unhealthy and may even die as a result. While a plant may survive a cannabis deficiency, it may not reach its yield and quality potential.
Are cannabis deficiencies a big problem?
Many growers have found that, despite their best efforts, cannabis deficiencies are still a potential problem for their precious crops. It’s all about being vigilant and acting at the first signs of a problem.
It's all about the pH with cannabis. For optimal nutrient absorption, the pH level of your growing medium needs to be within the right parameters. If it crosses over the line to be more alkaline or acidic, then your pot simply can't absorb nutrients, and a cannabis deficiency will occur.
The issue is many things can affect the pH level of your growing medium. Even the water you use carries a pH content that can throw your weed off balance.
What Nutrients Do Cannabis Plants Need?
Marijuana plants need three main nutrients in large amounts at the root. These are known as macronutrients and are nitrogen (N), phosphorus (P), and potassium (K).
Together they are the pillars of cannabis health and will feature on every cannabis deficiency chart.
Weed needs far more than just three nutrients to stay healthy and thrive. Secondary nutrients like calcium, sulfur, and magnesium also have vital roles in your plant's growth.
- Calcium: This nutrient is responsible for cell wall development. It also improves water absorption and helps reduce salinity in the soil.
- Magnesium: It’s vital for photosynthesis, stabilizing plant cell walls, and carbohydrate metabolism.
- Sulfur: Is a necessary nutrient for producing proteins, vitamins, amino acids, and enzymes. It also plays a role in forming chlorophyll and protecting the plant from disease.
Behind the scenes are a further ten micronutrients which cannabis plants use in small amounts. Although they aren't primary, they’re still important and play essential roles in many factors of weed health.
Micronutrient marijuana deficiencies are often the hardest to identify. Read on to learn all about their calling cards so you can diagnose and treat any cannabis deficiency that comes your way.
What's the difference between macronutrients and micronutrients?
Macronutrients are the substances that your weed plants need in high quantities. They are key in the primary biochemical processes for growth and health, especially during the vegetative and flowering stages.
In comparison, your weed plant needs micronutrients in trace quantities. They support the macronutrients in cellular biology and keep things ticking. Although the plant only requires small amounts of these, without them, larger processes can't function and marijuana deficiencies develop.
Macronutrients from air and water
Weed plants must obtain three other macronutrients to survive. Plants are built to be self-reliant in acquiring these elements as they come from the air and the water byproduct of photosynthesis.
- Carbon: Your plant's leaves have minuscule pores known as stomata. These "inhale" carbon dioxide from the air.
The fascinating thing is the stomata have guard cells that open and close the pores depending on if the plant needs more carbon. If these guard cells are compromised, several weed deficiencies can occur.
Carbon dioxide is crucial for weed health. Your plants take in this element and convert it to energy to grow and photosynthesize.
- Hydrogen: During photosynthesis, your plant releases water molecules which are turned into hydrogen. The reaction is a result of the plant harnessing light energy. The elements ions then drive the transport of electrons for further photosynthesis.
The process is a self-sufficient cycle in which hydrogen is a key component.
- Oxygen: Not all parts of your plant are exposed to light to photosynthesize and split carbon dioxide. The root system, for example, is underground and needs oxygen from the soil to survive.
Like with humans, oxygen is a vital part of respiration. Plants operate backward in comparison to us. They need it to release energy from glucose built up from photosynthesis.
Macronutrients from soil
The remaining macronutrients that are a must-have for cannabis are within the soil. Your plant can access these from either decaying organic matter or any synthetic fertilizers you add.
- Nitrogen: Nitrogen is a mobile nutrient in cannabis plants, and during the growing cycle, weed needs it more than any other. Over 90% of the nitrogen in the soil is made of organic matter known as microbes.
These microbes help mineralize nitrogen so that your plants can absorb it at the root level. Plants rely on nitrates from nitrogen for general health and growth.
It's a key substance in the chlorophyll process for photosynthesis and a component of amino acids, which are the base of essential proteins.
- Phosphorus: Phosphorus is another mobile nutrient. It circulates in your plant and occurs in every cell. It's on hand to support any new growth.
It has a long list of responsibilities within physiological processes:
- Energy transfer
- Photosynthesis
- Transforms starches and sugars
- It moves other nutrients around the plant
It's especially important during the vegetative stage, where it helps to build strong roots and stems. Later as your plants develop, it fights disease and supports the formation of flowers.
Phosphorus is also a cannabis breeder's friend. It supports the transfer of genetic attributes to any offspring. If your pheno hunting or cross-breeding you should make avoiding this cannabis deficiency a priority.
- Potassium: Without potassium, your cannabis plants would meet their demise fast. It, like phosphorus, is responsible for a lengthy list of major processes.
- Plant growth
- Stress tolerance
- Metabolic function
- Root growth and structure
- Active enzymes
- Synthesize proteins
- Water conservation
The Stotoma couldn't function without potassium. Although hydrogen production is essential from this water, the plant also needs H2O on the inside to live. When water levels are running low, potassium must be present to close the Stomata and preserve water levels.
The optimum pH and nutrient levels
Let's talk about pH levels. Monitoring the pH content of your potting medium, whether it be soil or hydroponics, will greatly improve your chances of avoiding any marijuana nutrient deficiencies.
Remember, the local water you use on your plants will carry pH. Don't fall into the assumption that you can test it once, and it'll stay the same either. Times of the year, varying rainfalls, and tap water treatments can all affect the pH. Getting a handle on your water source's pH is an ideal base to maintain cannabis health.
Soil and decaying material growers should aim for a pH of around 5.8 to allow for fluctuations. The majority of cannabis strains thrive best at 6.
These types of potting media should 'self regulate', naturally balancing out at the correct pH. Even so, it's not worth ignoring, as you could easily tip its pH level with feeds, fertilizer, and water.
In this scenario, you could cause weed deficiencies that are difficult to rectify.
Hydroponics growers should introduce adequate nutrients into their system by following appropriate product instructions. You should aim for a pH level no higher than 6. One of the benefits of a hydroponics system is that you can quickly flush your system to limit damages if you make a mistake.
How to identify cannabis deficiencies
When your plant isn't looking in tip-top shape, it's time to investigate possible cannabis deficiencies. It's crucial for your yield that you get on top of the problem as quickly as possible. A plant left to fight a marijuana deficiency will experience discoloring, stunted growth, minimal flowering, disease, and eventually death.
Thanks to the long leaves on cannabis plants, they're able to display obvious signs of distress early on. It's down to us to know what visual clues to look out for and interpret them for fast and effective treatment.
It's time to do some homework and unravel the signs of common marijuana deficiencies. Some weed deficiencies look and act very similar to others. By learning the unique symptoms, you can jump into action and save your harvest.
Cannabis deficiency chart
Your plant's appearance, especially its coloring, can convey a lot of useful information about your marijuana nutrient deficiencies. Use this handy cannabis deficiencies chart below as your guide to identifying the problem and course of action.
Macronutrient deficiencies
As soon as any signs of illness are visible in your weed, rule out a lack of nitrogen, potassium, or phosphorus before it's too late. Since much of your weed's vital functions can't proceed without them, treating a macronutrient deficiency is paramount.
Nitrogen deficiency
When a nitrogen deficiency in cannabis is present, you'll notice leaves at the base of your plant turning pale. Left untreated bottom leaves progressing upwards will turn yellow, curl, and eventually brown before falling off.
Don't be fooled by your plant going into hyperdrive and flowering fast. It's a sign of survival mode, and bud sites will be minimal, yielding tiny nugs.
To rectify this cannabis deficiency, you'll find many fertilizers or nutrient boosters high in nitrogen at your local gardening center. Fish or seaweed-based plant feeds are also rich in nitrogen amines. You can water these straight into the soil or foliar feed.
The latter allows the nutrients to be absorbed directly into the leaves. It's a faster treatment method for plants, not growers. Spraying or rubbing down the leaves is time-consuming but worth the elbow grease.
Phosphorus deficiency
A phosphorus illness is one of the easiest to spot using your cannabis nutrient deficiency chart. Dry leaves with spots of brown discoloration appear with a dark blue and green hue. You'll also notice in more serious cases purple and red dead spots in your leaf stems.
Left to take hold, horizontal and vertical growth will come to a halt. The leaves will then begin to take on a metallic bronze or purple color and curl before dropping.
Phosphorus deficiency in cannabis occurs when your pH levels drop into the alkaline zone. Keeping it as close to the acidic side at around six will increase nutrient bioavailability. Like nitrogen, this chemical is found in fish-based products. Feed your plant phosphorus-rich fertilizers, alongside fish meal and worm castings to boost its levels.
To prevent a phosphorus marijuana nutrient deficiency in the first place, opt for growing in aerated containers, which allow for better oxygenation. Rotted manure is also an ideal potting medium with mycorrhizal fungi.
Potassium Deficiency
Like most lack of nutrients signs in pot, a potassium deficiency in weed begins with yellowing leaves. In this case, it starts at the edge and tips before turning brown.
A tell-tale sign that a lack of potassium is to blame is when your plant begins to curl its leaves and stretch out.
A top tip from veteran growers is always to flush your grow medium before planting your weed seedlings. By doing this, you're ridding it of any prior overfeeding, which will interfere with potassium intake.
Adding chicken manure to the topsoil will keep this type of marijuana deficiency at bay. For prompt treatment, you can try foliar feed, a potassium-rich fertilizer. Organic seaweed-based products once again can also come to the rescue.
Can your Plants have Oxygen or Carbon Deficiencies?
Non-mineral essential elements oxygen and carbon are all vital for plant growth. Together they make up over 90% of your plant's dry weight. Without them, your plants will wither and die.
- Oxygen: Your plants can obtain oxygen through water and air. Without enough of it, weed root systems perish, leaves droop, and turn a pale yellow. A lack of oxygen almost always spells death for your marijuana.
Overwatering is to blame for oxygen deprivation or oxygen cannabis deficiencies. Soaking your weed in stagnant water causes root rot and is a death sentence for your pot.
Those that opt for a hydroponics system should incorporate a nutrient-rich solution into their feeding schedule. Better still, providing an air pump to keep your water oxygenated and continuously moving will help reduce the risk of marijuana deficiencies.
Soil growers need to avoid watering plants too often. Give your weed a chance to dry out between drinks and only provide what it can absorb over a couple of hours.
- Carbon: Your plant uses carbon via CO2 in the atmosphere. If there isn't enough of it, your plants' growth will become stunted, and it'll take in less water and nutrients.
Since you exhale carbon dioxide when you breathe, spending time in your grow room singing, talking, and pottering around will help maintain adequate carbon levels.
A fan is also a great addition to the room to circulate carbon-rich air. It's even better if this fan has outdoor ventilation. If you have a large number of plants in one room, then consider a carbon dioxide generator.
Marijuana micronutrient deficiencies
Although your plant only needs micronutrients in small doses, they are no less important. There are several kinds of this type of nutrient. Some are more common to cause cannabis nutrient deficiency, while others are virtually unheard of in cannabis.
Learning to recognize them and tell their symptoms apart for fast and effective treatment can be challenging. Below we've outlined the essential micronutrients of weed and explore how to identify and treat each cannabis deficiency.
Boron deficiency
Boron works hand in hand with calcium to create healthy cell walls and division. It's an immobile nutrient, and most quality soils provide an adequate amount making it a less common cannabis nutrient deficiency.
A boron deficiency in cannabis presents as yellowing, wilting leaves with indentations around the edges. Any vegetative growth is poor, and new leaves twist.
The easiest way to prevent this issue is to flush your potting medium–especially if it's been recycled–and add extra boron. A teaspoon of boric acid to a gallon of water should do the trick.
Iron deficiency
Iron is a semi-mobile nutrient that's essential for the use of sulfates and nitrates. It also plays a key role in producing chlorophyll, general metabolic and energy processes. If your pH gets out of whack or your plants get a build-up of excess manganese, copper, or zinc, a cannabis iron deficiency will occur.
Due to its links to many other chemical processes, iron cannabis nutrient deficiency symptoms are easy to misinterpret for something else. Like manganese, for instance, a lack of this nutrient displays yellowing between the leaf veins and affects new growth first.
Calcium deficiency
A calcium deficiency in weed is a big problem for the health of your plant. It's an immobile nutrient that needs the assistance of boron to travel. Without calcium, your cannabis will warp, and new growth will lack structural integrity.
This vital micronutrient also supports the flow of sugars and nitrogen through the weed. As a result, a low level of calcium will cause a nitrogen deficiency. At the same time, a lack of boron or manganese can cause issues with calcium absorption.
To spot a calcium cannabis nutrient deficiency, look for brown spots on young leaves. Left to take over, new growth from the top will come to a halt, and leaves will curl into unusual shapes.
Remember to check for the pinched indentations around the edges of your leaves that signal a lack of boron. If these 'zipper' patterns move to the center, then your calcium levels are alarmingly low, and your root system is likely also to have damage. Once your root tips begin to die, it’ll be hard to revive your plant.
A calcium marijuana deficiency occurs if your pH levels are too alkaline. To overcome this, supplement your plants with calcium and magnesium fertilizer. A teaspoon of lime to a gallon of water will also help boost your levels.
To prevent the onset of calcium deficiency, add some dolomite lime powder to your soil.
Magnesium deficiency
Magnesium is an essential nutrient. Without it, chlorophyll and photosynthesis can't happen. A lack of it is bad news for cannabis growers, as it’ll diminish your crop size.
As it's an immobile substance, magnesium deficiency in weed symptoms starts with new growth. The leaves show yellow spots and eventually turn brown before they die. Older leaves display signs of struggle with yellowing between the veins and rusty colored spots.
By the time a magnesium marijuana deficiency is visible in your weed, the plant will have been suffering for a while, so prevention is key. Plant your marijuana in quality compost, use large containers and bump up the nutrients with dolomite limestone mix.
If you're not so lucky to keep this marijuana nutrient deficiency at bay, it's most likely that your pH level has gone over 6. Most pro growers tackle the issue with a teaspoon of Epsom salts in 33.8 ounces of water should help to revive your plants.
Molybdenum deficiency
Unlike most micronutrients, molybdenum is mobile. It takes part in important enzyme systems that convert nitrates into ammonium compounds.
A molybdenum deficiency in cannabis is rare and is usually triggered by a cold snap. You'll notice the older leaves on your weed turning yellow before they curl and 'cup.'
There's not much that you can do if a molybdenum marijuana deficiency sets in. The best way to avoid it is to obey the growing season if planting outside. Consider bringing your plants inside if the weather forecast shows frosty nights.
Manganese deficiency
Manganese is an essential non-mobile micronutrient that works alongside many others. It’s responsible for several critical processes that keep your plant happy and healthy.
It’s a lesser-known nutrient which many growers overlook when trying to diagnose cannabis deficiencies. A pH level over six impairs your plant's ability to absorb manganese. A build-up of iron can also be at fault for locking out the nutrient at the root level.
Light green and yellowing new leaves signal a cannabis manganese deficiency. Left to run riot, they’ll turn brown, dry out, and disintegrate. Older leaves then follow suit with yellowing veins.
As you may notice, these symptoms are very similar to others. Growers often spend weeks trialing cannabis deficiency remedies, and by the time they discover it’s manganese, their plant's growth has come to a complete stop.
Foliar feeding manganese-rich fertilizers are the best way to tackle the problem. A compost and green-sand mix will also help aid its absorption.
Silicon deficiency
Like Molybdenum, a silicon marijuana deficiency in cannabis is uncommon. The mineral strengthens cell walls and encourages strong structures.
Most experienced growers will use silicon liquid feed to supplement growth from the beginning rather than correct a deficiency issue.
Sulfur deficiency
Sulfur is a critical micronutrient. Although immobile, it's used across your plants in many key processes. Without sulfur enzymes, fatty acids and proteins can't break down. It’s also part of the respiratory system and is responsible for marijuana terpenes and oils.
A lack of phosphorus caused by high pH levels triggers a sulfur deficiency in cannabis. As it's a secondary issue, it's rare to see a deficiency of sulfur in weed.
Nevertheless, if your leaves turn lime green with patches of yellow, a lack of sulfur is to blame.
Left to its own devices, your plant will stop growing, and its leaves will begin to dry out and fragment. This cannabis deficiency may not kill your plant, but it’ll leave you with a small crop of low potency weed that has dull terpene profiles.
Zinc deficiency
A cannabis zinc deficiency is detrimental to the health of your plants. The mobile metabolic nutrient has many roles. It helps to produce proteins, sugars, chlorophyll, strong stem systems, and growth hormones.
Zinc cannabis deficiencies are common in areas when the soil is more alkaline, in dry arid climates. On the other hand, it can also occur if your pH levels tip into acid.
A tell-tale sign that something's up with your zinc is when the weed leaf blades distort and rotate sideways. Check it out on your cannabis leaf chart. They may also wrinkle and discolor at the tip, leaving brown burn marks.
It's crucial to balance and maintain the pH of your soil or hydroponics system. Doing so should keep your zinc levels at a consistent rate and deter any issues.
Copper deficiency
Copper is a semi-mobile macronutrient that typically doesn't cause any headaches for growers. It aids the utilization of nitrogen and carbohydrates in your plants.
Most high-quality soils have adequate amounts of copper to feed your plant. If your growing medium isn't sufficient, leaves will start to wilt, and any new growth will twist.
You should always aim to prevent cannabis deficiencies of heavy metals rather than dosing your plant with them later down the line. You'll be smoking these plants, and we think you'll agree that ingesting metals isn't a healthy option.
Solve cannabis deficiencies and keep your crops healthy
The biggest problem growers face is identifying cannabis deficiency accurately and efficiently. Many emerging plant health issues look similar. For instance, most begin with yellowing leaves.
Misdiagnosing the issue can cause more harm than good. Laying down nutrients a plant doesn't need can cause a build-up and lockout of other essential substances.
To make diagnosing a marijuana deficiency even more tricky, simply leaving your weed in the cold or overwatering can also make it show the same signs.
Veteran cultivators spend time preparing their grow area to avoid the majority of the cannabis deficiencies. Acclimate your growing medium with local water, test its pH and supplement anything missing before you plant your seedlings.
Don't skimp on space, either. When potting your cannabis, ensure it has a big enough grow container, around five gallons for each plant. The roots will then have a large reserve of nutrients to feed off. In return, they'll develop strong root networks to support bigger, healthier plants.
Slow-release nutrient products are also a great way to help replenish your soil as your cannabis grows. Hydroponics growers should also regularly restock their nutrient reservoirs.
Nurture Your Nutrients
Nutrient management is a necessary skill to become a successful cannabis grower. Don't be intimidated by it; cannabis is just like any other plant. Use the weed deficiency chart to help you stay on top of any deficiencies that may arise.
Your first hurdle to cultivating healthy and bountiful crops, free of cannabis deficiencies, is finding a growing method that's reliable for you. Like anything new, a little trial and error are necessary at the start to help you learn and build confidence.
You can grow marijuana in various ways, indoors, outdoors, hydroponically, or in a greenhouse. Once you have the basics in place to provide what your pot needs, cultivating cannabis is easy. You could say it grows like a 'weed'!
