Common Marijuana Deficiencies and How to Fix Them

Common Marijuana DeficienciesCommon Marijuana Deficiencies

Common Marijuana Deficiencies

Just like humans, cannabis plants require a balanced and healthy diet in order to thrive. Just the right number of additives are needed to fulfil important vegetative functions, and if one piece of the puzzle is missing, growth and harvests will be affected. Luckily for us humans, the cannabis plant is good at communicating and showing what it needs – that’s, if we learn to look in a proactive manner.

If there is any level of nutrient deficiency to speak of, a cannabis plant will discolour and curl its leaves to inform you of what it needs. Aside from fixing each nutrient deficiency, we also have to look at other possible common issues that may lead to your marijuana plants being unhappy. In any case, use this guide to learn all about common marijuana deficiencies and how to fix them.

Overwatering and/or Underwatering

cannabis plant disease over water

cannabis plant disease over water

Believe it or not, but the act of watering might be underrated. Underwatering and overwatering are in fact, two of the most common problems among practicing marijuana growers. Fortunately, in most cases, the damage can be undone. Watch your cannabis plants closely to check if their leaves are drooping or hanging. Other signs of underwatering include stunted growth.

Once you notice these signs on your weed plants, you know it’s time to water them more frequently. If your leaves are drooping, it’s best to water them immediately. As for overwatering, this will cause the leaves to curl downwards and they will be rigid and tight. Fix it quickly, or it may lead to root rot.

When overwatering occurs, you need to cut down on water drastically and immediately. Before watering, also check if the soil is dry enough to water. If not, you need to wait. Give an overwatered cannabis plant some time to dry out and then resume an improved watering schedule.

Get your PH Right

ph meter cannabis plants

ph meter cannabis plants

Even if you get all the Nutrients right, if your soil’s pH levels are off, your entire crop is doomed. Cannabis plants grown in soil typically thrive with a pH of between 6.0–6.5. Any other number will make the roots struggle to absorb key nutrients. This is something you want to avoid at all costs, as it will cause a big problem, called nutrient lockout.

A Lesson on Marijuana Plant Nutrients

Another very common marijuana deficiency comes in the form of nutrient burn. Beginners and expert marijuana growers alike face this problem, as overfeeding is all too easy to do. When it comes to nutrients, the key is to take it easy and according to the recommended dosages.

If the edges of your leaves look burnt, they probably are. The burning shows at the tip of the leaves, so hold off on feeding nutrients for a week or two. This will allow the plant to flush out the high quantity of nutes.

Nitrogen Necessities

Nitrogen is a mobile macronutrient that plays a major role in photosynthesis and the formation of protein. Deficiency of nitrogen on cannabis plants shows itself in yellowing leaves, older leaves dropping off, and subsequently, decreased yields of your marijuana plants.


  • Most organic fertilisers contain adequate nitrogen
  • Apply compost tea as a foliar spray
  • Increase the amount of nitrogen in your compost grass clippings

Phosphorus Problems

As part of the macronutrient family, Phosphorus is directed to the areas that need it most. It also plays an essential role in photosynthesis and is thus, a crucial component of the cannabis plant’s DNA. Phosphorus deficiency manifests as brown spots on leaves, and abnormally dry leaves.


  • Apply a high-phosphate organic fertilizer
  • Add fish mix or worm casting to soil
  • Move your plants to a warmer location (25 degrees Celsius is ideal)

Potassium related issues

As the third and final in the macronutrient family, Potassium helps to regulate CO and the production of energy. Potassium deficiency manifests itself as brown and yellow leaf tips and edges and curled-up leaves.


  • Flush the medium
    • Add chicken manure to the soil
    • Apply organic seaweed as a foliar spray

Calcium Concerns

This immobile micronutrient helps hold plant cell walls together, and without enough of it, will lead to root tips and younger leaves forming abnormally.


  • Add bonemeal to your compost or soil
  • Add eggshells to your organic compost
  • Worm castings provide loads of calcium
  • Apply a calcium-magnesium supplement
  • Add one teaspoon of hydrated lime to 4l of water and use the solution to water your

Magnesium Menace

The most important micronutrient for means of photosynthesis, Magnesium sits at the heart of the chlorophyll molecule and enables it to absorb light and life. Magnesium deficiency will cause your marijuana plant’s lower leaves to dry out and turn yellow. Prevention can be done by adding dolomitic limestone to the growing medium. Also be sure to use compost that’s rich in manure.


  • Add 1–2 teaspoons of Epsom salts to about 4l of water and apply

Iron Indices

The fact that Iron plays an essential role in chlorophyll formation is part of the reason why this immobile micronutrient helps a cannabis plant’s metabolism. If your plant suffers from a lack of iron deficiency, you’ll notice the young growth at the top turning bright yellow in color.


  • Flush the medium and add an iron supplement
  • Incorporate seaweed in your feeding diet

In Conclusion

Indoor marijuana grow

Indoor marijuana grow

When it comes to the most common marijuana deficiencies and how to fix them, there is fine balance to achieve and maintain. Though it’s true that cannabis plants only need some of these nutrients in small amounts, a deficiency can cause big problems. Learn to see the signs and identify the deficiency, followed by prompt action. When problems arise, weed growers can ensure the health and high yield of their cannabis crops at all times.

Marijuana Grow School Online

To learn how to grow cannabis with easy step-by-step instruction enroll at the marijuana grow school today. Learn how to grow weed indoors and out and how to save money on your cannabis garden. Don’t waste time and money on your marijuana grow! Learn how to grow marijuana from the experts and grow better weed as a result!

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