11. Troubleshooting

Sick marijuana plant infested with spider mites

Nutrient Deficiencies

Problem Symptoms Cure
Boron Deficiency Tips of leaf plants turning brown or gray in newly sprouted leaves



Use compost or boric acid to get boron levels back to normal
Calcium Deficiency Big dead spots on leaves that have turned dark green in older leaves Uncommon for outdoor grows. Infuse calcium-rich substances like lime into the soil
Copper Deficiency Necrosis of younger leaves and flowers. Use copper fungicides to rejuvenate your plants
Iron Deficiency Yellowing on the upper leaves Read just the soil’s pH
Magnesium Deficiency Yellowing and wilting on the lower leaves Use Epsom salts
Manganese Deficiency New leaves will start to turn yellow and exhibit several necrotic spots.


Water-soluble fertilizer works well as a way to infuse the soil with manganese. Greensand and compost are also good options.


Molybdenum Deficiency Middle leaves will yellow. Any new growth will also start to turn up warped or it will be stopped altogether. The shoots will start twisting and the leaves may exhibit a sort of red discolouration at the tips. Extremely uncommon for outdoor grows.

Use a foliar spray or add molybdenum-based solutions to the soil


Nitrogen Deficiency Yellowing

of the leaves. The leaves will start to curl in and die if the deficiency isn’t treated fast. The deficiency works its way up from the bottom leaves to the top leaves.


Correcting a nitrogen deficiency is all about using the right fertilizer with the right NPK ratio. Look for fertilizer with a high amount of N.

Urine is also a rich source of nitrogen.

Phosphorus Deficiency Darkening leaf colours and slow growth. Over time, the leaves will start to curve back toward the plant and turn a tannish, brown colour.


Correcting a nitrogen deficiency is all about using the right fertilizer with the right NPK ratio. Look for fertilizer with a high amount of P.
Potassium Deficiency A potassium deficiency might actually make the marijuana plants appear taller and more vigorous at first glance,

but the bottom leaves might be dying.

The leaves may also be turning a tan or brown colour and developing necrotic spots in some locations.


Use water-soluble fertilizer to fix larger deficiencies
Silicon Deficiency Weak plants and pest infections Extremely uncommon in outdoor grows. Use liquid silicon.
Sulfur Deficiency Yellowing leaves. The growth can become stunted and the leaves narrower and more brittle than before.


Extremely uncommon. Use Epsom salts or potassium sulfate to solve it.


Zinc Deficiency Brittle and yellowing leaves. To fix a zinc deficiency, you also need to supplement in manganese and iron, as they are connected.




Pest Problem Cure
Your pets (cats & dogs) They might shit all over your precious crop (and that’s not good). Keep them away from your garden
Cutworms They feed off seedlings, killing them in the process Plant sunflowers near your marijuana crop or till the soil.
Crickets and Grasshoppers hey will eat every plant in your garden, including your precious ganja. If you notice an infestation, use a mixture of water and soap to deter them from ever coming near your garden
Deer Deer have been known to take quite a liking to mature cannabis. They can eat your buds in a whiff! Put up a fence or scare them off.
Fungus Gnats These little insects feed off the leaves of plants, eventually reaching the root system. Put a sticky insect trap near the base of your plant. To get rid of the larvae, use a mixture of water and peroxide.
Gophers Unlike moles, which are generally friendly towards farmers, gophers will eat the roots given the chance. If no natural predators are around, use garlic or castor oil to keep them away.
Leaf miners Leaf miners–you guessed it– mine the leaves for nutrients, planting their offspring under them in the process. You’ll notice them by the white skid mark they leave on the marijuana leaves. Smash ’em! There’s no other way to get rid of those hard-working pests other than getting violent.
Mealybugs In cases of infestation, you’ll notice a white web forming in the crevices of the plant. The leaves will start to gradually wilt and die. Get rid of any ants near your plant, as they usually protect mealy bugs.
Rats and mice Rats and mice can and will chew on everything. Your plant is no exception. If you live in an area with natural predators, then the problem is contained by definition. If not, you just need to make the environment unwelcoming to rodents.
Snails and Slugs These guys love to feed off marijuana plants. Use salt to exterminate them.
Spider Mites They feed off marijuana plants, extracting the chlorophyll from the leaves. Introduce a controlled population of ladybugs to deal with the problem or spray them with water and neem oil
Thrips Thrips feed off the marijuana flowers, severely hindering the maturation process. Use high-quality compost to avoid getting a thrip infestation. If you notice them on your plant, spray them with water and neem oil.
Whiteflies These white mofos feed off the plant’s leaves, spreading disease along the way. To top it all off, they can fly, making it difficult to deal with them. Attract natural predators by planting flowers like zinnias. Alternatively, you can use garlic to keep them away.



Disease Symptoms Cure
Gray Mould, Bud Rot,


Fungi infect virtually every part of the plant, from the stems and stalks to the buds and flowers. It does not discriminate between the parts of the plant that it enjoys. Use special antifungal remedies
Leaf septoria Yellowing of the leaves in outdoor plants that have been exposed to hot and humid weather. Till the ground thoroughly and add a fungicide in the compost, if you’re using any.
Powdery mildew Mildew is a fungus that thrivesin conditions where the humidity is above 55% and the temperature is warm overall. Infected plants display white powdery spots on the leaves and stems. The lower leaves are the most affected, but if left untreated, powdery mildew can spread fast. There are several sprays available on the market (including apple cider vinegar and even milk sprays) that can help mitigate the effects of the mildew.
Fusarium Fusarium is a fungus that lives in the soil and affects the root systems of marijuana.

Outdoor crops are especially susceptible to this infection. It’s the main culprit for the production of fusarium wilt, which can kill your plants if left untreated.

Outdoor growers can mitigate the risk by growing in containers, where the soil environment is more controlled.
Verticillium Wilt This fungal infection will cause the stem to wilt and turn brown. Use high-quality soil that drains well. There is no real cure for this disease, other than proper agricultural practices.
Damping off This is an infection of the root system, in which seedlings start to wilt and die off.


Make sure that your soil drains well to avoid spores from forming on the root system.


Environmental Stressors

Problem Cause Cure
Airy buds High temperatures can cause lack of potassium, which in turn leads to buds that are crumbly or ‘airy’. Use P-rich fertilizer during the flowering phase to make sure that you won’t have to deal with this, especially if you live in warmer climates.
Soil problems There are many types of soils that you might encounter when growing outdoors. Clay soils, sandy soils, and dried-out soils are only some of the types that present dangers to marijuana growers: For example, sandy soils do not hold any nutrients, as the water flows right through them, whereas clay soils do not offer good drainage.


There are several remedies to help you make unfriendly soils more welcoming, such as compost and permeable matter, like perlite.
Overwatering / Underwatering Watering isn’t as simple as it may seem. Too much water will drown them and too little will cause them to wither. If the soil looks dry, your plant needs water. If not, then it should be fine. It’s not exactly rocket science, but can be surprisingly tricky to get right!

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