Growing cannabis can be immensely rewarding, but it also comes with its fair share of challenges—even for experienced growers.
If you’ve noticed your plants are looking a bit off, maybe they have yellow leaf tips or weak stems, or perhaps something is moving in the soil… these are all red flags that need to be addressed sooner rather than later.
But don’t panic yet, rookie cultivator! Your cannababies are probably just going through a rebellious phase. Keep reading to learn about common cannabis plant problems and the steps you can take to get them back on track.
Cannabis Plant Pests
Yes, your cannabis plant can get bugs, bugs, baby. These little critters are the bane of any grower’s existence. They feed on plant sap, weakening the plant and potentially spreading diseases.
Check for symptoms like yellowing or discolouration, stunted growth, webbing or sticky residue on leaves, holes, wilting, and swarming bugs. The key is acting quickly once you spot the signs! These pests multiply rapidly and can decimate your cannabis plants if left unchecked.
Look out for these common cannabis pests:
- Spider mites
- Aphids
- Thrips
- Caterpillars
- Cutworms
- Fungus gnats
- Whiteflies
- Leaf miners
- Mice
- Stink bugs
- Slugs or snails
- Mealybugs
- Grasshoppers
- Barnacles
Even easy-to-grow indoor plants aren’t entirely safe from them, so stay vigilant when checking for this cannabis plant problem!
Image Source: Shutterstock
How to Get Rid of Cannabis Plant Pests
Prevention is key—but if you suspect pests are the problem, here are some steps you can take:
- Maintain a clean grow space and inspect any new plants thoroughly before introduction (we recommend using a magnifying glass!).
- Maintain excellent air circulation and prune undergrowth to avoid humidity/moisture buildup where pests thrive.
- If you notice any cannabis leaf problems like yellowing or holes, act quickly.
- Use gentle, organic insecticidal soaps, neem oil, or other botanical sprays approved for cannabis plants as instructed.
- For severe infestations, you can introduce predatory insects like ladybugs or lacewings.
Diseases
Your cannabis plants can get sick. Like humans, they’re susceptible to diseases that can cramp their style if not treated quickly. Most of the time, the issue lies in humidity or moisture levels not being regulated.
Plant health is determined by the environment in which it grows—too much dampness and poor air circulation can create the perfect petri dish for funky fungi and icky bacteria to take over. Mould, powdery mildew, and bud rot are typical symptoms of a sick plant—one of the most common cannabis plant problems growers experience.
How to Treat Cannabis Plant Disease
Here are some tips on how to nurse your plant back to health:
- Control the environment to prevent outbreaks by improving air circulation and keeping the grow area clean with fans and dehumidifiers.
- At the first sign of mould or mildew, remove the affected areas.
- Treat plants with a fungicide safe for cannabis with ingredients like copper, sulphur or potassium bicarbonate.
- Sanitize your whole grow area and equipment to prevent repeats.
- Regularly inspect plants, especially during the dense flowering phase.
Nutrient Deficiencies
Cannabis plants are sensitive to their nutritional environment, so it’s no surprise that cannabis deficiencies are one of the most common issues for growers.
Weed plant deficiencies can be observed in the leaves. Cannabis leaves that are turning yellow, curling up or down, or developing strange spots and stripes, are all signs your plant has a nutrient deficiency. The culprit to this issue is likely the cannabis soil or the nutrient solution (if you’re using a hydroponics system).
Cannabis plants are like hungry teenagers—they need a rich, balanced diet of nutrients to thrive. Just like a moody adolescent, they’ll let you know loud and clear if their nutritional needs aren’t being met in the form of cannabis leaf problems or worse.
So, what do these “hangry” signs look like? Here are some common cannabis nutrient deficiencies and their symptoms:
| Nutrient Deficiency |
Plant & Leaf Symptoms |
| Nitrogen Deficiency |
The entire plant turns pale green/yellow from the bottom up; stunted plant growth |
| Phosphorus Deficiency |
Leaves turn dark green/red/purple, especially undersides; stunted plant growth |
| Potassium Deficiency |
Yellowing/browning starts at leaf tips/edges and moves inward |
| Magnesium Deficiency |
Yellowing between leaf veins on older leaves; leaves curl/crinkle |
| Iron Deficiency |
The whole plant turns pale yellow/white while the veins remain slightly green |
| Calcium Deficiency |
Crinkling, deformed new growth; brown spots on leaves |
| Manganese Deficiency |
Dull yellowing between leaf veins |
| Zinc Deficiency |
Younger leaves start yellowing between veins |
| Boron Deficiency |
Brown blotches in the centre of leaves |
| Copper Deficiency |
Twisted, distorted leaves |
| Sulphur Deficiency |
The entire plant turns pale green/yellow; overall slow growth |
| Molybdenum Deficiency |
Older leaves turn pale green/yellow from the center outward |
How to Treat Nutrient Deficiencies in Cannabis Plants
As you can see, some plant and leaf symptoms overlap. So while these signs can be a good reference for weed plant deficiencies, it’s still a good idea to do a soil test to know for sure.
You also want to get your hands on a pH metre. Cannabis plants can only properly absorb nutrients within a specific pH range (typically around 6.0-7.0). If pH is off, the nutrient lockout will occur no matter how much of a certain nutrient you provide.
Regularly monitor your soil’s pH, use balanced cannabis-specific fertilizers, and adjust based on the plant’s growth stage. For example: Nitrogen is crucial in its vegetative stage, while phosphorus and potassium are more important during flowering. If plants develop a deficiency, foliar sprays can be a quick, effective remedy.
🌿 Read more: The Anatomy of a Cannabis Plant and Its Life Cycle
Image Source: Shutterstock
Environmental Stress
Cannabis plant problems can occur simply due to environmental factors. The wrong environment can take a toll on your plants, leading to cannabis leaf deficiencies or worse. Common causes of environmental stress in cannabis plants include:
- Extreme temperatures
- Improper lighting conditions
- Overwatering or underwatering
- Pollutants (smoke, dust, chemical fumes, etc.)
- Poor air circulation
- High or low humidity
To keep your plants happy, make sure their environment is just right. Both the vegetative and flowering growth states have specific temperature needs and light requirements.
| Vegetative Growth State |
Flowering State |
| 20-30°C (70-85°F) 18-24 hours of light |
18-26°C (65-80°F) 12 hours of uninterrupted darkness |
💡 Pro Tip: For indoor grows, use high-quality LED or HID grow lights positioned at the appropriate distance from the canopy to provide sufficient light intensity without causing heat stress or other cannabis plant problems.
Grow Your Cannabis Know-How—Become a Budtender at True North!
Are you captivated by the art and science of cannabis cultivation? Do you find yourself eager to share your knowledge and help others navigate their cannabis journey? If so, we want you on the True North team!
Join us as a True North budtender and become a pivotal part of our community-focused dispensary. This is your opportunity to transform your interest in cannabis into a rewarding career!
Apply at your nearest True North Cannabis Co.—we can’t wait to grow together!
