Like any other agricultural product, growing cannabis also involve common problems that every grower should be aware of. Yes, cannabis growers, most especially first-timers, face difficulties growing marijuana because of nutrient issues, overwatering or underwatering, pests, and other issues.
It’s a good thing that marijuana plants are resilient, with innate capability to withstand harsh environments or invaders. When you’re faced with common cannabis plant problems, don’t panic. Assess the signs and make an analysis of what’s happening to your marijuana plants so you can take the appropriate course of actions. Let’s learn the most common marijuana plant problems now!
1. Watering Issues
Overwatering and underwatering are commonly experienced by novice cannabis growers. Watering issues may cause multiple symptoms. They can even cause stunted growth. The contributing factors to successful cannabis grow include adequate lighting, airflow, nutrients, and humidity. However, water is one of the crucial aspects to keep your marijuana plants happy, healthy, and strong.
Let’s check the signs of overwatering and underwatering so you’ll know when to act accordingly.
Overwatering Marijuana Plants
You might be worrying that your marijuana plants need a constant supply of water. However, it’s a pitfall that most novice usually falls into. Marijuana plants use their roots to breath air aside from uptaking water. So if the root system of your cannabis plants is constantly getting swamped, they’ll likely drown.
Signs of Overwatering
- Drooping leaves
- Leaves tend to curl and become firm (because they’re full of water)
- A slow rate of growth or completely stopped (because of lack of oxygen to the root system)
How to Fix Overwatering
- Water less often.
- Check soil moisture. Wait for the topmost layer of the soil to look dry. You can also feel the soil or do a chopstick method to ensure that the soil is dry before you water again. Another test to test soil moisture is to put your index finger deep into the soil up to your knuckle. If it’s dry, you need to water your plants. Investing in a reliable moisture meter is also a good idea for accurate reading.
- Each cannabis plant should have adequate drainage. Make sure that the water doesn’t build up too much in the bottom section of the containers or pots. Excess water should drain out of the pots enough to leave the soil moist for the root system but not waterlogged.
Underwatering Marijuana Plants
As the opposite of overwatering, underwatering occurs when you simply are unable to meet your cannabis plant’s demands. If your plants don’t get adequate water, their root system will start to dry up, leading to stunted growth and reduced yield.
Signs of Underwatering
- Cannabis plants look lifeless and weak
- Leaves wilt and look fragile
- Leaves feel papery and brittle
- Crispy soil or dry growing medium
How to Fix Underwatering
- When the soil’s top inch has dried out, water you cannabis plants. Don’t leave it any longer or delay watering because it can lead to major problems, like nutrient deficiencies, leading to death.
- Make sure that you use the correct sizes of pots at different stages of your cannabis plants’ growth and development. For instance, gro small seedlings in small pots to make sure they uptake enough water.
- Check soil moisture before watering your cannabis plants.
- Check water quality by testing the pH. It should be 7, which is the neutral water pH. Too high or too low pH can cause problems because the pH dictates how well your plants can absorb nutrients.
- Use reverse osmosis filters to remove 95 to 99% of dissolved salts present in the water
2. Nutrient Burn
Novice growers usually encounter nutrient burn in growing cannabis plants. It is often a result of overzealous feeding of marijuana plants. It usually occurs when there’s a too much hydroponic solution that is applied, wherein the roots take more nutrients than what the cannabis plant can use. Nutrient burn also happens when the plants are cultivated in fresh compost manure as well as other plant mediums with too high nutrient levels. Remember that cannabis plants don’t really need plenty of nutrients in all stages of development. Nutrient burn is caused by feeding cannabis plants with a too strong nutrient mix or fertilizing too frequently.
Signs of Nutrient Burn
- Leaves appear brown
- Leaves look crispy
- Stunted growth
- Burning starts at the tip of the leaves
How to Fix Nutrient Burn
- Hold off feeding nutrients to your cannabis plants for a week or two when you begin to see the tell-tale signs of nutrient burn. It will allow flushing out a high quantity of nutrients.
- Monitor water pH which reflects the capability of the root system to absorb nutrients.
3. Nitrogen Toxicity
Nitrogen toxicity may result in feeding your cannabis plants too much nitrogen. Nitrogen is a macronutrient that marijuana plants use to grow and survive. Most nutrient bottles have three numbers that are listed next to each other, like N-P-K ratios. They symbolize the three main macronutrients including Nitrogen, Phosphorus, and Potassium.
Signs of Nitrogen Toxicity
- Leaves curl downwards
- Leaves turn dark green
How to Fix Nitrogen Toxicity
- Reduce the amount of nitrogen that is mixed into your nutrient feedings.
4. Powdery Mildew
White powdery mildew is usually a result of too high humidity in the grow room, accompanied with low or absence of airflow. It is one of the common fungi infestations you’ll encounter as a marijuana grower. In the long run, the powdery substance continues to spread to the other parts of the plants and produce more mildew like eating up your marijuana plants.
Signs of Powdery Mildew
- White powdery substance on the leaves and other plant parts
How to Fix Powdery Mildew
- You can kill the mildew by misting it with a mildew-eliminating spray.
- Lower the humidity and increase the airflow in the indoor grow room to stop the mildew from coming back.
5. Bud Rot
Bud rot is caused by levels of high humidity accompanied by low airflow. It can also be caused by overwatering, which results in rotting of cannabis buds. The rotting starts from the inside, slowly turning brown and moldy.
Signs of Bud Rot
- Buds turn brown and look moldy.
- Eventually, the whole cannabis bud is ruined.
How to Fix Bud Rot
- Increase the airflow in the grow room by using oscillating fans and ensure proper venting.
- Lower the humidity in your indoor grow space.
- Cut off all the infected buds.
- After the infected buds are removed, pay close attention to other buds to ensure they’re not infected. Practice proper handwashing and good hygiene to avoid spreading the bud rot.
6. Fungus Gnats
Sciarid flies or fungus gnats are small flying insects with a 3 and 5mm size. These are small and dark-colored flies that usually appear and spread on the lower parts of cannabis plants. It also happens in the substrate. Fungus gnats feed on sugars, decomposing organic material, and molasses. High humidity and low light intensity make your cannabis plants susceptible to fungus gnats. Warm temperatures also predispose your plants to this condition.
Fungus gnats are common guests in indoor crops and greenhouses. Hydroponic systems are highly sensitive to sciarid flies. Organic substrates with excessive moisture make an excellent habitat for fungus gnats.
Female sciarid flies lay around 50 to 200 eggs in the substrate and hatch after 48 to 72 hours in favorable conditions. For the next 2 to 3 weeks, there are four different stages of development that larvae pass through. The propagation is fast enough, which highly depends on the environmental conditions.
Signs of Fungus Gnats
- Stunted growth of cannabis plants
- Fungal infection
How to Fix Fungus Gnats
- Maintain moderate humidity in the grow room.
- Avoid overwatering your cannabis plants.
- Keep the top layer of the substrate dry to reduce the presence of insects.
- Cover the substrate with mulch like vermiculite so adult females won’t lay eggs on the substrate top layer.
- Apply neem flour to combat pests by pouring it on the substrate until it forms a thin layer to act as a seal.
- Chemical insecticides are considered your least option because of health and environmental concerns.
7. Heat Stress
Heat stress also occurs when a cannabis plant is placed too close or directly to the heat lamp. Heat stress also refers to a form of stress on cannabis plants as a result of too high temperature in your grow room. The ideal temperature in the grow room should be close o 75 degrees Fahrenheit at all time. However, it reaches below 80 degrees Fahrenheit, the cannabis plant starts to slow down.
Signs of Heat Stress
- As the temperature gets hotter, the fan leaves fingers will start to fold up or taco longways.
- Yellowing or browning of the edges of the leaves that are closest to the light source.
- Spots noticeable to the parts nearest to the heat source.
How to Fix Heat Stress
- Heat stress is the easiest cannabis problem to solve. Lower the room temperature to the appropriate levels.
- Reduce heat by adding a small fan that blows across the tops of your cannabis plants.
- Adjust the heat lamp placement to eliminate the problem.
- Vent out the hot air with the use of an exhaust fan to prevent heat stress and also treat its existence.
Fusarium is a genus of filamentous fungi living in the soil and may affect your cannabis plants. Most species are considered saprophytes, feeding on the debris of other soil organisms. Fusarium eventually develops as parasites, producing mycotoxins that can also affect humans causing skin infections. The colonization of fusarium takes place at the level of the soil, through the shallow roots or the stem, which moves all parts of the cannabis plant via the vascular bundles.
Signs of Fusarium
- Rotting and lignificación of the stem base
- Nutritional deficiency as manifested yellowing leaves
- Root rot
- Brown vascular bundles when the stem is cut
- The Fusarium fungus blocks the vessels as a result of colonizing the xylematic tissues of cannabis plants. Because of the blockage, the leaves turn yellow and wilt.
- Eventually, other parts of the plant are also affected, causing necrosis and in worst case cause death of the cannabis plant.
How to Fix Fusarium
- Get rid of affected plants
- Strict hygiene to prevent the problem from happening again
Aphids affect marijuana growers around the world. Aphids are a common garden pest with detrimental effects on cannabis plants. They are small sap-sucking insects which are destructive on cultivated plants. Aphids vary in size from 1 to 10 mm. It can be green, white, red, or black in color with two whip-like antennae and tube-like structures referred to as cornicles.
In early spring, winged female aphids hatch, giving birth to female nymphs. Only within a few weeks, young aphids are born. The number of aphids rises dramatically in a relatively short period of time. Aphids develop as males and females, mating to produce overwintering eggs by the end of summer.
Signs of Aphids
- You’ll see aphids on the stems and leaves of cannabis plants. The green varieties are harder to spot.
- Aphids suck sap from cannabis plants and leave a thick and sticky substance referred to as honeydew, that promotes the growth of sooty and black mold.
- The leaves curl, wilt or turn yellow.
- Stunted plant growth.
How to Fix Aphids
- Get rid of aphids by cleaning and pruning any infected areas.
- Use the water-vinegar solution to kill remaining insects.
- Introduce predatory insects like ladybugs.
- Use essential oils.
- Use organic insecticides.
10. Incorrect pH
Growing cannabis plants with the wrong pH level is a common reason why people experience cannabis plant issues. To prevent health problems, mix nutrients and water at the right pH. Remember that the pH level affects the absorption of nutrients by your cannabis plants. Invest in a reliable pH meter to ensure the water and soil has a neutral pH which is 7.
Growing cannabis is a tricky process, and there are so many things that can go wrong. Too little or too much water, heat, or fertilizer, mildew, mites, viruses, mold, issues with ozone exposure, fluctuations in pH, and nutrient deficiencies can jeopardize your yield and the quality of the final product. Keep these quick fixes in mind and research intensively if ever you encounter any of these common marijuana plant problems.