Causes of Stress in Cannabis Plants: Causes, Symptoms, and Solutions

Growing cannabis plants can be challenging for both hobby growers and commercial producers. One of the biggest obstacles is stress, which can slow growth, reduce yields, or even kill the plants. In this article, we take a detailed look at the causes of stress in cannabis plants and explain how to recognize and prevent it.

1. Environmental Stress

a) Temperature Issues

High temperatures (above 30°C / 86°F) can slow growth, cause drooping leaves, and lead to heat stress. Too low temperatures (often below 15°C / 59°F) hinder growth and can cause purple discoloration.

Solution:

• Ideal temperatures during growth: 22-28°C (72-82°F)

• Ideal temperatures during flowering: 18-26°C (64-78°F)

• Improve ventilation and climate control

b) Humidity Stress

Too low humidity (below 40%) can inhibit growth and cause drought stress. Too high humidity (above 70%) promotes mold and fungal infestations.

Solution:

• Vegetative phase: 55-70% RH

• Flowering phase: 40-50% RH

• Use humidifiers or dehumidifiers

c) Light Stress

Cannabis plants need light, but too much exposure can cause burns, growth disturbances, and chlorosis.

Solution:

• Maintain proper distance for LED & HPS lights (depending on wattage)

• 18/6 light cycle for growth, 12/12 for flowering

• No light leaks during the dark phase

2. Nutrient Stress

a) Overfertilization

Too many nutrients, especially nitrogen, cause "nutrient burn" (burned leaf tips).

Solution:

• Monitor EC and pH levels

• Use only recommended nutrient amounts

b) Nutrient Deficiencies

Too little potassium, magnesium, or calcium leads to growth problems, yellow leaves, and weak stems.

Solution:

• Conduct leaf diagnosis

• Use organic or mineral fertilizers

c) pH Problems

An incorrect pH in the soil (outside of 6.0-7.0) blocks nutrient uptake.

Solution:

• Check pH levels of water with a pH meter

• Use pH-Up or pH-Down to correct imbalances

3. Biotic Stress (Pests & Diseases)

a) Pests

• Spider mites: create fine white webs

• Thrips: leave silvery spots on leaves

• Fungus gnats: their larvae damage roots

Solution:

• Use natural predators like predatory mites

• Apply neem oil or potassium soap

b) Fungal Diseases & Mold

High humidity promotes powdery mildew, botrytis & root rot.

Solution:

• Improve air circulation

• Remove moldy plant parts immediately

• Use fungicides sparingly

4. Mechanical Stress

a) Improper Pruning

Incorrect or excessive pruning leads to growth disturbances.

Solution:

• Use LST (Low-Stress Training) instead of aggressive methods

• Prune only during the vegetative phase

b) Transplant Shock

Late or incorrect transplanting can damage roots.

Solution:

• Handle roots carefully

• Ideal transplant time: when roots reach the pot edges

Conclusion: Prevent Stress and Grow Healthy Plants

Cannabis plants are resilient but sensitive to various stress factors. By ensuring optimal environmental conditions, proper fertilization, pest control, and careful handling, you can avoid stress and cultivate healthy plants with maximum yield.

Recommended Products for healthy plants on Cannadusa

Aqua Master Tools Combo Pen P110 Pro pH EC Temp - 85,00€

BioBizz Starters Pack Erde - 82,00€

Plagron Top Grow Box Natural - 74,00€