What to Do About Spider Mites During Flowering?

by Jennifer

As cannabis cultivation becomes increasingly widespread, so do the challenges faced by growers. One of the most common and persistent pests that plague cannabis plants, particularly during the flowering stage, is the spider mite. These tiny arachnids can wreak havoc on yields and quality if not promptly addressed. In this article, we’ll delve into the specifics of dealing with spider mites during the crucial flowering phase, offering comprehensive strategies and solutions to mitigate their impact and safeguard your harvest.


Understanding Spider Mites

Before delving into control measures, it’s essential to understand the enemy. Spider mites (Tetranychus urticae) are minute arachnids belonging to the family Tetranychidae. Despite their small size, typically around 0.5 millimeters, they can cause significant damage to plants by piercing leaf tissues and sucking out the contents, leading to wilting, discoloration, and even death of affected foliage.

Spider mites thrive in warm, dry conditions, making them particularly problematic in indoor grow environments where climate control is maintained for optimal plant growth. Their rapid reproduction rate, with females laying hundreds of eggs over a lifespan of a few weeks, allows populations to explode rapidly if left unchecked.

Identifying Spider Mite Infestations

Early detection of spider mite infestations is crucial for effective control. However, their diminutive size and tendency to dwell on the undersides of leaves can make them challenging to spot with the naked eye. Growers should regularly inspect their plants, paying close attention to the following signs of infestation:

Fine Webbing: Spider mites produce silk webbing on the undersides of leaves, often forming a fine mesh that traps debris and eggs.

Yellowing or Bronzing of Leaves: Infested leaves may exhibit yellow or bronze discoloration, starting from the lower canopy and progressing upwards as the infestation worsens.

Stippling: Tiny yellow or white spots, known as stippling, may appear on the upper surface of leaves where spider mites have fed.

Leaf Curling or Wilting: Severe infestations can cause leaves to curl, wilt, or drop prematurely, impacting plant health and productivity.

Once identified, immediate action is necessary to prevent further damage and mitigate the spread of spider mites to neighboring plants.

Integrated Pest Management (IPM) Strategies

Effective management of spider mites during flowering requires a multi-faceted approach that integrates various control methods. Implementing an Integrated Pest Management (IPM) strategy tailored to your specific growing conditions can enhance efficacy while minimizing reliance on chemical interventions. Here are some key components of an IPM approach:

1. Cultural Controls:

Maintain Optimal Growing Conditions: Ensure that environmental conditions, including temperature and humidity, are kept within the optimal range for cannabis cultivation. Spider mites thrive in hot, dry environments, so maintaining adequate humidity levels can help deter infestations.

Prune Infested Foliage: Remove heavily infested leaves to reduce spider mite populations and prevent the spread of the pests to healthy plant parts. Be sure to dispose of pruned foliage away from the growing area to prevent re-infestation.

Promote Biodiversity: Introduce beneficial insects such as ladybugs, predatory mites, and lacewings to the growing environment. These natural predators can help keep spider mite populations in check without the need for chemical pesticides.

2. Mechanical Controls:

High-Pressure Water Spray: Use a strong jet of water to dislodge spider mites from plant surfaces. Focus on the undersides of leaves where mites tend to congregate. Repeat spraying every few days as necessary to prevent re-infestation.

Vacuuming: For indoor grow operations, consider using a small handheld vacuum to remove spider mites from plant foliage. Exercise caution to avoid damaging delicate leaves, and empty the vacuum bag immediately after use to prevent mites from escaping.

3. Biological Controls:

Predatory Mites: Introduce predatory mite species such as Phytoseiulus persimilis or Neoseiulus californicus to prey on spider mites. These beneficial mites can rapidly decimate spider mite populations when released at the first sign of infestation.

Predatory Insects: Release predatory insects like ladybugs (Hippodamia convergens) or lacewings (Chrysoperla carnea) to feed on spider mites. These natural enemies can provide effective control, especially in greenhouse or outdoor settings.

4. Chemical Controls:

Horticultural Oils: Apply horticultural oils, such as neem oil or insecticidal soap, to suffocate and disrupt the feeding behavior of spider mites. These products are relatively safe for use during flowering but should be applied with caution to avoid phytotoxicity.

Botanical Insecticides: Certain botanical insecticides, such as pyrethrin-based products derived from chrysanthemum flowers, can effectively control spider mites while posing minimal risk to humans and the environment. Follow label instructions carefully and avoid spraying directly on flowers or developing buds.

Systemic Insecticides: In severe infestations where other control methods have proven ineffective, systemic insecticides containing active ingredients like abamectin or spirotetramat may be warranted. However, these chemicals should be used judiciously, taking care to adhere to pre-harvest intervals and legal restrictions.

Preventative Measures

Prevention is often the best strategy for managing spider mites during flowering. By implementing proactive measures to deter infestations, growers can minimize the need for reactive control methods. Consider the following preventative tactics:

Quarantine New Plants: Before introducing new plants into your grow space, quarantine them for a period of observation to detect any signs of pest infestation. This practice helps prevent the inadvertent introduction of spider mites and other pests to your cannabis crop.

Maintain Cleanliness: Keep grow rooms or outdoor growing areas clean and free of debris that could harbor spider mites and other pests. Regularly sanitize equipment and surfaces to minimize the risk of pest transmission.

Monitor Environmental Conditions: Invest in monitoring equipment such as hygrometers and thermometers to track temperature and humidity levels accurately. Adjust environmental controls as needed to create less favorable conditions for spider mites to thrive.

Rotate Control Methods: To prevent the development of resistance in spider mite populations, rotate between different control methods, including biological, mechanical, and chemical interventions. This approach reduces reliance on any single control measure and improves long-term efficacy.


Dealing with spider mites during the flowering stage of cannabis cultivation requires a proactive and multi-faceted approach that integrates cultural, mechanical, biological, and chemical control methods. By implementing an Integrated Pest Management (IPM) strategy tailored to your growing conditions, you can effectively mitigate spider mite infestations while safeguarding the health and productivity of your plants. Remember to prioritize early detection, preventative measures, and judicious use of chemical interventions to minimize the impact of spider mites on your cannabis crop. With diligence and careful management, you can successfully navigate the challenges posed by these troublesome pests and achieve a bountiful harvest of high-quality cannabis flowers.


You may also like

Copyright © 2023