How to get rid of spider mites on cannabis plants

Spider mites are the most common garden pest to attack cannabis plants. These tiny mites love to make their home on plants in dirty indoor grow rooms or greenhouses, living on their nutritious sap. If left uncontrolled, spider mite infestations can have devastating effects on the health of your plants and the size/quality of your harvest.

WHAT ARE SPIDER MITES?

Spider mites are a common garden pest. They tend to live on the underside of plant leaves, and leave behind translucent eggs and protective silk webs.

Spider mites can be red or black in colour and can usually only be spotted with at least a 10x microscope. They feed off plant sap, stunting the growth of your plants and ultimately affecting their overall health and the size of their yields.

HOW TO SPOT SPIDER MITES

While spider mites are tiny, you can easily spot them by looking for the following telltale signs of the pest on your plants:

• Stippling. This looks like tiny white or yellow spots forming on the foliage of your plants.
• Small white, almost translucent eggs on the underside of leaves.
• Fragile silk webbing forming around leaves, buds, or branches.
• Visible mites on plant foliage (usually spotted with a handheld microscope).

HOW TO GET RID OF SPIDER MITES

Spider mites reproduce extremely quickly (one fertilized female can lay up to 140 eggs per day). Hence, you’ll want to act quickly at the first sign of an infestation.

Here’s how to get rid of spider mites on your cannabis plants:

• Start by washing down your plants with a strong jet of water. Do this early in the morning. If possible, try to bring down the pH of your water to about 3-4. You can do this using vinegar, nitric, phosphoric, or citric acid.
• Next, opt for a contact pesticide spray like insecticidal soap. These are safe to use on all kinds of consumable plants, including cannabis. When using contact sprays, remember to directly hit the pests and their eggs with the spray (the key word here is contact). If you’re a DIYer, you can make up your own insecticidal mite spray using water and garlic.
• Re-apply your spray according to the label instructions until all the mites have been completely removed from your plants. This will usually take multiple applications. Also, remember to switch up the sprays/pesticides you use. Mites are very good at building up immunity if only targeted with one specific spray.

Note: Never use systemic pesticides on cannabis plants. These pesticides enter the vascular system of plants and can be poisonous to both humans and animals. Only ever use pesticides that are safe to use on edibles like fruit and veg.

HOW TO PREVENT SPIDER MITES

Obviously, it's always better to prevent a mite infestation than fight one. Here are some simple tips for preventing spider mites on your cannabis plants:

• Don’t recycle soil from plants that have been infected in the past.
• Submerge all new plants in a non-toxic miticide before introducing them into your garden.
• Keep temperatures low and humidity high. Mites struggle to reproduce in these conditions.
• Immediately remove and destroy damaged foliage.
• Introduce predatory mites or insects into your garden. You can buy these online or at gardening centres.
• Keep your grow space clean. Spider mites love dirty, dusty environments, so make sure you clean your grow space regularly. This includes everything from your basic gardening equipment (like pruning shears) to your high end equipment like extractors.