How do you treat spider mites on cannabis?
Treat spider mites on cannabis with a three-week rotation of contact sprays, physical removal, and environmental control: isolate the plant, prune heavily infested leaves, then apply insecticidal soap, horticultural oil, or azadirachtin every 3 to 5 days so no new egg hatch survives. Keep the room near 70°F with relative humidity above 50%, since two-spotted spider mites reproduce fastest in hot, dry air. Confirm the pest first with a 10x loupe or a tap test on white paper, because nutrient burn and russet mites cause similar leaf damage.
Cannabis Fungus Gnat Solution Guide
What do spider mites look like on cannabis?
Look for pale stippling on the top of leaves, fine webbing at bud sites and stem joints, and moving specks on the underside. Adults are about 0.5 mm, eight-legged, and range from pale green to red or brown. A tap test shakes mites onto white paper, where they crawl slowly and leave green streaks when crushed.
Step 1: Isolate and scout
Move affected plants away from the rest of the garden before you spray anything. Tag and inspect every plant, checking the undersides of mid-canopy leaves and the base of fan leaves. Spider mites travel on hands, sleeves, and air currents, so work clean plants first and infested plants last.
Step 2: Cut the population down
Remove the worst leaves and any webbing around buds, then bag the debris and carry it out of the grow space. A strong water spray knocks mites and webbing off foliage and breaks up colonies. Vacuuming floors and wiping benches clears eggs and adults that drop from plants.
cannabis spider mites treatment
Step 3: Spray on a schedule
- Spray at lights-off or in the evening to limit leaf burn and protect beneficial insects.
- Cover leaf undersides, stems, and the top of the medium, because mites hide where coverage is poor.
- Repeat every 3 to 5 days for three to four weeks to catch each new generation.
- Switch active ingredients with each application to slow resistance.
Which treatments work on cannabis spider mites?
- Insecticidal soap and potassium salts of fatty acids: contact killers for eggs, nymphs, and adults, with few residue concerns late in flower.
- Horticultural oils (mineral, neem, canola): smother eggs and adults, and work best when temperatures stay below 85°F.
- Azadirachtin: disrupts molting and feeding, slow-acting but useful in rotation.
- Pyrethrins and spinosad: fast knockdown, though repeated use drives resistance and kills predators.
- Bifenazate and abamectin: strong miticides for vegetative plants, restricted or unregistered in many cannabis programs.
- Predatory mites (Phytoseiulus persimilis, Neoseiulus californicus): released in sachets or bottles for ongoing control.
Check your state pesticide rules and the product label before spraying cannabis, since few miticides are registered for the crop.
How do you stop resistance?
Rotate by mode of action, not by brand name, and log what you use and when. Mites can survive a product that once worked within a single season when the same chemistry goes on every few days. Keep one chemistry in reserve for a hard reset.
Do predatory mites work indoors?
Yes. N. californicus tolerates warmer, drier rooms and keeps working after spider mites get scarce, while P. persimilis eats more per day but starves when prey runs out. Release predators after knock-down sprays have dried, and stop broad-spectrum insecticides for at least two weeks before release.
Can you treat mites during flowering?
Options narrow once buds form. Water sprays, insecticidal soap, and hand removal are the safest choices, and heavily webbed buds are usually a loss because mold follows the damage. Oils and sulfur late in flower can leave residue and taste in the final product.
How do you prevent spider mites in the first place?
- Quarantine new clones and plants for 7 to 10 days before they enter the garden.
- Hold humidity above 50% and temperatures below 80°F where the strain allows.
- Clean tools, trays, and floors between runs, and remove plant debris weekly.
- Scout twice a week with a loupe, especially during hot, dry stretches.
How long until the infestation is gone?
Plan on three to four weeks of consistent treatment, because eggs hatch in roughly 5 days at 75°F and the cycle restarts. The infestation is clear when two scouting rounds in a row turn up no mites, eggs, or webbing. Keep scouting weekly afterward, since one missed egg cluster restarts the problem.