Spider Mites on Cannabis: Identification and Control
Spider mites reproduce every few days in warm, dry tents. A colony you notice on Monday can cover a plant by the weekend, so speed matters more than product choice.
Confirming them
Look for fine yellow or white stippling on the tops of leaves, then flip the leaf. Mites live on the underside. Under a loupe they look like slow-moving specks with two dark spots. Fine webbing between leaflets means an advanced infestation.
What favors them
Hot, dry, stagnant conditions above 80°F and below 40% RH. Raising humidity and improving airflow slows them meaningfully on its own.
Treatment
In veg, thorough leaf-underside sprays with insecticidal soap or a horticultural oil every 3 days for three cycles breaks the egg-hatch cycle. One spray never works, because eggs are unaffected.
Predatory mites are highly effective and safe in flower where sprays are not.
Do not spray flowering buds
Any oil or soap on developing flower creates residue and invites mold. Once you are in flower, use predators and environmental control only.
Frequently asked questions
- Where did they come from?
- Usually a new clone, a houseplant in the same room, pets, or your own clothing after being outdoors.