Spider Mites on Cannabis
Spider mites are the #1 pest for indoor cannabis. They're tiny (barely visible), breed fast, and can destroy a grow in under 2 weeks if left untreated.
What it looks like
- ●Tiny yellow or white dots (stippling) on leaf tops
- ●Leaves take on a bronzed or silvery appearance
- ●Fine webbing on undersides of leaves or between branches (late stage)
- ●Tiny moving dots on leaf undersides (use a jeweler's loupe)
Quick diagnostic checks
Measure before you treat
Plant diagnostic essentials
These tools help confirm the cause of spider mites before you change nutrients, watering, or the environment.
Carson MicroBrite Pocket Microscope
Inspect leaf undersides for mites, eggs, mildew, and harvest-ready trichomes.
Check price on AmazonGovee Bluetooth Hygrometer
Track temperature and humidity trends instead of guessing from one reading.
Check price on AmazonAC Infinity CLOUDLINE T4
Automate airflow to manage heat, humidity, and mold pressure.
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Causes ranked by likelihood
1. Brought in from outside or from another plant
Most commonSigns
- ●Recently brought plants in
- ●Been outside in your grow area
Fix
- ✓Quarantine any new plants for 2 weeks
- ✓Change clothes after being outside before entering grow
- ✓Neem oil spray all incoming plants
Recommended products
Captain Jack's Deadbug Brew (Spinosad)
Kills mites on contact — organic-safe, use through late veg
Neem Bliss 100% Cold-Pressed Neem Oil
Mix 1-2 tsp per quart with a drop of soap — coats eggs and adults
2. Hot, dry conditions favor mite reproduction
CommonSigns
- ●Temps above 80°F with RH below 40%
Fix
- ✓Raise humidity to 55-65% (veg)
- ✓Keep temps below 80°F
- ✓Mites breed 10x faster at 85°F than 70°F
⚠️When to worry
Always. Mites double every 3 days. If you see them in flower, your grow is in serious danger — act within 24 hours.
Gear that prevents this problem
The right equipment stops most grow problems before they start. Start here:
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