How did pests get into my sealed tent?

Q: How did pests get into my sealed tent?

Pests don't appear from nowhere in a sealed cannabis tent; something carried them in. The usual routes, most likely first, are new clones, your own clothes and hands after the garden, pets and houseplants, unfinished compost or open media bags (fungus gnats), and the intake air for tiny fliers like thrips and whiteflies. Low populations hide for weeks, so the source often predates the symptoms.

Short answer

Something carried them in. A tent is sealed against light, not insects: pests ride in on clones, clothes, pets, houseplants, potting media and intake air. The most common single source is new plant material. Supported; the ranking of routes is Grower practice.

Why

Clones and mothers are the main vehicle. Pests and pathogens move between facilities on cuttings, which is why quarantine is the first rule ^[1].

People and pets carry mites. Spider mites walk between plants and drift on air currents ^[2], and growers commonly carry them in on clothing after time in the garden (Grower practice).

Media breeds gnats. Incompletely composted organic matter in potting mix often carries fungus gnats in, and open bags attract egg-laying adults ^[3].

Air brings small fliers. Moths and other fliers arrive through open intakes or doors ^[4]; thrips and whiteflies are small enough to pass unscreened gaps.

Infestations hide. Root aphids live on roots out of sight and arrive on incoming plants ^[5]; reused media can carry them into the next cycle. By the time leaves show damage, the population may be weeks old.

The numbers

Route	Typical pests	Fix
New clones	Mites, thrips, aphids, root aphids, mildew	2–3 week quarantine
Clothes, hands, pets	Spider mites, thrips	Grow before the garden; change clothes
Houseplants, cut flowers	Mites, aphids, whiteflies	Keep them out of the grow space
Unfinished compost, open bags	Fungus gnats	Pasteurised media, closed storage
Unscreened intake	Thrips, whiteflies, moths	Fine screen or filter
Reused media, debris	Root aphids, gnats	Clean-out and fallow between cycles

What to do

List what entered the tent in the last month: plants, media, people, pets.
Check the most recent clone source first.
Screen the intake and seal gaps around ducts and zips.
Keep houseplants and pets away from the grow.
Change clothes and wash hands after outdoor gardening, before the tent.
Between cycles, remove all plant material and media and leave the space empty and dry for several days.

Common mistakes

Believing pests "spawned" from the soil or the seed.
Visiting the tent straight from the vegetable patch.
Reusing medium from an infested run.
Fixing the outbreak but not the route.

Full article: Sanitation and disease prevention for cannabis grows
Guide: Pest prevention for beginners
Answers: Preventing pests indoors · Do sticky traps work?
Terms: quarantine · IPM

Follow-up questions

Can spider mites come in on seeds?

Spider mites do not come in on seeds; seeds are the cleanest way to start a cannabis grow, which is why sanitation guidance prefers seeds or tested clean stock over untested cuttings. Mites arrive on clones, houseplants, clothes and pets, then walk between plants and drift on air currents. If mites appear in a seed-only grow, look at people, pets and nearby plants.

Can pests get in through my intake fan?

Yes, small flying pests can get into a cannabis tent through an unscreened intake, especially thrips and whiteflies, and caterpillar moths through open intakes or doors. Spider mites also drift on air currents. Fit fine insect screening or a filter on passive and active intakes, check it after each cycle, and keep the grow away from windows, doors and houseplants.

Why do pests come back every grow?

Pests that return every cannabis cycle usually survive between cycles or keep being reintroduced. Root aphids and gnats can persist in reused medium, mites and thrips hide in debris, and the same mother or clone source reinfects each run. Remove all plant material and media, clean then disinfect surfaces, leave the room plant-free and dry for several days, and quarantine incoming plants.

Sources

Punja ZK et al., 2019. Pathogens and molds affecting production and quality of Cannabis sativa L. Frontiers in Plant Science 10:1120. frontiersin.org/articles/10.3389/fpls.2019.01120/full

UC IPM. Pest Notes: Spider Mites (Publication 7405). University of California ANR. ipm.ucanr.edu/PMG/PESTNOTES/pn7405.html

UC IPM. Pest Notes: Fungus Gnats (Publication 7448). ipm.ucanr.edu/legacy_assets/pdf/pestnotes/pnfungusgnats.pdf

Oregon State University Extension. Corn earworm management in hemp (EM 9626). extension.oregonstate.edu/catalog/em-9626-corn-earworm-manag

Cranshaw, W. and Wainwright-Evans, S., 2020. Cannabis sativa as a host of rice root aphid (Hemiptera: Aphididae) in North America. Journal of Integrated Pest Management 11(1):15. Summary. entomologytoday.org/2020/07/24/rice-root-aphid-indoor-grown-