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Cannabis · Cannabis sativa

Why are there tiny webs on my cannabis plant?

Seeing fine webbing usually means you have spider mites. These pests suck sap from the leaves and can multiply quickly if you do not act. Check the undersides of your leaves for tiny moving dots.

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pests on a plant
Photo: Jules Verne Times Two, CC BY-SA 4.0

Check these first

  1. Inspect the undersides of leaves with a magnifying glass.
  2. Look for webbing between the leaf nodes.
  3. Check the soil surface for small flying insects.

Likely causes

  1. Spider Mites

    Most likely

    How to tell: Look for tiny white or red specks moving on the undersides of leaves and fine webbing between stems. Leaves may also show small yellow stippling marks.

    What to do: Spray the entire plant with neem oil or insecticidal soap every 5 to 7 days. Make sure to coat the undersides of every leaf thoroughly. Repeat this for at least 3 weeks to kill any newly hatched mites.

  2. Fungus Gnats

    Possible

    How to tell: You will see small black flies buzzing around the soil surface. They are attracted to damp soil and decaying organic matter.

    What to do: Let the top 3 to 5 centimeters of soil dry out completely between waterings. Use yellow sticky traps near the base of the plant to catch the adults. You can also apply a layer of sand on top of the soil to prevent larvae from emerging.

Pests on other plants

Find out what's wrong with your cannabis

The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

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When to worry

If you see heavy webbing covering the buds, the infestation is severe and may ruin your harvest. Small numbers can be managed, but act immediately to stop them from spreading.

Stopping it coming back

Keep your grow area clean and maintain good airflow with oscillating fans. Avoid bringing outdoor plants or clothing directly into your grow room.

Cannabis: pests? Check yours with a photo

Every plant is a little different. Take a photo of your cannabis and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.

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Questions people ask

Can I use dish soap to kill pests?
Yes, a mild solution of water and a few drops of unscented dish soap can work. Just be sure to rinse the leaves with plain water afterward to prevent burning.
Are these pests dangerous to me?
No, spider mites and fungus gnats do not bite humans. They are only a threat to the health and yield of your cannabis plant.

Guides to these causes

More problems with Cannabis

Back to the Cannabis guide

This article was generated with AI on from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.