Why does my Calathea have spider mites?

Calatheas get spider mites most often because of dry indoor air, which lets the mites breed quickly while weakening the moisture-loving plant. A newly brought-home plant or an infested neighbour is the next most common source, helped along by warm, stagnant conditions. Look for fine webbing and pale stippling, then rinse the plant and treat with insecticidal soap.

Most likely cause

Dry indoor air is the top reason a Calathea gets spider mites. Spider mites thrive in warm, dry conditions and their populations explode when humidity is low, exactly the environment created by heating and air conditioning. Calatheas need high humidity to stay healthy, so dry air both invites the mites and stresses the plant they feed on.

You can confirm it with a close look. Check the leaf undersides and joints for fine, silky webbing, and hold a leaf to the light to spot tiny pale stippling dots where mites have pierced the tissue. The mites themselves are pinhead-sized specks, often reddish, that move when disturbed. If you find these alongside dry air, mites are almost certainly the cause. Treating them and raising humidity together is what clears an infestation.

Other causes

These rank below dry air but all bring mites in or help them spread.

A new plant. A recently bought plant often arrives already infested; check any new arrival's undersides before it joins your collection.
Stagnant, warm air. Still, warm air with no airflow lets mites settle and breed; rooms that get hot and never ventilate are prime spots.
A dusty, stressed plant. Mites target weakened plants first; dusty leaves and a thirsty, stressed Calathea are easy targets.
An infested neighbour. Mites crawl between touching leaves and drift on air currents; a problem on one plant quickly reaches the next.

How to fix it

Isolate the plant. Move the Calathea away from all other plants right away so mites cannot spread.
Rinse it down. Shower the whole plant with firm, lukewarm water, focusing on the leaf undersides to knock mites off.
Treat the leaves. Spray thoroughly with insecticidal soap or diluted neem oil, coating both sides of every leaf.
Repeat on a schedule. Re-treat every 5 to 7 days for 2 to 4 weeks to kill mites that hatch from surviving eggs.
Wipe off dust. Keep the leaves clean so mites have nowhere easy to hide and the plant can recover.
Raise the humidity. Keep humidity above 50 percent with a humidifier to make the air hostile to mites.
Improve airflow. Give the plant gentle air circulation, which mites dislike, without putting it in a drying draft.

Cause	Tell-tale sign	Fix
Dry indoor air	Webbing and stippling, low humidity	Rinse, treat, raise humidity above 50 percent
New plant	Mites on a recent arrival	Inspect and quarantine new plants
Stagnant warm air	Mites in still, hot rooms	Improve gentle airflow
Dusty, stressed plant	Dusty leaves, thirsty plant	Clean leaves, keep plant healthy
Infested neighbour	Mites on a touching plant	Isolate and check nearby plants

Frequently asked questions

How do I know if my Calathea has spider mites?

Look for fine, silky webbing in the leaf joints and undersides, plus tiny pale stippling dots across the leaves. The mites themselves are specks the size of a pinhead, often red or pale, that you can see moving on the underside when you look closely.

Why do Calatheas get spider mites so easily?

Spider mites thrive in dry, warm air, and the heated or air-conditioned indoor air around a Calathea is exactly that. Calatheas also want high humidity to stay healthy, so dry conditions both invite the mites and weaken the plant at the same time.

How do I get rid of spider mites on a Calathea?

Rinse the whole plant under a firm shower of lukewarm water, especially the leaf undersides, to knock mites off. Then spray thoroughly with insecticidal soap or diluted neem oil, and repeat every 5 to 7 days for a few weeks to catch newly hatched mites.

Does raising humidity kill spider mites?

It does not kill them outright, but spider mites hate humid air and stop reproducing as fast in it. Raising humidity above 50 percent, alongside rinsing and treating, makes the environment hostile to them and helps prevent a return.

Will spider mites spread to my other plants?

Yes, easily. Spider mites move between touching leaves and drift on air currents, so isolate the infested Calathea right away. Check nearby plants for stippling and webbing, since they may already be carrying mites too.

How long does it take to get rid of spider mites?

Usually 2 to 4 weeks of consistent treatment. Spider mites breed fast and eggs keep hatching, so a single spray will not clear them. Rinse and treat every 5 to 7 days until you see no new stippling or webbing for two weeks.