The Green Journal

Plant Pest & Disease Identification and Treatment Guides

Identify and treat common houseplant pests and diseases including mealybugs, spider mites, root rot, and fungal leaf spot with step-by-step treatment guides.

Articles
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Editor Picks
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Editor's Feature

Pests & Diseases

Mealybugs on Houseplants: Treatment & Prevention

Mealybugs are one of the most persistent houseplant pests — and the reason most treatments fail is that people stop too early. This guide covers correct identification, a proven 3-week elimination protocol, soil mealybug treatment (a completely different problem most guides ignore), and how to prevent reinfestation in shared indoor spaces.

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All Pests & Diseases Plant Profiles Troubleshooting

Latest Plant Care Guides

Crawlable, practical articles linked to calculators and plant entities.

White cottony mealybug clusters on the stem joints of an indoor houseplant
Article · 11 min

Mealybugs on Houseplants: Treatment & Prevention

Close-up of spider mite damage on a houseplant leaf with fine webbing and stippling under bright indoor light
Article · 7 min

Spider Mites on Houseplants: How to Stop Them Fast

A hand holding a magnifying glass over a leaf with spider mite webbing and tiny red dots visible, with a spray bottle of neem oil beside it
Article · 5 min

Indoor Plant Pest Eradication: Full ID & Treatment

Two leaves side by side: one with white, powdery mold patches, the other with fine webbing and tiny specks from spider mites, magnifying glass highlighting the difference
Article · 5 min

Mold or Spider Mites? Identify & Treat the Difference

A ZZ plant with several yellowing, drooping stems in a plastic pot, a moisture meter reading 'wet' inserted into the soil
Article · 5 min

ZZ Plant Yellow Leaves? Summer Rot Rescue Guide

White fluffy saprophytic mold covering the surface of moist dark potting mix in a terracotta pot with a healthy Pothos trailing beside it
Article · 7 min

White Mold on Houseplant Soil — Causes & Treatment

Close-up of brown soft scale insects clustered along the stem of an indoor Monstera plant with visible honeydew residue
Article · 12 min

Scale Insects on Houseplants: ID & Treatment

Fiddle leaf fig houseplant with dark black sooty mold patches on upper leaf surfaces in a bright living room, showing contrast between affected and clean leaves
Article · 8 min

Sooty Mold on Houseplants: Causes, Fixes & Prevention

Extreme close-up of a monstera leaf showing thrips damage — silvery bronze streaking and scattered black fecal specks across dark green leaf surface
Article · 4 min

Thrips on Houseplants: Identify, Treat & Prevent

Whitefly infestation on a hibiscus leaf underside — a circular arc of pale yellow eggs and flat translucent nymph scales clustered along the central vein
Article · 7 min

Whiteflies on Houseplants: ID, Treat & Prevent

Frequently Asked Questions

How do I tell the difference between a pest problem and a disease problem?
Pests are visible insects or their physical signs (webbing, sticky honeydew, small moving dots), while diseases are typically fungal or bacterial and show as spots, mold, rot, or wilting without visible bugs. A magnifying glass or phone camera zoom helps confirm pests on the underside of leaves and along stems, which is where most infestations start.
What is the fastest way to treat a pest infestation on houseplants?
Isolate the affected plant immediately to prevent spread, then treat with insecticidal soap or neem oil spray, covering both sides of every leaf and the stem base. Repeat treatment every 5-7 days for 2-3 cycles, since most pest life cycles require multiple treatments to break — a single spray rarely eliminates an established infestation.
Are most houseplant diseases caused by overwatering?
Yes — the majority of fungal and bacterial diseases in houseplants, including root rot and many leaf spot varieties, are directly triggered by excess moisture and poor drainage. Improving airflow, reducing watering frequency, and ensuring pots have proper drainage holes prevents most disease issues before they start.
Can a pest infestation spread between different houseplants?
Yes, most common houseplant pests like spider mites, mealybugs, and fungus gnats spread easily between plants placed close together. Isolating a newly purchased or visibly affected plant for 1-2 weeks before placing it near your existing collection prevents most cross-contamination.