How Do You Fight Pests Naturally in Winter?

Winter is the season when your houseplants are most vulnerable to pests. Why? Heating creates a permanent tropical climate (warm and dry), ideal for thrips and mealybugs. Meanwhile, outdoor pollinators are absent and dormant plants are less resistant. In this guide, discover how to fight pests naturally in winter and durably protect your indoor jungle.

Why do pests proliferate in winter?

Counter-intuitively, winter is the most critical season for houseplants. Here is why:

• Central heating: creates a warm, very dry atmosphere, the ideal climate for thrips and mealybugs
• Dormant plants: their natural defences are reduced
• Lack of light: weakened plants are more vulnerable
• Poor ventilation: windows kept closed favour the build-up of pests
• Concentration of plants: often grouped indoors in winter, making spread easier

The 4 most common pests in winter

1. Thrips

The number 1 enemy of winter. These tiny insects thrive in the dry air from heating. Recognisable by the silvery spots they leave on the leaves. See our complete thrips guide.

2. Mealybugs

Very active in winter. They form white cottony clusters on stems, nodes and the undersides of leaves. Particularly difficult to eliminate. See our mealybug guide.

3. Aphids

Take advantage of the concentration of plants indoors to multiply quickly. Visible on young shoots as small green or black colonies.

4. Fungus gnats

Favoured by winter watering (often too generous out of habit). The larvae in the potting mix weaken the roots. See our fungus gnat guide.

Prevention methods in winter

1. Isolating new plants

Golden rule: any new plant brought home must be isolated for at least 2 weeks in another room. Inspect it daily. If there are no signs of pests, you can add it to your collection.

2. Regular cleaning of the leaves

Wipe the large leaves with a damp cloth once a month. This removes dust (which reduces photosynthesis) and disturbs hidden pests. Bonus: it lets you detect an infestation early.

3. Raising the ambient humidity

Humidity that is too low (20-30% in winter with heating) favours thrips and mites. Target: 40-60% humidity. Solutions:

• Electric humidifier in the room
• Dishes of water next to radiators
• Plants grouped together (damp microclimate)
• Regular misting of the foliage

4. Watching for warning signs

Weekly inspection (5 minutes per plant):

• Sticky leaves: honeydew = aphids or mealybugs
• Silvery spots: thrips
• Small black dots: thrips droppings
• White clusters: mealybugs
• Flying gnats: fungus gnats
• Fine webbing: red spider mites

5. Suitable watering

Reduce watering in winter (dormant plants use less water). Let the potting mix dry out between two waterings to prevent fungus gnats.

Natural treatment solutions

1. Neem oil: the all-round solution

Neem oil is effective against most winter pests (thrips, mealybugs, aphids, mites). Application: spray directly onto the foliage (top AND underside) every 5-7 days for 3 weeks.

2. Black soap: gentle cleaning

Black soap works by contact (smothers aphids and mealybugs). Very useful as a complement to neem oil. Dilution: 1 tablespoon per litre of water.

3. Jungle Buddies: for hidden larvae

Jungle Buddies (nematodes) eliminate the larvae in the potting mix. Essential against gnats and complementary to surface treatments.

4. Diatomaceous earth: a physical barrier

Diatomaceous earth works mechanically (pierces the insects' cuticle). Sprinkle a thin layer on the potting mix and around the pots as prevention.

5. Sticky traps

Thrips traps and other sticky traps catch the flying adults. An excellent monitoring and capture tool.

Our winter protection kit

Instructions for winter treatments

Frequency of applications

• Preventive: 1 application of neem oil every 2-3 weeks
• Curative (light infestation): 1 application every 7 days for 3 weeks
• Curative (severe infestation): 1 application every 5 days for 4 weeks + Jungle Buddies in the potting mix

Dosage and application

1. Prepare the mixture according to the product instructions
2. Spray generously on the tops AND undersides of the leaves
3. Include the stems and nodes (the mealybugs' favourite areas)
4. Apply at the end of the day (not in full sun for the few bright rooms)
5. Do not rinse after application

Risks to avoid

• Application in full sun: burns the foliage
• Overdosing: stress for the plant, root burn
• Treating a stressed plant: rehydrate and stabilise the plant first
• Mixing incompatible treatments: do not combine neem oil and black soap in the same sprayer (alternate the applications)

Anti-pest routine for winter

Weekly routine

• Visual inspection of each plant (5 minutes)
• Checking the sticky traps
• Light misting of the foliage
• Checking the ambient humidity (hygrometer)

Fortnightly routine

• Preventive neem oil spray (every 2-3 weeks)
• Cleaning the large leaves with a damp cloth

Monthly routine

• Checking the substrate (humidity, signs of gnats)
• Inspecting exposed roots
• Replacing the sticky traps

FAQ: pests in winter

Should you fertilise in winter to help plants resist?

No, dormant plants do not absorb fertiliser. You can, however, apply a Jungle Boost at the end of winter (late February) to prepare for spring regrowth. See our guide When to use fertiliser.

Why do my plants have more pests in winter?

Central heating is mainly responsible: it creates a warm, dry climate perfect for thrips and mealybugs. Combined with the winter weakness of plants and their grouping indoors, the context is extremely favourable to pests.

Can you ventilate rooms despite the plants?

Yes, and it is even recommended. Air the room for 10 minutes morning and evening. Plants cope very well (just keep them away from open windows in intense frost). Ventilation slows the proliferation of pests.

How long does it take to eliminate a winter infestation?

Allow 3 to 4 weeks with a combined and regular treatment. Reproduction cycles are slower in winter, which can be an advantage if you act early.

Should you throw away a heavily infested plant?

Not necessarily. Even in winter, a plant can be saved with intensive treatment. Isolate it in another room and treat drastically (neem oil every 5 days + Jungle Buddies + black soap).

In summary

Winter is the riskiest season for houseplants when it comes to pests. The key: active prevention (weekly inspection, adequate humidity, preventive treatment every 15 days) and quick reaction at the first signs. With a well-stocked natural arsenal (neem oil, Jungle Buddies, black soap, traps), you will get through winter unscathed.

To equip yourself, discover our complete collection of natural anti-pest solutions.