That lush, leafy plant by the window looks innocent—comforting, even. But during the winter months, some of the most popular “cozy” houseplants can quietly do the opposite of what you want. Instead of fresh air, they may be contributing to stale air, lingering moisture, and mold spores that have nowhere to escape once the windows stay shut.

The culprit isn’t always the species of the plant; it’s the way winter changes our indoor ecosystems.

Why Winter Turns Healthy Plants Into Air Quality Risks

In colder months, indoor plants enter a semi-dormant state. Growth slows down, light levels drop, and evaporation cycles stall. This means soil stays wet far longer than it does in July.

When watering habits don’t adjust for the season, excess moisture builds up around the roots. This creates a perfect storm for:

• Root Rot: Decaying organic matter that releases odors.
• Mold and Mildew: Fungal spores that thrive in damp potting mix and drift into your living space.
• Fungus Gnats: Pests that flourish in persistently wet topsoil.

In tightly sealed, energy-efficient winter homes, these airborne irritants circulate repeatedly, directly impacting your respiratory health.

The ‘Cozy’ Plant Most Likely to Cause Issues: The Peace Lily

Ironically, some of the most beloved houseplants are the easiest to overwater. The Peace Lily (Spathiphyllum) often tops this list.

While marketed as an “air-purifying” powerhouse, Peace Lilies are famous for “fainting” when thirsty. This trains owners to water them frequently. In winter, this instinct backfires. Constantly damp soil around a Peace Lily can lead to hidden mold growth, even if the plant looks vibrant above the surface.

Other moisture-loving plants that can trigger winter air issues include:

• Boston Ferns
• Majesty Palms
• English Ivy (if misted too heavily in stagnant air)

The Best Plants for Better Indoor Air Quality in Winter

If your goal is to scrub the air while windows stay closed, plant choice—and resilience—matters. The following plants tolerate dry soil and low light, significantly reducing the risk of mold:

1. Snake Plants (Sansevieria)

Snake plants thrive on neglect. They require minimal watering and are one of the few plants that convert CO2 into oxygen at night, making them ideal for winter bedrooms.

2. ZZ Plants (Zamioculcas zamiifolia)

The ZZ plant stores water in thick succulent rhizomes under the soil. Because they need so little water, the soil stays dry and inhospitable to mold spores.

3. Pothos (Epipremnum aureum)

Pothos is the ultimate “beginner” plant. It is highly expressive; it will tell you when it needs water, making it much harder to accidentally overwater during the dark months.

4 Rules to Protect Your Air Quality This Winter

You don’t need to evict your greenery. You just need to adjust your “plant parent” strategy for the season:

1. The “Half-Water” Rule: Most plants need roughly half the water in winter as they do in summer.
2. The Finger Test: Don’t water on a schedule. Stick your finger two inches into the soil; if it’s damp, walk away.
3. Breathable Containers: Switch moisture-sensitive plants to terracotta pots. The porous clay allows the soil to “breathe” and dry out faster.
4. Clear the Saucers: Never let a plant sit in a drainage saucer full of water. This is a primary source of musty odors.

Pro Tip: If you notice a white, fuzzy film on your soil, scrape it off immediately and sprinkle a little cinnamon (a natural antifungal) on the surface.

A Cozier Home Starts With Drier Soil

Winter comfort is about more than just candles and blankets; it’s about clean, breathable air. By swapping moisture-hungry varieties for winter-resilient ones and easing up on the watering can, you can ensure your “urban jungle” stays a healthy sanctuary all season long.

You're reading Is Your Winter Houseplant Secretly Ruining Your Indoor Air Quality?, originally posted on Decoist. If you enjoyed this post, be sure to follow Decoist on Twitter, Facebook and Pinterest.

Posted By : Chris A.