How many plants do you need in a room to purify the air?

Indoor air pollution is a major health concern. The air inside homes and other buildings can be more polluted than the outdoor air, according to the Environmental Protection Agency (EPA). Indoor air quality is affected by things like smoke, mold, pollen, chemicals from household cleaners, and gases like carbon monoxide and radon.

Adding plants to rooms can help remove some pollutants from indoor air. Plants draw in carbon dioxide from the air for photosynthesis and release oxygen. They can also absorb other gaseous pollutants like benzene and formaldehyde through their leaves and root systems. Certain plant species are better than others at removing specific pollutants.

Quick Summary

  • Indoor air is often more polluted than outdoor air due to pollutants like smoke, mold, chemicals, etc.
  • Plants can help purify indoor air by absorbing pollutants through leaves and roots.
  • To effectively clean the air in a room, you need about 1 plant per 100 square feet of floor space.
  • The more plants, the better – 15-20 plants per person is ideal for significant air purification.
  • The most efficient air-purifying plants are areca palm, English ivy, peace lily, snake plant, spider plant, golden pothos, and philodendron.

How Many Plants Per Square Foot?

So how many plants does it take to make a meaningful difference in indoor air quality? Recommendations vary, but generally the more plants, the better.

As a general guideline, aim for at least 1 good-sized houseplant per 100 square feet of floor space. So for example, to purify the air in a 20′ x 20′ living room (400 sq ft), you would want at least 4 houseplants scattered around the room.

Ideally, most experts recommend having 15-20 houseplants per person in the home or office space. So a family of 4 would want 60-80 total plants to get the maximum air purification benefit. This may sound like a lot, but smaller plants can be clustered together to take up less space.

Studies on Plants Per Square Foot

Research has tried to quantify exactly how many plants are optimal for indoor air purification. Here are some of the findings:

  • A study by NASA in 1989 recommended 2-3 plants per 100 square feet, focusing on high air-cleaning varieties like English ivy and spider plants.
  • An Italian study in 2014 found that 6-7 plants per 100 square feet (about one plant every 15 sq ft) reduced indoor pollutants by up to 30% after one week.
  • Other studies suggest concentrations of 10-15 plants per person, or roughly 1 plant per 7 square feet for significant air cleaning.

While more research is still needed, most experts agree that the more plants, the better when it comes to indoor air purification. Adding as many plants as reasonably possible is recommended, within the constraints of available space.

The Most Effective Air-Purifying Plants

While all plants refresh indoor air to some degree, some varieties are better than others at filtering specific pollutants. Here are some of the top plants for purifying indoor air:

Areca Palm

One of the best air purifying plants. Excellent at removing formaldehyde, xylene, and toluene from indoor air. Also boosts humidity levels.

English Ivy

Removes benzene, formaldehyde, xylene, and trichloroethylene from the air. Fast growing and low maintenance.

Peace Lily

Effective at eliminating acetone, benzene, formaldehyde, trichloroethylene, and more from the air. Also removes mold spores.

Snake Plant

Removes formaldehyde, trichloroethylene, xylene, benzene, and toluene. Thrives in low light conditions.

Spider Plant

Absorbs carbon monoxide and formaldehyde. Easy to grow and propagate by dividing clusters of baby plants.

Golden Pothos

Eliminates formaldehyde, xylene, toluene, and benzene from indoor air. Trails nicely or grows up supports.


An excellent formaldehyde fighter. Removes trichloroethylene too. Many varieties available.

Other good options are chrysanthemums, gerbera daisies, ficus trees, dracaena plants, and bamboo palms. Having a mix of different plants will help filter a wider range of pollutants.

Tips for Maximizing Air Purification

To get the most air-cleaning benefit from houseplants, follow these tips:

  • Choose plants known to remove indoor air pollutants best.
  • Add plants to rooms where you spend the most time, like bedrooms and offices.
  • Cluster smaller plants together to increase air-cleaning surface area.
  • Put plants near potential pollutant sources like kitchens, bathrooms, fireplaces, etc.
  • Add activated carbon or charcoal to the soil to boost filtration.
  • Clean plants regularly by dusting leaves and washing with water.

Properly caring for the plants with water, light and nutrients will help them grow bigger and stay healthy. Occasionally rotate plants between rooms to expose them to different pollutants. Replace any plants that are dying or diseased.

Other Ways to Improve Indoor Air Quality

While plants are great natural air purifiers, they are only one part of an overall strategy to improve indoor air quality. Some other tips include:

  • Ventilate regularly by opening windows or using exhaust fans.
  • Use HEPA air purifiers and filters.
  • Limit pollutant sources like smoking, candles, chemicals.
  • Clean and disinfect regularly to remove allergens.
  • Monitor humidity levels and avoid excess moisture.
  • Test for pollutants like radon and carbon monoxide.

Checking for signs of poor air quality like dust, odors, mold, or allergy symptoms will let you know if additional air purification steps are needed. Maintaining good indoor air quality requires diligence, but pays off in improved health and comfort.

Frequently Asked Questions

What are the benefits of indoor plants?

Indoor plants provide several benefits:

  • Purify the air by absorbing pollutants
  • Increase oxygen levels from photosynthesis
  • Reduce stress and boost moods
  • Increase humidity levels
  • Remove allergens like dust and pollen

How many plants should I have per room?

Aim for 1-2 plants per 100 square feet of floor space, or about 15-20 plants per person overall in the home. The more plants the better when it comes to air purification.

Where should I put plants in a room?

Place plants in corners, near air vents and windows, close to pollution sources like kitchens and bathrooms, and areas where you spend a lot of time like bedrooms and offices.

Do plants purify air at night?

Yes, plants still absorb pollutants at night even though photosynthesis stops when it’s dark. Certain plants like orchids even give off oxygen at night.

Do plants increase humidity or dry out the air?

Plants increase humidity through the water vapor they release during transpiration. However, some very high transpiration plants like ferns can reduce indoor humidity if the air is very dry.


Filling your home or office with houseplants can significantly improve indoor air quality. Most recommendations suggest at least 1 plant per 100 square feet, or 15-20 plants per person. Strategically placing air-purifying plants around possible pollution sources optimizes their ability to filter hazardous gases and particles. Along with other efforts like ventilation and air filtration, indoor plants offer a safe, natural and effective way to breathe cleaner air inside.

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