As Delhi wakes up to another morning of polluted air, a layer of dust settles on cars, windows, and balcony railings. However, amid the haze, money plants continue to trail down walls, marigolds bloom in pots, and hibiscus plants put out fresh leaves.
Their survival raises a question for anyone who tends a balcony garden. How do plants continue to grow when the air around them is so polluted? Are some plants better equipped to withstand poor air quality, and what can gardeners do to help them cope?
The question has become particularly relevant after Diwali. On the night of 8 November, Delhi’s AQI reportedly climbed to 2,283, according to real-time readings cited by The Times of India. The official Central Pollution Control Board (CPCB) average for Diwali day stood at 376. By 11 November, the city’s AQI was around 301, in the ‘very poor’ category, according to Business Standard.
Plants face the same polluted conditions, but their ability to survive depends on the species, duration of exposure, and growing conditions.
How does polluted air affect plants?
Plants need sunlight, water, and carbon dioxide to grow. Their leaves absorb light and exchange gases through tiny openings called stomata. Dust and particulate matter settling on leaves can interfere with these processes, affecting the light reaching leaf surfaces and the functioning of stomata.
As Delhi wakes up to another morning of polluted air, a layer of dust settles on cars, windows, and balcony railings. Photograph: (Invest India)
Prolonged exposure can also affect photosynthesis and plant growth, as research on particulate matter and plant physiology explains.
A high AQI reading does not mean every plant will immediately wilt. Some plants may continue to put out new leaves and flowers even as dust accumulates on their foliage, making regular care important.
Which plants can tolerate polluted conditions?
Researchers use the Air Pollution Tolerance Index (APTI) to assess how plants respond to pollution. It considers factors such as leaf pH, chlorophyll content, relative water content, and ascorbic acid levels.
An Indian study of plant species in Delhi included Dracaena deremensis and Tagetes erecta, commonly known as marigold, among the plants examined. Both were classified as pollution-tolerant in the study.
1. Marigold
Marigold is a practical option for a sunny balcony. It grows well in containers and produces bright flowers. Give it sufficient sunlight and well-draining soil, and avoid keeping its roots constantly wet. The Royal Horticultural Society’s container-growing guide explains how to choose suitable conditions for potted plants.
2. Dracaena
Dracaena is an option for an indoor or semi-shaded spot. Grown for its foliage, it can adapt to indoor conditions when it receives suitable light and is not overwatered.
3. Neem, peepal, and Pongamia
For larger terraces or open spaces, neem, peepal, and Pongamia are worth considering. A research paper by The Indian Journal of Agricultural Sciences examines pollution tolerance in tree species, including peepal and Pongamia. These trees are not practical for most small balconies, but may suit larger outdoor spaces.
Pollution-tolerant does not mean pollution-proof. Severe or prolonged exposure can still affect plant health.
Why balcony plants may struggle even without pollution
Polluted air is only one possible reason a balcony garden may deteriorate. Seasonal changes and everyday care also matter.
Winter temperatures and shorter days
As winter sets in, shorter days bring less sunlight, while lower temperatures can slow plant growth. Cold drafts and sudden temperature changes may damage sensitive plants. With growth slowing, plants usually need less water. The Royal Horticultural Society’s winter-care advice recommends moving plants to brighter spots, keeping them away from cold drafts and avoiding overwatering.
Plants face the same polluted conditions, but their ability to survive depends on the species, duration of exposure, and growing conditions. Photograph: (Image generated by AI)
Too much or too little water
Overwatering can leave roots sitting in water and lead to root rot. But letting soil dry out completely for long periods can also damage a plant. Check the soil before watering instead of following a fixed schedule. The University of Maryland Extension explains how excess water damages roots and causes leaves to yellow or wilt.
Poor drainage and cramped pots
Pots without drainage holes can trap excess water. Small containers can also restrict root growth, while compacted potting mix makes it harder for water and air to reach roots. Choose pots with drainage holes and repot plants when they outgrow their containers.
Insufficient sunlight
A flowering plant that needs direct sunlight may struggle to grow or produce flowers in a shaded corner. Without adequate light, plants may develop weak, elongated stems, pale or yellowing leaves, and fewer blooms. Before choosing a spot, check whether the plant needs full sun (at least six hours of direct sunlight), partial shade (around three to six hours of sunlight), or indirect light.
Also, observe how sunlight moves across your balcony or garden during the day. A spot that receives morning sunlight may suit some plants better than one exposed to harsh afternoon sun.
A little care can help plants cope
During periods of heavy pollution, dust can build up on leaves, especially on balconies facing busy roads. Gently wipe broad leaves with a damp cloth or rinse suitable outdoor plants with clean water. Research on how leaves capture airborne particulate matter examines how particles collect on leaf surfaces.
A flowering plant that needs direct sunlight may struggle to grow or produce flowers in a shaded corner. Photograph: (Greenway Biotech)
Check plants for yellowing leaves, dry edges, and drooping stems. These symptoms do not always indicate pollution damage; they can also point to watering problems, inadequate light, or temperature stress.
Balcony gardens cannot protect residents from Delhi’s polluted air or make outdoor air safe to breathe. But choosing plants suited to the balcony and adjusting care as the seasons change can help them remain healthy, even when conditions outside are difficult.
