How often should you water indoor plants?
What is the best time for watering indoor plants?
Which plants are best for air purification and easy to care for?
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Most plants will increase oxygen content in the air, and the more plants you have, the greater the effect. Just having a single plant will make a very small difference, but the effect will be much greater with, say, 6 houseplants. Many are also good at absorbing indoor pollutants along with carbon dioxide as well as putting out oxygen. The most commonly mentioned ones for both oxygen and indoor pollutants are Sansevieria, Peace Lily (Spathiphyllum), Dracaena varieties such as D. marginata, Aloe vera and palms such as Areca. All are relatively easy care, but will require the usual care with watering routine (more info below). Dracaena marginata tolerates pretty low light conditions and is easy care, but if you have pets, dracaenas are toxic if ingested,though toxicity on ingestion is not uncommon with many plants. Palms are obviously large plants, so consider whether you have the space for any of those. The ZZ plant (Zamioculcas zamiifolia) increases oxygen and cleans the air, and is particularly easy care,tolerating quite low light conditions.
There are many links to sites giving information about cleaning up air pollutants with houseplants and increasing oxygen levels; this link is specifically in regard to increasing oxygen, but the list of plants they give is by no means exhaustive, and not all of them are long term houseplants or necessarily very easy care https://lunginstitute.com/blog/top-5-plants-for-increasing-oxygen/
There are some rules to observe even with easy care houseplants - none should be placed near a heat source, all will need daylight in varying degrees (but often no sun is preferred), and all will require drainage holes in their pots, as well as watering regularly to a greater or lesser extent depending on the plant, along with never leaving any outer tray or pot full of water for longer than 30 minutes after watering.
In addition to the other answers, it is important to note that...
During photosynthesis, plants release oxygen. Photosynthesis occurs when a plant is exposed to light.
During cellular respiration, plants release carbon dioxide. Cellular respiration occurs constantly.
Plants do not photosynthesise at night (without light).
At night, plants produce only carbon dioxide.
As noted by others there are exceptions. For this reason, we only keep Sansevieria sp. in our bedroom, as it has the capacity to absorb carbon dioxide at night.
For clarity:
Plants absorb the energy they need through aerobic (cellular) respiration, which is a chemical reaction that uses the oxygen in the air and glucose from within the plant to form carbon dioxide and water. The plant derives the energy it needs to live from the water and carbon dioxide formed by the respiration process. To remain alive, the plant must respire at all times.
Cellular respiration is linked to photosynthesis but the outcome is opposite. Photosynthesis uses energy from light, primarily from the Sun and the carbon dioxide in the air to produce oxygen. Cellular respiration uses up oxygen and produces carbon dioxide.
Not only do plants respire at all times, the rate of respiration remains constant throughout the day and night. In bright light, the rate of photosynthesis exceeds the respiration rate, while in dim light the rate is about the same. In darkness, photosynthesis stops but respiration continues.
From Wikipedia...
Sansevieria - Air purification
According to a NASA Clean Air Study, along with other plants such as golden pothos (Epipremnum aureum) and corn plant (Dracaena fragrans), Sansevieria trifasciata is capable of purifying air by removing some toxins such as formaldehyde, xylene, and toluene. Sansevieria use the crassulacean acid metabolism process, which absorbs carbon dioxide at night, although oxygen is released during daylight. Nighttime absorption of CO₂ purportedly makes them especially suitable bedroom plants. However, since the leaves are potentially poisonous if ingested, Sansevieria is not usually recommended for children's bedrooms.
We recently bought a 1 bedroom+den condo, and I wanted to get some plants. I've never taken care of any indoor plants before, nor have I done any gardening in my life. I need something that is: -Easy to keep alive -Pretty -Produces quite a bit of oxygen
I was looking at this list: http://www.ourhouseplants.com/guides/50-plants-that-clean-the-air, but I don't know which ones are the lowest maintenance. If anyone has any recommendations (doesn't have to be on that list) please let me know!
Thanks!
Dont get a fern. They wont die but will linger to remind you what a poor gardener you are.
Here's the thing: most plants that are more proficient at cleaning the air and producing oxygen are going to be on the easier side of the spectrum as far as care is concerned. This is because they tend to rely on the air more for their nutrients and get less of their energy from sunlight. And because they don't receive as much light they require less watering. But here is the rub: to get a measurable impact in air-cleaning and oxygen producing from them you need a significant density of them. If I recall, along the lines of one every 3 square feet.
For the sake of giving a recommendation though some of the easiest are snake plant and zz plant, marginata is pretty good too as well as pothos and philodendrons.