Could a plant get too much light

How much light does my plant need?


Indoor plants need light to live. You need it for photosynthesis. But it is often surprisingly dark in the room: what we perceive as "very light" is often "Egyptian darkness" for the plants. The result: the leaves turn yellow, the plant takes care of itself.


Plants can be roughly divided into three categories: plants with a high light requirement above 1,000 to 1,500 lux, plants with a medium light requirement from 800 to 1,000 lux and plants with a low light requirement above 500 lux. Photosynthesis no longer takes place below 500 lux. The lux values ​​given above are, however, only indicative. In order to grow and bloom healthily, the plants sometimes need twice as much light. The brightness can be measured with a light meter, the lux meter or with a light meter for the camera. Some of the lux meters are already available as inexpensive smartphone apps.


But even without a lux meter, you can estimate the brightness in the room. As a rule of thumb, the light intensity directly behind the window is only 50% of the light intensity outside, 1 m deep in the room the light intensity is only 19%, after two meters it is around 10%. This means that everything that is more than 2m away from the window is too dark and needs suitable additional lighting. And no matter how bright it seems to us, a plant cannot get enough light directly on the wall next to or under the window.


However, the light output in the room can also be lower than you think. Curtains, dirty windows, multiple glazing, buildings opposite and shady green outside the window act as light eaters. It is also important that the plants collect their energy over very specific wavelengths (i.e. colors in the spectrum). So they need blue light to grow, red light stimulates some to bloom. That is why window glass that filters blue light out of daylight is not suitable for plants. Triple glazing is also noticeable to the plants, although it does not make it darker for us in the room.


Particular caution is required in winter when the days are short and the light intensity is low. Now the plants should move as close as possible to the window pane, because the combination of darkness and warmth in the heated room makes them susceptible to diseases and pests.


Note the direction of the compass


South windows: The time of direct sunlight is long, the windows are particularly suitable for cacti and succulents. Weeping fig, yucca and candlestick flowers also thrive here.


East and west windows: During the day, the plants get full sun for a few hours. Plants that cannot tolerate this can be shaded with the help of a curtain. Most plants get along well with these locations.


North windows: They are only suitable for plants that cannot tolerate direct sunlight or that get by with little light. Plants such as rubber trees, efeutute, cobbler's palm / aspidistra or zamioculcas can cope with these lighting conditions.


How do I know if my plant is getting enough light?


When a plant doesn't get enough light, it affects its growth:
- The plant stops growing and does not flower
- The plant leans strongly towards the light
- The plant gets light-colored leaves that fall off over time
- If the plant receives a lot of water and a lot of nutrients when there is too little light, then it comes to horny growth: The new shoots become long and thin and can no longer support themselves.


Put plants outside in summer


Many plants are grateful and thrive better if they can spend the summer on the balcony or terrace. But be careful: Even in spring with little sunshine, you need to get used to it in the shade so that your leaves don't burn, because the light intensity outside is about twice as high as behind window glass.


Which houseplant suits me?


You can use the houseplants dictionary to search for plants that match the locations that you have to offer. At https://www.zimmerpflanze.info/suche/ you can search the indoor plants lexicon for light requirements, humidity, water requirements and suitable temperature. Have fun browsing!