Questions tagged [light]

Illumination, required for photosynthesis. Use this tag for all questions about the required light levels for your plants. For questions specifically about artificial lights use the [led] or [grow-lamp] tags. For questions directly about the Sun and its effects in different conditions on plants use the [sunlight] tag.

Virtually all plants require light to power the chemical reaction known as photosynthesis, to produce sugars and cellulose (exceptions include some rare orchids such as Hexalectris which are at best partially photosynthetic).

Different plants have adapted to require different amounts of light. For example, trees that grow at high latitudes are generally adapted for poor light conditions, and low latitude desert plants are adapted for high light conditions.

There can be artificial light sources like lights or beside the natural source of light: .

Use this tag for all questions about the required light levels for your plants. Use it with tag(s) specific to the plants in the question.

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How many watts should grow light supply per unit area of edible greens?

There are many lighting products with different rated power. What is the typical grow light intensity (power per unit area) for edible greens?
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Will solar lights around my vegetables and flowers be bad for them?

I have a decent size vegetable garden and various annual flowers in my back yard. I recently bought some solar lights and put it around the plants. The lights stays on all night long, and I wonder is having a light source around them 24/7 (sun in…
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Does a luxmeter provide an accurate measurement of usable light?

Does a luxmeter provide an accurate measurement of usable light? What values constitute equivalents of 'shade', 'part sun/shade', 'full sun', etc?
Enigma
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What is the optimal LED wattage for a single bell pepper plant?

I plan on topping it to keep the canopy wide. I am most concerned with getting an LED fixture that doesn't fully activate photosynthesis. Granted I know that wattage isn't the best way to determine light output and quality of light but it is a good…
Enigma
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What should I look for when selecting lights for indoor cacti?

We grow cacti indoors due to the weather (UK). What should we look for when selecting lights? We have had mixed results with a new lighting system and have started to lose some. See one of the old guys clearly dying/dead and my precious Euphorbia…
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How will indirect sunlight affect indoor tomatoes under grow lights?

I'm deciding where to put my indoor vegetable garden for the winter. I will use grow lights as the primary light source but part of my decision decision is based on the value of indirect sunlight. Is a place that gets several hours of indirect…
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Is light direction or proximity more important when considering indoor natural light for plants?

I'm trying to provide my houseplants with as much natural light as possible inside my 2nd floor apartment. I have 2 large bay windows that face north, and can put my plants directly by the window/on the sill. Here they're very close to the window…
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Removing crumpled leaves from over exposure to light

I am currently preparing the seedlings for next springs growing in my garden. I have created my own green house - in theory with ideal conditions (full spectrum lights, high humidity, 30+°C all the time). However I initially misread that more light…
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How to soften water to water plants?

I am living in Tartu where the water is middle hard. I think that it is partially the reason why some of my plants are dying. I manage my plants by watering once a week by room temperature, 20C, water middle-hard showering them once a month -…
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Are there sources for what plants do require which uv light levels?

Tropical plants may require a higher UV level in the light, if not to grow, maybe to fruit. Are there studies / sources on that with actual quantities? Bamboo suggested in her answer to look at this page on UV strength, which I had seen already. It…
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San Pedro tipped over and broke

My San Pedro has been growing quite a lot the past 2 years, but very thin. It was windy the other day and found him tipped over. Not completely broke in half, only half way. So I tipped him back right side up and have braced him in place. I am…
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Advice on LED light periods for cactus

I want to grow large cacti, see my previous question. So I start with small plants and to keep them growing in winter time I want to give them LED (special grow) light. I was wondering about the best light periods for the small young plants. I am…
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Lighting Suggestions for Weeping Mulberry?

Just did a little trimming and while staring at it thought this area could possibly look nice with some type of lighting beneath the tree. Any suggestions on the type of light and where to place it? Thank you.
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Help with apartment gardening and lighting mainly concerning bougainvillea

I have recently moved apartments to be closer to school, and sadly where I have moved is a basement apartment without a patio or windows that get a lot of sun. I have a fair collection of plants and I want to continue adding to my collection. My two…
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Edible, indoor, winter plants. What lights? (and other advice)

I don't have any outdoor gardening space and I'd love to grow some edible plants indoors, preferably during the winter when the sunlight is low. I understand I need non pollinated plants, since my apartment is rather low in pollinators. I also want…
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