Running a light.....in a greenhouse??

Ok.....so im trying to explain to my buddy that running (supplemental) light during daylight hours IN A GREENHOUSE is absolutely assinine!

His belief is that during winter months it would be beneficial to run a light in the greenhouse to supplement the grey day & lack of sunshine.

Im trying to explain to him that it is pointless, as even the greyest day is providing more full spectrum than any store bought light, & all that light will do is raise the electric bill.......for nothing.

I am not the one with this brite (pun intended lol) idea.....

He dont wanna hear it from me, so lets hear it from the experts......lol, i will be showing him this thread....

I told em... "Why not just run indoor if your so obsessded with lights..."

your friend is correct. you are wrong. I am no expert. I do use supplemental lighting in a greenhouse, because its necessary when my par meter shows poor (useable)light.

When we uncover in the morning we leave the lights on until the suns high enough in the sky. We leave the lights on all day during hazy days.

Light in a green house is needed in short winter days. You turn the lights on to keep your plants from flowering.

If the day is only 12 orn13 hours long cannabis will flower as soon as it is sexually mature. Hang a cfl or two over each plant and make them come on as the sun goes down for a few hours to keep your plants from flowering.

I've seen some light setups that block so much sunlight, there is negligible gain. But unless you are wanting them to flower, you need to do a little light early or late to keep them in Veg.

I used to think about this "blocked light" too in my greenhouse. I found it to be negligible. The rays dont need to be shining directly on plants for them to flourish. My buddy grew some mj behind his garage that blew my mind. there was so much rubbish stacked to hide it, and shade for a good part of the day, yet his buckets rocked out back with little "direct" light. we got shit for good light in MI in some winter days. I dont grow out there anymore, but did for a few years. it sucks comparing to my indoor quality at the same time maybe I suck at greenhouse growing too, so....

but I guess this would depend on what kind of supplemental light is used, if/what kind of reflectors, how many of them.

good day

whitebb2727 said:

Light in a green house is needed in short winter days. You turn the lights on to keep your plants from flowering.

If the day is only 12 orn13 hours long cannabis will flower as soon as it is sexually mature. Hang a cfl or two over each plant and make them come on as the sun goes down for a few hours to keep your plants from flowering.

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I understand its place for light schedules. However were talking about supplementing sunlight with synthetic light.....which (to me) doesnt make sense

So your saying a 1000w light still emits more light than the sun on a cloudy day?

I too have grown decent bud in shady areas.........the greenhouse will be gettin maximum exposure....however, days will obviously be brighter in june than they are in january, on the "not so bright" days, i still dont see the use for a supplemental light, i believe a grey day still emits more light than any lightbulb, hence the reason you can still get sunburn on a cloudy day.

try to grow weed in the winter, or in a window in the winter to see.
depends on where you are in the world for sure. In MI, you need more light than what
the dark days will provide during the winter for success.
and no, I didnt use 1000 watters to supplement the grow. and yes, a 1k light at a couple feet from my par meter will
show more par value than any gloomy winter day. sure, those gloomy days spin my meter backwards with solar panels,
but that aint the same(I think?)

par (lux?)meters are cheap, and fun too. you can check all the corners of your room, plant tops, other rooms, greenhouse, sun, windows, etc. i got mine on amazon

Lacedwitgame said:

I understand its place for light schedules. However were talking about supplementing sunlight with synthetic light.....which (to me) doesnt make sense

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You would be correct with the lights on the sun is obsolete plants can only intake artificial or real at one time. But there is definitely a place for lighting in a greenhouse just winter and cloudy days every place is different but it's a good idea to have em

Afgan King said:

You would be correct with the lights on the sun is obsolete plants can only intake artificial or real at one time.

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source?

par lighting is par lighting, more = more.

you put a 20 watt cfl over a plant in a greenhouse and you think its only the cfl being used, or the more powerful sun only ?
how about different points on the plant, like sun on this side today and hid on top?

Why use supplemental lighting in a greenhouse?

Greenhouse growing is highly automated. Growers maintain precise control over the environment (e.g. temperature, humidity, air-quality, lighting, etc…). With the cannabis plant on a 12-hour photosynthesis cycle, it is critical in certain seasons and geographical locations to make up for lost daylight hours and light intensity—the sun might shine brightly in Washington state 14 hours a day in the summer, but the rest of the year supplemental lighting can be a necessity.

In addition to seasonal and geographical lighting changes, weather and particles in the atmosphere can alter the quality and quantity of light.

Artificial lights should be provided as a supplemental light source to deliver moderate light intensities that increase plant photosynthesis and crop growth during times of the year when the additional artificial light will augment natural sunlight to achieve maximum plant growth. Plants require light within a specific spectral range for photosynthesis to occur, and result in growth. Natural sunlight is the most effective means to provide plants with this light source. Technology has developed artificial light systems that can provide supplemental lights that are used in the greenhouse industry to augment natural sunlight. They really dont give a shit where their par light comes from, and will gladly use it all .

just putting a greenhouse over your plants can reduce the par light received by 40%, supplemental lighting for the win

chemphlegm said:

source?

par lighting is par lighting, more = more.

you put a 20 watt cfl over a plant in a greenhouse and you think its only the cfl being used, or the more powerful sun only ?
how about different points on the plant, like sun on this side today and hid on top?

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Doesn't the pigment moeity of the photoreceptors in the plant have to change according to light source? Whether natural sunlight or artificial? So whichever is more intense at that time is the one you go with as far as I've understood

The plants gonna chase the brighter source i would think.

Lacedwitgame said:

So your saying a 1000w light still emits more light than the sun on a cloudy day?

I too have grown decent bud in shady areas.........the greenhouse will be gettin maximum exposure....however, days will obviously be brighter in june than they are in january, on the "not so bright" days, i still dont see the use for a supplemental light, i believe a grey day still emits more light than any lightbulb, hence the reason you can still get sunburn on a cloudy day.

Click to expand...

Hell yea a cloudy day is strong.

a street lap or patio light can stop an outdoor grow from flowering keep it veg so i'm with you on wasting electric on day time hours but he needs the supplemental light for when the sun goes down if hes trying to keep it veg. if hes flowering then the short winter months would help it bud up. & your friend needs a black out too in the green house if he wants to bud any time of the year.

Everyone here knows what a light meter is. Greenhouses with supplemental lighting use the meters to determine natural light levels so that supplemental lighting can be added as needed.

This can include nighttime, dawn and dusk, winter, bad weather, etc.

We will see much more of this as LED lighting becomes commonplace and more wireless dimming equipped fixtures are installed.

Yes, they exist; I have 15+ of them stacked up in my living room right now.

Lacedwitgame said:

Ok.....so im trying to explain to my buddy that running (supplemental) light during daylight hours IN A GREENHOUSE is absolutely assinine!

His belief is that during winter months it would be beneficial to run a light in the greenhouse to supplement the grey day & lack of sunshine.

Im trying to explain to him that it is pointless, as even the greyest day is providing more full spectrum than any store bought light, & all that light will do is raise the electric bill.......for nothing.

I am not the one with this brite (pun intended lol) idea.....

He dont wanna hear it from me, so lets hear it from the experts......lol, i will be showing him this thread....

Click to expand...

You owe your friend a beer, cuz he's right.