What is the minimum hours of direct sunlight needed for greenhouse growing?

hurdy gurdy man · Jun 26, 2011

Can one grow buds with only a few hours of direct sunlight in the morning?

It seems that shaded sunlight is still pretty bright compared to a grow light.

Manitoid · Jun 26, 2011

People say at least 5 hours direct.

My light meter reads about as high in the shade outside as it does under a 1000w light bulb... ?

since greenhouses are usually translucent and not transparent, you may consider a more full sun location, as from even a short distance, people would not be able to see whats going on inside...

Depending on distance, they might smell what is going on though.

Manitoid

hurdy gurdy man · Jun 26, 2011

Thanks for the reply. Problem is, my GH is already built/located.

Good to know about the light meter.

Has anyone had success growing in a largely shaded GH?

It's getting late in the season, and any replys based on experience from fellow ICMag brothers and sisters would be greatly appreciated.

hgm

hurdy gurdy man · Jun 27, 2011

According to Mel Frank, "[w]hen the plants get bright, indirect light, all they need for good growth is about three or four hours of daily sunlight."

I've seen others post on this site that five hours of direct sunlight may not be enough, based on their experience.

If you read this, and have some personal anecdotes to share regarding lighting, please feel free to tell us what you know.

I think it would be helpful to others who conduct a search to see what experience has to say.

Thanks.

doublejj · Jun 27, 2011

What is causing the shade? Can you thin the shade trees?

I'd say go for it, what do you have to loose?

peace
doublejj

RidgeRebel · Jul 4, 2011

In all non plant specific gardening literature I have read, including The California Master Gardeners Handbook, and The Encyclopedia of Gardening; it suggests 6 hours are ideal. Based on my own knowledge about how different intensities effect growth, I'd say less than that would result in looser buds. Which, sometimes can still be acceptable. Especially in denser strains which may otherwise mold with proper lighting in greenhouses. And there's a difference between non direct (or partial i.e through trees) sun, and shade (wall, canopy), to be put into consideration.

Arthur Dent. · Oct 10, 2011

Hey There Confused peeps,HGM has a good question,

Lets speculate, The SUN (source of most of the Earths natural energy) is far more intense than any Bulb or light made by man, question is how use full is its refracted light?

I am offering up no answers only doubling up HGM's question as I am in the same boat at the moment. But as far as I am assuming the sun should be fine as long as the plant is not in so much dark it thinks it is in fact night time. as long as there is enough sun to illuminate the GH you plants will grow, Its the intensity issue I am worried about as is it worth have plants that simply grow? as I would prefer plants that Thrive and produce not simply grow.

Interested to see some response.

Namaste.
A.D (joint)

OldRod · Nov 28, 2011

Im sorry but must correct you for a little.
There is no speculation and sun arent brighter.
Sun give 50,000 lumen on top of Big Ben and on the ground but any bulb will loose lumens by distance.
Of course sun can not damage plant unless growing under sun arent natural process.

You said well, in shade plant will grow but she will grow under 100W CFL and 600W HPS just result arent same.
Its same for shade and direct sun.

Wont be negative but if we start with Shade, MINIMUM of direct sun etc etc than what to expect ? ... amazing harvest ?

just my 2c
OR

supermanlives · Nov 28, 2011

make hash with em all. leafy airy buds .

Hydro-Soil · Nov 28, 2011

Throw up a 1000w hps every 6 feet or so as supplemental lighting. That way you won't have loose buds.

Remember... you can lose a game in safety but you can lose a foot when you loose the hounds.

Stay Safe! :blowbubbles:

greenpinky · Nov 28, 2011

It'll grow I got a sun room that gets maybe 3 to 4 hours of direct sunlight it works not the biggest yielders but cant beat free light. Even a few hours

Ur Humbl Nr8tor · Nov 28, 2011

Makeshift GH. Around latitude 33, Winter grow, where average direct light was only about 3 hours a day.

Old Timer's Haze

Light and airy, yes but that's the strain.

Senor Garcia

Maybe a bit more leaf than if run in full sun, but again, this strain did very well with minimal direct sunlight. I find looser more sativa leaning strains to work well in winter greenhouses because the additional rH doesn't cause as much problems with botrytis.

Now go, run and see....

Arthur Dent. · Nov 29, 2011

I cant wait for you chaps to see my GH i have a thread so look anyways you will see what I mean about the Sun and refracted light...

Strain regardless, remember Im in Africa.

Namaste :joint:

waynekerr · Mar 6, 2012

What if you get great sunlight midday for about 5hrs, is it worth installing supplemental lighting at the start and the end of the cycle(I have a roll on cover that comes off at 7am and back on at 7pm)

RidgeRebel · Mar 7, 2012

if you're trying to veg, definitely. if you're just flowering outside, probably. depends on how bad the light is for the other 7 hrs, id imagine.

waynekerr · Mar 7, 2012

Nope all vege is indoor, finishing outside. Its those shady mornings and arfos that im worried about.

hurdy gurdy man · Apr 6, 2012

Thanks for all the replys.

Last season my greenhouse was unavailable due to security reasons. Next to relying on the black market, I'm the most paranoid in using a greenhouse to supply my needs.

This year I expect to be able to use it, and I will post a report with some specificity if I do. From what I can tell you at this point, some portion of the greenhouse gets direct sun 3-4 hours a day. The hottest (and sunniest) part of the day offers shade from 60 foot trees, so the shade still seems pretty bright. I will know more about temperature as the season progresses, and I figure out exactly how to approach this (e.g. plant count, pot size, etc.).

All that said, both from experience and research, I am reminded that some shade is probably desireable to control heat. Too much heat = l o o s e buds.

Good luck this season! :plant grow:

hgm

terryx1st · Oct 22, 2012

is it okay if i cant get the morning sun due to oak trees but get sunlight the rest of the day?

2 Legal Co · Jan 26, 2013

Were I you, I'd go talk to some folks in the area that operate GHs. One pertinent Q for them would be; How many hours a day do you need 'shade clothe' up to keep the full sun plants from burning?

There's a reason that Most if not All Commercial GHs have provisions made to hang shade clothe. I'm not familiar with how much and for how long, but every time I'm in a 'real' GH, There is shade clothe.

Most of the 'Wild Weed' I've seen, grows in creek and river bottoms,,,, shaded by big old willows and cottonwoods.... if that makes any dif... I dunno.

noyd666 · Jan 30, 2013

hi ,this is full sun all day, hot as up to 35c ,prob higher, 3to 4 corner big fans running some of the time, big drinkers at this time, usually crack 2 lbs per, as far as heat, buds are not loose at all. :tumbleweed:

What is the minimum hours of direct sunlight needed for greenhouse growing?

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