How much sunlight is too much sunlight or is there such a thing?

[Goodflower]

So I have a modified greenhouse (solid walls 7 feet up and have been using the regular greenhouse film for the roof) I wasn’t getting the results I had been used to getting with either my indoor room nor my outdoor plants so I decided to break out the par meter. I was shocked to see that Inside my greenhouse I was only hitting about 600 on the par meter and outside the meter was banging between 2000-2100 so I knew something had to be done so I bought some crystal clear hard panels and started replacing the roof. The results are mind boggling. Now that I have the clear roof it’s literally so damn bright I need sunglasses and I’m hitting in the 1800 range on the par meter. I’ll show photos of the difference below. First and second pic is when I just started the panels and you can see I’m standing under the plastic and you can see the obvious difference on the floor. The 3rd pic are my wet walls and the last pic is new roof all installed and getting ready to reset. You can see just how bright it really is now. I have plenty of ventilation as well as wet walls so I can control temps and humidity fairly well. I’m just wondering is it possible I’d get light burn from the sun in the greenhouse even though I’ve never seen light burn on any outdoor plant? Maybe I’m too high and over thinking now that I see just how bright it is because the golden rule as always been you can’t have too much light right?

 

[HolyGrailP]

Damn great effort and work though! Big respect!

About light energy input to plants, I can give you one of the most solid ways of look at the matter.
Google RTR strategy, I think you can have an idea by reading shortly. Also, keep in mind CO2 requirement increase as photosynthetic rate increases (in this situation, we can say when daily light integral and 24H temperature increase).

 

[HolyGrailP]

Also, just wondered what was the unit for that light intensity you measured?

Perhaps was it PPF or PPFD?

 

[Ca++]

Light burn isn't a concern. It might not even be real.

10% loss is very low. It must be pretty good, this new plastic.

 

[Goodflower]

Trying to get the benches finished up today so I can hydrate some coco bricks and get planted. Took a reading outside and inside today. First is outside second is Inside. It’s 10 am here so this is morning sun will be much brighter this afternoon.

 

[Goodflower]

2 pm reading at plant height

 

[HolyGrailP]

Trying to get the benches finished up today so I can hydrate some coco bricks and get planted. Took a reading outside and inside today. First is outside second is Inside. It’s 10 am here so this is morning sun will be much brighter this afternoon.

perhaps how many day length in average?
Will it shorten alot in the winter?

 

[Chi13]

Cannabis grows and thrives outdoors in the most intense sunlight on earth, as long as it has water. Has done for ever. I can't see that there would ever be an issue with too much sunlight.

Check this out from about the 15 minute mark.

 

[Goodflower]

Cannabis grows and thrives outdoors in the most intense sunlight on earth, as long as it has water. Has done for ever. I can't see that there would ever be an issue with too much sunlight.

Check this out from about the 15 minute mark.

Thank you so much for this video. Very informative!!!!

 

[Goodflower]

perhaps how many day length in average?
Will it shorten alot in the winter?

Not too bad I’m kinda on the same lat as socal.

 

[HolyGrailP]

Not too bad I’m kinda on the same lat as socal.

Nicee
Must be chillin
As chi13 said, water balance is the most important factor to finish plants life cycle (besides photoperiod and considering other factors in safe range such temp being above 2’C and below 50’C)

And for optimal growth with your light intensity, you need above 30’C of 24h temp with extra CO2
High probability is that plants will be healthier with high RH like above 80%.
(Assumption of 18hrs light but def that won’t be case so you can assume little lower Temp and RH and CO2 than what I mentioned)

Anyway, you can assume it is not the ideal of the ideal already.

Tho, if your aim is to finish plants life cycle to enjoy your smoke I think it does not matter so much to keep lower temp.
Just that your plants 100% will be off with assimilation balance so careful with botrytis or choose one that is resilient to botrytis!

 

[alexm78]

Nice work. Outdoor plants can handle different lighting conditions better than indoor plants because they're used to adjusting to the sun's changing intensity. You may need to adjust the height of your lights or use shading during the brightest parts of the day to avoid potential issues.

Not too bad I’m kinda on the same lat as socal.

Great.

 

[Thighland]

Interesting topic. I am growing in Southeast Asia where it's over 32+ (90+) everyday. Due to the heat, I am shading with insect netting. On my phone's PPDF meter I am reading around 1,250 under direct sun and 1,000 under the netting. The plants are visibly less stressed, growing well and very healthy.

Some plants are flowering and they seem fine, but I'm wondering if I should consider removing the netting for flowering? I am growing local varieties suited to the climate.