Lighting Light intensity for autoflowering plants (lux)?

[Death The Cultivator]

I think that's the most cost effective way to get an accurate PAR measurement for the few times your gonna want one.

Amazon product

Connected to a PC puts this in an affordable price range. Much better than measuring lux

 

[Hypathetical Gardener]

You shouldnt have to lower the light in flower.... You dont give more light in flower than you would during mid/late veg. Its getting the same hours so the same intensity is also ok.
Dli.
If im getting 700 during 18/6. And im reducing to 12/12, then im cutting 30%light. So we increase intensity to 1000 to make up for the lost time.

But if theres no lost time because we <3 autos amd keep to 18/6(ish), then theres no loss of light to make up for by increasing intensity.

 

[jackiejack]

Renting a PAR meter would be the best for sure... However, I am located in Europe and I am pretty sure that a service like this does not exist in my country Oh well... a lux meter will have to suffice

Amazon product

Connected to a PC puts this in an affordable price range. Much better than measuring lux

Is this a link? It's not clickable, just a picture.

 

[Death The Cultivator]

Renting a PAR meter would be the best for sure... However, I am located in Europe and I am pretty sure that a service like this does not exist in my country Oh well... a lux meter will have to suffice



Is this a link? It's not clickable, just a picture.

SQ-420 Smart Original Quantum Sensor | USB Output

The SQ-420 smart quantum sensor can be connected directly to a computer to take spot measurements or graph and log real-time PPFD using the included software.

www.apogeeinstruments.com

Saves you money if you can find a deal.

 

[lzr]

HOW MUCH LIGHT DO YOUR CANNABIS PLANTS REQUIRE?

• Clones and seedlings: 5,000–7,000 lux
• Vegetative growth: 15,000–50,000 lux
• Flowering: 45,000–65,000 lux
• Maximum recommended amount of light: 75,000 lux

I use the UNI-T UT383 and get 2.25 grams/W with a QB288 v2 Rspec 3000k running at 90W in a 2x2.

Right on! Are you using the readings as they appear or doing some math to covert?

 

[Wico]

Right on! Are you using the readings as they appear or doing some math to covert?

Nope that UNI-T UT383 has a hold function and I just check right under the lamp (beam shaping) to see if there are no 'hotspots'. And now I have a marking in my grow box to indicate the maximum height a plant in vegetation can grow and the lamp is just on a fixed height from seed to harvest 24/0.

63cm from top grow medium to bottom lamp and 30 cm is the maximum height I grow my plants in vegetation. I use LST and FIMing and if they grow hard I use HST (supercropping) all in a 2x2. I use RDWC and only veg, bloom and PK13/14.

 

[lzr]

Just found this and thought someone else may find it useful:

https://www.waveformlighting.com/horticulture/convert-lumens-to-ppf-online-calculator

The pull down box has different spectrum you can select.

 

[Anasazi]

According to How Much Light (PPF) Do You Need for Indoor Cannabis? - Coco For Cannabis
cannabis prefers a PPFD (Photosynthetic Photon Flux Density) of 500-700 (using the appropriate units).
From Convert Lux to PPFD - Online Calculator | Waveform Lighting
for a 2000 K HPS light, 60,000 Lux corresponds to a PPFD of 778, which is slightly more than the 700 maximum.

The widespread use of powerful LEDs has created a new health problem for growers, too much light.
Especially if LED users go by the Lux values that HPS growers do.
A Lux of 60,000 from a 3500 K Rspec LED corresponds to a PPFD of 5,324 which is way too much.
For an Rspec LED, to get a maximum PPFD of 700 needs only 27,000 Lux.
This matches my experience of getting light burn beyond 30,000 Lux.
My autos seem happiest at around 20,000 Lux, which corresponds to the minimum PPFD needed.
But autos do get more light than photos, which gives a greater risk of burn.

I feel like this is what i'm going through right now. Even at 18 inches away my plants have been baked by my leds. I'm thinking from now on I will have to run at 50% if my next grow gets that tall. Stepping up my lighting game has 100% backfired on me for my current grow lol.

 

[low_and_slow]

Max lighting also reveals plants that are less than healthy; it also doesn't help if you're already way outside ideal VPD since the plant won't make efficient use of the energy if not transpiring properly.

So if it's not too much heat, then it's probably not light intensity but overall plant health. Also with LED you need high leaf temps, without that you often see deficiencies you wouldn't see under HID.

So many lights have measurements online or on review sites, it usually gives you a good starting point for hanging. From there, it's going to be so individual that even a PAR meter might not be helpful. I mean, if you dial in exactly 699 micromoles per meter square seconds at the canopy with a meter, what's to say that plant doesn't hate it and still show stress? Maybe its sister neighbor loves it and wants to get closer...what does the meter tell you then?

For me I start where the LED Gardener said he got about my target intensity (18") during his online review, then just carefully observe my plants and adjust from there. If you're buying a light and cannot find a manufacturer or third party measurement at 12-18-24", what light are you even buying, lol?!

 

[Death The Cultivator]

Max lighting also reveals plants that are less than healthy; it also doesn't help if you're already way outside ideal VPD since the plant won't make efficient use of the energy if not transpiring properly.

So if it's not too much heat, then it's probably not light intensity but overall plant health. Also with LED you need high leaf temps, without that you often see deficiencies you wouldn't see under HID.

So many lights have measurements online or on review sites, it usually gives you a good starting point for hanging. From there, it's going to be so individual that even a PAR meter might not be helpful. I mean, if you dial in exactly 699 micromoles per meter square seconds at the canopy with a meter, what's to say that plant doesn't hate it and still show stress? Maybe its sister neighbor loves it and wants to get closer...what does the meter tell you then?

For me I start where the LED Gardener said he got about my target intensity (18") during his online review, then just carefully observe my plants and adjust from there. If you're buying a light and cannot find a manufacturer or third party measurement at 12-18-24", what light are you even buying, lol?!

If a cultivar can't handle 700ppfd then the issue isn't really the light but other aspects of environment as you previously mentioned.