[Veg'n'cobs] How much light do we need

[EfficientWatt]

Hi all,

Here is a little survey (1) and a secondary question for those who feel like tackling my problem (2)

1) I'm curious as to how much light, especially cob users, use in their VEG area. So how much do you use ?

150ppfd ? 200 ppfd ? more ?
Of course, this will vary according to needs ...

ie <1 foot growth vs >2 foot growth will require different amounts of light ...

Anyone have a rule of thumb ? @SupraSPL @greengenes @alesh ?

2) I'm about to build a veg light for a friend (originally designed to cover 1m² or ~3.5'x3.5') but he plans on covering more space than originally intended. How much can this light realistically cover for VEG :

The light specs :
4 CXB3070 5000K BD @1050mA .. so about 26000 lumens.
4x 120° degree lens

Thanks for sharing

 

[SupraSPL]

Many growers require a "pedal to the metal" approach when it comes to vegging, which makes sense for non perpetual setups, autoflowers etc. In that case you could veg under the flowering lights and go up to 800 PPFD for 20 hours, assuming you can keep the plant fed and you ramp up the PPFD somewhat gradually. Sudden increases in PPFD will cause the plant to "rearrange" and may sacrifice some of the leaves. No harm done most of the time, the new growth will be adapted for the higher intensity.

It is more efficient to veg under lower PPFD than 800. If you have a perpetual system (harvest every month or two) you can use much less, and base it on your system "timing". I use 250-300 PPFD to veg up 4 foot tall ladies and as little as 25-50 PPFD for short ladies that are on the "back burner". When it comes time to take them off the back burner you just pot them up and move them under the more intense lights. If you were unable to put up on time for some reason, you can increase PPFD to make up for it and maintain your timing.

For monthly harvests, without mothering, my timing is something like this

-First 2 weeks, cut clones and wait for roots. 25 PPFD 24 hours

-Next 2 weeks, pot clones into 4" pots. 50 PPFD 20 hours. Skip this step if you want to fast track them or extend this step to keep them on the back burner. You can pack them tight and fit a lot of varieties under a very small amount of light. This is ideal for a shelf system to make better use of space. They will not drink much and will grow slowly.


-Next 4 weeks they get potted up into 1/2 gal and put under 250 PPFD 20 hours. use 1 gallon and or increase to fast track them. After a few days they will start to blow up and drink quite a bit. They will get hungry.


-Next 4 weeks they get potted up into 5 gal bucket and put under 300 PPFD, veg up to ~3 feet, then cut clones before the flip. Increase PPFD to fast track them or make up time.

-Next 8 weeks flowering under 750 PPFD. Might want to dim during first and last week. use 2 flowering tents in 12/12 flip flop for monthly harvest.

 

[SupraSPL]

2) I'm about to build a veg light for a friend (originally designed to cover 1m² or ~3.5'x3.5') but he plans on covering more space than originally intended. How much can this light realistically cover for VEG : The light specs :
4 CXB3070 5000K BD @1050mA .. so about 26000 lumens.
4x 120° degree lens
Thanks for sharing

I figure it will put down 77 PAR W, which would be 344 PPFD in 1 sq meter. If you increase to 2 sq meters 172 PPFD which is OK for shorter ladies ~6-18".

 

[churchhaze]

Another question... If you run 24:0, can you get away with running a lower ppfd than with 18:6?

I would like to think yes. A lower ppfd would mean the plant takes longer to reach saturation of leaf starch.

 

[PurpleBuz]

Another question... If you run 24:0, can you get away with running a lower ppfd than with 18:6?

I would like to think yes. A lower ppfd would mean the plant takes longer to reach saturation of leaf starch.

yes absolutely. I run most of my veg lights 24x7 under low lighting. However, to keep the plants acclimated to stronger lighting I give them at least 8 hours of strong lighting, maybe 2/3rds of flowering intensity. simplicity saves me a lot of timers, since I can switch them manually and not worry about premature flowering.

 

[Gropadawan]

Many growers require a "pedal to the metal" approach when it comes to vegging, which makes sense for non perpetual setups, autoflowers etc. In that case you could veg under the flowering lights and go up to 800 PPFD for 20 hours, assuming you can keep the plant fed and you ramp up the PPFD somewhat gradually. Sudden increases in PPFD will cause the plant to "rearrange" and may sacrifice some of the leaves. No harm done most of the time, the new growth will be adapted for the higher intensity.

It is more efficient to veg under lower PPFD than 800. If you have a perpetual system (harvest every month or two) you can use much less, and base it on your system "timing". I use 250-300 PPFD to veg up 4 foot tall ladies and as little as 25-50 PPFD for short ladies that are on the "back burner". When it comes time to take them off the back burner you just pot them up and move them under the more intense lights. If you were unable to put up on time for some reason, you can increase PPFD to make up for it and maintain your timing.

For monthly harvests, without mothering, my timing is something like this

-First 2 weeks, cut clones and wait for roots. 25 PPFD 24 hours

-Next 2 weeks, pot clones into 4" pots. 50 PPFD 20 hours. Skip this step if you want to fast track them or extend this step to keep them on the back burner. You can pack them tight and fit a lot of varieties under a very small amount of light. This is ideal for a shelf system to make better use of space. They will not drink much and will grow slowly.
View attachment 3559071

-Next 4 weeks they get potted up into 1/2 gal and put under 250 PPFD 20 hours. use 1 gallon and or increase to fast track them. After a few days they will start to blow up and drink quite a bit. They will get hungry.
View attachment 3559075

-Next 4 weeks they get potted up into 5 gal bucket and put under 300 PPFD, veg up to ~3 feet, then cut clones before the flip. Increase PPFD to fast track them or make up time.

-Next 8 weeks flowering under 750 PPFD. Might want to dim during first and last week. use 2 flowering tents in 12/12 flip flop for monthly harvest.

I know this is old, but I want to thank you for this advice on how to continually grow without mother plants. I'm following this to the letter and it's working great. I especially like the low light back burner advice. I didn't know you could give the clones low light and no nutrients they will stay small for weeks. Excellent advice!