COB's

[Rev. Green Genes]

Hi guys. I'm on my second grow with cobs. I have some questions, because I'm getting lots more issues ever since I started with my COB's.

I am using a 200 watt 3500K VERO by Timber Lights.
This grow is one month in, GSC by Autoseeds.
75 degree F
30-40 RH (low, but I always have low RH)
Lights at 40 inches not dimmed. (dimmed during seedling stage)
in Hydro, 500 PPM Green Planet nutes, and 5.8 to 6 pH.

These were stunted some as babies, but even after the recovery I get lots of ruffling, and what I always associate with 'lights too close' problem.

I know I let the pH get off at germ, but once that was fixed and the plants recovered the new growth looks great, but as the leaves age they discolor and ruffle, dry out. I never had this problem with Blurples or HPS lights. The lowest leaves are discolored primarily from the pH spikes, but the upper several sets are not a pH problem. They are new.

I'm hoping for some advice on COB's, how high I should have them:? how can I manage them better? Is it the light radiation doing this or is it something else?Is it because the lights interfere with nutes uptake? like needing calmag by the gallon??

 

[Dewey Matter]

Obviously the light distance is also dependent on actual power of your cobs and space they fill. But I use 6 Vero29Cs (1750 FV) and keep them around 30in during veg, dimmed to around 25%. And closer to 24in during mid flower, dimmed to 60-75%. Your plants seem to be “praying“ and you have some stretch, so they're likely not too close right now. Depending on the feed, you may need to add calmag (1ml per L) as cobs+autos = increased need.

 

[Arthur]

Looks like they can't keep up with transpiration rate. Loosing more fluids than the plant can get thru the root system. Your temps and humidity have your VPD up in the 1.4 to 1.7 range and @ this stage should be closer to a .8.

Betting if you could get your humidity up your see an improvement!

 

[RivetGrrl]

Did you recently raise the lights up? The leaves curling up at the margins is a classic sign of light/heat stress and they won't change, but the new growth will show any improvements. It's strange that they are praying up to the light but curled up like that.
I can't see CalMag def but need to see a close-up picture of the leaves please.

 

[Rev. Green Genes]

Thanks for the replies everyone. I often give advice here, but find myself second guessing on this one when it's my own plant. Go figure.

Depending on the feed, you may need to add calmag (1ml per L) as cobs+autos = increased need.

I will be adding calmag as I'm about to swap out the rez I think. I hate adding cal mag to a hot rez, it messes with pH something awful sometimes.

Looks like they can't keep up with transpiration rate. Loosing more fluids than the plant can get thru the root system. Your temps and humidity have your VPD up in the 1.4 to 1.7 range and @ this stage should be closer to a .8.
Betting if you could get your humidity up your see an improvement!

My gut tells humidity that is the main problem, but I keep second guessing the COB's because I have so little experience with them.

I can't see CalMag def but need to see a close-up picture of the leaves please.

I'll get a better picture in a bit. I have a few things to settle before I'm back with them.

 

[Arthur]

Thanks for the replies everyone. I often give advice here, but find myself second guessing on this one when it's my own plant. Go figure.


I will be adding calmag as I'm about to swap out the rez I think. I hate adding cal mag to a hot rez, it messes with pH something awful sometimes.



My gut tells humidity that is the main problem, but I keep second guessing the COB's because I have so little experience with them.



I'll get a better picture in a bit. I have a few things to settle before I'm back with them.

Maybe the COBS are showing more of a problem that always existed, just not as pronounced?

 

[Frenjamin Banklin]

I’ve used those buckets lids , they are almost transparent and I see a few holes. How are the roots Looking? I assume that was the first thing you checked but figured I’d ask again. I run DwC with Cobs and 12/18 inches works for me