Browningish of leaves? help a grower out!

[Growin4myhead]

ok, so new grow this time new style, problem only appears to be on larger fan leaves....possibly from cloning deficiency? all new growth appears vigorous and green, healthy as can be.

Lucas formula (GH FLORA)
1200 w air cooled HPS 20" over canopy
aeroflo 30 modified
water temp 64F
1040 ppm .5 conversion
5.5PH
Room temp 79F
humidity 52%
40 gal res

 

[skydy]

could be potassium toxicity

 

[Growin4myhead]

hmm well I'm hoping someone has a more definitive answer, but as its not affecting new growth I'm going to assume it was a problem from when they were still little baby clones.

 

[HealingKronic]

looks like sunburn to me... lights too close? switch from a lower wattage to a higher wattage too quickly?

 

[Growin4myhead]

looks like sunburn to me... lights too close? switch from a lower wattage to a higher wattage too quickly?

Lights are 18" away. but define switching too quickly? They went from 300 watt flouros to being under the hps.
Thanks!

 

[HealingKronic]

did you go directly from the fluros to 18" under the HPS? if so that is too drastic too fast and it caused "bleaching" or "light poison". they need to be "hardened off" when making a change like that by placing the plants under the lights for a couple hours a day and slowly increasing over a week. or you can put them directly under the HPS but start at 3 feet above canopy.

 

[Growin4myhead]

well that seems to make perfectly good sense, only problem is max height above plants when they are new is about 24" because its in a short room. I usually only grow 1 foot to 18" plants. I knew I should have got those Lumatek dimmable ballasts!! That explains why this happened to both of my last crops...... maybe ill throw a 400 watt HPS in the clone area and use that a week before flowering to bring em up to speed. Thanks for the info!

 

[HealingKronic]

in that case i would suggest starting them off for 1 hour under HPS on day one then 2 hours on day two and so on for one week before flower then put them in a 30 hour dark period before full flowering under your HPS

 

[Stonercool]

Yeah, I agree that the light knocked your plants out.

Think about it this way - when you suddenly sit out in the hot sun in a country closer to the equator, you are going to get burnt really quickly. Especially if your skin isn't used to it.

You need to ease your plants into it, just like outdoor plants get. Outdoor plants slowly get more and more light as they move through the seasons. You need to think about ways that you can bring natural growing conditions into your grow room.

When you can duplicate outdoor conditions, you will see your plants respond better.

No quick fixes in nature either.