Under new light and problems arise

[rifraf262]

I have had my plants under a fluorescent light until a few days ago when I moved the plants under a 400w HPS. On a few of the older leaves there are brown spots forming which may be caused by light burn or heat stress, I really have no idea.
Possibly relevant info:
1. There we no problems until two days after I put the plant under the light.
2. It is about 2 feet away from the light.
3. Watered with distilled water.
4. It is a soil grow.
5. I feel that it is unlikely a pH or nutrient problem because there have been no problems up until now.

 

[DrGreenThumb]

looks like the same problem im having with my plants, i want to remedy it before it gets to the whole plant..

How far is the lamp from your plants? if its a HPS you gotta keep it about 18 - 22" from your canopy

 

[MrOysterhead]

im having this problem on one of my plants too , the lght is like 17 1/2 in hes away,

 

[ZMAN]

could you of splashed some water on them and let it sit thier.

 

[rifraf262]

I have a fan on the plants at all times so any water that has possibly gotten onto the leaves would have been evaporated very quickly, although water may have gotten onto the leaves at some point. It seems like this always happens whenever we put the plants under this light.

 

[ZMAN]

water acts as a magnifier and can burn leaves if left to evaporate if its under hids. other then that i cant think of much because you say it only happends when you put them under that light?
could be lacking some nutes.

 

[rifraf262]

Lacking nutes? I was afraid that this would be a problem with too much. I have always been pretty stingy with the nutes.

 

[rifraf262]

Could it have been a shock from moving it under a HID light from fluorescents? The amount of lumens it is getting is much higher than before. Just a thought.

 

[rifraf262]

Leaves that are burned have purple stems (something i just noticed), is this normal?:

 

[Stoney Bud]

The purple stems and the leaf problem lead me to thing that you may have a Potassium (K) deficiency. If that is it, then bumping your nutes up should work to fix new growth. It won't fix the damaged leaves.

When you increase light, you also increase the transpiration rate of the entire plant. Increased transpiration means increased need for nutrients. That's why it appeared after adding more light.

Nutrients should always be given to the maximum dosage the pant will tolerate without harm. If you deprive the plant of nutrients, it'll pay you back with ill health.

What strength of nutes are you giving your plants?

 

[rifraf262]

Wow, that actually makes a ton of sense. It explains why problems started happening under the new light. I have been using a very dilute fertilizer that I just dissolved in water, so I would be lightly fertilizing everytime I watered. I will be using miracle grow 15-30-15 or 18-18-21 (I have both). Which one would be recommended or should I look for something else?

 

[ZMAN]

stoney hit it right on the head.

the 15-30-15 will be good

 

[Stoney Bud]

Just be careful that you don't go too far the other direction. Increase it in steps, slowly. See how the plant deals with it.

 

[rifraf262]

thanks a lot guys, very much appreciated!

 

[Stoney Bud]

I shifted Crazy Horse's post over into another thread so we could examine what's going on with his crop.

His thread is at:

Click Here

 

[BSki8950]

im havin the same issue