Should I be concerned?

[Grower_Dude]

Hello and thank you for reading this post.

These two plants are about 2 weeks into a 13 hour off 11 hour on light cycle and are flowering.

Yesterday, they looked fine, but today, I am seeing some browning / yellowing near the tops of the plants.

The PH meter shows a value just below 7.

Any thoughts?

[SativaWeed]

Hey there Dude! It's looks like a potassium deficiency from the necrotic leaf tips and the mottled and pale spots on the others. A potassium (K) deficiency can be treated with any high-K fertilizer. Old growth doesn't absorb the nutrient so won't be affected. But, new growth will show signs of getting healthier within a couple weeks. For faster results the fert can be used as a folier spray also. Hope that helps some!:)

[Grower_Dude]

Thank you for the advice.

My PH Meter also has a meter for combined NPK, and it shows that the levels are fine, but I have no idea how trustworthy such a thing is.

I have a 15-30-15 nutrient (Miracle Gro Bloom Booster). Would that work or is that too heavy on the phosphorous?

Best,

GD

[slowmo77]

whats your ph? if it get to high or low it can lock things you need out. heres a link that might help. good luck

http://www.marijuanapassion.com/forum/showthread.php?t=1908

[Grower_Dude]

One other thing....

Could this have happened if the top of the plants were too close to a 600 watt HPS lamp? I had to change things around in the closet yesterday, and at one point, I noticed that the tallest plant's top was bent against the light guard. I moved it right away, but perhaps a burn like that happens quickly?

I've rearranged the plants to make certain that this won't happen again.

GD

[Grower_Dude]

Thank you for the links regarding PH.

My plants soil range from 7.0 to 6.2 according to my Ferry & Morse electronic soil tester.

This tester also claims to provide a fertilizer analysis (from too much to too little) but I have no idea if this is in anyway reliable. If it works, then the nutrient level in the soil ranges from the low end to the high end of the ideal range.

GD

[slowmo77]

IMO that thing doesn't work right more than half the time if then.. its the same one i had.

[Grower_Dude]

So, should I sprinkle some coffee grinds on the topsoil before the next watering? That should reduce the PH somewhat I would think.

[trillions of atoms]

buy some PH down and water in- or DL.-




did you use dolomite lime in your soilmix?

[camcam]

I have seen alot of people don't buy PH up or down why is this? I bought 1 litre of PH down for £10 (same price for PH up) and it wil last forever and a day - so cheap I don't understand???

[Grower_Dude]

I had no idea such a thing existed! I will look for it now.

About the browned leaves--when I rearranged the closet the other day, the plant in the first two pictures touched the glass for about a minute or so. I wonder if that burned the plants....

[Grower_Dude]

buy some PH down and water in- or DL.-




did you use dolomite lime in your soilmix?

No, I didn't really using anything like that. I started with Miracle Gro potting soil. It promised to help with under/over watering, and since this is my first attempt, I thought that might be a good thing.

[slowmo77]

is the plant thats damaged the one that was touchin the light?

[Grower_Dude]

is the plant thats damaged the one that was touchin the light?

The first two pictures are of one plant, the second two is the other.

I know for certain that the first plant wedged up against the lamp for about a minute while I was working in the closet. I am not sure if the second one did or not. Either way, I'll need to raise the lamp a few inches at least.

Is there an optimal distance between the top of the plants and 600 watt HPS?

Again, thanks to all for posting.

[Grower_Dude]

So, I went to a friendly hydroponic shop where I was able to purchase a kit that comprised a bottle of pH Up, a bottle of pHDown, and a pH testing kit.

It appears that water in my area runs about 8.5 or so (both my pH meter and the pH testing kit gave the same result). I suspect that I may need to add small amounts of pH up to my watering regimen. Currently, my pH meter shows soil ranging from 6.7 to 7.5.

FtB