Thread: Nute burn? Mg? K? - Getting really bad.

Hey everyone. First time hydro grower. I'm been having some problems with my plants and haven't found the problem yet. Now it looks like they are going to bite the big one.

The symptoms started with some brown/copper spots on the lower leaves. They started near the middle of the leaf, in between the veins as a single brown/copper spot. It then quickly progresses into larger brown/copper areas. Eventually taking over the entire leaf. It started on the lower leaves and has been makeing its way up the plant. After a few days the leaves turn all brown and curl up with just a hint of green patches, brittle to the touch (in fact when I touched the leaf it crumbled).

I bought some Cal-Mag and used 50% strength and sprayed in on the leaves. Didn't help. I read some more and thought purhaps I miss diagnosed and maybe it was actually a K problem. So, once again I sprayed the leaves with a higher K and still nothing.

I have flushed the system to rid it of an salts that might be locking up the rockwool. Still no luck. I'm affraid they are dying. Please take a look at the pics and let me know what you think. The one on the left has always given me some problems, you can see it is a little weak. The one on the right was doing good until recently. Now it is becoming like the one on the left.

Please help with any suggestions. I'm using GH 3 part formula in a hydro drip system. Currently I'm using the vegitative formula on the back of the bottles (that's 3-parts Grow, 2 parts micro, and 1 part flora) at 50% strength. Started at 30% strength as the symptoms got worse I increased to 50% thinking it was getting enough. 400mh lamp about 20 inches away from the tops of the plants. My PH was at around 5.9-6.0 but after reading that K is absorbed at around a 5.2-5.6 I lowered my PH to around 5.4-5.5 hoping that it would absorb the K.

I'm not going to be that helpful troubleshooting hydro, but one suggestion I would make is to decrease the intensity of the light when you know your plants are under stress. Salt buildup in the leaves makes them scorch easily. I can't remember why, sorry.

Originally Posted by hbbusa28

My PH was at around 5.9-6.0 but after reading that K is absorbed at around a 5.2-5.6 I lowered my PH to around 5.4-5.5 hoping that it would absorb the K.

Good move. It looks like a possible K problem to me too.

Did I understand correctly that you are spraying the Cal Mag on the leaves instead of putting it in the resevoir? Put your ph back to 5.8 and stop spraying fertilizer on the leaves and put it in the water as directed on the bottle. In fact I'd spray your leaves off with some sort of distilled water or something and try and get all those fert salts off (and move your light way up when you do until the leaves dry).

Thanks. Yeah I brought up the lights last night. I'll spray with PH distilled water tonight. But as for spraying on the leaves, after talking with many people including the Hydorponics store owner, everyone agrees that for a quick injection of missing nutes to spray the leaves. Is this not something I should do?

But overall, I brought back the PH, raised the lights and still no luck. The bloching keeps progressing.

Well that's a new one on me. Nowhere on the bottle does it say to spray it on anything and I have a feeling you will see more damage before you are done. I was spraying my young plants several times a day with sodium free seltzer water but like a bonehead I didn't check the ph of the stuff first (ph was 3.8) and did some nice damage to some of my leaves. The damaged leaves continued to decline slowly over time even after I discovered the problem and stopped but eventually the plants gave out a lot of healthy new growth and I pruned the dying leaves off so I wouldn't necessarily look for the burned leaves to return to normal. Watch for new, healthy growth and go from there.

I wouldn't spray my leaves with nutes/additives either. nutes burn leaves generally...In hydro you don't need any faster application than adding to the rez. And I would spray them down with a ph'd water solution.
Just FYI... I have taught some things to my local hydro store guys...In fact, I have surprised them with some of our secrets.
I am not calling your hydrostore guy wrong, but just because someone runs a hydro store doesn't mean they are experts...unfortunately. Remember, anyone can grow hydro if they have all the toys. IMO peace

p.s. You have lost the affected leaves...you have to look for healthy new growth...that is key. from now on, It is the new growth you must monitor...goodluck

Thanks for the advice guys. I'll stop spraying the leaves. I think I found the problem. It could have be K and Mg for all I know. I think the PH was locking up the nutes. Once I dropped it down the problem stop progressing. The res PH was 5.9-6.0 but when I check the run off PH it was a bit higher. Once I flushed the rockwool with PH around 5.6-5.7 and made sure the run off was the same the plant perked right up.

Thanks again.

Originally Posted by hbbusa28

Thanks for the advice guys. I'll stop spraying the leaves. I think I found the problem. It could have be K and Mg for all I know. I think the PH was locking up the nutes. Once I dropped it down the problem stop progressing. The res PH was 5.9-6.0 but when I check the run off PH it was a bit higher. Once I flushed the rockwool with PH around 5.6-5.7 and made sure the run off was the same the plant perked right up.

Thanks again.

You may need to try for 5.2 to 5.5 for about a week. Cover the rockwool before you get alga. Remember Rockwool holds water around the root ball and you can root rot a plant quick so keep an eye out and smell often.

Thanks. What will it smell like. The plants are giving off a slight spearmint type of sent right now. Just started last night.

P.S. I also moved my light up to about 23 inches. I think the 19-20 inches away was giving it some heat stress as well.

New pics. The old stuff is of course still F'd but the new growth doesn't look bad. The plant on the left is still a runt and I'm not sure if that is ever going to get any better. But the one on the right doesn't seem bad. This is two days since the last photos.

You will know, very bad odor but you do need to cover tray and rockwool or the light will kill the roots that stick out as well as alga will grow on the rockwool.

I'm glad they are doing better

Sorry seems like a stupid question but how do you cover it? With a black trash bag?

After I read your last post I took a good look at the rockwool and there is a green patch on top. As welll as some roots starting to come through the side.

those cubes should be covered, if no wrapper on the side then burry them under some black and white plastic!
they lookin better already. but the algea will kill your roots, all roots need to be kept out of the light, i would have roots all over the sides and bottom of that plant by now!,dont you intend to do anything else wth her, ie move into a NFT system, or a hydro grow!,
you can grow and flower off in that cube, ive seen it done, but they gotta be light proof and well maintained, flushed with enzymes once a week!, and fed a low PH of 5.5 if the blocks or cubes arent washed out , or allowed to dry out too much the EC and PH will rise due to evepouration, increasing the ph and EC will have a detrimental effect on the plants, there was reacently an article in the spannish grow mag, cannamao or yerba! where they try out nutrients in thei way, maintining the roots within a three inch cube and flowering of in it! extreem test to see how good the nutes are , but hey they had a decent looking crop!, try using mineral magic to rid the algae, it also helps the plants with antipathegens and celular growth! by general hydroponics. sprinkle on to the green areas, and use it under the drippers! if ya have any!

good luck!

welcome to the world of endless possibilities,,,,,hydroponics

I do love hydro.....!