heat stress or nute problem?

hello hello people,

I recently started my first ever grow. So far its gone pretty well, but i have been very naive and am learning a lot about my plants every day. Over the past 2-3 days my plants have started getting little dark yellow-brown patches on them and I'm having trouble figuring out the problem, as these symptoms seem to point to various problems.

I think it might be heat stress, as I am growing the plants in a cupboard which if I'm honest, is probably a bit small and may not get enough air circulation. Hoping to fix this 2moro with some new intake/outake fans. My plants are around 4 inches below a 200w CFL light. I've just ordered an electronic pH tester though as I have been using some tap water as well as distilled water throughout watering. I know I shouldn't have done this, I got lazy and am now paying the price.

My plants are around 3 weeks from seed, only started giving them nutrients recently, as in a few days before this problem occured, so I am also wondering if I have used too much. The food I have is Miracle Grow all purpose (soluble). Or maybe I just gave them too much water.

I've hopefully attached two pics below for your viewing pleasure. Not sure if you can tell by the pics, but some of the leaves are also curling up slightly, not very much, but they aren't flat. The stems look healthy and leaves seem a good colour in generally, however my plants are growing a lot slower than my flatmate's, who is growing in a larger cupboard closer to an open window. Any help would be awesome guys, sorry that my first post is begging :)

Three weeks might be too soon to start the nutrients. You said you're using MG nutes? Is your soil also MG, because if so you may not need nutrients for close to 6 weeks in. I started my nutrients at about 4 weeks. With your lighting being a CFL, I dont think it is heat stress, but assure that you back in off about 5-6 inches as that is a high wattage for a CFL.

Im inclined to say its nute burn. The pics are good as far as the marks, but I cant tell how big the plant is. But Im fairly certain it does not need nutrients yet.

thanks for the quick reply, my soil is "westland" for indoor plants, mixed 50/50 with vermiculite. the plant from the base of the stem to the top leaf is barely taller than a DVD case.

Reckon I will back off on the nutes for a week or so and see if they improve. If I've over-fed them should I try a soil flush or is that a bit OTT?

cheers

That particular spotting hints at a pH issue causing a lockout of a micronutrient.

What I'd need to know is your ingoing water pH, and your runoff pH.

If it is the pH, and you dont have a way of testing it until the meter comes. Look into mineral water at stores. Another user found a brand that listed their pH at 6.8, which is the pH your aiming for (6.5-7). DVD case seems around 6 inches, which is about the time I started the nutrients. So if you see an improvement with corrected pH, I would continue feeding a small amount.

thanks guys, i'll get the pH info asap, in the meantime i'll switch to proper mineral water and see how they look. should i try a soil flush to be on the safe side?

Quote:

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Originally Posted by evilbeaver

thanks guys, i'll get the pH info asap, in the meantime i'll switch to proper mineral water and see how they look. should i try a soil flush to be on the safe side?

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I can't tell you which direction the pH would go if you flushed. Mineral water isn't always at 7 (the stuff I buy comes out about 8.)

A really good flush with pH 6.5 water should have a great impact in bringing the soil to proper acidity. You might add a teaspoon of vinegar per gallon of water to help bring that pH down.

yea the label of the mineral water i've been buying says the pH at source is 7.5, so might add a drop of vinegar when i next water. overall the plant is looking pretty healthy at the moment, lots of new growth at the top and no new marks.

as most of the damage is on the lower fan leaves, i was thinking about cutting them off. tbh i was thinking of doing this anyway to encourage a more "bushy" shape as my grow space isn't massive. any thoughts on whether this is a good or bad idea?

you guys have helped a lot already, cheers :thumbsup:

edit:

the miracle grow nutes i use is 24-8-16 btw, maybe too much potassium?

When you tire of playing guessing games, perhaps if you were to fill-out the troubleshooting form we'll have this figured-out in no time. But this guessing game is costing you time and effort with little to no return.

The link is in my signature. Copy-n-paste the form here, and answer the questions as best you can.

Insufficient lighting and ph issues are a guess. Perhaps a good guess, but only in knowing the entire story, can we offer a valid solution.

Heck...could be something as simple as being drops of nutrients killing the leaf tissue. (can't let the nutrients splash or pool on the leaves, or dead spots will occur)

Miracle Grow instructions are for a two week period.

What is your experience level? first timer

Your Equipment:
.1) Type and wattage of lights. Plug & Grow 200w CFL lamp
.2) Distance from tops? 4 Inches
.3) Reflector type? None, have foil on top of cabinet, but thats it.
.4) Is there a consistent fresh air supply? Window in grow room is always open, actual grow is in a wardrobe with door open 18hrs a day
.5) Do you have an exhaust fan and a circulation fan? 8" fan blowing air in, back of wardrobe removed to allow air to pass right through
.6) What are the bulb wattages, kelvin ratings, and schedule? Bulb is 200w, 2700k, on 24/7.

Your medium:
.7) Specific brand and type of soil. Westland indoor soil mixed with vermiculite 60/40.
.8) Size of container. 3 gallon pot
.9) Did you use peat pucks (or similar) to root clones or germinate seedlings? Germinated with wet paper towels

Your nutrients and water:
10) Source of water? Originally tap, switched to bottled with 7.5 pH
11) Method of checking water ph. None, still waiting on tester to be delivered
12) Method of adjusting water ph. None so far
13) Specific brand and N-P-K ratio for each bottle. Miracle Grow all purpose soluble plant food, 24-8-16. Began feeding 1wk, plan to feed once per week. 0.75ml per 1litre water
14) How often are you watering between feedings, and how much per watering? Once every 3 days, ~3/4 to 1litre per plant
15) Any additives or tea's? None
16) Are your ph levels stable, or do they fluctuate? Unknown as of yet
17) What is your ingoing water's ph? ...your runoff ph? Unknown as of yet
18) Do you foliar feed? No

Your growroom:
19) Indoors or outdoors? Indoors
20) What size of closet, room or hut? Wardrobe, 2x2x5 feet
21) What are the temps and humidity levels while lights are on? ...With lights off? 25c lights on, 21 lights off
22) Have you seen signs of insects in the growroom? None

Your strain:
23) What strain are you growing? Barney's Farm LSD - indica dominant
24) From seeds or clones? from seed
25) Is this an autoflower strain? No


Filled out as best I can, as I said in previous posts, I entered in to this grow with a real happy-go-lucky view of things and have been way too naive on the care/attention needed (never realised the importance of pH etc).

Thanks for the link to the troubleshooter rusty, am sorry if I went about this the wrong way, but gotta say thanks so far to the help you guys have extended.

Water ph a tad high, but likely the soil buffers are still doing their job. 6.3 to 6.8 ph is acceptable range for ingoing liquid ph. (for both, the water and the nutrient solution) Did you get a soil probe or a ph pen?

Miracle grow instructions are usually for a two week period. Go with the low figures recommended, and sneak-up on the maximum dose the plants can handle. I believe I was using a teaspoon per gallon per week. (1/2 teaspoon per gallon, twice a week) Been a while though, so you'll have to double-check if that sounds right per instructions. (too many nutrients used, too crappy a memory)

Did you let the leaves get too close to the light?
Check the undersides of the damaged leaves carefully, and look for little black spots. If you see none with a magnifying glass, then it might be either some drops of water or nutrient solution splashed on the leaves and left to dry, (a no-no) or possibly overdoing the MG. Way back when I used MG, I had better success dividing the feeding days into twice a week at half-dose. And actually...I've never lost that habit regardless of the nutrients I use. (it works well)

I ordered a soil tester, not arrived yet. Tryin to get my hands on some litmus paper as well seems nowhere around here sells it anymore though.

Think it may be possible I overfed them, and in fact started feeding way too early. You're right about the MG feed routine, the pack recommends 1.25ml spoon in a litre of water every 2-4 weeks.

Don't think I let the plants get too close, I've been over-cautious in fact. My flatmate has his almost touching the light, where as mine are a few inches. His look fine (and are bigger). I don't really want to do this as I work 24hr shifts and the rate its sprouting recently would worry me. Although my flatmate keeps an eye on them :thumbsup:

Can't see any black marks on the bottom of the leaves. Will try posting an updated pic later. cheers man

I've lost the cable that connects my phone to my pc so can't upload any photos atm, but the plants are looking really good.

I've not given them any nutes since my original post here, and have also been watering exclusively with bottled mineral water. The evil spots haven't spread any further and theres lots of fresh growth going on. I will resume feeding soon and see how they react.

If everything goes to plan I think I'll put them into flower in around 3 weeks time and hopefully will have some nice results to show you guys, thanks a lot for your help :thumbsup:

Good luck, and keep us informed... :thumbsup: