Yellow leaf tops

Hello everyone,

I started my first grow about 33 days ago, i decided to grow Autoflowers.

Grow light: 280W Greenception GC-9 LED
PH water: always around 6,5
PH earth: also around 6,5
I use 5 gallon fabric pots and i grow organic.
I mixed my earth with: 10% perlite, 78% Light mix, 10% worm castings and 2% Pre mix (3/3/5)
Since than i have not fed my plants for the first 18 days, at that point yellow leaf tops started to show.
Then i started to feed them with a compost tea with worm castings, molasses, Liquid seeweed and Pre mix (3/3/5).
After i have read a lot in the internet, i thought it would be a Kalium or Magnesium deficit soo i fed the plants 7 days after the tea with a topdressing of Bat Guano (1/10/1), Palm ashe (0/1/30) and with a little bit of Lava rock pulver for Magnesium and other metals.
Until now nothing really changed, it gets worse every day.

I hope someone can help and sorry for my bad english im not native.

For some more informations,

How long has this problem been going on? 13-14 Days now
What STRAIN are you growing? 2x Northan Lights 3x Green Jelato Autoflowers
What was the establishing technique? (seed or clone?) Seed
What is the age of your plants? 33 days
How long have they been in the soil mixture they are in now? 33 day from the beginning in the 5 gallon fabric pot
Were they in the same mixture when they were seedlings/smaller plant? If not, what mixture were they in before? Always
How Tall are the plants? They are growing good, it is hard to tell you how tall they are because of LST
What PHASE (seedling, vegetative or flower) are the plants in? they are going in flower right now
What Technique are you using? (SOG, SCROG etc) LST only
What size pots are you using? (Include how many subjects to pot) 5x 5 gallon pots
What substrate/medium are you using? What brand of soil mixture are you using?(percentage of perlite, vermiculite...etc?) Look in my first post, the brand is called Biobizz
What brand Nutrient's are you using? Guanokalong and Biobizz
What is the pH of the "RUN-OFF"? 6,43
What method of pH test was administered? Using Strips? pH pen? PH pen
How often are you watering? All 3-5 days with 0,8 gallon or 3l
What is the Day/Night Temp? (Include fluctuation range) 73-77F
Tell us about your ventilation, intake exhaust and when its running and not running ? 2x mini ventilations and filter + exhaust running all the time
Is the grow substrate constantly wet or moist? after watering wet for around 4 days when the soil starts to dry out at the top i water again.
What water are you using? Reverse Osmosis (RO)? Tap? Bottled? Well water? Distilled? Mineral Water? Tap water
Have any pest chemicals been used? If so what and when? No
Are plant's infected with pest's? i dont know

nobody?

burnt tips indicates nitrogen burn. lay off the nutes its causing more problems. just water with tap at 6.5 for 2 weeks then start adding lite bloom nutes at 1/4 strength and i like to start adding molasses to swell. get some potassium silicate add that first then the bloom nutes then the molases then add ph down to 6.5. good luck

Ok Thanks, i will try it like you told me.
But i cant understand how a nitrogen burn happens after 18 days withouth giving them anything to feed.
Green leaves until day 18, no feed but they startet yellowing.

Caribo said:

Ok Thanks, i will try it like you told me.
But i cant understand how a nitrogen burn happens after 18 days withouth giving them anything to feed.
Green leaves until day 18, no feed but they startet yellowing.

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Your soil mix already has plenty in it. The nutes are doing overkill. You have to flush the nutes out over multiple watering. Let the soil completely dry out and next watering check your runoff. Just place a saucer under the pots to catch the runoff and check the ec or ppm. whats the ec or ppm of your compost tea? it might be to hot

To be honest i dont have a EC pen, because people told me that you dont need a EC pen when you grow organic.
But i guess i will buy one now, so i can give more details.
Probely it was to much to add so much worm castings and pre mix in that light mix, it would annoy me if i fed them to much.
I started feeding when the yellowing happened, so i did it wrong from the start.

Thanks for the answer.

You definitely need a ppm or ec metere. i use a hanna instrument. Start off slow and work your way up. You gave it a compost tea and then a top dressing the plant doesn't have an estalbished root system. it can't handle large feedings. Thats why you need to check the ec of your res and the runoff of your soil. Any set backs diminishes your yield. You want to keep the plant healthy for a full 9-10 weeks in flower. Your yield decreases if you jump the gun and accidentally give your plant a 1800 ppm or 2.8 ec first week of flower. Or you forget to ph down and water with a 8.5 all mistakes ive seen in grows. look at the labels on bottles and bags and then always decrese that by half and work your way up. your plants will thank you

Tib420 said:

You definitely need a ppm or ec metere. i use a hanna instrument. Start off slow and work your way up. You gave it a compost tea and then a top dressing the plant doesn't have an estalbished root system. it can't handle large feedings. Thats why you need to check the ec of your res and the runoff of your soil. Any set backs diminishes your yield. You want to keep the plant healthy for a full 9-10 weeks in flower. Your yield decreases if you jump the gun and accidentally give your plant a 1800 ppm or 2.8 ec first week of flower. Or you forget to ph down and water with a 8.5 all mistakes ive seen in grows. look at the labels on bottles and bags and then always decrese that by half and work your way up. your plants will thank you

Click to expand...

Ok i will flush them today, they seem to dry out today evening, and i will at least check the PH of the runoff. I orderd a EC Pen now it should be here tomorow. i will give you more informations then. The problem is getting bigger it seems like there are brown points on the leaves now, at least on 1 plant.
I hope it will change soon. should i flush my plants with every watering? because i nerver did, 0,8 gallons on a 5 gallon pot is barely enough that a little bit of water is comeing out as runoff.
By the way when you make a compost tea, you use air stones from an aquarium right? i used that airstones in my normal water as well. Is that a bad idea or?

Thanks for the Answer

N

Caribo said:

Ok i will flush them today, they seem to dry out today evening, and i will at least check the PH of the runoff. I orderd a EC Pen now it should be here tomorow. i will give you more informations then. The problem is getting bigger it seems like there are brown points on the leaves now, at least on 1 plant.
I hope it will change soon. should i flush my plants with every watering? because i nerver did, 0,8 gallons on a 5 gallon pot is barely enough that a little bit of water is comeing out as runoff.
By the way when you make a compost tea, you use air stones from an aquarium right? i used that airstones in my normal water as well. Is that a bad idea or?

Thanks for the Answer

Click to expand...

If you flushed today just leave them. Its a cycle you water, let the sol dry till the plant is nearly wilting, then water again untill you get a little runoff. Your plant will tell you when it needs water. Let it dry when it starts to droop water the pot slowly till you get runoff, then wait till the plant slightly droops again. All of this depends on your lights and temps. Leds run cooler so the soil styas moist. HPS run hotter so the spil drys out faster. Everything is a factor when growing. Id hosnestly stop the nutes for awhile until your new growth leaves are green again

Ok i have done so, i watered today with around 1,3 gallon instead of 0,8.
There was like 0,05 gallon or 200ml of runoff on every plant and the PH was 6,8-6,9.
I watered with a PH of 6,4, i will now wait till they are completly dry but i think that will take around 4-6 days.
I will check the runoff of the next watering with the EC pen.

Thanks mate.

perfect they should bounce back. make sure the soil is completely dry. soil may look dry on top but stick your fingers down in it and the roots may still be wet

I cant believe that both of my Northern Lights are green already again. First Picture
My Green Gelatos are still looking really really bad, i hope on the second flush they will do a little better.

Thanks again my friend, i cant tell you how much i love competent help.

I'd probably wait till you see them nearly wilt (drooping leaves) be patient. then boom water again and I'd hit em with a flush to lower your ppms or ec down again. Your soil mix is probably still pretty hot. id fill up a whole tray full of runoff maybe (1000ml) maybe more depending on your ec or ppm of the runoff when you water again.

Tib420 said:

I'd probably wait till you see them nearly wilt (drooping leaves) be patient. then boom water again and I'd hit em with a flush to lower your ppms or ec down again. Your soil mix is probably still pretty hot. id fill up a whole tray full of runoff maybe (1000ml) maybe more depending on your ec or ppm of the runoff when you water again.

Click to expand...

Ok i have now Flushed the second time, 4 plants with 1000ml runoff.
I still need to flush 1 plant, she was not dry at all. i got my EC pen now and on the last one i will check the ppm.
After that flush you would water normal again? And you would slowly start to add Flower feds?

depends. what's ur ec?

Ok i told you that i have only 1 Plant left to flush and this plant is by far the worst looking one.
I flushed her for about 1000-1500ml and i checked every 100ml the ppm

It started with 2800ppm and the last 100ml was 2250ppm

But i think the ppm is not that high on my other plants.
What is the recommended ppm?
And if i do for example a compost tea, what ppm should that compost tea have?

By the way my Tap water has a ppm of 79.

Ok i watered today again, here are the results.

Plant 1: 1290ppm and 6,8 PH
Plant 2: 1160ppm and 7,0 PH
Plant 3: 1380ppm and 7,04 PH
Plant 4: 1450ppm and 6,97 PH
Plant 5: which is the bad looking plant from above 2250ppm and 6,9 PH

I watered with PH water 5,8 because the PH was high.

The measure of ppm and pH are more for hydroponic grows. You're using a home-made potting soil and you are feeding way too much. Even in a hydroponic grow your ppm levels would still be high, and 2250 would start killing a plant by poisoning with excess nutrients. This is why you're seeing the yellowing. You have dark green leaves with yellow/brown leaf tips indicating excess fertilizer. I'm guessing that not only are you feeding at high ppm levels you're feeding too frequently.
At any rate, you don't need to feed too often in soil as potting soil will trap nutrients in its fibers. You water/feed once an adequate amount, then just water when dry. Repeat the feeding days or perhaps weeks down the road, or maybe never again if your soil already has plenty of nutrients, meaning that you bought it or made it that way. This is why people like to use a super soil recipe - they mix it, let it sit for a couple months, then plant with it. Super soil is a water and forget it kind of mix. The nutrients are already in the soil because you put them there.
Unfortunately, your pics are a good example of how new growers are too aggressive in giving nutrients. You also have a pH problem as you don't need to water with water that has its pH lowered. You wouldn't do this to a house plant or plants outdoors so don't do it to any other plant.
pH of water is around 7.0. When you add nutrients, the pH tends to drop based on exactly what you're adding. When nutrients stay among fibers of soil and you add 5.8 pH water to the soil, you're preventing the soil from naturally raising it's pH some. In other words, you're forcing soil to stay at a lower pH than what might be good for the plant. So don't pH plain water; it's not good to do.
One of the problems with nutrient containers is they don't say how often to feed. They might say how much to give per gallon or liter, but not how often. For a hydroponic grow you'd give the same amount, for much of the plant's life, to maintain that level as the dilution in just using water is high. But using potting soil, you don't need to keep feeding and feeding as some will stay in the fibers, especially if your soil grow has nutrients already. So you feed a much lower ppm and less frequently in soil.
For better success, research super soil recipe and once mixed, let it sit for a couple months, then plant in it. Just water and nothing else unless you now for a fact that you need to add something. If made right, you shouldn't have to add much. You must use a large enough container to last the entire grow. When finished, recycle the soil by mixing in small amounts of the same nutrients and let it sit for a bit, then use it.
So what now? Just water, but you've pumped so much fert into the soil that these plants might not survive.