New grower: Nute burn or something else?

Hello everyone, I'm a first time grower and I've been having a couple of issues. I'd be very happy to get some feedback from the community here. I am just wrapping up my 6th week here and my girls are starting to flower. All three are autos. From probably the second or 3rd week, I've had varying degrees of yellowing in these 3 plants.

Plant 1 seems to be the hardiest one. It's been a light lime green colour the whole time. Yellowing and brown spots have mostly been on lower fan leaves but are starting to appear closer to the top. Of the three, this plant looks healthiest, but had the most burnt tips. Leaf stems are turning pink/red. This plant has a runoff Ph of 6.15 and a runoff EC of 1.25.

Plant 2 has been bouncing back and forth between drooping and perking up. It started a similar balanced lime green colour, but lately the green parts are getting greener and the yellow parts are really standing out more. Yellowing started on bottom and is now throughout. More browning throughout the plant than plant 1, but less burnt tips. Leaf stems are darker red than plant 1. This plant has a runoff Ph of 6.14 and a runoff EC of 0.95.

Plant 3 has been a weird one. It was super dark and small at first. Now it is suddenly as tall as plant 1 but the leaves look very sad lately. Because the greens are darkest on this plant, the yellowing really pops. The most brown spots of the 3 plants, and some very curly leaves around the buds. Was drooping like crazy earlier this week, but perked up a bit. It has less burnt tips than plant 1, but more than plant 2. Leaf stems are also turning a pink/red colour. This plant is in a 3 gallon pot, where the others are in 5 gallons. This may be why the runoff is so different, with a Ph of 6.26 and a EC of 0.75.

When plants 2 and 3 started to droop, I thought I was under watering them. Now, as I've regulated their watering schedule, I'm not sure what the issue is. I am alternating one day with full feed, one day with just water (recently I've switched from plain Ph adjusted water to still adding the calmag and silica supplements). I'm up around 1.7 EC on my feeding days, and I usually Ph to between 5.9 and 6.0.

Seems to be varying degrees of the same problem possibly in all 3 plants, but I don't really know. Any suggestions are very welcome and appreciated.
 

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Deficiencies, nute burn comes at the tips, feed them more food
Good to know, thanks. Sorry if this is a silly question, but do you think I should just cut back on the PH'd water feedings, and just give them water with nutrients for a while, or is there potentially an issue with how frequently I'm watering? I usually do one good feed with about 15% run off every morning.
 

HandyGringo

Well-Known Member
They are indeed in Coco. I was not aware of that. Thank you very much for the tip.
I think it's also viable only to give nutrients on every other watering. But more than that and you're asking for deficiencies.

I made the same mistake last year, watering my coco like it was soil, and ended up with loads of deficiencies.

Coco doesn't hold nutrients as well as soil does.
 

Absorber

Well-Known Member
Awesome. Lately I've been shooting for 5.8-5.9 Ph on my feeds. Perhaps I'm a bit low and that Phosphorus, Calcium and Magnesium aren't getting through very well. I've been told to go with a lower Ph on autoflowers, but it looks like 6.3-6.5 might be a better target range.
I run hydro ( a variation of a flood and drain system)so i let my pH float between 5.8 - 6.3 I haven't tried coco though.
 

ec121

Well-Known Member
I am alternating one day with full feed, one day with just water
Don't do this. You should be feeding multiple times daily (or at least once per day) in coco at an appropriate EC.

Doing a water/feed protocol places osmotic stress on the plant because it has to constantly go back and forth between manufacturing sugars (to handle the high EC of the water) and then converting those sugars to starches (to handle the low EC of the water), and that energy could be used toward growth if the EC is kept consistent.
 
Don't do this. You should be feeding multiple times daily (or at least once per day) in coco at an appropriate EC.

Doing a water/feed protocol places osmotic stress on the plant because it has to constantly go back and forth between manufacturing sugars (to handle the high EC of the water) and then converting those sugars to starches (to handle the low EC of the water), and that energy could be used toward growth if the EC is kept consistent.
You guys were all correct! I'm watering twice a day now and feeding every time and they are thriving now :)
 
Is your entire pot really drying out twice a day? That seems excessive. But I'm glad to hear they're doing better!
No, the entire pot isn't drying out. But they've been a lot thirstier than previous weeks now that they are flowering. The first watering is about 1.2 litres at 8am in a 5 gallon pot, of which approximately 200-250ml is running off. The second is approximately 600ml at around 4pm and I'm getting around 50-100ml of runoff. It took a few days to get to those amounts, where I was getting runoff in each feed.
 
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