Yellowing of Leafs in Flowering (Confused as to which deficiency)

Hi guys,

hope all is well. I'm a fairly new grower and this actually is my first post. I tried to read about my problem online but unfortunately couldn't come to a definite conclusion. I have 4 Autoflowers under a 400w light grown in soil. 2 are Think Different and 2 are Blackberry Kush. A while ago the leafs on the bottom and the middle started to turn yellow, but like yellow spots within the veins of the leaf. I figured it was a magnesium deficiency and bought magnesium sulfur to eliminate the deficiency. Although it kept spreading. I thought I didn't put enough magnesium sulfur in the water and watered them twice again with about 8 teaspoons of magnesium sulfur.

Unfortunately the leafs keep on yellowing, but now from like the edges inwards. Seems to be a nitrogen deficiency now, but the plants are 8 weeks old.. The farthest one of the 4 plants has even yellowing on the edges of the top bud's small fan leafs.

The growth definitely seems stunted, since nothing has really changed for the past week in terms of bud growth or trichome production.

I use the hesi soil nutrients pack and add half of the recommended dose to the water. One is the Bloom Complex with a 3-4-4 ratio (50ml/10 L water recommended) ( I do half) and the other a Phosphorus Complex with a 0-7-5 ratio (25ml/10L). So in the Bloom there is still nitrogen.

(I wasn't at home over the weekend and the plants were definitely underwatered for a day or two, which definitely didn't help.. but I can't change that now :/ )

Please Help. I wanna harvest fat and dense buds in 2-3 weeks.


PS: Temperature is always between 23-30 Degrees Celcius (Depending on the day and time) and Humidity is usually between 40 and 50%. I also check ph with color drops and always make sure its between 6 and 7

looks like you have more than 1 deficiency, i know nothing about those nutes so all i would say is just give um plain tap water for 4/5 days then a light feed, someone else will prolly put you right

thanks for the help. But wouldn't plain tap water just increase the deficiency?

I could be wrong, but that looks more like calcium deficiency than anything else. Have you run any cal/mag at all while feeding?

No Cal/Mag only magnesium sulfate (magnesium salt), which I got at a garden store.

Well, I would wait and see if someone else weighs in on this to get a consensus. I'm thinking it's a calcium issue. I would do what bobtokes says for now though. Just use some regular tap water. It has phosphorus, calcium and the like in it in trace amounts anyway. Better to err on the side of caution for now rather than hurl more into the unknown and cause an even bigger issue.

Yeah that makes sense. I mean it's not that terrible if they miss one feeding right?

One of the plants is probably ready to harvest next week. Kinda grew faster than her sister (Blackberry Kush). So shes just getting plain water from now anyways. But I think the 2 Think Different plants will still need 2 more weeks (at least). There the one is also ahead of the other by probably a week or so.

The problem I have, since I'm fairly new to growing is that I've read about all the symtoms of the most common deficiencies, but the symtoms sometimes overlap. Which makes it hard to figure out the problem :/

The1StonerStory said:

I've read about all the symtoms of the most common deficiencies, but the symtoms sometimes overlap. Which makes it hard to figure out the problem :/

Click to expand...

It certainly does; and so many of them look so very much alike. I would just ride the storm out if you only have two weeks. In the grand scheme of things, you should be flushing (using water only) for the last two weeks anyway to make sure you get as many chemicals out of your buds as possible.

I wouldn't bother adding anything if you're that close to home. In all likelihood, you'll be harvesting before any real recovery begins in earnest anyway.

Greetings. I don't flush for the last 2 weeks anymore. You know how much weight they put on then, How much they stack up? quite a bit. Anywho. Looks like P def to me that started the Ca and scratching at K and of course late N. I would wait for a better answer than mine. It may come it may not.

#Random

I'd like for them to put on some more weight, so I actually wanted to wait with the flushing until the last week.

I was actually hoping I'd get 50g off each plant. But for now I don't know if that'll be the case. Especially with the deficiencies stunting growth.

The1StonerStory said:

The problem I have, since I'm fairly new to growing is that I've read about all the symtoms of the most common deficiencies, but the symtoms sometimes overlap. Which makes it hard to figure out the problem :/

Click to expand...

the more experienced you are the more you look for what may have caused a problem in the first place, once you've narrowed the symptoms down its usually easy to work out whats going on and why, especially when your using the same nutes and medium for your grows
most new growers have a hard time working out whats going wrong, it will come

I really hope so. For now I'm dependent on more knowledgable people on these forums

only take pics in white light. can't see color in sodium. however 8 tsp of mag is way too much. you probably poisoned them with that. as far as other issues are concerned, it's hard to tell what it is. after so much mag it might be impossible now to tell.

I didn't have time to switch the lights. They're in the dark period during the day, otherwise I'd take the pictures in natural daylight. But yeah 8 tsp might have been too much. at the beginning though it definitely looked like a mag deficiency and it didn't stop after I added like 2 or so tsp so I thought it wasn't enough :/

One of the Think Different plants (the one that'll probably take the longest to harvest) is starting to display heat stress at the top of the cannopy. The thing that's confusing me is, its around 23 C degrees in the tent and I have a fan blowing between the lamp and the plants. While without the fan, at 28-30 C degrees, and the lamp closer to the plants the plant didn't show signs of heat stress..

no offense, but I bet you were wrong about the mg def and you might be wrong about the heat stress? do the edges curl upward? even 2 tsp of mg may have been too much, especially if that wasn't the problem.

no offense taken lol like I said I'm fairly new to this. I'd just like to find a solution ^^ the leafs are curling upwards at the top of the cannopy

Have you given them a P/K bump?

like I said I've always watered with the bloom and phosphorus (P/K) nutrients. Recommended dose 25ml/10L but I've always done half so far. Should I give em a full dose the next time?

I use a bloom nutes and week 5-6 I bump it with more PK only and same N. These weeks is when the plant uses the most P/K making buds. These are also the weeks P defs show up and that is right around week 4. #IMO