Rust leading to yellowing

[Emilya Green]

It's not about not believing, it's about understanding. One does not learn anything when he does not understand the reasoning behind it
Like you said, recommendations are usually (lots) more of what the plant can use. That was my reasoning for giving smaller doses, every watering. I was giving little over half the recommendation, so when using your method I put less nutrients in the soil overall. Hence my confusion.

My nutrients are from the Plagron Terra line,I forgot to mention this in my initial post. So definitely not bio.

Due to the poor choice of my timetable, I'll keep it short. I have just enough time to water the plants before I go to work and read your post.

I have watered 3 of the 4 plants now with just water. The 4th plant, who was also the fasted deteriorating plant, had none. Pots where light, 4th was noticeable heavier.
Here is what on of those simple moist meter said (about 2/3ths into the pot), and I have watered accordingly. In steps, like your water recommendations.

Before we go any further in this conversation, given the vast array of Plagron products, I need to ask exactly which medium you are in and exactly which nutrients you are giving. Then, even though you are trusting a $6 meter to tell you when to water, I will still try to figure out what you are doing wrong. Until I can be armed with the facts, I feel I am arguing with the instructions on your bottles as you interpret them, and we are not getting anywhere.

 

[Poezebeest]

I agree. First of all, I do appreciate you invest time to help me figure out what's happening. I will try to better explain what I do and why I do it.

Before I go into further detail, I wish to say that I usually don't use that '$6 meter'. I don't like it and certainly don't trust it. I just hoped it could give some indication. When I read your topic about 'the proper way to water', I see you mentioning using a moisture meter to find the wet/dry table. It's the only moisture meter I had laying around, I supposed you used a little more advanced tool for this.

Medium and nutrients:
My medium is just universal potting soil. Nothing fancy, just potting soil you can get at any garden shop. I mixed this soil with perlite (1/10). At the bottom of the pot there are some clay pebbles, just enough to cover the bottom.

The nutrients I use are Plagron Terra grow/bloom. Additives (universal) I have used and want to use are enzymes and green sensation.
I did grow some plants once, back in 2008. The soil and nutrients are the same type I used back then, so there shouldn't be any problems there.
I also use 'Biobizz CalMag' and 'Bio Nova Ph-' (phosphoric-acid).
I also have a bottle of 'Plagron CalMag Pro' I purchased this week, for the future. I'm unsure if it's safe to switch in my current grow session.


Water:
I find this one of the hardest things about growing, as I never feel sure if I water too much or too little. I don't have tensiometers yet (planned for future) or any other reliable moisture meters.
My lights go on in the morning, I open the tent, inspect the topsoil and plants. Then I pick up the pots and decide to give water when they feel light.
When I'm home that day, I might wait till around noon to add water. I never water before the lights go out.

My plant are 80 cm high and I give them 750 ml. If I give a liter or more, pots stay moist and feel heavy for longer than a day. I usually have a few drops coming out of the bottom side of the smartpot.

When watering, I never give it close to the stem. I first water in between the stem and the edge of the pot, then give some more around the edges. Going all around the pot.


Amount of nutrients:
My plan was to gradually build up the amount of nutrients week by week, but not till the maximum suggested. Then lower a bit when the booster is added.
What I've observed from other growers is they stick with a grow schedule, mainly centered around the EC of the water they give. I have no EC meter yet, but I'll get one for next time.

I was advised to give a maximum dose of nutrients, which I did. I did have mixed feelings about this as I've always seen people advise never to do that.

I will include a screenshot of the schedule of my nutrients and a few pictures of the deterioration of the plants in the last couple of days. The rate of deterioration greatly concerns me, as it looks they won't take this for another 4-5 weeks. The problem has picked up the pace even in the healthiest looking plant.

 

[Poezebeest]

Regarding amount of nutrients, I forgot to talk about CalMag. It might be related to my problem.
I didn't give it right away because I didn't really know what to expect under LED. They didn't show any signs of deficiency, my water is hard water, so I thought it would be best to wait.

Looking at my notes, the very first time I used CalMag was during week 6 on 2 plants (one week on 12/12). Looking at my pictures, there wasn't really any sign of magnesium or calcium deficiency, only something that looked like nitrogen deficiency. So I guess I used it for prevention. I gave them 0.4ml/l. I'll provide the nutrient schedule of the product in this post.

A week later I used it again on all plants. Mostly for prevention, except for one plant who had something that looked like some calcium deficiency. There where some rusty spots on the leaves discolored by the previously mentioned nitrogen deficiency. I used 0.4 ml/l and 0.65 ml/l on the plant with the rusty spots.

A week later I used it again, every plant got 0.8ml/l. This would be around the time my current problem started. The very first picture in this thread shows the first signs.
Because the problem was worsening (some leaves turned yellow over night), I was alarmed and started asking around on the internet. Someone said I've started too late with CalMag and I better give some more.
So I started giving some (almost) every watering since then, in low dosage (0.4 ml/l). At first it seemed to stabilize. It wasn't 100% fixed but at least the leaves didn't turn yellow overnight anymore.

Then rusty spots suddenly started appearing everywhere. After finding no clarity on the internet, I came here to find help. I didn't give them any CalMag the day I made this thread (because I watered already), but they got a larger dose the day after (1ml/l) together with the large dose of nutrients. Yesterday they only got water, except the one who got nothing.

It won't be long before I have to water again, pots are getting dry. No work today, so I can wait a bit longer, awaiting a reply. I'm inclined to just give them water once more, since all the nutrients seemed to have worsened the problem.

 

[Fenderbender]

hmm maybe you are experiencing a lockout, even if you've been low with the nutes before, the first pictures do show burnt tips all over.
Hard water can be a pita to work with, I'm in BE, and well when I boil a kettle of water I can see crystals forming at the spout from the steam.
A proper flushing? Followed by a good dry out and then maybe some distilled water nuted and ph adjusted for the next feed?

 

[Poezebeest]

@Fenderbender A lockout is also what I'm thinking about.

I suppose with flushing, you mean giving lots of water? I have never done that before. How much water would be required for a proper flush (3 times potsize?) and do I also ph down said water?

 

[Poezebeest]

Searching the forum, I found I can give just tap water, not worry about ph and 3 times pot size. I'm just not completely sure what follows next. Do I let it dry completely after, which probably takes several days? Or do I already give back some nutrients shortly after?

 

[Fenderbender]

I'd PH the water so you keep the right acidity, and how much? well lots, you need to saturate the pot with water, wait a few minutes for salts and nutrients to dissolve then force all that water out by flooding the pots again.
You'll need somewhere to work where you can catch all the run off.
Ideally one would measure the EC of the run off to see where you're at until it matches the EC of the water you put in it but otherwise just do it in the sink or shower or outside.

Also are your smart pots elevated? can air get under them? put them on some roosters or a few rails, so the bottom of the airpot isn't touching ground as that will keep it moist and wet under there that caused me some problems when I first started using smart pots.
Maybe also get a fan blowing circulating around the pots as yes after flushing things will be wet a couple of days, then introduce nutes again when she needs water.

 

[Poezebeest]

They currently stand on plant dishes they barely fit in, so water doesn't spill on the floor when watering. I have some elevated grills (roosters, or whatever they are called) to place them on.
I have a fan hanging high up in the tent. It already creates airflow around the pots. The tent is too small to place it on the floor.

 

[Emilya Green]

Before I go into further detail, I wish to say that I usually don't use that '$6 meter'. I don't like it and certainly don't trust it. I just hoped it could give some indication. When I read your topic about 'the proper way to water', I see you mentioning using a moisture meter to find the wet/dry table. It's the only moisture meter I had laying around, I supposed you used a little more advanced tool for this.

Sorry... this reply needed more time than I had yesterday to deal with it. I will get back to this later this morning, but for now let me talk about the moisture meter.

First, the light and nutrient measurement parts of that meter are junk... totally worthless readings. Even the moisture meter has its limitations. There are essentially two readings on that meter... moist and wet. Moist tells you nothing... the entire container will usually show moist at some level. What you are interested in is where the top of the water table is... because then you know how much water is in the container. Gravity causes the water to sink to its lowest level and if you carefully put the probe in the soil, and keep moving it downward, at some point the meter is going to peg all the way to the right side and indicate wet. A half inch above that is moist... but once you are in the water it will go wet.

The level of this water table will fall a little bit each day as the plant uses up the water. Your goal is to wait for the water table to fall down into the last inch or two of the bottom of the container. This is when you water, because it will take a long time for that bottom couple of inches to dry out, one because of the rock layer you put in the bottom and two, because of capillary action between the roots and the sides of the bag. Also, monitoring where the water table is, gives you a solid indication as to how fast your plant is using up water. Watch the top of your water table for a few days and see how it steadily falls, and try to work out exactly how much water that is.

I don't think you need a flush... but if you want to do one, it wont hurt anything. It is simply a very thorough watering. The soil can't hold any more water than it would if you had just watered with plain water, so the container will dry out just as if you had only watered and not flushed. Flushing IS 3x the container size... it is a lot of water. We only pH adjust so our chelated nutes are in the proper range to be released to the plant, but when flushing there are no nutes, so there is no need to pH adjust. Plain tap water works well, and warm tap water helps to dissolve the salts and move them out of there, better than cold water does. There is no need to add nutes after flushing, just treat it as your inbetween water only watering in your f/w/f/w schedule.

 

[Emilya Green]

It won't be long before I have to water again, pots are getting dry. No work today, so I can wait a bit longer, awaiting a reply. I'm inclined to just give them water once more, since all the nutrients seemed to have worsened the problem.

f/w/f/w if you are not willing to do this, I have nothing else I can advise you to do. This should not have even been a question... stick to the schedule. Again, after breakfast this morning I will get back to the discussion about your feed. The nutrients are not causing your problem... the way you are applying them is. More soon. I promise.

 

[Emilya Green]

f/w/f/w if you are not willing to do this, I have nothing else I can advise you to do. This should not have even been a question... stick to the schedule. Again, after breakfast this morning I will get back to the discussion about your feed. The nutrients are not causing your problem... the way you are applying them is. More soon. I promise.

having said this, I see that plagron advises nutes every time. This is what I don't understand, why they are advising you to do this in soil. This practice is against everything I know about soil. Maybe they are giving such light dosages of nutes that this is possible... I just don't know yet. I will get back to you after I research this system a bit and see why they make such suggestions.

 

[Poezebeest]

I have just finished the flushing and I have some findings that may shed some light on things.

I ran 3 buckets through each pot. After each bucket, I placed the plant on a grill above a plant dish while refilling the bucket. Placed the plant back in the sink on a grill and emptied the plant dish.
I didn't Ph the first bucket, but I did for the 2nd and 3th.

After the 3th time I waited a bit, so the water could leak out some more. I decided to measure the ph of that water. The last bit of water isn't much, maybe 100 ml.

First plant seemed ok, the last bucket was ph 6.3 and that bit of water that leaked out was ph 6.2
I did the same for the second plant, but ph 6.3 came out 6.0
Uncomfortable with this, I decided to measure that water for the other 2 plants for the first 2 buckets as well.
3th plant: 1st bucket went in 7.9, last bit that came out 6.2/ 2nd bucket 6.5 -> 6.1/ 3th bucket 6.5 -> 6.2
4th plant: 1st bucket 7.9 -> 5.9/ 2nd bucket 6.6 -> 5.9 / 3th bucket 7.1 -> 6.0. I did place this plant over an empty plant dish and it leaked out some more, that bit was 6.5. (weird?)

Is it safe to assume my soil is/was more acidic than it should be and is causing all my problems?

Then the question remains what made my soil acidic? While searching for solutions, I came across wrong ph levels in soil several times. I remember reading somewhere that ph- can build up in the soil. I have no idea if this is true or not, though it seems plausible.

 

[Emilya Green]

I didn't Ph the first bucket, but I did for the 2nd and 3th.

Over thunk... and unfortunately, wrong. The plant starts sucking up water as soon as that first bucket hits. If you wanted to take advantage of any nutes left in the soil, it is THAT bucket that should have been pH adjusted, and then the ones after that wouldn't matter, since the plant will have already taken its big drink. Again, no harm done, just a little humorous as I recall doing the same thing when I was new.

 

[Emilya Green]

Think of runoff water as water in a coffee percolator. You have a cheap soil that is going to break down into micro particles rather quickly, and some of that is going to come along in the flush water. Your soil probably has sphagnum moss as part of its makeup, and over time, that does break down and go acidic. This is what is most likely flowing out with your flush water. This does not mean that your soil is acidic. Checking the pH of runoff water in soil is mostly meaningless... you get a lot of false readings because of sediment flowing out of the soil, and in the case of normal runoff (not a flush) the pH will also depend on your arbitrary decision as to how much runoff to produce... the more water, the lighter the concentration of things that affect your pH reading.
In a strong soil that isn't breaking down, your runoff pH should eventually be the same as the pH of the water you are putting in the top.

 

[Poezebeest]

Ok. There is no way for me to know what the exact makeup of the soil is. I just bought "quality potting soil", you make it sound like I cheaped out on the soil
Anyway, I thought it was worth mentioning because it was such a big difference in ph. As it's not my field of expertise, those numbers seemed troubling. Could it be considered a good thing those particles are now flushed away?
On the places I usually went, I sometimes see people talking about measuring runoffs to see the difference between what goes in and what goes out. Coming here almost feels like a culture-shock, hehe.

What would be a strong soil? Does strong potting soil exist and how can you recognize it?

As far as my plants go, I guess waiting is all I can do now. Hoping it won't get worse.

 

[Emilya Green]

Ok. There is no way for me to know what the exact makeup of the soil is. I just bought "quality potting soil", you make it sound like I cheaped out on the soil
Anyway, I thought it was worth mentioning because it was such a big difference in ph. As it's not my field of expertise, those numbers seemed troubling. Could it be considered a good thing those particles are now flushed away?
On the places I usually went, I sometimes see people talking about measuring runoffs to see the difference between what goes in and what goes out. Coming here almost feels like a culture-shock, hehe.

What would be a strong soil? Does strong potting soil exist and how can you recognize it?

As far as my plants go, I guess waiting is all I can do now. Hoping it won't get worse.

Sorry, didnt mean to make it sound like you scrimped on the soil... but there are designer soils that are made for what we are doing. Check out Roots Organic soils and Fox Farm's soils... these are strong soils. What I mean by that is that they have a lot of good stuff not just mixed into them like a typical commercial soil, but they are then well composted to "bake" those components into the soil. This is the difference... in a strong soil the components become an integral part of the soil, whereas cheap soils (commercial grade) are just a mix that still isn't combined into what I would call soil.

Yes, sorry about the culture shock, but there are a LOT of people who do not know how to properly run soil. A lot of online want to be gurus will talk for decades about the need for checking the pH of the runoff, something that is very valid and valuable in the coco world, but totally worthless in the soil realm. When you can't know for certain what is coming out, like you can in coco, insisting that people make this measurement is just silly.

 

[Emilya Green]

Could it be considered a good thing those particles are now flushed away?

Yes, that is another function of the flush. You not only flush away the built up salt and clean out old unused nutrients, but you also reset the soil, flushing away the peat and other things that break down and decompose during the grow.

 

[Emilya Green]

I need to get upstairs to my grow rooms in the attic and get some critical work done up there. Then we will delve into the nutrient recommendations a bit more. I want to see if you have figured out the water meter yet... it is a good tool if you use it correctly. Have you been able to find the top of the water table in your containers yet?

 

[Poezebeest]

Take your time. There is nothing I can do now anyway, the lights are out.
Considering I just threw 3 buckets in each pot, I'd say the tables are pretty high right now

I have tested them out earlier, when I took those pictures. Like you would expect they go from the dry/moist border at the top, then stay in de moist zone for a while till reaching the wet zone. Pushing deeper, it suddenly points all the way to the end. This is when I reach the water table, right?

I feel uncomfortable repeatedly forcing those pins through my roots though, it feels like roots snapping.

It's just a 3-in1 meter, it's all they had. I just bought it to test it, without much expectations, when I was buying other stuff. Considering how much an actual soil ph pen costs, it would be absurd to believe this cheap meter would give an accurate reading.

 

[Fenderbender]

So what did the plants say? If it's the first time they've had that much rain might be a bit droopy?
If that's the case might want to poke some holes with your meter in the soil for aeration.
Did you just use soil? might want to consider perlite to layer in with the soil next time, so you get good drainage and oxygen to the roots and it doesn't stay a wet mess for a long time after watering.