Yellowing Leaves

ok, thanks for filling in that info.

Ok, I can offer advice for a few things, and just thoughts for a few other things.

nutes: I havent used that brand, so I cant really speak to it. but, I'd say it's too early to be using full strength nutrients like that though, and that you might want to flush well and then feed them 1/4 strength nutes and see how they take it.

moisture/ph meter: please tell me you arent using that cheap green plastic meter with the long metal probe you got for ten bucks at home depot or something. if so, just go ahead and throw it out right now, it is useless. (not trying to sound like an ass, i'm speaking from experience)

Get a liquid PH tester and test both the water you put into the soil (and adjust it to 6.5 or so) and the runoff. the runoff water will give you a clue what the soil PH is.

as for watering, have you heard of the 'weight' method? next time you water your plants, do it really fully...do it a bit extra, make sure the soil is pretty well evenly watered. then lift it up and gauge how heavy it is. now, when you want to know how much water is being held in the soil, you can judge it against that weight. you dont want to water again until the pot is significantly lighter than it was when wet.

also, best practice really is to not water plants until they are showing the first signs of wilt, then do it thoroughly, slowly and evenly. if you do this you'll get to feel the two ends of the weight spectrum.

as for the PH down, I know organic juices can be used immediately, such as lime or lemon juice...but i'm not sure about their long term activity in the soil. I'd say it would be an easy enough thing to find out via google though.

If you're lookin for a liquid PH meter on the cheap (relatively so) I got this meter off ebay
HANNA HI 99104 Pocket pH Tester/Meter/Checker, HI99104 - eBay (item 370061310325 end time Jun-23-08 15:20:24 PDT)

haha, in fact now that I look I actually got it from that seller. arrived super fast.

also, with watering...the amounts you are saying dont make sense to me. I actually work with volumetric liter flasks all day, and am quite familiar with the size. For two liters of soil, 500ml of water seems like....a pretty normal watering to me.

It isnt necessarily a bad thing to give the soil a really good soaking, as long as you drain the water out the bottom you'll be fine, the water holding capacity of your soil determines the water/air ratio which is the really important aspect of soil moisture, but you want to make sure when watering that you're getting a good amount of the soil wet, you want to make sure it's not just streaking through the pot and quickly into the pan. the best way is to drip it slowly on the soil, this helps it get to more areas. alternatively, you could just flood the hell out of it for a few minutes, then pick it up and watch all the water drain through...hear the air being sucked in from the top of the soil, filling the soil pockets with fresh air.

also, best practice is to water away from the stem, to encourage the roots to go in search of water.

ok, sorry if i'm rambling or if you already know this stuff, its late and i'm high.

indeed overwatering is a problem, but what that usually means is that someone is watering too often, not too much each time.

ok actually going to bed now.

damn, didnt realize you were in the UK....get some sleep!

Almost always when plants start getting yellow from the bottom up its a N deficiency..

in case of a N defficiency what is the best remedy to fix this.

theblindcamel said:

in case of a N defficiency what is the best remedy to fix this.

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This link seems to be pretty good:

https://www.rollitup.org/marijuana-plant-problems/38772-guide-diagnosing-plant-problems.html

Barking Mad said:

Sorry. The plants are about 20days old, I was watering them with about 100ml water every 2 days. For my nutes I have been adding Ionic-'Grow' (7ml pr ltr) since day 1, this has all the nutes that are needed. I have a 400w MH about 18" above the tops. I wanted to start a journal but am not sure how to, I have started a photo album which is open to view and added comments to the pictures detailing what I am doing. Oops I forgot, the watering may have been a bit much but I now have a neter so will not be overdoing it anymore. They have not been watered for a day, I am leaving the soil to dry out to encourage the roots to grow (I hope). I also have got a PH meter and it is saying the PH is 7 but the test kit I have reads about 6.5. To be on the safe side, how do I reduce the PH without using PH down (which I can not afford until next week.)

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Hi Barking Mad,

In my opinion these plants are too young to be suffering from nute deficiency. To be honest I think you have been over-feeding and, more importantly, feeding too soon. Feeding too early can cause a lot of damage to young plants. Bear in mind that even nute-free soil has enough natural nutrients and trace elements to feed your plants for about three weeks, so you really shouldn't feed before the plants are at least three or four weeks old. And I see you are now using soil with fertilizer in it - soils like this can feed for several months. Your plants may be suffering from nute burn, which can often look very similar to nute deficiency. Look here International Cannagraphic Magazine Forums - The Complete guide to Sick Plants,pH, and Pest troubles! - way down near the bottom of the page there are a couple of pics of plants with nute burn.

My advice is DO NOT give your plants any more nutes, particularly now that you are using soil with fertilizer - flush the plants with plenty of water (about two or three times the volume of your pots) and see how they go for a few days. There may be some permanent leaf damage to those older leaves but you should see some general improvement fairly quickly if nute burn is indeed the problem. And definitely cut down on the watering. Water well, until you see water run out the bottom of the pot, about every three or four days IF they need it. This is much better for the plants than watering little and often. When you do start feeding, every other water is enough and always less than the "stated dose" (as TMB77 said, start off with about 25% of the stated dose and gradually work up). But you have plenty of time to worry about feeding, especially now with that new soil you are using

greenb.

gardenandcats said:

Almost always when plants start getting yellow from the bottom up its a N deficiency..

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thats not just yellowing though, its that spotted burned color indicative of over-fertilizing. check out the really bad leaf in the second picture, looks like classic nute burn to me.

Thursday night I flushed three of the worst affected with tap water that had been standing for 24 hours. I also filled 3 2litre bottles with tap water they have stood for about 30 hours. now. I have just checked the pH and it was 7.5, I have brought it down to 6 and was going to flush the others. Instead, I have a plan. I will leave them for a couple more days until they need watering again, then I will flush them with just the water (checking the pH again first). I am not going to add any more food and watch how they do. As long as it clears up then I will slowly introduce the nutes again at a smaller rate. This is my plan for the next week or two. Hopefully (if I did it right) here is a picture of my set up, can you say what, if anything, I am doing wrong. Thanks, Oops, I forgot to mention, the temp has been a constant 70/74f for the last 50 or so hours, during daylight hours I have a small window open for ventilation, at night I keep it open but black out the light with a thick curtain and have set a fan (see pic) to run for an hour then off for an hour. I know it should be nearer every 5 mins but I don't have a timer capable of that (yet). Any advice or suggestions welcome, and could somebody tell me how to set up a journal please??

It's a good plan Barking, but remember you have just put them in soil that has nutrients already added to it. Don't make the mistake I made and add even more nutes unnecessarily or too soon - you will regret it. Your plants will not be shy about telling you when they are hungry, so don't worry too much about food. They look great in your new pic btw. I wish you and your plants all the very best. Keep up the good work

greenb.

Thankyou greenbehemoth, yes I have stopped the nutes completely, the only addition to the water was a few drops of lemon juice to bring the pH down to 6. I am still getting used to using this site, have you any idea why my pics are so big? everyone else seems to have thumbnails on their posts? Thanks for the link to the sick plant forum, I have been looking for exactly that sort of info, bookmarked it straight away. Cheers.

If you click on the "Go Advanced" button when you are going to post, down below the "Message" box you will see "Additional Options". Click on "Manage Attachments" and that will allow you to upload files from your computer. To set up a Journal, just go to the "Grow Journals" section of the forum https://www.rollitup.org/grow-journals/ and start a new thread. Hope this helps. And thanks much for the rep Barking

You stated you E.C. was 2.6-----Please explain-------Thats very high for such a young small plant.

heres some pics from the GROWFAQ that YOU should take a LOOK at SOMETIMESSSSS
Nutrient Solution Burn:
There's a good chance that this leaf was subjected to nutrient solution burn. These symptoms are seen when the EC concentration of hydroponic solutions is too high. These symptoms also appear when strong nutrient solution is splashed onto the leaves under hot HID lamps, causing the leaves to burn under the solution.



Figure 2
Many hydroponic gardeners see this problem. It's the beginning of nutrient burn. It indicates that the plants have all the nutrients they can possibly use, and there's a slight excess. Back off the concentration of the nutrient solution just a touch, and the problem should disappear. Note that if the plants never get any worse than this leaf (figure 3), then the plants are probably just fine. Figure 4 is definitely an over-fert problem. The high level of nutrients accumulates in the leaves and causes them to dry out and burn up as shown here. You must flush with clear, clean water immediately to allow the roots to recover, and prevent further damage. Now find the cause of the high nutrient levels.


Potassium (K)
Potassium is involved in maintaining the water status of the plant and the
tugor pressure of it's cells and the opening and closing of the stomata. Potassium is required in the accumulation and translocation of carbohydrates. Lack of potassium will reduce yield and quality.
Potassium deficiency:
Older leaves are initially chlorotic but soon develop dark necrotic lesions
(dead tissue). First apparent on the tips and margins of the leaves. Stem and branches may become weak and easily broken, the plant may also stretch. The plant will become susceptible to disease and toxicity. In addition to appearing to look like iron deficiency, the tips of the leaves curl and the edges burn and die.
Potassium - Too much sodium (Na) displaces K, causing a K deficiency. Sources of high salinity are: baking soda (sodium bicarbonate "pH-up"), too much manure, and the use of water-softening filters (which should not be used). If the problem is Na, flush the soil. K can get locked up from too much Ca or ammonium nitrogen, and possibly cold weather.


Figure 13

hope this helps u out and let u know that the growfaq is ur friend