Another Yellow Prob.....Micronutrient Def?

[WongFoo]

This is my second grow and the 1st must have been a massive fluke cause im having big problems now.
Im about 65days into veg using bag seed, premium potting mix only, 400w HPS, water pH is about 6.5. Temperatures can range from about 5c-25c, I have no idea about humidity, pots are around 3 gallons. (9lt)
After about 3 weeks I began feeding them every 2 weeks with an all purpose chem fertilizer N:K 19.7:8.4:16.4 and they were going well. About a month ago a few plants began to yellow from the top, eventually turing a bright yellow/gold colour, the leaves feel really soft and growth has stopped, shade leaves getting grey spots, some lower leaves still green but with small yellow spots. All leaves are hooking downward.

I then flushed and gave them a diluted dose of chemical potassium and the all purpose fert and one seemed to green up a bit, the others didnt seem to get any worse but they didnt get any better. I then sprayed them with a diluted phosphorus:calciumotassium tea which didnt seem to make much difference, maybe delayed further yellowing.

The most effected plants had a pH run off of over 7.3, the greener had around 6.5. I flushed all plants with a pH over 7 and it brought the pH down to 7.0. The greener plant greened up even more but the others are still the same.

Any help would be greatly appreciated, Im pretty rusty and I dont want any of my babies to die.

 

[sproutco]

This ones easy. Ph in potting soil, your nutrient solution, runoff, etc should be 5.6 to 6.2 instead of 7 or whatever. Micronutrients become less soluble at a high ph like iron. You will have to adjust your water with acid. Try that and see if that does not solve your problem.

 

[WongFoo]

Ok what should I do to bring it down? In the last week I have made sure that anything I fed them was around 6.4. The water I am giving them is out of a fresh water creek + rainwater - around 6.4.

 

[WongFoo]

Sorry missed the acid part, Ive got a heap of fresh squeezed lemon juice, will try tht and see how it goes. Thanks!

 

[sproutco]

You could add 1/3 teaspoon powdered sulfur to a 6" size pot. Better...go to the auto parts store and get some battery acid. It may be called qual. You may need to make a stock of maybe 1 teaspoon acid to 1 gallon of water (3.8L). Then gradually add an ounce or two of this stock to your fertilizer water till you reach maybe 5.8 ph. You will have to experiment/titrate on how much to add. This may take many tries of too much or too little. Remember how much you used to get the right ph so you will be able to repeat. Be careful handling the acid.

 

[WongFoo]

I havent added anything other than the fertilizers I have mentioned and that solution has a pH of 6.4-6.2. Could low temperatures be causing the pH to rise? I dont think I have treated the sick plants any different to the healthy ones.

Im definitly gonna give the acid test a go though.

 

[sproutco]

Did you add dolomite lime to the soil or was it already added? Your n p k fertilizer with micronutrients (I hope) may not contain calcium or magnesium or sulfur. How do you judge how much fertilizer to add? PPM or teaspoons or whatever.

 

[WongFoo]

I havent added anything to the soil its straight out of the bag, and the bag doesnt give any hints as to whats in the mixture other than it is premium quality and high in nutrients.
The fertilizer I was using contains sulphur(0.22), magnesium (0.06), maganese (0.24), zinc (0.03), copper (0.02), boron (0.02), molybdenium (0.0014). I notice now that it doesnt have iron and calcium.
I bought some miracle grow all purpose a few days ago and was going to switch to that next feeding.
I have been using a 1/3 a teaspoon of fertilizer per 2liters of water but I admit that I have only begun testing the pH of this solution this past few weeks (after I found out about this board and the wealth of advice is has to give ) and it seems to be around 6.5 or a bit lower.
I have been judging how much to used based on what it says on the pack which is to use one teaspoon per 5 liters of water but I have been using less than that.

 

[sproutco]

No iron or calcium? You will need to find a fertilizer that contains at least iron too. I bet your potting soil has little lime added. You can fix low calcium (no calcium) and low magnesium (that fert. your using has very little) by adding 1/4 teaspoon calcium nitrate + 1/4 teaspoon magnesium sulfate/epsom salts in with your other fertilizer. You could use this low rate of cal/mag with every watering. Even with dolomite lime added to the soil, calcium and magnesium levels will often run low. Epsom salts you can get at the drug store and calcium nitrate you can find at a good garden center. I found a 50# bag for $10 by calling around. Tomato growers use calcium nitrate to stop blossom end rot of the fruit. Use the sulfuric acid/battery acid and you will supply your plants with sulfur and lower the ph to 5.8 to 6.0 Miracle grow does not have sulfur, magnesium, or calcium but will at least have micronutrients including iron. It is all ammonia/urea nitrogen and is kinda crappy. Better fertilizer for all purpose growing would be 20-10-20 soilless/peatlite fertilizer by peters or masterblend. (note that this has higher micronutrient levels and is not the general purpose 20-10-20) It is 60% nitrate nitrogen and 40% urea or ammonia nitrogen. This is desirable. Higher percentage of nitrate nitrogen the better. You can get 25# bag for $20 plus shipping over the internet. You would still have to add calcium, magnesium, and sulfur. Adding dolomite lime before planting (unless added already) would supply calcium and magnesium. Gypsum could be added before planting to supply some more calcium and sulfur.

I cannot stress enough to be very, very careful handling the sulfuric acid. Like I said, it is a good source of sulfur for the plants. If you are unsure you can do this safely, try vinegar instead. You can get the sulfur for the plants by using the epsom salts at a low rate.

 

[Verite]

Never saw a plant suffer from a sulfer def since most water sources besides distilled and RO have plenty of trace elements in them. Then again I never saw anyone recommend battery or sulfuric acid when theres plenty of good things out there botanists use including of all things intriguing... ph down.

 

[sproutco]

A plant may have a deficiency and not show any symptoms like a yellow leaf. This is called hidden hunger. Just as a guess, I would say "ph down" you find will probably be phosphoric acid. Sulfuric acid is probably best because sulfur is considered neutral in that it does not really promote growth but just changes within the plant. Its reaction is infinite in that the reaction is very strong and powerful. Most of the acid is "used up" in the reaction versus a weak acid where some of the acid doesn't react. Plants require quite a bit of sulfur to "grow" probably as much as magnesium. Plants can tolerate alot of sulfur and excess probably never occurs. Adding phosphoric acid would add phosphorus and this would promote growth/add more phosphorus when it might not be needed. Nitric acid would add nitrogen and you might not need more. Hydrochloric acid would add chlorine and plants require very little although this acid is good in that it is considered neutral and does not promote "growth". All of this becomes important when you are trying to be a very precise grower.

 

[WongFoo]

Ok for watering I'll add the calcium and magnesium mix + acid. For fertilizing I'll get some new 20-10-20 soiless/peatlite, add 1/4 teaspoons calcium nitrate and magnesium/epsom salts + the acid. All while checking the pH of the solutions and run off, making sure the pH of the run off is going down.
Just one more thing if I decided to go for vingegar instead of battery acid would I use the same amount? any specific vinegar?
Thanks for your help sprout

 

[sproutco]

There is a long thread over in the organic grows where they were talking about which vinegar to use to lower ph. Use the search feature here at ICMAG to find it. Try white vinegar. If you used the vinegar every rate for the other fertilizers would be the same...you would just be adding less sulfur. Aim for ph 5.8 to 6. You will have to experiment on how much vinegar it will take. You may only want to add the cal/mag (70 ppm ca + 30 ppm mg) every second or third fertilization in with your regular fertilizer. You are having to guess as to what the lime in the soil is doing that is probably in your soil mix. Main thing in flowering is probably to reduce nitrogen to prevent leafy growth. (This may mean using gypsum/calcium sulfate instead of calcium nitrate when you add cal/mag in with the other fertilizer because it would not add nitrogen. Use about 1/4 teaspoon gypsum to 1 gallon water = 60-70 ppm Ca. This is probably better to be using anyway for both flowering and vegetating but will be harder to disolve) You would just use less fertilizer overall to do this. I might make a couple of applications in flowering of something like 10-30-20 or 15-30-15 instead of 20-10-20 to boost up your phosphorus levels. Peters or masterblend peatlite/soilless 20-10-20 used at every watering: try 1/2 teaspoon (125 ppm n) to a gallon of water to start for a normal sized plant for growth and 1/4 teaspoon (65 ppm n) to a gallon of water for seedlings. In really good light and for extra growth try 3/4 teaspoon (188 ppm n) to a gallon of water. It is better to have a gram scale so you can measure in parts per million rather than my teaspoon estimates. Burning of leaf tips is a good sign you are using too much fertilizer. Make sure that when you water that you wet the soil well and there is runoff from the drain holes. Ocassionally it is good to use just plain ph adjusted water without fertilizer to remove any built up salts.

Give all this a try and through experimentation make it better. Please send me a pm and let me know what the plants do.

I found the masterblend peatlite/soilless 20-10-20 (note this is not the all purpose formula but is for soilless growing with elevated micronutrients) on the internet at the greenhouse mega store. Just google that. Look for their supplies rather than greenhouses and click that link. Within their online store, go to the fertilizer/water soluble fertilizer section. It is $20 plus maybe $13 for shipping. Pretty good deal for 25#'s.

 

[minds_I]

sproutco ...go to the auto parts store and get some battery acid.

Hello man,

Gotta question your sources on this-no need to handle caustic acids friend. Yes it will do what you what it to do with regard to pH and providing sulfer-but you are trying to kill a fly with a sledge hammer.

Why such extreme measures that do not merit justification?

minds_I

 

[Verite]

The reason they use phosphoric acid is because its a primary ingredient plants use and something desireable and easily used by the plant in the levels it has in it. Sulfur on the other hand is a secondary ingredient used by plants but not nearly in the same levels used by primary nutes.

Phosphorus is also fairly immobile in the soil and not prone to leaching which is why boosted amounts come in more contact with the roots. Sulfur on the other hand is highly mobile in the soil and quickly taken up by the roots and well as easily leached from the soil.

Heres a couple good links on nutes interaction. The second one is a great pdf file on all nute requirement elements.

http://www.farmtested.com/56.html

http://www.farmtested.com/download/plant_nutrient.pdf

 

[WongFoo]

What about using a bit of sodium biphosphate from an aquarium ph pack?

 

[sproutco]

Just use white vinegar for ph down. Adding sodium is not desirable. Make sure to read everything that has been written in the thread since you have been busy.

 

[WongFoo]

Ive read it all thanks for your help

 

[WongFoo]

Hi all

I cant seem to get the ph to lower in most of my plants, I have been using white vinegar adjusted water at 5.8 for over 3 weeks now, watering only when the pots were light, making sure I had some water coming out of the bottom of the pot. 2 plants have lowered to 5.8 but their lower leaves are curling up and dying within days, losing more than 50% of their leaves in a week. These leaves have black spots down the middle and turn extremly pale, then drop off without warning.
The other plants still have ph of 7, some of them have dying leaves in the same condition mentioned above, but not as severe. One plant appears to be overwatered with drooping leaves but I know Im not overwatering them. These plants are in the same condition they were in 3 weeks ago, some days looking better, some days looking worse.
One thing that is worrying me is a feint bad egg smell, roots appear to be browning where they reach the bottom of the pots. I will check the roots as soon as the soil drys out as I have only watered them yesterday. The plants have been in these pots since they were 2 weeks old seedlings and havent been repotted since.

400WHPS 1 1/2 - 2ft away from plants, lots of fresh air.

Will the ph stay high if the plant is rootbound or if the roots are rotting? I am going to repot them asap.

 

[sproutco]

I have been using white vinegar adjusted water at 5.8 for over 3 weeks now

Your not adding fertilizer? Here's how to test your ph: http://www.icmag.com/ic/showthread.php?t=32760