Do we need to pH adjust our nutrient solutions?

I thought that was just for when you needed a body to stick under the cornerstone of a church :hmmmm:?

That old Roman book wasn't exactly what I expected it to be. It's more like a lengthy conversation (as many works from that era were). But it's still interesting. It just doesn't really go into depth about anything. They knew about grafting onto rootstock of a different plant (even a different type of plant) 2,000 years ago. And might have known as much - or more - about "green manure" than many of us do today.

On-topic question: I've seen mention that the buffers in the stuff we grow cannabis in (when we're growing in soil(ish) ) last long enough to get through a grow. Is that "on average" or "always?" Some people switch to a flowering light schedule after four weeks (or even as soon as the plant is mature enough to flower), while others go eight weeks or longer. And some feel that strains that have a 70-day flowering period take too long, lol, while others... It's been almost 20 years since I lost them, but I used to have one that flowered for 16 weeks and another one that took about 20½ (RIP, Nevil Schoenmakers, and thanks for all the buzzes).
 
When I started growing it was fun. Now that it's getting more technical it's lost it's fun & became work. The more it becomes work, the more expensive it gets. The more expensive it gets, the more growing loses it's appeal.
 
InTheShed said:
According to this we don't need to struggle to control our nute pH, just struggle to control our medium pH!

Or it isn't after all.

I know right? I kept asking different ways until he finally gave me a straight answer. I told him that was going to throw a lot of folks for a loop!
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Youse pH perfect advanced nutes my pH stays at 6.5 6.6
 
TorturedSoul said:
Is that "on average" or "always?"
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The answer is "on average." If your tap water is very high in alkalinity then I would imagine that you could burn through your buffering capability before the grow was finished.

If you can get a water report from your utility that will let you know how your water is, or a slurry test will let you know if your soil has drifted out of range.
 
Speaking of my tap water... The last time I checked its pH, it was 8.5. That's 100 times (logarithmic scale) more alkaline than what has traditionally been recommended people give their soil-grown cannabis plants.

Is that a problem? Usual mix is 37.5% Fox Farm Ocean Forest, 37.5% FF Happy Frog, 25% (additional) perlite. Grows usually don't last longer than five months or so.
 
TorturedSoul said:
Speaking of my tap water... The last time I checked its pH, it was 8.5. That's 100 times (logarithmic scale) more alkaline than what has traditionally been recommended people give their soil-grown cannabis plants.

Is that a problem? Usual mix is 37.5% Fox Farm Ocean Forest, 37.5% FF Happy Frog, 25% (additional) perlite. Grows usually don't last longer than five months or so.
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If Iowa topsoil can buffer 11+ Anhydrous down, I'm sure 8.5 is OK.
If it hasn't bothered it up to now; why are you worrying now?
from Soil pH | Agriculture and Food

"The buffering capacity of a soil indicates the capacity of the soil to resist pH change. Hydrogen ions in soil are present both in the soil solution and adsorbed onto the soil surfaces. pH measures the concentration of hydrogen ions in the soil solution. Soils differ in the number of surface sites able to accommodate hydrogen ions. Soils with large numbers of sites able to hold hydrogen ions are able to resist change in the concentration of hydrogen ions in the soil solution and therefore have a high buffering capacity.

Soils with a high proportion of clay or organic matter have a larger number of surface sites able to hold hydrogen ions and are able to resist a decrease in pH. However, once acidic, highly buffered soils are able to resist an increase in pH. When hydrogen ions in the soil solution are neutralised by lime, hydrogen ions from the soil surfaces are release into the soil solution to maintain equilibrium and resist increase in pH. Better buffered soils are slower to acidify but require more lime to lift pH when they do acidify."
Fox Farm growing mediums buffer so you should be OK.
 
Elvin said:
If it hasn't bothered it up to now; why are you worrying now?
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Because I adjusted it up to now.

Elvin said:
Better buffered soils are slower to acidify but require more lime to lift pH when they do acidify."
Fox Farm growing mediums buffer so you should be OK.
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I used to run pelletized lime through a coffee grinder and add about a tablespoon per gallon to Fox Farm soil products, and water them, about a month before use, in case I got one of their "oops" batches. I don't remember which type of lime.

I don't have any lime left, and I burned up the coffee grinder, lol. My soil is a couple years old (but unused, still in the bag). I haven't read of any issues with the brand for three or four years. Knowing how "the Internet" works, I assume that to mean there haven't been any for at least six :rolleyes: .

Next round will be autoflowering plants, so they won't spend a great deal of time in there anyway. On the other hand, I grew a couple last year (I think it might have been the same "set" of soil, but cannot swear to it), didn't have a functional probe for my pH meter so I didn't bother with adjustments... And began seeing deficiency symptoms halfway through flower, which went away after I borrowed someone's meter.

So IDK what to think.
 
InTheShed said:
High pH doesn't indicate the alkaline content of water.

Back to my source:

Water Alkalinity vs pH - What's the Difference? | PT Growers and Consumers

Learn about the distinction between water alkalinity vs pH, understand their significance in horticulture, and select the right fertilizer accordingly.
www.pthorticulture.com
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I'm sure glad I'm using Iowa top soil w/perlite in my bags now. Buffers w/no issues throughout the grow and other than the perlite it is free.
 
As a form ‘Husker and one who used to de-tassel corn in eastern Nebraska back in the ’60s, is good to see that good midwestern tops soil used for other crops. :yummy:
 
BigD13 said:
As a form ‘Husker and one who used to de-tassel corn in eastern Nebraska back in the ’60s, is good to see that good midwestern tops soil used for other crops. :yummy:
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It might be just good genetics in a particular seed but I've got one GG#4 plant with the longest fan leaves I've seen on this particular broker's version (Sativa leaning; I prefer the short-leaf Indica leaning versions) and the rest are almost big.
Iowa soil works really well with outside grows so why not inside?
Besides, my homemade bags are at least 7-8 gallons per and I've got 7 of those in the flower tent ( 3 GG#4, 2- Amnesia, 2 OG Kush that I did not top but am making some nice lollypops with those colas) 3 more in veg (Purple Kush) plus 4 pots of cuttings in a different tent. I figure at least a couple of cuttings per pot will look good enough to grow; got to fill the tents somehow.
Buying growing medium would really be expensive. At least Lowes sold me my perlite for half price because the bag had a hole.
 
TorturedSoul said:
Last soil I bought at a big box store had more bugs in it than a foreign embassy in Moscow. And none of the ones around here seem to sell perlite in volumes larger than 12-quart bags. Surely cannabis gardeners aren't the only people who buy it four cubic feet at a time, but... IDK.
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Amazon is my normal source. 4 cubic ft. for $48 delivered. My local purchase was of old stock that does not look like they are replacing.
Those 4 cubic bags are sure nice and they were really nice a year ago when they were over $10 less. There used to be a seller in Illinois that did them for $32 delivered but now they are higher than Amazon.
 
TorturedSoul said:
FORTY-EIGHT DOLLARS?!? Fawk... But you get "free" shipping, though, right? :rofl:

There's a local greenhouse/etc. that sells them for just over half that. Unfortunately, they only order the stuff once per year, and I was doing the hiding out at home thing at the time.
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"local" for me to get that price involves a 60 mile drive each way so if you figure a mileage rate of 57.5 cents (Federal mileage deduction rate) my out of pocket savings is wildly offset by my true costs. Just the cost of gasoline for my Silverado might be more. Then there are that 2 hours of just sitting there driving instead of doing something useful like watching TV at home. But given the price jump online recently (last year I could get it for under $33 delivered) those local low prices likely have risen as well (when they restock).
Heck, I could buy FFOF for just above $20 a bag if I wanted to drive for that too.
Fed Ex guys around here almost always are in bonus territory every day because it is so much cheaper to buy online than to drive to buy stuff.
I used to save around $20 on a bag of dog food (EVO grain free; $72 in-store, $55 delivered to me) but when one lives next door to Bum-F#ck Egypt instead of in town one also looks at the cost of driving to buy stuff as well as the price to just buy the item.
I'm out of milk but I'm not going to drive 25 miles round trip just to get a gallon; when the dog biscuits are gone (Walmart only had 1 box) that is when one must go to town.
 
Yeah, I can see your point. I'm not quite as far from civilization (yuck) as you are, it appears. But there's some of that. The nearest "indoor garden" store - since a new one opened - is something like 91 miles away. And I don't own a vehicle, so that makes it a little worse. Mail-order (online shopping) is more than a convenience, and I favor capitalism, so... I guess I'm just a grumpy old fart, lol.

BFE, heh... I saw a piece of undeveloped acreage advertised for sale, "cheap." Worked out to be something like $850/acre. Ad mentioned that it was only a 45-minute drive to the nearest city. Being curious, I checked - it looks like the nearest road is three or four miles away, and is more like a fire access trail (old logging road, actually). So I guess that was figured with the assumption that the new property owner will have some sort of HD offroad transportation. Oh, and that nearest city... had 1,217 people, according to the 2000 census.

Be nice to have it, though. 47 acres, that's not huge - but it would be enough to provide a little breathing room and privacy. Year-round stream, wildlife, no light pollution at night. Only Internet access would be by satellite, and an off-grid lifestyle would be recommended unless you wanted to spend a fortune on getting a power line ran. Acceptable trade-off, methinks. At least until you fell off a ladder and had to get to the nearest medical facility with a dislocated shoulder or something. <SHRUGS> Life is a compromise.

- - - - -

One thing I have never tried doing was to dig up some of the local ground and use it in an indoor grow. It's mostly red clay (and rocks). I am now thinking that it's probably better buffered than the stuff that comes out of a bag, is that correct? I've always kind of looked askance at the thought of doing the "organic" thing indoors, and in relatively small containers - so I haven't paid much attention, and haven't put any real effort into trying to understand this stuff until this year. Kind of a self-imposed handicap, in regards to knowledge/experience. I probably should have tried to learn more about it when I still possessed a young man's mind.
 
InTheShed said:
"If I’m growing in ProMix HP and I mix up the nutrient solution and it reads 7.4 pH, it is not necessary for me to adjust that number down using phosphoric acid or the like. I can pour it into the pot at 7.4 and my plants will be able to uptake those nutrients?"

His response was a direct "Yes."
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I have run this experiment, ProMix HP, MegaCrop, tap water @ pH @7.3, no pH adjustment.
K def/lockout symptoms had me learning to adjust pH pretty quick. I pH my feeds @5.8 now, and am having a very positive response. All is well now with a healthy MC green. The response was very quick as well.

My state is "blue" on the water hardness map, so water quality may have exasperated the issue. YMMV.

Just throwing out this data point. I didn't want to mess with pH'ing my feeds, as I had seen others complete the MC grow cycle without it. I tried, but it would have killed my girls.
 
Rad Man said:
I have run this experiment, ProMix HP, MegaCrop, tap water @ pH @7.3, no pH adjustment.
K def/lockout symptoms had me learning to adjust pH pretty quick. I pH my feeds @5.8 now, and am having a very positive response. All is well now with a healthy MC green. The response was very quick as well.

My state is "blue" on the water hardness map, so water quality may have exasperated the issue. YMMV.

Just throwing out this data point. I didn't want to mess with pH'ing my feeds, as I had seen others complete the MC grow cycle without it. I tried, but it would have killed my girls.
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That sux.
Could it be the MC? I keep reading posts by those who use it that end up needing to pH for some reason. I actually use it on tomatoes without issues but that is container-grown tomatoes in front of the house with a water drip on them.
I use Kelp4Less's line on my indoor weed grow and never have these issues concerning pH.
But then I'm using real Iowa topsoil (not factory-made growing mediums in the bag) dug out of the ground with perlite and water to run off so there is not a possibility of nute accumulation.
 
I think the alkalinity of the tap water is a factor here. That may be why we're seeing such a range of results.
I've seen people on this forum, who's opinion's I highly respect, get a different result. So there is some variable going on.
HP Pro-Mix is said to be buffered, dolomite I think, but I wonder to what strength, in comparison to good 'ole topsoil.
For me, 5.8 feeds are working wonders. I think I will be staying with MC as it is simple and effective. Plus, a little bag goes a looong way! I'm tempted to throw some random pH tap water at my girls to see, but I'm now at the 50% mark in flowering.
I've got enough to worry about trying to avoid budrot, and cal/mag issues. and taming the "stretch" monster.
I have to give MC credit, I have had no issues after I started pH ing these girls feed. Would I like to skip that step? I sure would. However, it is a small price to pay to avoid the "Let's have a shit show in the garden" episode. :)
For folks in the "Iowa topsoil", I would think the buffers could be much better/stronger/diverse.
Ps: I may have to try MC on the tomatoes... fighting a little bud rot on some of those, and they were planted in containers with good ole potting soil! LOL
 
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