Ph. The primary factor

Im curious as to the opinions of other outdoor growers on this often under considered aspect of cannabis growing. Its my view that the results of any OD grow are at the most basic level, entirely dependent upon the degree to which the grower has controlled the Ph.
I like my ph to be 6.8. No less than 6.7 and if it is less im dumping on the lime. I know some of the experts recommend lower numbers 6.3-6.5. Thats too low in my view for OD and inhibits nutrient uptake in cannabis. A Ph reading of 6.5 is the first ingredient to small, slow growing crop. I would much rather see 7 than 6.6. I also adjust my Ph near the end of the veg stage, just before flowering sets in with a water soluble lime, mixed and applied so that the plants can fully utilize the nutrients that are available to them in the soil during the critical time of flower development.

I beleive a lot of growers think that they are controlling nutritional usage and availability to cannabis by the amount of ferts they pour on the plant. I would argue ph impacts uptake more than how much and how often ferts are applied. If the Ph is 6, you can dump nutes on a plant until the cows come home and its still going to be yellowish and slow growing. If the ph is 6.8 smaller amounts used less often are much more effective.

Diagnosing poor plant growth in my view is easy and simple, giving that the plant is getting enough water and sunshine. If poor growth is observed, check the Ph. If the Ph is right, then the plant is starving. If its not, fix it immediately, feed a little and the plant will grow well.


what do you think?

I don't think cannabis requires all that high a ph, but lime is cheap and bumping it up to 6.5 or 6.8 won't hurt anything. You (and I) have grown a lot of field crops; we're conditioned to think like alfalfa growers where anything much below 7 guarantees poor results. With weed we should probably think more along the lines of rhododendron growers; those guys have to add stuff to knock their ph down to 5.8 or so to get good plants. Again, lime is cheap, I've done OK in 7.0, and if 6.8 makes you feel confident, go with it.

6.5 is fine with me(it would take too much lime to ajust my native soils all the way to 6.8-7), I usually don't worry about the PH too much unless it is definately outside of the favorable range for Cannabis- 6.5-7.5

The 6.3-6.4 PH is too low for soil growing(maybe OK for Hydro?) from the research I did for my PH thread, where have you heard growers talking about that range(6.3-6.4) being optimum??

Here is my thread- Is your outdoor soils PH correct?

Hey fisheadbob and BC, we have a debate! Its a wonderful way to learn.

I think it depends on how and when we measure results. The inspiration for this thread are 4 aurora indica plants that i am currently growing at 2 different sites but less than 1 mile apart. Both sites were planted on the same day in mid may with similar plants about 4" tall and both have recieved identical feedings over the period. Sunlight in both sites is approximately 7 hrs. The only difference in the 2 sites is that I had measured the ph in one and adjusted it appropriately to 6.8 but because rain had delayed my activiy the other site recieved no lime and measured 6.3 and i said to myself "it will be alright". The difference in the 2 grows?

The plants at the site where I adjusted the ph are well over 6', are dark green and obviously healthy.






The 2 plants at the site left unprepared with the ph of 6.3 are not anything to photograph and wont be entered in any contest. Those plants are barely 4'. They appear healthy, they are green with no apparent problems, just smaller. Ill take some pics for comparison and post them this week, but the final conclusion is already obvious to me. Come harvest time, the plants grown in the adjusted soil will yield perhaps 25% more than the plants that were improperly prepared. While the differences are only at the margins, they exist and boil down to the difference between a decent result and a maximum result. I want my efforts to yield the maximum result.

I know that indoors and hydro the ph can be lower. But outdoors, i say jack it up. Look at this bucket plant grown in Miracle grow at 7.


Response? Are you guys saying that their would be no difference in plant growth and response as long as it remains within that tolerance range? My interest is the optimum range?

No debate here!

No debate here!

The optimum range is 6.5-7.5 from my research, this seems to be the general consensus. I do agree though that anything below 6.5 is definatly outside of optimum, no real debate there, and it would seem that 6.8-7 is probably the optimum range of the optimum range of course.

That said, I'm just a self-provider, not so much a hobby grower, and I have tried to be a good example to beginer growers, so I try not to get too complicated and anal with fine tuning, which may make my examples more intimidating and less interesting to folks thinking about giving guerrilla self-providing a try.

Basicly, I guess I'm a KISS kinda guy(Keep It Simple Stupid).

I never pay attention to ph.

maybe i should

PH

PH

Indoors, outdoors doesn't matter, the more humus you have in yer soil the more the plant will feed, regardless of PH ( within reason of coarse ). Humus also allows the plant to feed on ions and compounds of ions that would have other wise been unavailable to the plant. It's hard ta beat mother nature, she's been at it along time. Take care... BC

No Debate, My bad. I wasn't clear in my earlier post. We aren't growing rhododendrons where an acidic soil is preferred, and a low ph is bad for pot plants. Lime IS very cheap and outdoor growers should definitely keep an eye on their ph and adjust accordingly to keep it in Backcountry's suggested range. I like his comments about not getting too anal, K.I.S.S. . I don't think, though that a slightly out of whack ph will have monstrous effects, growing is kinda cumulative; the more things you do well, the more likely you are to have good results. SB does a lot of things well and his results show it. Which isn't to say that we couldn't do something stupid which could cancel out all of the good things.
I did stop outdoor growing and went to indoor hydro where the recommended ph levels are lower for some strange reason, looks like I applied hydro ph levels to outdoor plants. My apologies. I wonder why a plant that would do well in hydro with a lower ph needs a higher range outdoors ? My last outdoor effort was when I had more girls than my hydro setup could handle, ph about 6. I evicted a few and put them in the prior years outdoor spot, rockwool and all. Ph was probably high 6s from prior years limings, and while the girls got scant attention they thrived right up until the deer came to visit. 2 observations : 1) the root systems were great, growing nicely through the rockwool into a nice large pancake system. And 2) while I'm in a remote area the paranoia factor was much higher with the 3 outdoor plants than the 5 indoor. (#3 Shoot deer)
Lastly, great lime thread, Backcountry. My old Co-op had 2 signs about lime. One was CROPS NEED LIME the other was LIME TAKES TIME or about 6 months to do its' neutralizing act, less time if you start mixing it in

Hi all. Good discussion and no reason for apologies fisheadbob. I enjoy hearing other opinions and priorities. I often question my own beliefs so as not to become myopic. I learn when i have to support my beliefs with reasoning. That being said, let me counter some of the reasoning presented in the responses.

Goodness DirtDevil. The fundamentals of growing any plant should be observed if there's to be any real hope for success. Every farmer of every crop grown in the US, determines the Ph of his soil before ever planting the first seed or seedling. Always. Why is that do you think? Do you think cannabis is exempt from basic growing requirements? The answer is enlightening to the cannabis grower.

B.C., you couldn't be more right, and its a crime of nature that every site I plant in isnt deep rich humous laden loam, full of worms and intricate roots,enzymes and a naturally balanced ph. Unfortunately they aren't. Do I accept that I cant improve the conditions and go ahead, or do I take the minimul effort to bring it closer to the conditions you describe?

BC, We're in agreement on the range and the optimum ph and I too only grow for my own use,( and unfortunately, the use of a number of lazy friends and family. I have to grow 2X as much as I smoke due to my inability to say no to the people I love).
I would however, counter your KISS philosopy with my own of
" anything worth doing is worth doing right". I have paid out the wazoo for seeds, gas and electricity, germinated, rooted, bought soill and bulbs, carried heavy loads, lurked around at daylight and the middle of the night and risked my very freedom and then too plant and not do all i can to reap the maximum benefit from all i have put in? Not me, especially when I can increase the product from my efforts as much as 25% or more simply by taking 5 minutes to check the ph and then spend 2$ pumping it up to a level that will optimize my yield. There are some basics that all farmers have to consider.. PH, N,P,K and drainage. Its my view that failure to consider any of those components will result in diminished satisfactiond

At the end of the day however, what each of us expect or need from our efforts is individual and we will all recieve out of it what we put into it.

fisheadbob, i believe the ph indoors and in hydro is less important because the plant doesnt really have to extract the nutrients from the soil as it does in nature. It's being poured directly on them. That sign about lime taking time is outdated. Fast acting, water solubles can adjust in days.
You are very right about the effects of doing stupid things. I have some expertise on the subject!

Yes silverback, but I am doing it right, the jars full of bud at the end of the season say so, I am still not convienced that raising the PH 3 points higher is going to really make much difference.

I do believe that adding too much lime too quick could introduce too much Calcium(and Magnesium If you are using Dolomite) to the soil, which could cause a lockout just about as bad or worse than only changing the PH the few points it takes to help the plant grow healthy.

I suppose there are more sides to the " anything worth doing is worth doing right", adage you mentioned than you think.

So to clarify, when I would have to use too much Lime to ajust the soil all the way to 6.8, it was not because I'm not willing to spend the money, it because I don't want to cause a severe disbalance of Calcium/Magnesium, which could cause problems of its own.

Looking at my soil last autumn and this spring made me use lime. With succes I think.
Growing on the same spot many years have given me "fingerspitzgefühl".
No testing. I depend on my feelings

Paddi

mine get nothing for ph outdoors. rain water should keep it around 6-7ph anyway.

Too right Paddi, wish I'd done that. All that rain we had on soils here last year has washed the guts out of them. Alot of Ph issues here, you dont notice till its too late. An old farmer I used to know, dug a hole out 8-12 inches deep bend down & smelled it. He said there is a certain smell to soil in good order, a bit like bread. Sour soil smells like stale bread, soil in good order smells like fresh oven baked bread, it has a beautifull "earthy" smell to it. Try it one time & you will know what I mean. Most farmers will lime 1 year in every 4-5. I seen a lot more probs over the years caused by low ph than high ph!
Most high Ph probs can be put right by foliar sprays. It aint so easy with low ph.
Heres classic low ph, looks like N deficiency, but its not.

It looks better now..
cheers Silver.

Paddi, those of us growing in the same soil each year need lime and everything else more so than others. Cannabis is a hungry plant and can deplete the soil as much as corn. I believe the activity of loosening and working the soil and inproving the drainage, may also be improving the leaching capacity as well. The little rapidtest ph meters work great and are 10 or 12$. They will last several years and i feel in my case, the increased yield and the need to use less ferts has more than paid for it.

Hey farmaz. that picture is a good example and i havent looked in a while, but the infirmiry section used to be full of pictures like that. The new fast acting refined limes are water soluble and can be mixed with water and over 2 or 3 waterings, you can raise the ph as much as one point. I check mine in mid to late july and add a bit where necessary. In ground growers can adjust their ph mid season with the introduction of the new products without any harm. You can have that youngster jumpin in no time. Hydro growers often adjust the ph at flower.

BC, filling the jars is the#1 goal isn't it and thats what were all after. As long as that happens, its been a good year and a successful year.
Many of the older style limes, dolomite/hydrated arent very functional for the cannabis grower and nitrogen shouldnt be applied within 30 days of their application. In recent years however, gardeners raising hydrangeas and Rododendron(me) have wanted to adjust their ph quickly to get the colors that win prizes at the monthly garden club meeting . Cannabis growers can benefit from these breakthroughs in ph adjustments.
Many of the new, water solubles are 95% calcium carbonate, wont burn and can be used in combination with fertilizer appllcations. . The new products are much better and work quickly. One other positive to having the proper ph, at least in my view is that one actually uses less fertilizer as the plant can access the nutrients that are available more effieciently.

smokeymacpot, I'd be willing to bet good money your efforts to adjust your ph would result in a very favorable return on the effort.

Is Azomite one of the "newer" limes?

Can you give a description of how you test and ajust your soils silverback?

Many of the older style limes, dolomite/hydrated arent very functional for the cannabis grower and nitrogen shouldnt be applied within 30 days of their application.

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Hmmmm, I don't know about your comment about the Dolomite being disfunctional, its worked just fine for me for years, I use it on Cannabis and in my veggie garden every year. I can't say I've ever had a problem using Dolomite on the same day I mix in Manure and plant a babie either, it may not be the pros choice but in practical application in the field, again, no problems for me.......

At any rate, I guess we have found the difference between a Hobby grower and a practical grower, but don't get me wrong, I'm not being critical of your obsession, its just not for me, especially when the basic approaches have worked so well in my experience.

No problem BC. Although I don't really consider it an obsession. Anything in life that i have ever done, ive tried to do it to the best of my ability. Its the way i was raised. Gardening of all plants is a hobby for me as well. I try to use the same effort for my Rododendrons and marigolds as i do my cannabis.

I don't know about the Azomite. I havent heard of it. The brands i am familiar with are Epsoma's Garden lime and Penningtons Fast Acting. Both are finely particled, crystaline,clear in apearance, water soluble, fast acting and consist primarily of calcium carbonite and can be used in conjunction with other nutrients.

For Ph testing, i follow your KISS philosophy. I use the cheap little hand held meter from Rapidtest that you can buy at lowes or walmart or at Rapidtest.com. They cost about 12$. I teste one against a higher priced model and it was accurate to within .1 and thats close enough.

For n, p, k, i quit testing. I have one of those kits but theyre difficult for me and ive found no benefit from using them. I mix in a 40lb bag of compost in early spring, adjust my ph and then feed them heavily. Another KISS approach. If the ph is right, nutes are so readily absorbed, feeding becomes easy

The reason I made the statement that dolomite is less functional is due to the length of time it takes to work into and react with the soil and the recommendations by the manufacturers that nitrogen not be applied for at least 30 days. On our fields here, we have lime dumped and have to wait weeks to apply the nitro.

Dolomite lime works just fine and i too use it in my garden, but i can work there freely. Usually, my access to grow sites is not so liberal. Because of the length of time dolomite takes to dissolve and react in the soil,(several weeks at best), it makes the whole process of adjusting the ph more difficult and lengthy in the guerilla grow site, whereas the water solubles reacht within days. Apply it monday, come back on friday and you know the score.

silverback said:

smokeymacpot, I'd be willing to bet good money your efforts to adjust your ph would result in a very favorable return on the effort.

Click to expand...

okay then, how can i monitor and adjust my outdoor ph? i have a bed maybe 40cm deep and 1m x 1m, it is full of a soiless mix of peat compost, perlite,vermiculite, water crystals and a handfull of slow release ferts. plants are in, its not possible to anything mix in the soil.
i always lower my tap water to ~ph6.5 indoor and plants look very healthy and grow fast. is rainwater not ph6-7?
i have ph paper to measure.

Hey smokeymacpot.
You can monitor your ph at your site with one of the cheap little rapidtest ph meters. They're cheap and effective. Ive never had any luck with the paper and have found it difficult. Im not sure about rainfall. I bet because i live in a low lying sheltered area and there are many coal fired electrical plants in the area my rain may be a bit acidic. Ive never measured it or considered it relevant. The ph of the soil determines the capacity of the plant to absorb nutrients and I can adjust that. I cant do squat about the ph of rainfall.

I cant help but ask what qualities of your native soil disallow you from adjusting it as opposed to completely replacing it with a soiless mix? The natural vegetation around your plants indicates to me an acceptable capacity for root development, so if its clay, it cant be too heavy. Are your local farmers adjusting their soil and growing food or feed crops such as corn or soybeans? Just curious?

Thats a tasty lookin bud shot man. Lets burn that rascal.