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?

[fishheadbob]

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.

[BACKCOUNTRY]

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?

[BACKCOUNTRY]

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).

[DirtDevil]

I never pay attention to ph.

maybe i should

[B.C.]

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

[fishheadbob]

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!

[BACKCOUNTRY]

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.