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Whats an ideal Ph level of water for a Soil grow??

Discussion in 'Marijuana Plant Problems' started by robside, Dec 11, 2010.


    robside Active Member

    The title says it all,,,What should the ideal Ph level of my water & or water nute mix be when watering & or feeding. plants in SOIL. 4 AK-48's in FFOF soil mix, 400w hps,.

    DrFever New Member

    i found that keepin it in the range of 6.3 to 6.8 works well for soil mixtures always fix ph after nutes have bin added my waters ph is like 7.6 after making 1000 ppm feed my ph reading is 6.5 i leave it depending on your nutes you may not have to lower your ph

    bigv1976 Well-Known Member

    I have never checked the ph of a soil grow. Soil is an excellent buffer and IMO you dont need to worry about ph in soil unless you are adding a ton of shit to it.
    dandyrandy likes this.

    Ferredoxin Active Member

    What he said. Just remember that nitrate will cause the soil to increase in pH, and Urea and Ammonium will cause it to decrease over time.

    Equinox117 Active Member

    Franco’s tricks on pH

    There are many ways to grow good cannabis; the path each grower takes depends on knowledge, background, and philosophy. Those who dare to adventure off the beaten path, and keep curious about new possibilities, usually end up becoming really good growers. By trying new systems, new mediums, new feedings and new genetics growers can improve the quality and quantity of their output. Due to the illegal status of the plant, there has been relatively little scientific research on how to grow cannabis. On the other hand, there has been abundance of practical experience, as cannabis is one of the most cultivated plants on earth. Trial and error has been the traditional way of learning for the large majority of growers, and only in recent years, thanks to Internet and to cheap air-travel, the cannabis community has been able to link and to exchange information, data and genetics at an unprecedented pace. This has resulted in an explosion of the cannabis industry in general. Soil, hydroponics, coco fiber, aeroponics, organic feedings, synthetic feedings; each system has its positive and negative sides, and each can deliver great cannabis, if done properly.

    Of all factors that determine a successful crop the most important are: air, light and feeding. And for feeding intake, pH levels are crucial for optimum results.
    A small minority of growers has completely organic operations (meaning they use soil collected from forests, use predators to fight pests, and make their own compost exclusively from organically produced food) where controlling the pH of the watering solution should be done exclusively using lemon juice (to lower the pH) or limestone (to higher the pH).

    But most growers use some form of synthetic feeding, so they don't mind using nitric acid or phosphoric acid to lower the pH of the feeding solution, and calcium carbonate to increase it. Most growers need to lower the pH of their feeding solution; it is actually rare to have to increase it. The difference is in the stage of development of the crop. During vegetative growth, nitric acid works best, while during the flowering period phosphoric acid is the most indicated. This is because of the binding that happens with Nitrogen or with Phosphorus already present in the feeding.

    But the question always coming back is: what's the right pH?
    The answer is easy, jet complicated. The easy part is: safe levels are anywhere in between 5.5 and 7.0.
    Cannabis can successfully assimilate most of the nutrients needed when the pH is in between these levels, especially if all other important factors (air, light, watering frequency) are at 100%.
    Of course, to optimize quality and quantity it is best that all nutrients are assimilated at the optimum moment. Therefore it is advisable to keep pH around 5.5-6.0 during vegetative growth, and to increase to 6.1-6.5 during flowering. This way the Nitrogen is best absorbed during vegetative growth, and Phosphorus, Potassium and microelements are best absorbed during flowering.

    Because of the different conditions and optimal levels, it is worth examining a few typical situations.
    In case of outdoor guerrilla growing, it is difficult to control the pH of the earth. The best is to make sure the soil does not contain too much clay. For the rest, the only control is trying to balance well the feeding solution. Best in these conditions is to start at 5.5 pH then move on to 6.5 during flowering, and up to 7.0 during the end of the crop. A high pH at the end will reduce the chance of bud-rot or fungus development.
    Indoors, it really depends on the medium and the strains.

    In soil, with most indica strains, it is best to start at 5.8 during vegetative growth, move to 6.2 during flowering, and end at 6.4 at harvest. With more sativa varieties it is advisable to start at 5.8 and then smoothly go up to 6.8 at the end of the flowering.
    In hydroponics, the trick is to remember that the pH of the medium tends to jump very high very fast. Therefore, it is best to stabilize the pH of the medium at 5.5 before starting the grow cycle, and keep it slightly lower than one would do in soil. Flowering can be done at 5.8-6.0, and the end of the flowering should be done at 6.2-6.3 for indicas, and 6.4-6.5 for sativas.

    In coco fiber the game is similar to hydroponics, while in aeroponics the pH should be stabilized between 5.5 (grow) and 6.5 (flowering) for perfect intake.
    Adjusting the pH at the right levels will ensure that even the microelements are absorbed properly, which will boost resin production. And will also ensure that the plants stay green well into the flowering, guaranteeing maximum surface available for photosynthesis when the buds are building up.
    During my career as grower, breeder and seed maker I met several growers that were able to produce the finest product without controlling the pH of their nutrient solution. But it was cases of serious natural-born green finger. The large majority of growers benefits from controlling the pH and applying the theory to the practice, while remembering that it is always useful to experiment and fine-tune the values to tailor the genetics and the unique environment.

    directly from the strainhunters site (greenhouse seeds) hope it helps

    testa Member

    this quote says it all... no need to adjust water PH in soil grows as the soil and root zone will buffer itself.
    Guerilla Gardener

    Guerilla Gardener Active Member

    I do mine @ 6.5 in soiless promix BX

    kurtdirt1 Active Member

    I understand this is an old thread but your response can be somewhat misleading to the new grower.

    Smaller potted plants do not necessarily have enough soil to act as a buffer. Some growers may run into issues with ph swings/nutrient lockout and not think to look at their in going water/nutrient mixes.

    It is a good idea when growing in pots with soil to know where you stand with your mixes. You may do just fine whereas another grower may be extremely disappointed and frustrated at their seemingly elusive answer to their problems.

    Aye1frmDay1ny Member

    Do you guys think a mix of foxfarm grow b1 aslaska fish ammonium and urea phd at 5.5 good or should I bring it to6.0 I've always fed them at 6.0 but wanna give it more fox to get it bigger before it turns

    MichiganMedGrower Well-Known Member

    For buffered soil it is only neccesary to acidify. The water if it has very high alkalinity.

    The water and feed will adjust to the ph of the medium if it is properly limed. Or oyster shelled.

    And as stated above we need to know how our water, fertilizer and soil react over time. The acidic nutes and peat balance out the calcium in the water and soil. It should all self adjust.

    I use 8.0 well water. It it has a low alkalinity for well. 3.0 ec. Perfect for gardening. The high ph does not reflect the hardness. They are separate things. I never adjust ph. If the ph gets low on the pot I have likely salt. Holdup and just need to run some fresh unadjusted tap water through to clean out and re set the medium.

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