its the end of the 3rd week of vegetation & a few of my plants lower fan leaves are turning yellow with brown spots on leaf tips.the yellowing starts at tips & in middle finger of leaf first, then the yellowing slowly heads toward leaf stem, brown spots only on tip portion of plant & run 1/3rd of the way to the stem of the affected leaves. thought it might be a PH problem but they are all 7 ph. next I think it may be a nitrogen deficiency, or a zinc deficiency. its not a heat problem the room is a constant 75 degrees, & i’m pretty sure its not an over-watering issue issue, but I need to know what it maybe & how to correct it as I am about 6 days from going to 12/12 hrs HPS600 for flowering for 8 weeks. I sure would appreciate all your help on this one as I am a total beginner at this & I value your opinion as the Professional grower & problem solver. FYI I grow in soil, not hydroponics.
On the one chart that I use, older growth wih yellow and some brown spots could be Nitrogen, Potassium or Manganese; however, that is just based upon glcing at a chart and not having any pictures to compare.
I’ve noted ona number of diagnostic threads, that older growth vs. newer growth can also help isolate things. e.g. Yellowing on new growth would be more liy to be Iron as oposed to nitrogen; however, you may want to fill out a support ticket, (there is a link in the forums, and also in some individual posts), post a photo or two and see what the experienced folk have to say
I’m wondering if it might be more of a nutrient burn along the lines of a nutrient salt toxicity building up in the soil.
The pH should be closer to 6.5 in soil.
The support ticket questions would be helpful, we could do to know a lot more, what type of water are you giving it, and other relevant info, specifically nutrient concentration (EC/TDS) as well as pH, in everything, the plain water, nutrient mix and the root-zone itself:
water ph6.0, I lowered my soil ph to 6.5 'im growing indoors in soil, they are autofemine super skunk seeds from you guys.my grow space is 6 ft long,3 ft wide,7ft tall, using a 600 watt MH open bulb in reflector I have sunshine #4 soil mix from hydro shop here in Kentucky. I did notice it after my 1st foliar spray, have stopped since this started.older lower leaves only affected,starts in middle finger of leaf then slowly spreads to leaf stem, then brown & die off.
Your soil is out of range 6.0 6.5 is where you want your ph to be
There is only one accurate way to adjust the pH. This is using pH test or a pH meter. When the pH level is outside the range, the nutrients are less available to the marijuana plant. This means that the roots don’t have access to them and now the plant indicates deficiencies, even though the nutrients may be present. If the pH level is outside the proper pH range, marijuana plants have small dark-green leafs and grow very slowly, when growing in water or soil. Check the pH (by using test strips or a pH meter) before you plant them in soil or planting mix. Your PH should be 6.0 . 6.5 range