Hey all. I'm growing a bubblegummer, she's into flowering and I've been getting fairly regular pH problems just into flowering. I've tried flushing, but even putting 2-3 times the volume of the pot through doesn't seem to make much of a difference, the runoff stays at around 6.3, even when I put dolomite lime in =/. What brand and type of soil? soil, peat based. Indoors or outdoors? indoors What strain? bubblegummer, female. How old are the plants? around 3 months-ish. It's been growing fairly slow. What type of lights and how many watts? One CFL, red, 125w. On 12/12 atm. How far from the lights? 1-4 inches. What is your watering frequency and source of water? Tapwater left to sit out. I'm in a city, but my water is quite good, around 40-50ppm. I typically have to give it a drop of pH down, since it's usually at 7-7.5. The water is usually 6.5-6.6 when given to the plant. I've started to stop during that last flush and am waiting to see if it makes a difference. What, how much and when was it fed? NPK? Not since before the flush, but is fed with a fert designed for tomatoes and with seaweed extract. The fert is 6-3-10, and added Mg. What is the medium/runoff pH and PPM if in hydro? Runoff is around 6.2-6.3, medium is a peat based compost with about 20% perlite and some dolomite lime added recently. What are the temps and humidity in the room? temps are around 25-27 during the day, and around 20-22ish during the night, though we've had cold snaps where it's been as low as 18 (all in celcius) Humidity is a bit on the low side, between 10-40%, higher when the lights are off. What size pots? Not sure, had to make a custom pot to fit into the PC case, but it's roughly 30cmLx10cmWx15cmH Any bugs? Look real close. No bugs. Any other pertinent info? I'm just wondering if there's anything I could do to save her now, since I really don't want it to die after all this time put into it. Also, transplanting could be tricky, since the plant is woven through a scrog grid. Here's some photos taken ten minutes ago.
sounds like a small pot for a plant that big, you could be root bound and why are you flushing if you have a deficiency? flushing is for excess nutes, if you don't have enough then washing out what's left won't help at all
I didn't think it was a deficiency, I thought it was a problem with the soil pH, since whilst the water is 6.6 in, it's 6.2/6.3 out, so I assumed it was because my pH was off. Do you all think it's a deficiency? Since if it is, that would be a lot simpler to fix I reckon.
That is a solid Magnesium deficiency. You need to add epsom salt every water, especially using RO water. Page 252 in the growers bible is a mirror image of your pics. My knowledge, your ph is much better between 6.3-6.5. The later being the best for nuit consumption in soil. Mag deficiency is common indoors. The lower leaves, and later the middle leaves, develop yellow patches between dark, green veins. Rusty-brown spots appear on the leaf margins, tips, and between the veins, as the def progresses. The brownish leaf tips usually curl upward before dying. The entire plant could discolor in a few weeks, and if sever, turn a yellow-whiteish tinge before browning and dying. This will diminish harvests as flowers progress... I use a type specifically designed for plants. Do you check your ppm of your nuits? The plant consumes nuits better with a lower ppm/ec. I keep mine around 650-750ppm.
Ahh, okay. I just read somewhere that you shouldn't try adding more nutes until you fix the pH problem,but you're right, I probably should now. I want to give it a few more days though, let the plant recover and dry out a bit. She did get some seaweed extract on the last bit of water to go through in the flush. Should I use some of my usual tomato feed, or would a different one be better? Ah, cool, thanks. I've got epsom salts, though I don't use RO water. How much should I add? I'm thinking a tablespoon to a 2ltr jug? (in addition to some of my usual tomato feed)(even though I won't be using the full 2 litres). As for the pot size, I kept it small to try and limit the growth of the plant so it wouldn't outgrow it's PC box. It's full of holes though, so theoretically' the roots are being air pruned. Transplanting now would be tricky though, what with the plant woven through the scrog screen, so I'm leaving that for a last resort. Thanks for all your help in either case guys =). EDIT: regarding pH, the quoted pHs are runoff though, so I was assuming the soil pH was even lower? Or am I misunderstanding it? If so, my bad, I'm high xD.
On the espom salt you should add 1 tsp/gal with every watering, maybe 2tsp at the most! or foliar spray at 1/2 tsp a liter. Soil runoff should be around 6.5ph for max nuit absorption.
Cool, I will do. Does it look like I need to add supplementary calcium? I've got some finely powdered calcium carbonate, would that along with some epsom salts do in the meantime?
I, myself, run Botanicare Cal-Mag plus at 5ml/gal up till week 4 of flower then drop it and continue using epsom salt as a finishing agent. I run my fresh water rez at 250ppm of cal-mag and an extra 50ppm of epsom salt ( mag-sulfate). So they get cal-mag water everyday. Look into getting a better NPK. Something like flora nova bloom from General Hydroponics or their Grow, Micro, Bloom line.
With a ph run-off of 6.2 your plants are starting to slip into nutrient lock-out of P, Ca, and Mg... corrective action would be to raise the ph to 6.5 run-off and after ph has been sorted, then you can add nutes at 50% the recommended dosage.
Stupid question here, but how do I go about changing the pH of the runoff? I tried flushing it through pH-ed water and a small amount of dolomite lime mixed in, and it barely made any difference.
How much water did you use? Normally it takes at least 3x the volume of your container. (1gallon pot requires 3 gallons)
Hmm, maybe not enough. I think I used just under 3x the amount. I just kinda stopped since it didn't seem to be making any difference. Should I flush it again then, giving it a few days to recover, or should I just go for it now?
Problem is, Peat if 4 to 4.5 ph and retains nutrients... with the lime added it's adding to the issue of ph correction. I'm a firm believer that lime should never be used in cannabis cultivation because it carries a neutral ph of 7 and will keep the ph level elevated, cannabis prefers a slightly acidic soil. You could pluck that girl up by washing the roots with plain water very slowly and gently, then set that girl into some fresh soil, your girl will hardly notice, and don't add lime, just a teaspoon of epsom per gallon of water.