Hey folks! This is my second time growing LSD, and my first time growing from clones, lollipopping, and using SCrog. These plants were in wonderful health until I switched into flowering, and now there’s all kinds of stuff going on and I was hoping you fine people could help shed some light for me into what’s going on.
Here are some details on the grow:
Strain: LSD (clones; the mother I grew from seed)
Growing medium: Soil (Foxfarm 420)
Age: 26 days into 12/12 flower (76 days since transplanting rooted clones from rapid rooter cubes into soil)
LST: Yes, SCroG
Grow pots: 3 gal “smart” fabric pots from Vivosun
Nutes: General Hydroponics GO Soil line. Once per week of half strength of Bloom, CaMg+, and Bud with pH correction to bring it to about 6.5.
Water: Tap (San Francisco city water; uncorrected pH is about 8 with low dissolved solids)
Temp: Max around 79ºF during the day, min around 63ºF at night
So I have what I think are 2 different problems. The first is that many of the leaves have turned quite purple. I’ve read that this can be caused by a phosphorous deficiency either by a lack of the nutrient in the soil or by cold temps at night preventing P uptake. But the temps don’t dip below around 63º at night and I’m using GH’s Bloom and Bud nutes once per week already (and leaf tips bend down if I use any more) so I’m not sure how this would be happening.
The second problem is what I think is a Mn deficiency. This leaf pattern has appeared on around 10% of the leaves. Mostly the larger, older leaves but there are signs starting to show in the small leaves beneath layers of bud. I’ve been checking soil pH the best I can by using runoff from the lower part of the fabric pot, but it’s looking good at between 6 and 6.5 for each of the plants I can measure (I can’t measure all of them because not all of them have water runoff out the sides of the smart pot). Maybe I’m wrong that it’s Mn?
What are you growing under (lights)? Please be specific.
You are right: phosphorus and probably calcium. You have to up your nutrient load which is why I’m asking about your measuring equipment. If PH is off, adding nutes won’t help as they are not soluble in the wrong PH.
You have some older leaves that are simply dying. Very unlikely to be a moly def.
I’m measuring the solution after mixing using pH dye in a test tube, and then after watering I get some of the runoff from the bottom of the pot and measure it in the same way. Usually the runoff is around 6.0. I’m not directly measuring TDS myself, just looking at other folks who live near me reporting that TDS for this part of the city is usually pretty low.
What are you growing under (lights)? Please be specific.
I’m at about 50% of the recommendation on the box right now. Think I should try upping frequency that I give nutes (currently about once every 7 days), or keep the frequency the same and up to 75% of the recommended quantity?
You have some older leaves that are simply dying. Very unlikely to be a moly def.
I am hoping the same too. The mother plant did the same when she got into flower. But the pictures I’ve seen of Manganese deficiencies looked too close to these leaves to ignore right off the bat. I’d be thrilled if these are just old dying leaves! They don’t get a ton of light down there anyway.
I just had another thought too. Could those yellowing leaves be due to fungus gnats? I had a minor infestation that I treated with neem oil and azamax about 2.5 weeks ago, and haven’t seen many adults in a while. Could this still be from them?
I would say your not feeding enough. Once a week water is probably not enough.
Your way of measuring ph is also not a reccomended way to be correct. Best to buy a digital ph pen.
Yeah seems like under feeding, but you really got to know what pH and tds you’re working with, ph off could be making the nutes not available regardless of how much you feed.
@Hellraiser I have one of those, but it’s always so finicky to deal with I just gave up and went with the pH drops. Think it’s really going to make that much of a difference?
@BetrayedSoul I water every other day (pH adjusted) but only use nutes once per week. Think I should increase the frequency of nutes or keep that the same and increase the amount of nutes per feeding?
If your ph is off by just .2 it makes a difference. And that’s probably what can easily be done using drops.
Just submerge tip of ph pen in the water to read what it’s at. I dont get how one could be finicky unless it is broke or uncalibrated.
As far as feeding I am actually not the perfect person to ask as I am a hydro grower. But I would guess you should feed every other watering. That’s my best guess. But that would also depend on the tds readings of water in and out to see how plant is using the nutrients.
Which also goes back to ph. As stated if ph is wrong it causes a nutrient lockout meaning the plant can not take in the nutrients if it is at wrong ph.
Yeah, I don’t get finicky for a properly working ph meter, you do need to check them now and then and make sure they are calibrated using calibration solution. Ph is too important to not get right.
I might just need to recalibrate it. Whenever I put it into liquid it takes over a minute for the numbers to stop changing, and even then I can take it out of the liquid and put it back in and the reading will be slightly different. I ordered that TDS meter you recommended and that pH 7 solution to check the pH meter’s accuracy.
Related question: is taking the runoff reading for soil pH good enough? Or do I need one of those soil pH probes?
The glass bulb is somewhat delicate and if it is allowed to dry out it will fail. If it is stored in R/O or distilled it changes the chemical composition of the glass and…it fails. Storage solution is recommended.
Drops, strips etc just are not accurate enough for our purposes. And, yes: you can grow weed without using or measuring PH. But we’re here (or at least I am) to grow primo cannabis. So hitting the parameters right is a big help to do that.
I did not have good luck with the inexpensive ph meters. I wish I would have purchased this ph meter first. I have since learned buy once cry once. Since I bought the meter below I have been a happy camper. I calibrate at the beginning of the grow season in August and then check it every two weeks. Since September I have only had to calibrate one more time because I saw the measurement change by 0.2.
That used to happen to me as well until someone here clued me into what I was doing wrong a couple of years ago. After adding anything (especially pH adjustments) you need to mix thoroughly and then wait for everything to bond/stabilize. I like to wait 15 minutes after doing a pH adjustment. After that, it usually only takes 5-20 seconds for the meter to stabilize. So, in case you’re not waiting - give that a try.
And, I highly recommend the Apera PH20 meter that @Bubblehead posted above.
@Hellraiser: Testing the runoff is better, those cheap 3 in 1 probes are useless for accurate ph measurements.
That’s what I was figuring. I just need to find a better way to get consistent runoff. Some of these fabric pots leak like a sieve out of the bottom, and some don’t leak at all. I’ll keep working on figuring that out.
@BetrayedSoul@Myfriendis410: Yeah fair enough on the precision of the pH reading. I just bought some more calibration powder and storage solution. Hopefully the meter isn’t already ruined from lack of use over the last couple of months. I’ll use that pH 7 solution to verify its accuracy. If it is ruined, I’ll probably go with the nicer one that @Bubblehead and @TommyBahama recommended.
@TommyBahama: That’s really interesting, regarding needing to wait 15 minutes after an adjustment. Doesn’t that make it take a really long time when you’re doing a different nute combination than normal since you don’t know exactly how much pH Up/Down you need to calibrate it?
@Covertgrower: That was my first thought too, but then I was reading that temp-based lockout of P doesn’t usually occur until 50º or below, so I had ruled it out. Is that not in line with your experience?
I’m also hesitant to increase the nutes because a lot of the newer leaves are showing signs of burn already, even at the once per week feeding @ 50% strength. Although I suppose I could try only using Bloom and CaMg+, and leaving out the Bud supplement and seeing how that goes.
Side note: does anyone think that the yellow/brown spots could be from fungus gnats and not lockout?
Oh, if you’re new to this you may want to take notes for a little while. After a few adjustments you will have a general idea of (for example) how many drops of pH-down you need to go from 6.9 to 6.5. You may find it handy to make a chart(don’t use this one as your water will be different) like this:
You mix all your nutrients and supplements, wait 15 minutes, then take a pH reading and make your adjustment. After the initial adjustment I just wait 5 minutes for subsequent readings and adjustments.
Sorry, I mistyped the above. Let’s try again:
Mix all your ingredients, then wait a few minutes. Check your pH.
Make your initial pH adjustment. Mix well and wait 15 minutes.
Check pH again. Adjust more if necessary. If changes were made, wait 5 minutes and check again.
Ahh this is great! I hadn’t been measuring pH changes like this and it was obviously working against me. I’m following your advice now. It worked nicely yesterday, especially the waiting. It really impacts the pH of the solution a lot more than I thought. Once it changed almost 1 entire pH level just by sitting for 15 minutes! Thank you.
