Calcium deficiency?

[Cberdahl]

I give the plant (GG#4) Cal-mag every watering since the brown rust spots started appearing 2 weeks ago. The bottle calls for 1tbs per gallon of water and I give it 2tbs sometimes 3tbs. PH is always 6.3-6.5 and it slows the symptoms but I'm still getting little brown spots between the veins on lower leaves, which spread quick (24-36hrs) and consume the leaf. Should I give it more or less? Is it not actually a calcium def??

Medium: 2/3 Fox Farm Ocean Forest / 1/3 Coco coir
Nutrients: All Fox Farm nutrients suggested on feed schedule + General Hydroponics Cal-Magic
Room R/H: 45-50%
Lights: 2x 600w LEDs

Thanks!

[Mr.furley]

Hello Cberdahl,
so I would ask what your runoff PH is? I think you are give way to much cal-mag to your plant. I think you may have nutrient lockout if your giving that much and still show a deficiency. Is the most showing quickly closest to light?

[Mr.furley]

Also pictures in natural light of whole plant are best, just cant see the real deal under grow lights.

[NebulaHaze]

I agree with Mr.furley, those are extremely high amounts of Cal-Mag. Typically you only want 0.5 tsp to 1 tsp/gallon (that is in teaspoons, not tablespoons). It's very possible the high amounts are causing lockout. I also agree it's a good idea to test the runoff pH (especially if you've been providing very high levels of nutrients) and it will help us spot possible problems if we can see the plant in natural light.

Overall the plant actually seems pretty big and healthy though, and the buds appear to be developing nicely

[Cberdahl]

Late response on my part here... thank you for this information! I ended up cutting out all nutrients and she finished perfectly. I guess I was overkilling on nutrients and cal-meg because there seemed to be enough nutrients built up in the soil to last the final month. Great learning expierence.

[Mr.furley]

Glad to hear your Harvest was a success. Growing cannabis is a great learning experience each and every time.

[Cberdahl]

Yes, thank you again! Here’s my new plant, with more knowledge...day 42 flower. Wedding cake is the strain. I keep her in the laundry room at night bc the Rh is perfect. Took the dryer sheets out of the room too just in case. Some yellowing going on though and trichomes are still clear so going to feed with some nitrogen. Would you agree or have suggestions??

[Mr.furley]

I would recommend skipping the nitrogen at this stage, it is yellowing between the margins on the Leafs so up your big bloom 15 ml. Did you water just before the picture?

[Cberdahl]

No, I hadn’t watered. She needed to be watered and did so this morning with your suggestions. I’ll post a follow up picture in a few days. Some of the healthy leaves are turning purple/redish.

[Mr.furley]

Did they perk back up after watering?
Can you give a run down of how many milliliters you're feeding of each nutrients and what's your water schedule is?

[Cberdahl]

The big leaves did not perk back up after the feed but the smaller ones did some. I gave 15ml (3 cap fulls) big bloom, 15ml nectar of the gods, 10ml terpinator, 5ml tiger bloom. Honestly, the plant kinda looked the same the rest of the day. Here’s a photo, her lights turned out about 2hrs ago.

I usually follow the fox farm feeding schedule and add other nutrients in. I measure by “cap full’s” (which is about a teaspoon or 5ml) and add a half cap more every feed until I see any negative effects and then hold there. I water every 2-3 days, feed once every 2-3 waters... the pot size is only 3.7gal. Should have used bigger pot but learning as I go. I keep ph in the water at 6.2-6.5. The soil is fox farm ocean forest which has a 6.3-6.8 ph.

I know I could measure out each ml and document everything, check ppm’s, ph level of run off and so much more but I’m a double major in finance and economics. I just don’t have the time to care for her in that way right now. But when schools done, oh yes... I’ll be very dilegent and change my approach.

[Cberdahl]

[Mr.furley]

Your plant looks beautiful, especially with a busy schedule. I'd like to ask are you skipping Cal-mag and Grow big entirely?

[Cberdahl]

I was under the impression that cal-meg was a slow moving mineral, so I applied cal meg the first 3 weeks hoping that would sustain the life cycle. I’m going to give a healthy dose with just water in a few days. I haven’t given her Grow Big in probably a month. The nitrogen level seemed a little too high for flower phase.

[Sheesh]

Good idea to give her a mini flush, IMO. You may have some salt buildup locking out nutes a little. After flush, go back to normal nutes + cal-Mg, a little light on GB if any is even needed at this stage.

[D.A.A.S.69]

Cberdahl ,nice looking plant.
@MrFurley, knows his sh-t, about growing MJ, if you dont believe it ,look at some of his past grows, over the last couple of years,.
You are doing a nice job yourself, lol

[Mr.furley]

Cberdahl, I think you have a magnesium deficiency. A good idea is to add some in, like 5ml of cal mag every other watering till two weeks before harvest. It may not hurt to give a little grow big, like 2.5 ml or half a cap full.
your plant will be fine just missing some nutrients and showing you it's needs.
keep us post.