42 day old Gold Leaf photo. It appears random leaves are dying and taco-ing. Here’s some pictures. If you need further info let me know.
FYI - those new buds on the 1st pic belong to a different plant.
First off, some interesting, basic facts…
Your marijuana plants need 18 essential elements. They get carbon, hydrogen,
and oxygen from atmosphere and water. They get the 15 other elements via their
roots. These elements are sometimes grouped as major, secondary, and trace elements.
The groupings are determined by how much of each element is needed–some are needed
a lot more than others, but all are necessary.
The major elements are nitrogen, phosphorus, and potassium. The so-called secondary
elements are magnesium, calcium, silicon, and sulfur. Some people group these seven
elements as “macronutrients” because they’re required in larger weight amounts than
the remaining essential elements your plants need. Those are called micronutrients,
and they’re very important even though your plants don’t need as much of them. We’re
talking about iron, zinc, copper, molybdenum, boron, manganese, cobalt, and chlorine.
Until recently, silicon wasn’t even included in the essential element list, but modern
research on marijuana plants indicates your plants use silicon to build strong cell walls,
resist pests and diseases, and to create THC glands.
Nutrients problems most likely to reduce growth rate, THC percentages, and harvest
weight often involve nitrogen, phosphorus, potassium, and calcium. But problems with
deficiency or excess of any of the 18 essential elements is likely to cause serious
trouble for your marijuana plants.
How do you know your marijuana plants have nutrient deficiency or excess? Look at your leaves.
If they’re not lime green, upright, and looking like the perfect marijuana leaf photo
accompanying this article, your leaves are trying to tell you something.
But here’s a twist…it may not be your organic fertilizers, soil, or hydroponics nutrients
that are actually causing the problem. Signs of nutrient element shortages or excess may
merely be a symptom of the real cause of the problem. For example, low temperatures
interfere with nutrient uptake. So you can’t solve a temperature-related nutrient
deficiency problem by increasing your nutrients dosing…you solve the temperature
problem instead, so your marijuana plants can take in what they need.
The Right Amount of Nitrogen
Makes Your Marijuana Healthy and Green
Nitrogen makes up 78% of the dry volume of our atmosphere and plants need to
capture it if they want to grow at all.
No doubt you already know nitrogen is the big N in the N-P-K on your hydroponics
nutrients bottles, and it’s a big, important ingredient for your marijuana growing success.
Unless your plants are in the final weeks of flowering phase, yellow leaves
(especially lower leaves) are signs of trouble, and the troubles are most often
a nitrogen deficiency. It starts with the bottom leaves and works its way up until only
the newest growth is green.
On the other hand, if your marijuana plants are overdosing on nitrogen,
the leaves will be extremely dark green.
Either way, nitrogen problems mean big trouble for your marijuana plants because nitrogen is
absolutely necessary for plant survival because nitrogen is a primary elemental support for
protein synthesis, growth, leaf development, metabolism, and root health.
If you oversupply nitrogen, you get marijuana plants that are too tall, thin, and gangly.
It’s harder to get successful flowering from plants that have been overfed nitrogen.
If you see that the very tips of your leaves are yellow, that’s an almost sure sign of nitrogen
deficiency, which occurs most often during a fast-moving grow phase or when you’ve switched
to an improperly-configured bloom fertilizer during flowering. Many brands of hydroponics
nutrients do not contain the right ratios of nitrogen, phosphorus, and potassium, or they
contain the elements in forms that are not easily available to your marijuana plants.
These potential nutrients problems are especially harmful in flowering phase, when your plants
only have 12 hours to run their photosynthesis metabolism.
Nitrogen deficiencies first show up as leaf tip yellowing, especially on lower leaves.
Then it spreads to affect entire leaves, and moves up the plant. When you do research
on marijuana strains before you buy seeds or clones, take note of the strains that are
said to be heavy feeding. Those will likely want higher parts per million of nutrients,
and they are hogs for eating nitrogen, potassium, and phosphorus. In bloom phase, your
marijuana plants want less nitrogen, and more potassium and phosphorus.
The only time you tolerate signs of nitrogen deficiency is when you’re more than halfway
through flowering phase. During those closing weeks, your marijuana plants are focusing on
floral production so they sucks stored nitrogen out of leaves rather than doing the work of
That’s why you don’t need to add extra nitrogen (beyond the amount found in a properly-configured
flowering base nutrients product) to flowering crops after they’ve passed the midway point of
flowering cycle: excess nitrogen during flowering negatively affects bud development, taste, and aroma.
Fixing Nutrients Problems to Save Your Marijuana Plants
In later articles in this series, you’ll see a more detailed program for analyzing and fixing
marijuana nutrients problems but it’s important to understand a couple of things right away.
One thing to know is that organic or “natural” fertilizers often fail to remediate a deficiency
fast enough because they aren’t immediately bioavailable to your marijuana plants.
If you’re absolutely sure your marijuana root zone pH, grow environment, water, and other factors
are what they should be, and your plants are still showing signs of nitrogen deficiency in soilless
hydroponics marijuana growing, it almost has to be that something’s wrong with your base nutrients.
What are your remedies? If you’re growing in soilless hydroponics using synthetic hydroponics
nutrients, you have it pretty easy.
First, make sure your pH meter is working perfectly (or use the new pH Perfect base nutrients
that automatically buffer and adjust pH to the ideal sweet spot). Flush your
plants (I prefer
Final Phase or Flora Kleen), dump your reservoir, fill with reverse osmosis
water, and feed with
quality hydroponics base nutrients. When I say “quality hydroponics
nutrients,” I mean a reliable
brand of hydroponics base nutrients other than the brand you were using when
the nutrients deficiency
You can also experiment with slight up and down adjustments of nutrients
strength (ppm) or nutrients
water pH and see if that corrects the problems. For example, many of us
follow the dosage instructions
on nutrients bottles and end up with 500+ ppm during flowering. In some cases,
that’s too much, and what’s
really strange is that using too much nutrients can result in nutrient deficiencies.
So try changing your dosage 50-100 ppm in either direction, and see if it makes a
Try adjusting you pH from 6.2 to 6.0. Different nutrients interact with root zone
water differently, so that you might get absorption of 12 elements, but the pH is
wrong for three
other ones. Even small adjustments in pH (unless you’re using pH Perfect base
nutrients in which
case it doesn’t matter), can affect individual element’s absorption.
As the Big G man above so eloquently stated… u seem to be having nutrient deficiencies.
The brown spots, then dried up crispy leaves Looks like calcium deficiency to me. Have u been supplementing calmag?
Also ph could be thr culprit. If its out of range (6.3-6.8 in soil 5.8-6.2 in hydro mediums) it can and will lock out various nutrients
I have not been using CalMag. This is being grown in Ocean Forest soil. I planted on 11/23. I’m using the Fox Farm trio for nutrients. I fed Grow Big and Big Bloom at half-strength for the 1st time 14 days ago. A couple days later I fed the same but full-strength 600 ppm. 9 days ago I added Tiger Bloom to the mix using the full recommended dose. It tested at 1450 ppm. I fed the same mix 6 days ago also. I didn’t realize that the Gold Leaf seeds that I ordered were photo variety. I added the Tiger Bloom because the Blueberry and the Jack Herer I had planted at the same time started flowering. I hadn’t changed the lighting schedule yet because I didn’t know I had to. I figured the Gold Leaf would start flowering soon so I treated it the same as the autos. It was at this point that the Gold Leaf started showing yellow tips and some leaves started browning. I thought maybe the added phosphorus was the issue. 2 days ago I pulled the Tiger Bloom from the mix and fed Big Bloom and Grow Big at 6.4 ph and 550 ppm. I also changed my lighting to 12/12 to get the Gold Leaf to flower. It’s showing sex so I think it’s ready. I’ve ph’d my water consistently between 6.4 and 6.8 except at the very beginning. I mistakenly assumed distilled water would be neutral. It tested at ~5.6. In case I haven’t mentioned this is my first crop ever. I will absolutely order some CalMag today as it seems from reading various posts that this is a very beneficial additive. Do you think I should boost the strength of the Big Bloom to add nitrogen for this plant? Thanks. I’m glad for the help.
I was worried reading ur answer with no mention of ph but i saw 6.4 somewhere. Right on the button.
Distilled takes the ph of whatever it is touching. In a jar it maybe 5.8 but if u poured it thru 7pH soil it would read 7. Reason being pH requires solids to conductify (fake word btw). And its ppms are nearer to 0. So no solids to ph.
11/23 means the FFOF is nearly depleted. Its usually good for 4-6 weeks. Good to know u got ur moneys worth. Time to start feeding as u know. But FFOF (the soil) mostly feeds NPK along with a few micronutes. U have to supplement ur on calmag when growing and usually i dont need it til flower or about this age.
And with regards to upping yr feed levels… ur going into flower. (How long from 12-12 flip?) so don’t necessarily up N value. Follow ur schedule (be it 25%, 50% or 100%) as closely as u can. And only adjust if you see issues.
I flipped to 12/12 2 days ago. CalMag is on order. Thanks again.
What lights are you under and how far away?
Have you done a runoff test to see what the TDS is? You could be high at this point depending on pot size. @PurpNGold74 is right that OF should be close to depleted by 6 weeks but that is dependent on the soil volume.
Have you done any flushes? Because FF recommends them at every change in nutrient regimen. And FWIW that line is famous for building salts which need to be leached away.
Before doing anything radical I would try to take a few data points and run em up the forum flagpole. Purp is good at diagnosing stuff so you are in good hands.
Learnd from the best
My light is an HLG 100v2. I’ve been keeping it around 15" away. It might be a little further away from this plant as my Jack Herer is kind of tall. I’m using 3 gallon fabric pots. I’ve done no flushes. I’ve never read to do that unless you overdosed your plant. I tested the runoff once. I think I got 2800 ppm but I realized it was probably high because I hadn’t filtered out the actual solids. I’m curious now so I will do that late tonight when I can open the tent. I appreciate all of you being so generous with your knowledge.
Quick question and maybe a revelation to me. You said distilled water will take on the ph of the vessel it is contained in. I’ve been pouring a gallon of distilled water into my watering can and adjusting the ph before I water. I always have to use ph up. It takes very little. Am I creating a problem by doing this?
TDS won’t see un dissolved solids FYI so your 2,800 is likely pretty close IMO. Which is high.
The schedule I just looked at didn’t indicate regular flushes in soil; just coco. It did indicate any irregularities in the leaves to perform a flush using Boomerang and Sledgehammer.
Might not be a bad idea.
Nope. Look at it like this.
- Distilled water
- Add nutes (this adds solid to ur distilled and the ph DROPS)
- Add ph up into range
Sounds right to me
I think you can go a bit higher: 1,900 or so in FFOF. But we’ve seen some in the 5,000 range which is pretty high.
Should I ever adjust the ph of distilled water when I’m just watering?
Nope. But definitely check it. Its a guestimate of ur soils ppms and ph. Closest u can get without a slurry test (mixing root area soil and distilled, mixing, and sitting an hour)
Distilled water requires no adjustment. It is free of solids and is not possible to measure with an EC type meter as there is no path for electricity to flow. You will only get spurious readings. If you were to add ONE drop of PH Down to a quart of distilled then measured it, you would likely see PH in the 4’s.
I use R/O which is much of a muchness to distilled and when plants are young and only getting water I don’t bother PH’ing: I just feed em R/O straight.
I did some testing on my plants. The Gold Leaf that has been having the most issues tested at 2490ppm, 4990EC at 64f. The runoff ph was 4.86. I have one of those cheap 3 in 1 soil meters and the soil tested at 6.9 ph. The Jack Herer runoff tested at 2090ppm, 4190EC at 64f. Runoff ph was 4.98 and soil ph was 6.9. The Blueberry runoff tested at 1310ppm, 2620EC at 64f. The runoff ph was 4.93 and the soil ph was 7.2. I don’t know that I trust those soil ph numbers as that meter I have doesn’t inspire confidence but who knows? Thoughts? Thank you.
3 in 1 meters are essentially worthless so your instinct was correct.
You can do everything you want with a simple TDS pen.
FYI every 500 ppm equals 1 EC. Your reading for 2,500 ppm would be around 5.0. I think you are just missing a decimal.
Assuming low soil PH, you may want to top dress with dolomite lime to bring into range. You are low enough to cause problems.
Thanks for responding. I wish I knew how the ph got low. My plants have received RO or distilled water and ph adjusted nutrients. I adjusted the ph after adding all the nutes. I poured the ocean forest straight from the bag into the pot. No additives. Is there anything special about dolomite lime? This is what I have available locally.