Phosphorus deficiency?

Advertise with us
AC Infinity
Shop deals on ebay
This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
2RedEyes

2RedEyes

Well-Known Member
Joined
Dec 11, 2016
Messages
3,259
Reaction score
8,141
This leaf is from the bottom of my autoflower plant. It appears to me like a phosphorus deficiency but I am giving it a decent flower nutrient in earth juice Bloom plus a little calmag. I referred to the GWE (grow weed easy)website and read that this deficiency can be caused by incorrect ph of the soil. I ph my nute mixture to about 5.5 and just measured the runoff from this plant at 6.8. Now the GWE site says for good phosphorus uptake the soil ph should be between 6.2 and 7 so I’m right there. I guess the yellowing could be normal at this stage but the brown spots worry me and there are brown spots on the next level up as well plus the leaves overall are kinda droopy or wilty almost like it needs water but the soil is not dry. I’m using an LED that is probably not great for flowering but it’s what I have and a couple of 2700k cfl’s as additional light. Temps are in the high 60’s to middle 70’s depending on time of day and light schedule.
Also the soil is FFOF on the bottom 30% and Roots Organic on the upper 70%.

View attachment 2F363477-1097-481C-A5C6-E55070A3D5FE.jpeg
 
why do you have ffof at bottom and RO on top? is this new? im thinking your mix is doing something. and PH going in is too low. I dont sweat what the run off is. as long as my nutes/water is 6.5-7.0 going in
 
I would also raise the temps to 77* - 80*
 
Another picture of a different leaf. Seems like a phosphorus deficiency but I’m not at all sure what to do about it. It’s getting sufficient nutes I believe and the ph is right about where it should be. What else Can I check?
The plant is an autoflower and has been in bloom for about 2 weeks. These pics are of the very bottom leaves but it is starting to move up the plant and the new sugar leaves around the buds are very small and weepy or curved down like they are wilting. It has had plenty of moisture and never been completely dry but I don’t think I have over Watered it either.

View attachment 86D261BE-3FB0-4260-86C8-E56320CA02C2.jpg
 
Redeyes,


I had exactly the same problem.
My leaves looked just like those but my problem was treated with lime, {Calcium} and cleared up.
So was it phosphorus deficiency?
Give them some lime as they probably are already awash with phosphorus
but are unable to use it for {'some chemical reason'}
{The 'reason' is ph!}


Good luck...


The Poet...

.
 
Thanks for the input Poet, I did give it a shot of Cal/Mag at each feeding and the phosphorus def doesn’t really add up either since it’s in a fairly rich soil and getting good and appropriate nutes, at least I think so. It’s looking better today. One thing that could have caused this wilting though is it stretched quit a bit and the top of the main cola got pretty close to the lights. I lassoed it and pulled it down and took out one of the CFL’s I added so now it has a little more room to develope buds. That still doesn’t explain what happened to the lower and mid leaves. I can’t wait till spring when I can move outdoors again.
Anyway thanks Poet!
 
2 Red Eyes,


Hey man... my leaves looked exactly like yours and I solved the problem with hydrated lime mixed with water.
Just a shot of Hydrated lime PH'ed to between 6-7 and the leaves green right up.
I got some garden lime {not soluble} and mixed with the soil.

Minerals is what the plant needs.
Theres no minerals in potting soil or liquid nutes either.
Next check I get I'm expanding my minerals to Azomite and adding worm castings too.
I already add blood and bone meal, epsom salts and espoma garden tone, then cut the liquid nutes in half!
I was not using my PH test kit either, now I PH constantly.

The picture of your leaves is phosphorus deficiency and like mine the plants were awash in phosphorus
but the PH being off made the plants unable to use it!
My plants are looking real good now.


Good luck...


The Poet...


.
 
The Poet said:
2 Red Eyes,


Hey man... my leaves looked exactly like yours and I solved the problem with hydrated lime mixed with water.
Just a shot of Hydrated lime PH'ed to between 6-7 and the leaves green right up.
I got some garden lime {not soluble} and mixed with the soil.

Minerals is what the plant needs.
Theres no minerals in potting soil or liquid nutes either.
snipped


Good luck...


The Poet...


.
Click to expand...

I'm seeing this a lot in my hydro set up. Cal/Mag helped but I'm intrigued by the "minerals" comment. I'm using RO water with 3 part nutes.... how do you add minerals to a hydro set-up?
do I add lime to my rezes?
 
2 Red Eyes,


If 'RO' water 'reverse osmosis' is like rain water,
it doesn't have any minerals.
The sick leaf in your picture looks exactly like mine did.
I use rain water and had sick leaves for two years till some one at the Hydro store
told me rain water is devoid of minerals.
I used to use water out of the machine to brew and also to water my weed.
That's when my problems with my plants started too!

Of course minerals can't evaporate, I knew that!
But I kept watering with 'RO' water or rain water, I just didn't know.

'Hydrated lime' mixes with water in a second.
I use less than a teaspoon [per 5 gallons] and PH'ed to 6-7 it is good.

Can't you use that in hydro?


Luck and later,

The Poet...


..
 
If you are losing leaves at the bottoms of your plants and it is semi random then it is natural yellowing off of leaves that the plants deem inefficient due to lack of light. The plant draws out the available nutrients (causing leaf to yellow) then it cuts off the moisture and the leaf browns and falls off.

This occurs during the veg stage with plants grown indoors because the light is not as pervasive as sunlight. During the flowering, the lowest leaves that are hidden under the canopy will yellow off quite fast as the plant is using all of its energy to produce flowers.
 
the brown spots are necrosis where the living tissue has died. 1 of the problems related to auto flowering strains that the life cycle is short enough it difficult to troubleshoot nute issues. They go from veg to flowering so quickly getting the nutes right is a problem. I personally would add mycorrhizal fungi to help with uptake of the nutes.
 
Hushpuppy said:
If you are losing leaves at the bottoms of your plants and it is semi random then it is natural yellowing off of leaves that the plants deem inefficient due to lack of light. The plant draws out the available nutrients (causing leaf to yellow) then it cuts off the moisture and the leaf browns and falls off.

This occurs during the veg stage with plants grown indoors because the light is not as pervasive as sunlight. During the flowering, the lowest leaves that are hidden under the canopy will yellow off quite fast as the plant is using all of its energy to produce flowers.
Click to expand...

for pete's sake....
should I be regularly changing my T5s ?
I knew to change the HPS and MH but fluorescent too?
How long for LEDs
 
The T5 lamps will degrade over time just like the HPS/MH. This is because they all are full of chemicals that break down over time. I would change the T5 floros at least yearly...

The LEDs are different as they don't use any gasses. I wont swear that they don't break down over time as "everything does breakdown". But I imagine the breakdown will be slower and most likely the LED will actually fail before it will degrade much, just because of the nature of its makeup.
 
I have tried a trick with several of my Autoflower plants that I have grown in the past. I kept them under 24/7 light and they didn't go into flower as soon as they reached maturity (like they normally do) I was able to veg them long enough to get them significantly bigger. Then I dropped them back to 20/4 and the immediately went to flower. I cant swear this will work for all Autoflower plants, or that it wont stress an Autoflower plant, but I had great luck with them.

The other side of that coin is: if your going to grow an Autoflower for 6wks (to get more size) then why not just use photoperiod plants. I don't have a good answer for that :eek:
 
You must log in or register to reply here.

Similar threads

Greengal
Mg deficiency?
Replies
12
Views
1K
SubmarineGirl
SubmarineGirl
bombtombadil
Need Cal/Mag? Week 7 flower getting rough...
2 3
Replies
43
Views
4K
CrashMagnet
CrashMagnet
its_pink
Bottom Leaves Dying (first grow)
Replies
9
Views
2K
pute
pute
Y
Deficiencies... Could Use Some Help
Replies
14
Views
1K
stinkyattic
stinkyattic
A
leaves looking sad and turning purple along with brown spots
Replies
19
Views
2K
Bubba
Bubba

Latest posts

Back
Top