Fan Leaves and The OD Grower

[D.S. Toker. MD]

This is one of the most important tools i have discovered in determining the health of my outdoor plants.

I have come to learn that the large, primary fan leaves provide a constant, daily indicator of the plants needs and health and i have learned to watch those leaves like a hawk- they truly are the canary in the coal mine where cannabis is concerned. Those leaves are the most sensitive part of the plant and are the first to respond to any negative condition the plant might experience

If you see primary/fan leaves yellow, even 1 leaf, it should trigger an understanding that there is a problem and the problem is likely to become big quickly. By the time 2 of these large leaves are lost the need to act becomes critical because the plant has began to drop its biggest leaves in an attempt to accommadate for the deficiency. Low moisture, bug damage, nutrient deficiency, or disease, the first indicator that all cannabis plants provide to the grower that there is a problem is presented in these large leaves and that holds true whether the plant is 2' tall or 10' tall... The grower that watches these leaves and addresses the plants needs in accordance to the health of these leaves will have a healthy cannabis crop and harvest a maximum yield.

The loss of these large leaves creates an irreversible condition in cannabis in that once they are gone, the plants growth and maturity is effected. The plant wont get as big and the buds wont get as big. If the problem that is causing the leaf drop isnt quickly addressed, then secondary leaves began to yellow and fall and at this point, the plant has experienced irreversible damage to growth and yield..

Its often suggested that its normal for these leaves to yellow and fall from the plant as it gets bigger. Its my view that is a myth. Not until a plant is in its 5th or 6th week of flower should primary leaves begin to yellow and fall from the plant. Any yellowing prior to that point indicates deficency, disease or damage of some respect.

Stay tuned to the condition of those leaves and you will be rewarded.

 

[THC123]

indeed i also watch those leaves like a hawk to decide when it is time to topdress

Outdoors , i start removing them halfway through flower cuz there are just too many but in the veg i leave them on

 

[smokeymacpot]

this applies to indoor and outdoor and its also what i use to determine how hungry my plant is. when those old fan leaves start yellowing, its telling me its hungry for N. the biggest bad piece of info ive seen on these forums is to stop feeding N as flowering starts.. which is when it needs it the most!
ive seen what happens if you miss that important early flowering feed and you end up with a tiny bud on a stick, you can never recover from that bad mistake.

 

[D.S. Toker. MD]

I agree.

I actually posted this because of all the "when do I water" posts. If you watch the big fans, they will begin to yellow at the first sign of low moisture. A week later 10 leaves will have dropped from the plant.

Also smokey, the first thing i do when i see yellow fans is look at the color of the rest of the plant. Nitro is one of the first thoughts.

 

[Dr_Tre]

Quick question:
As plant gets taller lower leaves get shaded, so they eventually turn yellow and fall, no?

 

[D.S. Toker. MD]

No Dr.Tre. Ive really looked at this issue extensively over a number of years. I not only studied cannabis plants, but at one point i did a quick study of native hebacious weeds and the condition of their lower leaves. They dont yellow either because of low light . Nutrient, moisture defieciencies and pest damage is in my view, the cause for all lower leaf yellowing.

I currently have plants that are 8' tall and the ground below them is dark, but they dont have yellow leaves at the bottom. I certainly have some that have yellow shades but im working on them to find out why.

Here's one in which the lower 1/2 of the plant is in the dark. It has a few yellows but its bug damage.

 

[.clunk]

I also agree about continuing with a nitrogen feeding for the first bit of flower as this is when the plant is going through it's "stretch" phase and will easily add another 8-12" of height and width. I've always stopped additional nitrogen feeding after the first two weeks of flower, then used Heavy Harvest Fall blend (12-14-13) after that which still has a fair bit of Nitrogen. I've had great success with this method but I'm wondering if I'm missing out by not continuing with another shot of high N somewhere in there.

In the quest to achieve the best yields, maybe you can shed a little light on when to stop additional N feeding in flower.

 

[Swamp Thang]

For a couple of weeks before I read this post by D. S Toker about yellowing fan leaves, I had begun to notice a few of the lower fan leaves of my Thai plants doing just that, in ones and twos at first, but then to my dismay I saw a clusters of young, newly sprouted leaves and tops suddenly just going limp and rotting away.

I removed all foliage that faded in this way, but now whenever I go back to check the plants, yet a few more leaves are dead, which is really beginning to bother me. The plants are all tied down for nice horizontal growth and excellent sunlight exposure, and the rains are over here, so mold can't possibly be a factor.

The plants are starting to flower with little popcorn buds, making me hesitant to add more handfulls of 5-year old fermented cow manure, which is the only fertilizer which I can obtain in these parts. Back before planting, I loaded my swamp tubes halfway full with a mix of mostly that cow manure and some worm cast soil, topping it off with pure worm cast soil. This formula worked well in the past, so I am baffled with the way this year's crop is starting to go wrong with the exact same mix.

Since all these plants are in swamp tubes, I assume they couldn't possibly be short of water, though I dumped a bucket on each planter just to be sure today. DS Toker, would you suggest that I go ahead and add a chitload of manure now to stop this trend, despite the plants already starting to flower ?

I sure would appreciate any advice that would help me arrest this depressing trend and save my crop, since the only smoke available on sale here is the most vile tasting, stale reeking, low-potency crappy shake and dust-weed imaginable. Much as I love to get high I wound up quitting altogether because there is nothing worth smoking here at all.

 

[smokeymacpot]

I also agree about continuing with a nitrogen feeding for the first bit of flower as this is when the plant is going through it's "stretch" phase and will easily add another 8-12" of height and width. I've always stopped additional nitrogen feeding after the first two weeks of flower, then used Heavy Harvest Fall blend (12-14-13) after that which still has a fair bit of Nitrogen. I've had great success with this method but I'm wondering if I'm missing out by not continuing with another shot of high N somewhere in there.

In the quest to achieve the best yields, maybe you can shed a little light on when to stop additional N feeding in flower.

i never stop feeding it N in flower, after that first few weeks of flowering it wont need much, but you just look at the leaves and if they are starting to yellow again, despite feeding with a balanced fert, then swap a feed for a mostly N one.
your not missing out.. unless you get too much yellowing and then fan leaf loss.

 

[smokeymacpot]

For a couple of weeks before I read this post by D. S Toker about yellowing fan leaves, I had begun to notice a few of the lower fan leaves of my Thai plants doing just that, in ones and twos at first, but then to my dismay I saw a clusters of young, newly sprouted leaves and tops suddenly just going limp and rotting away.

I removed all foliage that faded in this way, but now whenever I go back to check the plants, yet a few more leaves are dead, which is really beginning to bother me. The plants are all tied down for nice horizontal growth and excellent sunlight exposure, and the rains are over here, so mold can't possibly be a factor.

The plants are starting to flower with little popcorn buds, making me hesitant to add more handfulls of 5-year old fermented cow manure, which is the only fertilizer which I can obtain in these parts. Back before planting, I loaded my swamp tubes halfway full with a mix of mostly that cow manure and some worm cast soil, topping it off with pure worm cast soil. This formula worked well in the past, so I am baffled with the way this year's crop is starting to go wrong with the exact same mix.

Since all these plants are in swamp tubes, I assume they couldn't possibly be short of water, though I dumped a bucket on each planter just to be sure today. DS Toker, would you suggest that I go ahead and add a chitload of manure now to stop this trend, despite the plants already starting to flower ?

I sure would appreciate any advice that would help me arrest this depressing trend and save my crop, since the only smoke available on sale here is the most vile tasting, stale reeking, low-potency crappy shake and dust-weed imaginable. Much as I love to get high I wound up quitting altogether because there is nothing worth smoking here at all.

how does the plant look overall.. light green leaves?
i would try and feed with something fast acting, so a liquid N fert. are you sure you cannot buy anything like that? even a seaweed fert is N i think. if you really cant find something then you can possibly use old(not fresh!) piss lol
goto the nutrient forum and discuss what you can get hold of and wether piss is high N and medium or low P&K.

 

[Swamp Thang]

Thans for the reply, Smokey. Hearing from you that more nutrition might be in order, I'll make a tea from my 5-year fermented cow manure, and pour that into the planters.

Other than the relatively few leaves that are yellowing or rotting towards the base of one plant out of four, the majority of the plant leaves are deep green in color, and the buds are slowly filling out with no sign of mold.

I'll post pictures soon. Sure hope the yellow leaf syndrome stops soon after I add the extra plant food.

 

[hamstring]

Not a ton of experience in this question but I have had leaf spot the last couple of years and the very large fans leaves, the biggest few on the plant seem to be affected first.
Just anecdotal experience from last two years but after reading this I will pay more attention.

 

[D.S. Toker. MD]

Hey

Some good info and discussion. I have a little check list that i go through when i see one of my shades turning yellow.

1. has a bug dammaged it, or the leaf stem broke?
...if the answer is "no"

2. I immediatelyl look at the soil for moisture. Low moisture is in my mind, is one of the top 3 reasons for yellowing fans. I take into consideration the last rain and feel the soil

3.Then i look for insect damage/infestation, but generally if your plants are infested with a pest, youll know it pretty quick.


4.Then i look at the overall plant - the color and the growth rate. If its pale green or yellowish or not really growing, its probably a nute problem/ probably nitrogen combined with ph. Nutrient defiecency is the #1 reason for fan leaf yellowing. It often starts in mid july as the plant begins its preflower stretch. This is the 30-45 day period where the plant will basically double in size. The plant is growing so fast that it needs a full dose per week of the high nitrogen fert to keep the fans healthy.

When i look at the plant, if it shows some overall yellowing, i hit it with a 3/4 dose of high nitrogen water soluble fert. 20- 8- 12. I wait 2 days and look again. If there is improvement, i add another full dose of high nitro. If i dont see much improvement, i hit it with 3/4 dose of 10-24-6. I do this because i dont really know what nute is deficient.

If these approches dont work, i usually add PH UP to my water.

A couple of footnotes.

*Once a fan yellows if you dont act fairly quick, you can loose practically every fan on the plant within a week. YOur window for impact is about 4 days.

*In tackling this problem, there is no place for organic nutes such as manure tea or fish emulsions or granular ferts because the nutes need to start working now and you really need to see real results day after tommorow or other actions will be required. Neither organic or time released nutes act that quickly.

*Different strains require vastly different amounts of nutrients. For example, i have a number of GHs white widow plants and they litterally required a full dose of high nitrogen ferts every 6 days and more if it rains. I also grow Blue Hash, a much bigger plant and a full dose seems to last weeks in the plant.

*The use of flowering nutes depletes PH dramatically. A ph of 6.8 at the beginning of flower can be reduced by 1 whole point, to 5.8 within 4 weeks, from the pottassium and other elements in the flowering nutes and can reduce bud size and yield dramatically. A light dose of PhUp in your water can help minimize this problem

Swamp Thing, Smokey's advice is good. But your situation raises a good point. Often when you first spot some lower leaves yellowing and then rotting, its because all of the available nutes or water is going to the most prominent parts of the plant and it can remain green for a week or so before other leaves begin to yellow. But, a generally green plant that has yellowing fans CAN indicate that its a nute different than nitrogen and in fact may be a mag, or pottassium defieciency. If my plants were green and i didnt have bug damage, i would hit them with a 20-20-20 or flowering nute with lower nitrogen.

 

[feenom]

2. I immediatelyl look at the soil for moisture. Low moisture is in my mind, is one of the top 3 reasons for yellowing fans. I take into consideration the last rain and feel the soil

low soil moisture = yellow leaves??? never have i seen a leaf yellow before is droops because of lack of water....

*Once a fan yellows if you dont act fairly quick, you can loose practically every fan on the plant within a week. YOur window for impact is about 4 days.

lose every fan within a week??? what one a 6inch starter? a full sun outdoor plant will not be gone in a week after the first yellow leaf shows...most likely yellow leaf is due to nitro deficiency and that will not cripple a plant left alone nearly that fast...

*In tackling this problem, there is no place for organic nutes such as manure tea or fish emulsions or granular ferts because the nutes need to start working now and you really need to see real results day after tommorow or other actions will be required. Neither organic or time released nutes act that quickly.

this is the funniest one, go ahead and dump some ammonium nitrate or other straight chemical ferts on your nicely amended outdoor soil...do you know what these ( salts ) due to the biology of your soil??? KILL IT. same thing that happens to a snail when it comes into contact with salt, it dies. I have learned this through my studies of actively aerated compost tea.

if you top dress and water in a high nitro gauno you will see results the next morning... please people don't freak out when you start to see a little yellow, yes your plant is telling you something, but no do not hit the panic button....

 

[diamondmine]

Very good points on both your parts I hope it stays civil I can see good info from you both.

 

[Sideways]

I have also seen yellowing from rootbound plants, they choke themselves out. If they have plenty of rootspace, no problemo.

 

[feenom]

I have also seen yellowing from rootbound plants, they choke themselves out. If they have plenty of rootspace, no problemo.

very true indeed i have seen this happen with my mothers!

 

[santasapimp]

uh oh. i removd a bunch of HUGE fan leaves to make more light for the soon to come buds (should be starting to nug today)

am i gunna notiec significant decrease in yield

 

[THC123]

if you top dress and water in a high nitro gauno you will see results the next morning... please people don't freak out when you start to see a little yellow, yes your plant is telling you something, but no do not hit the panic button....

I agree , i always start topdressing if i see a little yellow , most of the time sooner , but those organic pellets work faster then one might think , just not full throttle , that takes 2 weeks

uh oh. i removd a bunch of HUGE fan leaves to make more light for the soon to come buds (should be starting to nug today)

am i gunna notiec significant decrease in yield

well i never removed fan leaves this early but i'm sure you will be fine
i always start removing them halfway through flower and i get great yields

 

[D.S. Toker. MD]

Hey fenom

low soil moisture = yellow leaves??? never have i seen a leaf yellow before is droops because of lack of water....

I saw it for years before and went through a number of serious droughts before i finally realized what it meant. Thats also how i learned that after the shades and even secondary leaves fall off of the plant, the maturation process in the plant becomes damaged and the plant may never mature. Now i know and watching those leaves is my main indicator for deciding when and how much to water.


lose every fan within a week??? what one a 6inch starter? a full sun outdoor plant will not be gone in a week after the first yellow leaf shows...most likely yellow leaf is due to nitro deficiency and that will not cripple a plant left alone nearly that fast...

The plant wont be gone but the big shade leaves willl, yes within a week. I just had this happen with a bunch of white widow plants i have growing. I checked them last week and saw 2 or 3 big yellow fans and right there on the spot I knew I had to decide whether to go back and mix up some ferts and come back, or come back next week and let them fall. I opted to come back this week and to no suprise, there were 20 big yellow leaves on and around each plant. Loosing those big solar/ energy panels will effect the yeild i get from those plants


this is the funniest one, go ahead and dump some ammonium nitrate or other straight chemical ferts on your nicely amended outdoor soil...do you know what these ( salts ) due to the biology of your soil??? KILL IT. same thing that happens to a snail when it comes into contact with salt, it dies. I have learned this through my studies of actively aerated compost tea.

You may be right about the guano or teas acting quickly, but those are off limits to most outdoor guerilla growers. A black bear or boar hog would tear the fence down run my skinny ass of and rip up every single plant just to lick the dirt. Skunks and oppossums will take whats left

My native soil has a ph of about 6.8 , and is fairly rich so alot of the time i i dont do anything but dig a hole and plant. But we have 120 acres of corn in the bottom and 40 acres of soy beans that have had ammonium nitrate applied by the ton. From working on the farm for a lot of my life, I know that ferts equal yeild period. Plenty of nitro, big yeilds, little nitro, little crop. Ive been to a dozen workshops by the agriculture extension office about fertilizer and yield. Its difficult for organics to compete in crop yeild

if you top dress and water in a high nitro gauno you will see results the next morning... please people don't freak out when you start to see a little yellow, yes your plant is telling you something, but no do not hit the panic button....

The only time i hit the panic button is when i see Powdery Mildew. Then its a friggin 4 alarm fire!