What causes bottom leaves to yellow and shrivel up?

V

vinny2times

Active Member
I’m in week 4 of flower and everything has been going very well. I had to travel for work for 3 days, and when I came home the bottom leaves were yellowing/browning and shriveling up and falling off. The top half leaves are still green and perfect. What would cause this?
 
Gotta have pictures. My first guess would be what @dtl420 said. But there's even a small chance it could be something like mites. Spider mites generally start at the bottom and work their way up, killing the leaves as they go. But, you're more likely starving them.
 
Could also just be the plant's normal response to that stage of flowering and many will yellow even if you feed them more.
 
It has been recommended to me to give more MG (magnesium/epsom salts) in flower. If they lack MG the leaves yellow and it usually happens 3-4 weeks in flower.
 
the timing is right, but the reasoning is wrong.
the reason peoples leaves turn yellow in flower, almost always, is they didn't keep up with the veg nutes long enough when they flipped to flower.
the plant is cannibalizing its lower leaves to feed N to the new growth and buds it has to form during the stretch and flowering period.
the whole thing with cal-mag and cutting it off at the third week of flower is a coco thing, not applicable in soil. cheap coco doesn't come "charged"...the manufacturer of better brands will pre-soak it in cal-mag before you ever get it. if it hasn't been charged, it has a deficit, and you have to feed it extra to fill that deficit and still have any available for your plant. you've usually fed the coco enough by the second or third week of flower to fill the deficit, then you can cut way back because your medium isn't eating at least half of what you put in anymore.
calcium and magnesium are both important, and can cause problems if not available, but not the problems you're having
 
Just because a Leaf go yellow Low down the plant ,does not mean its a Problem,The first leaves to come through,normally die of ,But saying that all that growth is ripped off at some point any how,It happens a lot with Clones time to worry is when the top of the plant goes yellow.
 
Don't ignore the possibility of a root based problem. Club foot from over watering, root aphids, or rot can kill off the root structure and cause your plant to starve, which is what you are seeing.

The most obvious diagnosis is a lack of N, but that may not be it.
 
Everyone if forgetting why you need mag in flower. Most people switch to a bloom feed in flower and lack nitrogen. What does mag do? It helps the uptake of N.

If not using bloom it still helps uptake of N.

There is a difference in the look. If it needs mag it will yellow all over the plant and the leaf viens will be green while it yellows between the veins.

If it is yellowing from the bottom up if most likely needs N.
 
whitebb2727 said:
Everyone if forgetting why you need mag in flower. Most people switch to a bloom feed in flower and lack nitrogen. What does mag do? It helps the uptake of N.

If not using bloom it still helps uptake of N.

There is a difference in the look. If it needs mag it will yellow all over the plant and the leaf viens will be green while it yellows between the veins.

If it is yellowing from the bottom up if most likely needs N.
Click to expand...
Magnesium helps with the fixation of nitrogen from the air, but not necessarily with cannabis, mainly legumes..it won't help nitrogen uptake in soil..if the nitrogen is in an ammonium form rather than nitrate form, it will actually hurt the uptake of magnesium! Magnesium carries phosphorus through the plant..so a deficiency in magnesium will soon be followed by a phosphorus deficiency. Without a picture it's hard to tell as lower yellow leaves don't all look the same and is not necessarily a nitrogen deficiency. For the record, molybdenum, while needed in the smallest quantities compared to all other elements, is responsible for turning nitrate form of nitrogen into ammonia in the plant. So if feeding with a high dosage of nitrate nitrogen as oppose to ammonical nitrogen, then yes, in that case, molybdenum would help nitrogen get absorbed faster. Try to post a pic..it will help alot!
 
Blitz35 said:
Magnesium helps with the fixation of nitrogen from the air, but not necessarily with cannabis, mainly legumes..it won't help nitrogen uptake in soil..if the nitrogen is in an ammonium form rather than nitrate form, it will actually hurt the uptake of magnesium! Magnesium carries phosphorus through the plant..so a deficiency in magnesium will soon be followed by a phosphorus deficiency. Without a picture it's hard to tell as lower yellow leaves don't all look the same and is not necessarily a nitrogen deficiency. For the record, molybdenum, while needed in the smallest quantities compared to all other elements, is responsible for turning nitrate form of nitrogen into ammonia in the plant. So if feeding with a high dosage of nitrate nitrogen as oppose to ammonical nitrogen, then yes, in that case, molybdenum would help nitrogen get absorbed faster. Try to post a pic..it will help alot!
Click to expand...
I stand corrected. Calcium then. A lot of people use cal\mag and not Epsom.
 
whitebb2727 said:
I stand corrected. Calcium then. A lot of people use cal\mag and not Epsom.
Click to expand...
Too much calcium would lockout magnesium, though it's not usually common as calcium i believe is the most abundant element in 'soil' even though the plant doesn't use it the most. Into flowering, calcium can be reduced in favour of a raise in magnesium, but the ratio of cal to mag should always be no less than 2-1. At 4 weeks into flowering you're at the mid point..plants are at their hungriest, once a pic is posted, better help can be provided, until then we're shooting darts at a dartboard:)
 
Hey everyone. Sorry for the delay. I was traveling for work the past few days. Here are some pics. It’s getting worse. I think I’m just not giving them enough nutes, so I’m going to be feeding every watering instead of every other watering and increasing the PPMs to around 1100. Let me know your thoughts.
 

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