Leaves drying out near harvest

[Surfer Joe]

I have a bubble bucket plant and a soil plant in the same small grow tent and both are nearing harvest. Both are autos but different strains (white widow and northern lights).

They have grown fine without problems so far, but the leaves on the top colas and other top flowering stems of both plants have become dry/brittle and the edges are curved up a bit and the tips break when I bend them.
It affects both the fan leaves and the sugar leaves near the tops of the flower stems. The leaves a bit further down on the branches are still soft and silky.

The plants don't share the same nutes but they are in the same environment, so I am wondering whether the dry leaves are caused by heat, the fan or the natural progression of top leaves as the colas mature.

The tent has a 7 inch oscillating fan that sweeps across the tops of the plants. It sits about one foot away from the plants because the tent is not very large.
I have a 600W dual spectrum hid light in an air-cooled reflector and the light was about 10 inches above the tops ( I have since moved it up to about 16 inches above the tops).
The humidity and temps in the tent average 18-28C and 45-70% humidity.

Since it affects both plants, it should not be due to the nutes.
I suspect the light or the fan, but I wonder if this is also a natural part of the life cycle of the plants.

Also, should I just trim those dry leaves off and let the buds get a bit more light before harvest?
The plants have plenty of other leaves further down on the branches, and I notice that people often show photos of plants near harvest that look like they have been trimmed of most leaves on the flowering branches.

Any advice would be appreciated, as I don't want to screw up a decent grow right at the end. Thanks.

 

[Surfer Joe]

This is a photo of some of the leaves. A few inches lower, the leaves are still soft and supple.

 

[DrFever]

here check out my last few posts here might help you out with your issues http://www.marijuanapassion.com/forum/showthread.php?t=67335

 

[buddogmutt]

Most times some nute lock out is occurring. I'd simply flush and let them finish.. You're too close to being done to attempt a "fix" IMO...

 

[Hushpuppy]

That to me looks like you are having a hard time maintaining your atmosphere and the temps and humidity are swinging a lot. That and the lights being too close is what is drying those tops out. That dry curl is classic of having too dry/hot air directly above the plants.

You have already done the first fix by backing up the lights. One off the best methods for determining light distance is to place your hand over the top of one off the colas directly beneath the light, with your palm down. After about 20 seconds, iff the light is too close, your hand will get uncomfortably warm(not necessarily hot but just warm enough that it isn't comfortable). You want to then move the light back up away from the plants until you can hold your hand in place ffor about 20 sec and not get uncomfortable.

This is radiation heat that won't be affected by having the fan blowing above the plants. It is the light intensity causing it. Now having the fan blowing the plant tops around so that they sway real good will help with that some if the light isn't too close, but then you have the problem of the fan over drying the tops if the humidity isn't staying at or above 60% within that air space.

I always keep my lights about 18" above my plants and maintain good ventilation through the tent so that ffresh air is coming in constantly during lights on. This keeps the humidity at a more workable level and removes the stale air.

BTW; the buds are looking really good If the leaves turn brown and crispy then I would snip them off.

 

[Surfer Joe]

Thanks. I kept a daily grow log that includes the room temps the tent temps and the pH, EC and ppms and shows the fluctuations that have been going on.
I suspect that the pH crashing every day is due to the small bucket size (20L bucket).
The root ball is huge and I have to top up with about 4L of water every day and the bucket only holds 14L of nutes under the mesh pot, so there is not a lot of liquid in the buckets to help stabilize the fluctuations.
If you can read the grow log, maybe you can notice some pattern that might help explain some other reason for the pH crashing about 5 days after using fresh nutes.

 

[Surfer Joe]

Most times some nute lock out is occurring. I'd simply flush and let them finish.. You're too close to being done to attempt a "fix" IMO...

My next nute change will probably be the final one before the flush and the canna guide I have been following recommends a low dose of nutes with mostly just cannazym and canna boost and a very low ec/ppms for the final week.
After that, I want to use canna flush and then just plain water for a few days before harvest.
I assume that in hydro, flushing must be very quick since the plant consumes about 4L/day so it should clear itself of chemicals faster than a soil plant.
Do you think that is a good plan?

 

[trillions of atoms]

Dry brittle leaves could be a low humidity problem... Fans to high on them too.

 

[Hushpuppy]

I am not at all surprised to see you chasing pH constantly with this setup. The reason is partly water/air temps as each off these will affect how the plant eats and drinks. Also temp change will, by itself affect the pH some (but not a lot if the temps don't swing far).

The other reason has to do with the size reservoir of water and the type off nutes you are using. Some nutes will work great in a give setup, while working horridly in a different type of setup. For example: I use AN Jungle juice 3part in hydro system that holds roughly 30-40gallons off water for 4-5 plants. For plants just set in fflower, I start them around 900-1000ppm at 6.2pH. Within 3 days the pH will drop to 5.5-5.7 but I will see very little drop in ppm. With each week off flower I am increasing the nutes to a max of 1400ppm and continuing to have to raise my pH every 3-4 days. Often my pH will drop to as low as 4.5 before I can raise it back up. I am typically having to top up my water 2-3 times before I do a water/nute change (which is every 2 weeks) I try to maintain ~78f air temps and ~68f water temps.

Now if I was using GH fflora 3part, My pH would swing the opposite direction. I would constantly have to lower the pH rather than raise it. I have also noticed that the pH will often do differently during fflower as opposed to during veg as the plants are taking in more P and K and less N.

This is why many times people struggle with plants when they are growing multiple strains at the same time without having learned the patterns of growth for each of those strains.

I think what you are experiencing with your pH is not at all unusual for hydroponics. If you changed to soil growing, you would have less problems with this, but soil growing has its own problems as well that you must learn.
I believe your solution is going to be 2 parts: first is to switch ffrom individual buckets to either much larger totes or to interconnected totes with a connected external reservoir. I much more prefer this as I don't have to lift plants constantly. I can leave my plants undisturbed and do all of my changes and flushing through the outside rez which is much more accessible.

The second part of your problem is that you need to better maintain your atmosphere so that it is more stable in temp and humidity. You can do this by either getting a much larger tent to grow in so that there is a buffer air space within the grow area, or enclose a larger air space around your grow tent so that you can buffer that air that is coming in from the garage and maintain a more stable atmosphere within the grow tent. My preference is to enclose a larger "room" to have my grow spaces and work space within that I am able to control the atmosphere better and easier so that there are no large swings in the numbers.

All that said, it appears all of your hard work is going to pay off if that pic you posted is any indication of your whole grow. I would be quite pleased with the results, just not all the work involved.

 

[Surfer Joe]

Thanks, Hushpuppy for that very informative reply.

This winter has been a disaster here, with more rain than has ever been recorded and no snow or real cold.
My poor garage has been a totally dank (and not in the nice sense) place with a huge amount of humidity all winter (80- 95%), a leaky roof and even mould that grows on the wet ceiling, so the air intake to the tent is sucking in that damp air.
It's not my property, so I can not do any changes to the garage.
The humidity is around 45-50% with lights on and then it goes up to 65-70% with lights off. I put in an oil radiator to go on while the lights are off since it tends to both heat a bit and dry the air some, but I still have a lot of fluctuation between lights on and off periods.

Normally here in winter it is colder and much more dry and the humidity is much lower.
I can't really control my garage room conditions and unfortunately I don't have room for either a bigger tent or a larger rez setup here.
I did buy a small dehumidifier yesterday but that was for the harvesting since I am going to dry inside my house in a spare room and I want to maintain the best conditions so I don't mess up the pot at the last hurdle.

I have been using a data logger to test out the drying room conditions with a small heater and a small fan and the de-humidifier before the harvest so that I can get it as stable and ideal as possible before I harvest and put in the plants to dry.
As soon as I can finish the testing (maybe 2 more days) I plant to put the dehumidifier into the grow tent as a last line of defense against the humidity.

I have been amazed by the size and lushness of the hydro method compared to my first grow in small clay pots full of soil, but I think that I am going to try airpots next rather than hydro and see how that goes.
This will be my last grow before summer because I will not be around on a regular basis.
I will do an airpot grow starting around August and then try another hydro grow next winter and hope that we get a normal, colder and drier climate.
I just hope that I haven't been growing mould instead of pot.

 

[Hushpuppy]

Very humid conditions are definitely a PITA, and not having the ability to change the size off your grow space makes it that much more difficult to control. If you have a spare room in your house, why don't you bring the grow tent into that room where you can better control the atmosphere? Air filtration within the tent and within the room will eliminate all of the odor, and the dehumidifier will remove the moisture created by the plants.

I think getting the buds inside with a dehumidifier will be key to preventing mould and mildew development. Don't try to dry them too fast though as that will cause them to be quite harsh. The challenge to getting the best flavor is to dry them as slow as possible without allowing mould to develop. I found with my dryer that by slowly replacing the moistened air around the buds with drier air once every hour with an hour off still time, allowed the moisture to slowly be drawn out of the buds from the inside out. I did this by building a cabinet with an extractor ffan that was on a timer so that the air was pulled out for 15min then off for 30min for the first 2 days. Then I went to on for 15min and off for 1hr for the next several days until they were dry enough to be moved to jars for curing.

 

[trillions of atoms]

^^+1


Dry as slow as possible! Keep a GOOD EYE on the drying / curing buds...a few hours can yeild disaster w the right conditions!!

clean all jars really good or use clean food grade tupperware.

Mold or mildew can populate in a jar and further contaminate future buds that go in the unclean container.

 

[Surfer Joe]

What level of humidity and drying time you would aim for in the drying stage?

I am currently testing my drying area with a data logger and a fan and small dehumidifier and a small oil-filled radiator.
I took a couple of small branches that had a few small buds on them from the lower sides of the plant about a week ago (flower day 52) and put them in the drying room.
They had a little nice smell the first couple of days and then the smell faded.
Is that a sign of too quick drying, or normal, or because they were unripe buds to begin with?
The room conditions have been around 15C and 55% humidity, but it ranges up and down a bit and I need to check the range recorded by the data logger tomorrow to decide if I need to change or put anything on a timer.

 

[trillions of atoms]

I run m humidity low surfer joe if I can at under 50%humidity.

I test the buds by putting I a jar w a small hydrometer, If they are over 65% humidity when sealed in a jar I keep drying. If they hit 65% it's onto a tub and added a 62% humidi pak and seal them up.. Burping till they reach 62%. Then I seal um up n let the pak do the rest


Smoke it up at that point!

 

[Surfer Joe]

Thanks.
I ordered about 10 boveda 62 packs a few days ago in preparation.
I'm having trouble bringing the drying room humidity down below 52 or 53%. The dehumidifier is pretty small.

 

[trillions of atoms]

Those are good paks! What I use