Expert Advice needed!

[sheik_yerbouti]

Hey all, looking for help with a problem I can't get sorted out. It's not a major dilemma or a anything but I really curious as to what the cause is as my plants are growing fine but I don't want it to get worse and want my beautiful perky healthy leaves back.

So as you can see the leaf margins are curled down, some of them almost folded in half. I haven't changed nutrient concentrations for a while except for adding Potassium Silicate.

grow info:

Medium - Pro-mix hp with 40% perlite
Temps - 25deg (77 f) high and 15deg (59 f) low. Wandering if large temp swing could cause?
Nutes - GH FloraNova 1.0 EC, 4 mil/gal Fulvic, 1 mil/gal Pot Silicate. I added the pot silicate right around when the plants started doing this so I'm thinking this could be the problem but overdosing with potassium silicate? Never heard possible and using the label recommendations.
PH - from 6.0 to 6.3

One thing I should add is that I moved the plants from their veg room to the flower room when this problem started. Around the same time I also introduced Potassium Silicate into the mix. The plants were extremely healthy, happy and perfect before I made these changes. The difference between my flower room and my veg room is that my bulbs are vertical in the flower room and it isn't properly insulated causing lower night temps.

My best guesses are that the addition of potassium silicate shocked or overdosed the plant as this was the only thing that changed in my nutrient regime.

Or the temperature differences from night to day are somehow responsible, either directly related or possibly that the cold air in the room sits at the floor level causing cold roots temperatures either directly leading to the leaf curl or possibly low oxygen in the root zone as it takes a little bit longer to dry out as compared to my veg room. I do let them mostly dry out and it only take 3 days after a good watering so I'm not convinced low oxygen is the culprit.

Any Ideas? any input is appreciated or new ideas especially from people who have had something like this before.

Thanks

 

[legalizeDK]

"My best guesses are that the addition of potassium silicate shocked or overdosed the plant as this was the only thing that changed in my nutrient regime."

i think you are right

 

[Humility]

It could also be that you haven't done a ph'ed clean water flush in a while. That coupled with the addition of the potassium silicate could have caused lockout issues.


I'm very very new at this but I'm seeing P- in the petioles and the darkness of the leaves. Leaf darkness/shape of leaves could also be overwatering or, more likely my guess P- in conjunction with N+. The downward curling leaf tips seems to indicate as much.


Finally the tops of the plants have the characteristic yellowing beginning at the back of the leaf moving towards the front presenting at the top of the plant - classic Fe-.

So my diagnosis is possible overfert with the Potassium Silicate but what appears to be P-, Fe- and N+.


The tips of the margins of your leaves look good. I think they're straight on potassium. I'd flush the medium with very low ppm rust water that has a tiny bit of fast acting P in it. Mostly water though.

 

[Midnight Tokar]

I also think over-feeding, frequently plants will do well UNTIL we force flowering. I think the stress from forcing flowering coupled with over-feeding will show problems we don't normally see in veg.

 

[Galactic]

Re: Expert Advice needed!

Your ph looks high. Slight over N. Need to flush with 6.0. Silica overfert is lol but did possibly raise ph for lockout...

 

[sheik_yerbouti]

"My best guesses are that the addition of potassium silicate shocked or overdosed the plant as this was the only thing that changed in my nutrient regime."

i think you are right

Ok, thx

It could also be that you haven't done a ph'ed clean water flush in a while. That coupled with the addition of the potassium silicate could have caused lockout issues.


I'm very very new at this but I'm seeing P- in the petioles and the darkness of the leaves. Leaf darkness/shape of leaves could also be overwatering or, more likely my guess P- in conjunction with N+. The downward curling leaf tips seems to indicate as much.


Finally the tops of the plants have the characteristic yellowing beginning at the back of the leaf moving towards the front presenting at the top of the plant - classic Fe-.

So my diagnosis is possible overfert with the Potassium Silicate but what appears to be P-, Fe- and N+.


The tips of the margins of your leaves look good. I think they're straight on potassium. I'd flush the medium with very low ppm rust water that has a tiny bit of fast acting P in it. Mostly water though.

Hey thanks for the informative reply.

I have been watering with a straight h20 feeding every 3rd feeding and I did give all a good watering and will be doing another. I don't like doing a total flush as it can take too long for my liking to dry out again, however it is a good idea so I'll try it out on a plant and see if it helps. I do plan on giving another good watering with straight h20 so if lockout is the problem 2 waterings of h20 should fix.

As for the light green at the top, I'm pretty sure that's just the new growth being lighter than the rest don't ya think? In my journal another guy mentioned the purple petioles. I have some of the same strain in veg that is healthy, I'll check to see if they have the purple petioles as I know it can be a strain thing. But if not than that is a good diagnoses. One more watering and then an addition of a higher concentrated P nutrient. I was planning on using the "grow" formula until stretch was over than slowly introducing more "bloom" formula with higher P.K values anyway so it would fit into my planned nute regime.

Thx again

 

[sheik_yerbouti]

I also think over-feeding, frequently plants will do well UNTIL we force flowering. I think the stress from forcing flowering coupled with over-feeding will show problems we don't normally see in veg.

Ya, probably has something to do with all the new stresses of moving to new room, forced flowering and then the addition of Potassium Silicate. I'm sure I didn't overfeed nutes as I have been giving them the same 1.0 EC for weeks now but I did add the Pot Silicate.

Your ph looks high. Slight over N. Need to flush with 6.0. Silica overfert is lol but did possibly raise ph for lockout...

I'll test my soil tonight, I always water with PH'd water and have been in these pots with the same soil for weeks now so kinda odd that all of a sudden they react to a PH problem unless like you said it was caused by the Potassium Silicate. I was thinking that somehow now that the plants are flowering their nutritional needs have slightly changed enough causing the potential N overdose if the PH did get too high. I don't have too much leaf claw or any burned tips though which I have done way too many times in the past by overdosing the plants. Really trying hard to keep the nutrients to a low level and not OD as I learned the hard way enough times by now.

 

[sheik_yerbouti]

Update: Checked soil PH and its sitting right around 6.0 so any issues aren't PH related. Hoping that another watering will fix the problem. Also the petioles on my healthy plants in veg are purple as well, not as purple mind you so something along these lines may be related to the problem.

 

[izzywozzywizzy]

Hi ,i had same prob ,really cold nights and hot days ,25 to 30 deg drop differrance my daytime was 82 and nite 57 and had same look ,I could be wrong but a heater might help you and me at night.cheers

 

[SeaMaiden]

You never report the relative humidity, only temps. Learn about vapor pressure deficit. I think RH needs to be raised. Also, they look off. Dark green + reddened petioles, may equal P-, slight. Fooling around with pH might correct that.

 

[sheik_yerbouti]

You never report the relative humidity, only temps. Learn about vapor pressure deficit. I think RH needs to be raised. Also, they look off. Dark green + reddened petioles, may equal P-, slight. Fooling around with pH might correct that.

I don't monitor RH that closely as I don't have a closed growing environment so it is what it is. When I check its always around 45-50. I live on the west coast Canada so the natural RH is fairly moist. I did test the soil PH and it was a solid 6.0, If nothing else works I'll screw with PH but I do have a hard time believing that with the Soil buffering the PH it could really be a problem.

Did a quick search on the VPD, are you suggesting my problem could have something to do with that? I really do feel like it is some kind of environmental control thing more than a water or nutrient thing. Not sure how I could control the VPD with an intake/exhaust setup. This is makin me go crazy!

An odd thing happened the other day with some plants of the same strain I had in Veg. They were perky and happy with leaves rigid and pointy, this was under horizontal lighting with a MH. I then put them around a vertical light because I am currently switching my bulbs from horizontal to vertical and they started to exhibit signs of the same droopy leaves. Just a start of it but I'm wondering if it could have something to do with the angle of light or light intensity, stress of some sort?

I'll be adding more bloom fertalizer into my nutrient regime as I have been using mostly grow, I'm pretty confident that the purple stems are a strain thing but some plants I noticed having purple veins so hopefully the added P will help out.

Thanks for stopping in, I really want to get to the bottom of this.

 

[Humility]

VPD is more difficult than it needs to be really. The basic idea is super simple - hot air stores more water vapor than cold air. This is the same concept/principle as accelerating the speed of dissolving by one of three methods - agitation (stirring), increasing the surface area of the solute (most easily represented by solids such as crushing ice in a cup of water), and finally - increasing the temperature of the solute.


The hotter the air, the more water it stores. So if you have 50 wets in the air and the air temperature is 10 degrees and you then increase the temperature to 20, or 50 degrees you will still have "50 wets" in the air, but the air is now capable of storing more water than at 10 degrees and so "50 wets" will feel less wet at 20 or 50 degrees than it will feel at 10 degrees.


I think the correlation is "temp to rh, 10 under = max" , and then that is only for veg, flowering should ALWAYS be 30-60 percent, most people recommend 45-55 percent RH.


So wtf is "temp to rh, 10 under = max"? That's the way that I remember that if the temperature is 75 degrees, RH should be around 65. If the temperature is 80, RH should be around 70 and although plants shouldn't go higher than 80ish degrees F unless you're supplementing with CO2, if the temps are 85, RH for maximum performance is around 75.


VPD is simple. The hotter the air, the more water the air can hold. SeaMaiden is tired of people being instructed to "Fill the truck with 20 boxes and send it off! That's the best number!!" despite how big the truck is. The truck needs to be filled just right, and the capacity of the truck needs to be taken into account to accurately determine that number.

 

[llebz0rs]

def overfeeding. flush and build up slowly for a few days. leaves turning dark green and on the verge of claw leafing.

 

[JimmyRow]

You never report the relative humidity, only temps. Learn about vapor pressure deficit. I think RH needs to be raised. Also, they look off. Dark green + reddened petioles, may equal P-, slight. Fooling around with pH might correct that.

RH?

 

[SeaMaiden]

RH?

= relative humidity. In combination with temperatures, one arrives at what is called the vapor pressure deficit, measured in kilo-pascals, if I recollect correctly. It is the plant's circulation system, and results in transpiration, movement of water and nutrients through tissues, etc, etc, etc.

 

[JimmyRow]

= relative humidity. In combination with temperatures, one arrives at what is called the vapor pressure deficit, measured in kilo-pascals, if I recollect correctly. It is the plant's circulation system, and results in transpiration, movement of water and nutrients through tissues, etc, etc, etc.

Thanks. I too was wondering about the OP's RH. Sorry for confusion.... I've been blessed enough to cultivate in climates w/ extremely high humidity, and low. Blessing and a curse..

Keep the knowledge coming. I always learn a 'lil sumptin reading your post..