HEAT STRESS, but its not hot...

[StoneyBud]

Cool Teddy D, watch for stretching. Don't get your light so high up that the plant starts stretching like crazy.

I guess your thermometer isn't the type you can push into the soil?

It might be a good idea to get one of those so you know what's happening in there, temp wise.

Can you take some pics of your plants and post them?

 

[teddy d]

yeh i wil in a day or two. i use a digital thermometer at canopy level. should i just get a glass mercury thermometer to push into the soil?

 

[StoneyBud]

yeh i wil in a day or two. i use a digital thermometer at canopy level. should i just get a glass mercury thermometer to push into the soil?

I've used a glass thermometer in soil before, but that was when I couldn't afford to do it right. Soil probe thermometers are cheap now. $10 and up, depending on how fancy you want it.

I use a BBQ remote temp sensor. It's made for sticking the probe into a hunk of meat on the grill, but it works perfectly as a water or soil temp probe also. Its accurate also. Digital, and no wires. I can put the readout anywhere while I'm watching it. I've gone ahead and bought a second one as a backup in case the first ever quits. It's been about a year now. Not bad for $30. I've measured temps from 34F to 180F using it.

It's a "Oregon Scientific AW129 Wireless BBQ Thermometer with Probe Thermometer and Remote"





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[shuggy4105]

too much light....Light-bleaching is what you may be experiencing.

That chart is based on established plants.

Pics would solve any diagnosis problems....

Good luck bro,

Shug

 

[teddy d]

the first two are what i would expect to see from heat stress.

the second two photos are the new growth. it looks exactly like when i had massive cold stress this past winter. the "claw" like curl, and large ridges making the leaves look kinda like clay is the only way i can describe it.

will a leave develop in this manner due to cold AND heat stress?
with the cold it took me months to figure it out cuz the temp read 70F and i was given every answer under the sun even the grow shop guys didnt know.

are both these different looking symptoms heat realated? (the strain is Nebula BTW)

 

[StoneyBud]

Your curl could be from several of, or one of:

1. RH low on leaf surface from too much air being blown on it.

2. RH of the entire room might be too low.

3. Nutrients are too strong.

4. pH too high and causing lockout.


No way I can tell from where I am, which one or ones of those is causing your problem.

The RH is easy. Try misting the plant lightly with plain water a couple times each day. That will radically increase the RH on the surface of the leaf. If the leaf relaxes and/or the new growth shows no sign of curl, then you've found your problem.

The nutrient strength is also easy. Water with only plain, pH adjusted water for about 4 or 5 days. If the new growth has no curl and the old growth stays looking the same, then that could be it.

Test your pH and make sure its correct. Test the run-off from your container AND what you're putting into it.

Good luck man!

 

[teddy d]

1. I did have a fan blowing on the plants because of the temps but now it just blows above the light not on the plants at all.

2. RH averages about 50%

3. using FFOF with plain water. it burned them when they were first tranplanted but they are about 10-11 inches tall now and should be able to handle that soil from past experience with this strain.

4.water ph is between 6.1-7.0 on average ( for the first few weeks i just keep it between 6-7 since FFOF is ph balanced I have never had an issue before.

yesterday I removed the heater completely, and changed the exhaust timer to run every 30 min on 30 min off. the outside basement temp is 64F. the thermometer under the light at canopy level now reeds 77F, but it feels cold as heck in the room to me (will measure room temp now). After battling stunted plants due to cold weather all winter im really nervous about any air temps/currents/drafts under 70F.

this is what I ran into before. I million different ideas about what could be causing the "claw leaves" but every issue I addressed never helped untill I put in a heater to give the room its own stable temp seperate from the radiant heat from the bulb.

I cant imagine im seeing cold stress and heat stress at the same time, but thats really how it appears to me

i was so confident that this would be stress free given that i have dealt with just about every issue in the book and learned to diagnose most issues right away. but this claw leaf thing seems to be a "could be 100 things" issue

 

[StoneyBud]

64F is low for the ambient temp, depending on the root-zone temps.

In a perfect world for MJ, the soil temp would be at 75F and the above ground plant temps would be the same.

If you lower the above ground temps to 80 and then lower the root-zone to 70, it's the same thing. An average of 75 for both. MJ works this way within reason.

No, you can't take the root zone to 50 and the above ground temps to 100. That's outside the safe zone on both ends. It makes no difference that they would average the needed 75F. The averaging only works in cases where both temps are within the safe zone of 65-90.

With your ambient temps being at 64F it really makes no difference if the area the plants are in measures at 77F at canopy level. Your lights are acting as heaters for you.

Directing the flow from your fans above the plants, so that the grow area temps heat it before it hits your plants is a great idea. Blowing the 64F air right on the plants might lower the canopy area temps below the 77F you're getting.

If the "claw" went away when you raised the ambient temps of the room, then I'd say that was your cure. Part of becoming a seasoned grower involves adapting to the many cause and effect possibilities that you can run into. Temps both below and above ground are very important.

It's temping to try new strains all the time and fun to have a cool selection of weed, but it has a draw-back. You never get a strain where you're completely familiar with it's characteristics during growing.

With new strains, you always have a learning-curve where you have to react to problems for just that strain. If this type of growing is your choice, then keeping notes on exactly what works is very, very important so you don't have to guess later when you grow it again.

Hopefully, simply redirecting the fan air to not hit the plants, but so it is warmed to the 77F temp before hitting the plants will work for you to resolve the "claw".

When you do figure it out, note it for this strain. It may not work with the next strain when you have another whole set of problems.

 

[teddy d]

no, I think you are confused.

the grow space is a room built in the basement. the actual basement is 64, after removing the heater the abient room temp(grow space) with the light as the only heat sorce is 72, and the canopy is 77.

but when the exhaust runs it creates negative pressure in the room and draws cooler 64F air from many cracks ect. thats what creates cold drafts. i dont have an intake inlet because the room is light tight, but a far cry from air tight.

 

[StoneyBud]

no, I think you are confused.

the grow space is a room built in the basement. the actual basement is 64, after removing the heater the ambient room temp(grow space) with the light as the only heat source is 72, and the canopy is 77.

but when the exhaust runs it creates negative pressure in the room and draws cooler 64F air from many cracks etc. that's what creates cold drafts. i don't have an intake inlet because the room is light tight, but a far cry from air tight.

Sorry, without pics of your grow setup, I was guessing that you had a fan in the doorway of the grow area blowing air in.

I'll just give up now. I can't picture what setup you have without pics, so I'll quit guessing.

Good luck!

 

[teddy d]

thanks for the help.

 

[shuggy4105]

I think you may be confused as to what Stoney`s saying...

Your root-zone temps may be too cold whilst your canopy is in the safe temp zone.

Also, that the gals may be perspiring at a high rate due to the fan blowing directly onto the tops ,making the RH too low (on the leaves), causing leaf curl.

Get a simple thermometer and place it on top of your soil to see the difference. A probe will do the same job.

My two cents, have you looked into Mg def? Just a thought, looking at the curl. They also look really dark in colour...

Just another wee tip for you; Try not to be so condescending when chatting in reply, the folks here are here to help.

Good luck man

P.S the pic is of a 'cold to warm' scenario.

 

[teddy d]

yes i did not realize exactly what he meant. i thought he was telling me how to manipulate the root temp to compensate for canopy temps.
i did not realize he was saying it could be the actual problem.

condescending? at no point was I being condescending...

i actually just thought someone was being condescending to me! when in fact he was making a joke. tone/intent is hard to detect on the net.

I highly appreciate any and all advice. nothing i ever say is meant to be taken that way, so im sorry if thats how im coming across.

im still a beginner and am just trying to learn.

(i dont think its a mag def though cuz my ph is pretty good and the soil was burning the plants up until a wekk or two ago. now they seem to be adjusting to the "hot" FFOF.

 

[shuggy4105]

Transplant shock, I`ve recently experienced the same problem when moving to a slightly more acidic soil, with similiar looking effects as to which you`re experiencing too.

You`re right, it`s very hard to judge someones temprament online. Just as I may have rushed to judgement myself.

Good luck though cuz, keep us updated on the progress
Shug

 

[StoneyBud]

You're very welcome teddy d and thank you for trying to clarify, shug.

Plant biology is a fantastically complicated field. There are thousands of things that happen within and near plants that result in what we simply see as "produce".

Each problem can be a combination of conditions and rarely is it only one condition that causes radical problems in plant growth and health.

Two very important parts of the whole are the temperatures above the ground and below the ground in the root zone. Each have a huge impact on how a plant grows, uses its available nutrients and the over-all health of the plant.

The leaf curl is perhaps, as shug has said, a result of too much moisture leaving the surface of the leaves due to rapid transpiration. Slow that transpiration down and it may end the curl on new growth. The old growth will more than likely retain the curl despite your cure.

If the new growth and the over-all health of the plant are good, then it should result in a good formation of buds and yield at harvest.

 

[teddy d]

Plant biology is a fantastically complicated field. There are thousands of things that happen within and near plants.

so true! after dealing with dozens of problems. I was finally confident, and was thinking:

grow all the same strain, same pots, same soil, same enviroment, same nutes. Remove as many variables as I could. I felt so confident in my ability based on my experience observing problems before they become a huge iissue.

I was reading a forum where everyone was talking about "THE CURL" AND THAT IT IS A NITROGEN TOXICITY...

 

[shuggy4105]

Possible, although they most likely mean downward curl, as in taking the 'claw' effect.

Don`t get me wrong I did mention in a previous post your gals leaves look very dark. This can be a co-symptom of many deficiencies though so not full-proof by far.

Even though you`re dealing with the same strain; each plant may have very differing needs. It`s all down to the stability of the genetics.

Any joy with a solution yet, and have you looked at the defficiency charts?

here`s some further pics of heat stress and light bleaching etc...Heat stress

Light Bleaching

Also light bleaching and heat stress

 

[teddy d]

Possible, although they most likely mean downward curl, as in taking the 'claw' effect.

yes but if you look at the last two pics I posted they are "claw" like. i reduced the temps for a while and the deges stopped curling up. but now about half of the larger established fan leaves have downward tip curl and the new growth is full claw.

I think its over fert.
ive noticed yellow tips all over but not cripsy. im almost positive is nute burn. I think this strain is sensitive (nebula) cuz im using ocean forest soil with plain water. when first transplanted the soil burned the crap out of these plants so im pretty firmiliar with the way nute burn looks. but these plants are going on about a month old and they are really getting quite large Im pretty surprized to see tip burn on plants this big with not additional nutes, and curling...

btw nebula is notorious for having dark green leaves with almost a deep purple look to them , and dark purple stems.