Canna coco grow problems

[earthwormgod]

Hi all,

I've been trolling around here ever since my old home (AN forum) went down, and I have to say this seems like a great place with knowledgeable people.

Here is a little background on my situation. I was one of the unfortunate people that got hit with the infamous "Hydrohut problem" (pics to follow)
anyway, after loosing LOTS of plants I converted a half bath, put up some poly and voilà, everything started to come back to life.

This run is in Canna coco. Using Canna nutes, coco pots and Canna coco. This is my first run in coco. My PH is 5.8, water temp is 69f, room temp is 80f, Im running a 600w HPS and hand feeding (setting my drip up tomorrow)

As you can see in the pics, some of the plants leaves are curling upward and they are a bit wrinkled, also, I'm starting to see some purpling in the stem
The only thing that I know I was doing wrong was the lack of ventilation. I have a 6" helper fan exhausting the light, a 4" Vortex bringing in fresh air from the adjacent room, but I wasn't exhausting the room at all (except opening the door a few times a day) To fix the problem I installed another 4" vortex to exhaust the room tonight.

This looks like a phosphorus deficiency to me but I'm confused as to how that is possible with Canna nutes. Maybe Im under watering?

Any help is appreciated!!!

pics are in my gallery - I cant seem to add them to the post yet.

I also posted in the coco coir forum but thought I should have posted in here instead. Hope that didnt break any forum rules.

 

[Rosy Cheeks]

Leaves curling upwards, and only the top fan leaves? I'd say they came a bit too close to the HPS my friend. Heat stress.

 

[MynameStitch]

I also agree, heat stress, move the light up some.

 

[earthwormgod]

Thanks for the help.

Maybe someone could clarify something for me. When you say heat from the light, are you referring to the actual temp or lumens or both? The reason I ask is the temp at the canopy is only 76f and the light is 20" away from the top of the plants.

I guess I just don’t understand how its heat stress.


On another topic, since the plants healed from the hydrohut, they have been growing super fast. Generally this is not a problem, but, I only have so much height in the room and I haven’t flipped to 12/12 yet.

How can I slow these plants down from vertical growth?

If I top them and/or take clones from them, how long do I need to wait till I can induce flowering?

Also, sisnce these plants were from clones, and there is no real defined tops, can I still top them to slow them down from growing vertically?

 

[Rosy Cheeks]

It's not just about the temperature, it is about the whole growroom environment. Two very important factors to concider are air humidity and ventilation. Low air humidity will make your plant less tolerant to higher temps than high air humidity.
A boosted ventilation (wind) will drive the moisture from the leaves and make them more fragile.
The heat (in the form of infrared radiation) and light output from a HID lamp is different from the heat and light coming from the sun. The 18/6 or 12/12 hours of constant bombardment of light photons (or light waves, if you prefer Max Planck's theory on light/energy rather than Einstein's) is actually an aggression on the leaves, wearing down the cuticle and cellular structure of the epidermis (leaf surface). While the Cannabis plant wants nothing more than to be fed with as much light it can take, it sometimes get too much of the good stuff. When the leaf surface is no longer capable of regenerating the damage caused by 'abrasive' light, the leaf fries.

Only your plant can tell you when that limit has been reached, you will have to adapt accordingly.

There are many different ways to slow down vertical growth. Closing in your lights (perhaps not for you), increase nutrient strenght, use a light source higher on the Kelvin scale (a more blueish-white light), flipping gradually from 18/6 to 12/12 rather than straight, etc. There are several products on the market that slows down vertical growth, most of them hormone based. Foliar spraying Fulvic acid during the initial weeks in flower will slow down vertical growth somewhat.

 

[earthwormgod]

Thanks Rosy, very informative.

Will using fulvic acid have any negative affects on the plant?
I would think using fulvic acid would actually stimulate growth not slow it down?

Also, If I take a few clones, how long should I wait till I can flip the plant to 12/12?

 

[Rosy Cheeks]

No, Fulvic acid will only have positive effects on the plants, in difference to many of the hormone-tampering products used to reduce stretch (take Superbud as an example, which contains a plant growth regulator called paclobutrazol, believed to or at least suspected to be carcinogenic. Besides that, growers report that buds are less potent after using Superbud).
Fulvic acid does stimulate growth in the sense that it improves the plant's capacity to assimilate nutrients, therefore helping it to grow faster by improving its metabolism. It just doesn't stimulate vertical growth, or rather stretch.

The stretch in stem tissue that your plants produce when flipping the lights is a natural reaction to less light (6 hours less per day cycle if you go from 18/6 to 12/12). It is called etiolation, in which starch levels drop, strengthening tissues and fibers begin to soften, cell wall thickness decreases, vascular tissue is diminished, auxin levels rise, and undifferentiated tissue begins to form. The result is that internodal stems elongate. That way, if a plant grows below a canopy shutting out light, this reaction will make it stretch above the canopy, to where the light is, IOW a survival mechanism. But when the flower mechanism sets in, the plant will concentrate all its resources on bud/flower production rather than leaf/stem production, and the stretch pans out. This takes aproximately a couple of weeks, depending on genetics.
We don't know exactly how yet, but it seems like Fulvic acid reduces etiolation simply by speeding up the transition process between vegetative state and flower state, which also means that bud growth will start earlier after flipping the lights (can't say no to that, can you?).

Keeping Nitrogen levels high stimulate shoot growth, which is partly why you should keep nutrient concentrations high after flipping the lights, and stick to vegetative nutes (rich in N) until bud growth starts.

 

[earthwormgod]

Great Info, Thx.

What strength do you recommend when using Fulvic acid as a foliar spray? Also, how often do you recommend spraying it?

Back to my other question. If I take cuttings how long do I need to wait till I can flower the plants?

 

[Rosy Cheeks]

That depends on the concentration of the Fulvic acid. It should be noted on the bottle. I use GH:s Diamond Nectar, and I believe it's 2-3ml/l. Overdosing on Fulvic acid won't do your plants any good, but no harm either.

You can take cuttings whenever you like, even in flower, and you don't have to wait any particular amount of time after before flowering. Whenever you take cuttings, you will stunt the plant temporarily (depending on how many you take in relation to the plant's size, it will have a greater or lesser impact). The stunt generally lasts a few days, while the plant 're-organize' itself within in order to produce new growth elsewhere.

I know some growers actually cut or otherwise stunt the plants right after flipping the lights, because the stunt will equally affect the etiolation, keeping the stretch down.