Sick plants

[CaptainHarmonic]

Our girls are sick Its not clear to us what exactly is the issue. Perhaps a mag deficiency... Light stress seems unlikely since they're under a flouro. Could cold be an issue? Our temp is always around 78 - 80 degrees in the room, but the soil does feel cool. definitely not a pH issue.

There's this bizarre leaf tacoing kind of effect on the tops only, plus yellowing of older leaves with erratic brown spots and even brown streaking. Nute burn perhaps? We haven't fed them anything yet, but we're using Just Right Xtra Organic soil, which is this newfangled coco coir based soil, which has several organic based nutrients in the bag.

I tried to include a lot of decent pics!


How long has this problem been going on? Week or two.
What STRAIN are you growing? Fast Manitoba x Manitoba Poison i believe
What was the establishing technique? (seed or clone?) seed
What is the age of your plants? few months
How long have they been in the soil mixture they are in now? month or so
How Tall are the plants? 3 feetish
What PHASE (seedling, vegetative or flower) are the plants in? veg
What size pots are you using? (Include how many subjects to pot) 3 gal pot
What substrate/medium are you using? What brand of soil mixture Just Right Xtra Organic, coco coir based soil
What is the pH of the "RUN-OFF"? right around 6.5. ppm was 1000+
What method of pH test was administered? Using Strips? pH pen? meter
How often are you watering? whenever the soil is dry
What size bulb are you using? t5 flouros
What is the distance to the canopy? went from a foot to several feet, no difference.
What is your RH Factor? (Relative Humidity) stays around 70%
What is the canopy temperature? 78 to 80 typicallyat all times
Tell us about your ventilation, intake exhaust and when its running and not running ? a/c runs on and off as needed. a/c exhausts outside of room. passive intake. filtered air actually exhausts into room.
Is the fan blowing directly at plants? yes but it rotates
Is the grow substrate constantly wet or moist? not contstantly
What water are you using? Reverse Osmosis (RO)? Tap? Bottled? Well water? Distilled? Mineral Water? RO
Are plant's infected with pest's? no

 

[LolaGal]

Maybe over watering? Just a thought.

How do you test to see if the soil is dry?

Best to use one of those cheap probe things you stick in the pot.

Don't know anything about your medium.

 

[Hazy Lady]

They look like they are in need of some Mag and Cal, leaf curling is usually heat/humidity related and though your RH is a bit high @ 70% i don't think your plants look too bad, I would leach the pot's just so i have a fresh start PH wise and then feed at 1/4 to 1/2 strength adding some Cal-Mag or Epsom salts at 1 teaspoon per 10lts and they should be fine, i would try and reduce the RH to 50/55% if it's possible?.

 

[CaptainHarmonic]

We don't water very often in veg, especially since we have been using this soil. Typically we wait until the plant droops and begs to be watered or the soil is bone dry and the plant is very light.

 

[40AmpstoFreedom]

Cal mag big time. Yellow between veins and it is starting from the tip of leaf to the back...So looks like cal and mag def for sure.

And if anything those girls are under watered! 600ml-1 litre of water per gal of soil works for me every 2 days in veg.

PS: for future reference if ti was a N deficiency it starts from the back and goes forward and the veins tend to not stay green.

 

[Mr. Greengenes]

Underwatering and overwatering go hand in hand. Both can kill roots, and often we do the one and try to fix it with the other. If a plant has it's roots at the bottom of the pot, which most plants do a week after repotting, it's much harder to overwater. I only use the wait until the soil is pretty dry method right after repotting. When the plant gets bigger and is obviously filling the pot with roots, I basically never let it get dry. A fast growing plant in a smaller pot can be left in a tray with some water for a few hours, and all that will happen is it'll grow like crazy. Hit peak flowering just as the plant becomes a tad rootbound with that watering technique and you'll get huge, heavy buds.

 

[CaptainHarmonic]

That's pretty interesting actually. So far we've been going by the rule that you water only when the plant needs it.

 

[10k]

Waiting for the soil to get bone dry is never a good idea. In soil grows I would follow the instructions I give in the lift the pot method (in my signature)

However, you are running a coco coir based mixed soil medium and it should NEVER be allowed to get to the point of being "bone dry".
Provided that your containers have adequate drainage and aren't compacted too much, your coco is much better off staying slightly moist.

If it were a straight coco coir, I would advise feeding daily to run off using a coco specific nutrient package, but yours is more like a soil and should be treated as such following the 'lift the pot' method. Just don't let it get overly dry any more. The method you were using, of waiting for plants to droop and beg for watering is very stressful on the plants and may have contributed to them starting to become root bound.

Pot em up and begin feeding per HazyLadys instructions,
but be cautious as you're not running very intense light so a little goes a long way nute wise under those t5's

hth,
10k

 

[CaptainHarmonic]

Thanks for the advice. I did notice that the coco soil didn't seem to need much watering. Literally since they were repotted about 2 weeks ago we haven't watered them. I kind of figured our watering habits might need some adjustments!

I gave a few of the sick plants some CalMag, and obviously they needed to be watered bad... will post an update in a week or so when I have some results.