6 weeks in, only 4 inches tall

[knubie]

Hi everyone, first time poster and grower here. I have two different seeds planted (rocklock/lemonskunk) and they are both having the same problems.

These guys sprouted about 6 weeks ago and seemed to be growing well (albeit somewhat slowly) under CFLs for the first two weeks. Then I added a 150w HPS. I had about 6 leaf sets on each plant, but eventually the tips started drying up and dying, at the same time the plant just stopped growing. It did this for about 2 and half weeks. About a week ago after 4 sets of leaves dropped off the plants started to slowly grow again.

I never added nutes since they just seemed to small to have a nutrient deficiency, but i'm guessing that may be the problem after all. Just wanted some opinions.

indoor or outdoor indoor
soil, soilless, coco, aero, or hydroponic soil
Soil type/brand Fafard potting soil
Anything you have added to the soil lime and peat moss
Soil or slab runoff pH 7
Water source tap
Source water pH 7
Age of plant 6 weeks
Type of fertilizer none
Lighting source and distance from plant 150w HPS & 2 CFL, 18"
Air temperature 70-80 during the day, night i don't know, lower i'm sure
Air % Relative humidity ~20%
Lighting schedule 18/6
Type of ventilation your room has good ventilation

thanks in advanced for the help!

See photos:

knubie Reviewed by knubie on 12-14-2010. 6 weeks in, only 4 inches tall Hi everyone, first time poster and grower here. I have two different seeds planted (rocklock/lemonskunk) and they are both having the same problems. These guys sprouted about 6 weeks ago and seemed to be growing well (albeit somewhat slowly) under CFLs for the first two weeks. Then I added a 150w HPS. I had about 6 leaf sets on each plant, but eventually the tips started drying up and dying, at the same time the plant just stopped growing. It did this for about 2 and half weeks. About a week Rating: 5

[purpleskunk777]

To me it looks like your pH might be off. Slow/ceased growth is usually a tell-tale sign of a nutrient lock of some sort.

What method are you using to test the pH? If it's a liquid kit, it might be skewed due to particulates in the water sample. Those cheap pH pens that you stick into the soil are notoriously shitty, bluntly put. If you're using one of these methods, I would suggest investing in a nice pH pen (one with an electrode); a little expensive, but pays for itself in the long run.

[oldmac]

Hello knubie,

Welcome to the boards. :thumbsup:

The 1st thing that sticks out to me me is your Ph level.
For soil you should shoot for abt. 6.3 Ph.

I was not familiar with Farfad soil, so I just googled it, it contains a time release fertilizer, that they say is good for 6 months. So don't add anything else to you know how the plants react to it.
Not sure of the makeup of that soil, it may be closer to a "soiless mix" like Pro-mix or Sunshine and if that's the case you would need an even lower PH, like abt 6.

Hope this helps you and good luck growing.
OM

PS: nice start by filling out the trouble shooting form
instead of us playing 20 questions.

[emilya]

Soil type/brand Fafard potting soil
Anything you have added to the soil lime and peat moss
Soil or slab runoff pH 7

Hi Knubie! I'm a noobie too, but something here sticks out for me after all the reading I have done lately. You say you added Lime to the potting soil. This would generally be added to increase the PH and I am betting that you now have soil that is very much on the alkaline side.

I will leave it to those with more experience to tell you how to fix this, but 6 weeks is pretty excessive not to have plants that are many times larger than those... something pretty fundamental is wrong here.

Im going to watch this thread closely so that I can learn how to fix this problem if I ever do something similar, and I am sure that I will someday.

Good luck with your grow...

Emmie

[knubie]

Hey guys thanks for the replies.

I too suspected the ph in the soil was off, so I bought some Espoma organic soil acidifier, but i didn't add any yet. Is this stuff safe to use? As for the ph meter it's a HoldAll moisture/light/ph meter with two probes that stick into the soil. I know nothing of the quality or even how much it cost since my roommate bought it, but it does look rather cheap. I plan to hit up the gardening store tomorrow, any brands you can recommend?

Thanks again

[Rusty Trichome]

Hi everyone

High. :thumbsup:

Anything you have added to the soil lime and peat moss

Why? The lime I can understand, as Fafards is pretty acidic. Most peat-based potting mixes are going to be acidic unless buffered. But why the additional peat moss? It's ph is something like 4.5ish.

Lighting source and distance from plant 150w HPS & 2 CFL, 18"

Too far away. 12-16 inches is where I keep my 400w HPS, depending on maturity. CFL's don't work much past 6 inches or so.

Do not add anything else that will make the soil more acidic. You'll stunt or kill the plants.

Soil probes are crap, so don't put much stock in their accuracy. A ph pen is your best bet.