Why are my babes so tiny? And so quick?

[mitra]

Hi all, I am totally scratching my head and could use a little help on this one.

this is my third grow, and I moved since my last grow, so I’m growing in a new environment.

My setup:
1m x 1m x 2m tent
250w hps @20/4,
AN nutes, maybe a little old
11-12 L pots with Plagron light mix
4 plants @ day 33
Temps above canopy: 28C daytime, 18 night;
Humidity day time around 40%, sometimes even lower. I have the tent in a cave that was really moldy before, so we have a dehumidifier in the cave and I have been hesistant about raising the humidity. But I am wondering now...

This is what my plants look like now, they are Dinamed Auto. The left one is the biggest of this grow, LST’d, and already developing frost. (My other 2 plants are even smaller, one is DP Charlottes Angel Auto, the other one Dinafem IPCBD auto, they are almost as developed.

This is what my plants looked like in the last run at day 33, with the same cultivation method, in this case it’s DP ABBK

My question is why are they so tiny and so quick to flower? How come there was no stretch?
What can I learn here and is there something I can improve?

I forgot to mention that in my last 2 runs I was vegging with 250w MH, then flowering with HPS, while this run, my MH blew out on day 2, so I’m going HPS all the way...

Thanks for looking, and all the best for you good people!

 

[DTOM420]

My guess is the HPS spectrum isn’t as good for veg as your MH. I would t have thought the difference would be so profound but I’ve been having less veg growth with my 3000k LED light than I’d like with autos; so, maybe the spectrum is the problem. It’d sure make sense since autos will certainly show the effect of lackluster veg growth with their defined cycle length. It was enough for me to order some new boards to build a dedicated light for veg. Since you said not much changed from your last grow besides your light and your location, the obvious culprit would be your lighting. I popped a DP AutoUltimate seed recently, one of the strains that didn’t do great for me under the 3000k LED on the last round, and this new one is twice as big as the first one; and it’s under a 6500k fluorescent array! I don’t have the new LED veg light finished yet. Could be a variety of things that caused this latest bean to be turning out better; but it sure seems suspicious that it’s doing so well under a spectrum that’s really considered an optimal veg spectrum. Just a thought anyway.

Good luck and happy growing!

 

[mitra]

Thank you @DTOM420. I will def use a MH bulb again after this strange grow. For this grow, though, it’s too late.
The other suspect factor to me is humidity, which has been very low in veg here. It’s a mystery to me, because my whole tent became tiny, and fast flowering. The land of the Hobbit! I would like to figure out why exactly...

 

[DTOM420]

Thank you @DTOM420. I will def use a MH bulb again after this strange grow. For this grow, though, it’s too late.
The other suspect factor to me is humidity, which has been very low in veg here. It’s a mystery to me, because my whole tent became tiny, and fast flowering. The land of the Hobbit! I would like to figure out why exactly...

Just to be clear...I’m not experienced enough to be an anthority. So, hopefully one of the real gurus will chime in here for some advice you can take to the bank. But it only stands to reason that, when you change something and the results decline, there’s a darn good chance that it may be the cause. Plus, back in the day, when I started growing we always used MH for veg and HPS for flower. Nobody I knew tried vegging with a HPS. So, anecdotally, it would make sense that an HPS light wouldn’t provide optimal vegetative growth - when all other variables remain the same. Hope it works for you!