New grower plants short not getting taller

Help I’m a novice grower. White widow auto flower (f). All the 3 plants look really healthy they are 15 days old. My one plant is getting taller, but the other two are short and stocky.

What is your light situation?? What r you using?? Fill out a support ticket so people can more accurately help you!

This is the light I am using. Approximately 2 ft above plants in a grow box with aluminum foil lining.

@cindyklatt Is tht model dimmable? I do not use spider farmers but considering the short node spacing it seems its a bit intense for them…
2ft height is ideal

This is my third grow, so I’m learning. My only issue now is my plants are consistently SHORT, mostly around 12-16 inches! And some are not as branched or bushy as they should be. The plants have all been healthy and developed tasty, nice size colas.

Here’s the details: auto seeds from ILGM White Widow, Wedding Cake and Northern Lights; 1200 watt LED Viparspectra lights height closer than company recommended but not burning plants; I have three lights over five plants in a 8x4 grow tent with pitched roof; good air circulation, using rain water; Advanced Nutrients as recommended but at half strength every time I water, using Micro, Grow and Bloom and Voo Doo, Piranha, Bud Igniter, B-52, Bud Candy, Overdrive, and Flawless Finish;

The previous two I tried 24 hour light schedule, but this last grow went with a 18/6, then 12/12 schedule. I also added the supplements to the MGB base nutrients. This has led to bigger buds, but still very short plants.

I also previously used de-chlorinated, pH about 6.5-7 tap water. This last time I had rain water to use. The temperature around 80-85 day, 75 night.

I also grew Blue Dream auto this last time. Those plants grew as tall as they are supposed to be, but not as bushy. The colas are nice size, however.

Any ideas on what is going on with White Widow, Wedding Cake, and Northern Lights autos? It seems to me that something happens, or doesn’t happen in the vegetative cycle. The plants seem to be on target, but start producing flowers by 3 weeks. Any ideas are appreciated.

Below are the plants at 7 weeks

I forgot to say I’m using cloth grow bags, 2 gallon size, and using soil-less mixture. Thanks for any ideas to make plants grow taller.