I have an auto flower plant but grows very skinny. I see puffy nice plants when I see pics but mine grow very skinny. I am sure I am doing something wrong. I have it in 24 light , 2x 85w HID
There's a lot of factors to consider. Could be strain/pheno related, but I'm going to guess it's your lights/lack of circulating air. Those look like CFL's not HIDs. You're going to need a fan to circulate the air and strengthen the stem. CFLs are almost always going to create skinnier/less dense plants as opposed to HID lighting. What nutes & soil are you using? There a lot variables to consider here, and more information would help. How old is this plant? How many watts are those bulbs each? What strain is it? Also depending on the strain, 24 hours of constant light might be more negative than beneficial, the plant might be stressed. Try 20/4 or 18/6? (Unless it's an auto that likes 24 hours of constant light)