Hasn't grown yet.

[CRH777]

Well I'm 15 and my penis hasn't started to grow (3.5 hard). when should it start growing and why hasn't it started yet?

[alvin]

all people is different

[ashdyn]

I was really really really small until right before I turned 16.

[SillyShyGuy]

Everybody's body is different. My friend who is 17 years old has the same size as you, maybe you will grow later.

[deregisterme]

Well I'm 15 and my penis hasn't started to grow (3.5 hard). when should it start growing and why hasn't it started yet?

We all develop at different rates. It can possibly start growing as late as 17 or 18. As long as you've started, you should be OK. You can get hormone injections from your doctor, though they only consider that usually at 16, if you haven't started at all yet.