man page for
-p, --password PASSWORD The encrypted password, as returned by crypt(3). The default is to disable the password. Note: This option is not recommended because the password (or encrypted password) will be visible by users listing the processes.
You should make sure the password respects the system's password policy.
But there doesn't seem to be any other way to create an account. Also, it says the default is to disable the password - what does that mean?
I am using Debian Wheezy