Smelly Purple Stems

Hi guys,

I have 3 month old plants that are about 18 inches tall, out of the 9 plants that I am growing 4 of them have got smelly (as in skunk) purple stems, is this ok?
The breed is BIG BUD.

Secondly, how much longer have I got to wait until I can tell whether the plants are gonna be male or female?

Finally, how long do I have before any male plants can effect the female plants.

Yes, this is my first time and no the seeds are not feminised.

Thanks in advance.

Pearce -

yeah big bud can do that .. and I started smellign mine around a month but its not the stems .
as soon as you flower you can tell ..or they may show faint signs now . ( I reccomend snipign clones ) and flowering thoose to see wich are m/f
when the balls drop they can fuk

I got a 600w HPS in a (1.2 x 1.2 x 2.0) grow tent, I thought that in this type of environment they should have started showing by now. How do I know which are m/f by taking snippings?