Per Sq Meter yield

I am a new to this. What is a good number of plants for my first grow?

What can I expect with a 600 watt MH/HID light on my first grow?

What is realistic for a soil grow the first time and how many is safe for my first trial?

Do it up!!!!

A couple of big ladies, or a dozen little girls, all depends on what/how you want to grow
Dr. Jekyll

Go with 2 dozen, as you will likely kill a dozen, then the other dozen be will half male, of which half your females will become hermie.
Mr. Hyde

Pretty much sums up my first grow

I don't have to room for a lot of plants. I was planning on going with feminized seeds.

Three plants with a good veg. Should be able to harvest at least 12 ozs. Less plants to watch over , and a lot of room for some fat buds.

I say grow 5 as some will not germinate and then you can go from there dont expect a big yeild its your first. Do you have a ph meter ppm/ec meter. Better start with those first or you will end up with nothin your first grow/grows are for learning realistically dont expect poundage or ounces. What type of lights etc. Atlot of variables to distinguish

I have 9 indica in 5gl tall pots under 600w in 42"x42" space. I'm 10-14 days away from harvest and it's looking to be about 1 - 1.25 lbs of good bud.

Um, everyone seems to have skipped the question of the day here.

Do you really mean in 1 square meter of space? OR should I ask, In what size area are you going to use?

Some seed breeders give a gram yield value based on a SOG (sea of green) grow, In a square meter. These value's are estimated for plants set to flower at 8 - 12 inch's in height, breed dependent.

So to effectively answer your question we should know these things.
How much space are you going to grow in?
What size pots do you intend to use for soil?
What strain do you intend to grow?

Rules of "thumb" for newbie's
600w should do well for Indica or Indica dominate strains in a 4x4 area.
1 gallon of pot size SHOULD produce 1+ oz. of quality dried product (In time as you learn, you SHOULD be able to dbl that - don't get excited and expect that yet!)

I would, If I were you, Grow 4 plants in 3 gallon pots, in a 4x4 area
I would attempt to hold them to 32 to 36 inch's at finish......Read up on how much Cannabis strains "stretch" in flower.
I would "top and lollypop" 2 of them and just "run" the other 2 so you can learn the difference of what you'll get. (search "how to top" here at this site (read the post from uncleBen) - how to "lollypop" too.

I hope this answer is what you were looking for!

Good Luck