When to top potential mothers from seed?

Hoping for a little advice from some more experienced than I...

I am growing 8 white russian and 8 indian haze (Joey Weed) from seed. My intentions are to come out with 1 mother plant of each strain.

I plan to top these plants as to bush them out, and root the tops to reveal the plants sex. So I know which plants to cull out. Male. You know.

My plants are now about 6 inches tall (+- 2in) and about 6 weeks old (+- 1 wk). 4-5 leaf sets (is that what they are called?) going up the stalk.

My question is... When should I make my first cut off the top as to make smaller bushier plants? I don't want to do it to early, however, I have heard that early is key. Anymore suggestions would be great as well. How many times should I top, other training techniques, anything I should watch for?

Growing under a 400 watt MH with cooltube in a 70 cube ft room. Exhausted and air cooled w 440 cfm fan. Active intake with 125 cfm fan. Both fans on full speed. h - 7 ft, w - 5 ft, d - 2 ft closet. 16 inch osci circ fan posted mid heighth. Light hung 12-16 inches above plants. Grown in soiless mix, currently 6 inch square pots, fed with Canna Substra and much love.

I am growing these mother plants to be moved to an armoire cab flourescent setup where mothers will be maintained, clones rooted, and veg grown to height, cab dimensions: (6 ft tall, 3 ft wide, 2 ft deep). Veg will then be moved to flower in my closet where they are now. In the closet they will be flowered under the same setup, uprgraded to 600 watt HP sodium. Might drop in a few large compact flour on the outer borders where they will not be blocking light from the HP Sodium.

After I move my two mothers to the cab, I hope to flower any other females from my 16 plants. Then when the plants from seed are harvested, I already have my line of clones to be moved in and start my perpetual thing.

I have grown 3-4 yrs outdoor. This is my first full indoor. A different game, but i have a little experience.

I must say, they are looking real good.

Hope some of you vets can shed a minute and give some advice. It would be much appreciated. Thanks.

I'm well read and a bit experienced, as I run my moms like you want to. Well.. I'm getting my cloning down, anyways. So.. I am good w/ 2 leaf sets and make sure your top has 2 leaf sets that are snippable, plus a set to leave (and cut, if you wish) and cola. So.. your plant should have 5 leaf sets and cola, in my opinion. I snipped my hopeful mom's top this way and she did fine. The next time I took clones, there were 2 tops. I snipped them all the way down to the original crotch and now, there are 4 tops!! You see where I'm going with this. My mom is under 46 W CFL, so you're aware. I get clone-able height roughly every 2 weeks. My plant is bushy, happy and healthy.

ON THE OTHER HAND.. my clones have not taken. I think I got this figured 2 days ago or so, though. I have been nuting. N causes plants not to root! D'OH! So.. I flushed once, I will flush again tonight HARD and will probably flush one more time and I'm expecting the clones to take this time. I've cloned a million ficus. This isn't that different, except that I never nuted my ficus.

Luck.

dontbethatguy: For what its worth, from my limited indoor growing experience, I've topped my plants at about the same height as what yours are now. Looking back on it, I don't think I really needed to as much as I thought. I mean, it keeps the height down, so they are more bushy instead of a tree. But my plants turned out fine. Right now I have two of them as mothers. One of them likes to churn out cloneable branches, and the other mother is a little greedier. They clone fine tho.

Elephantrider: I realize you CAN do it, but why do you keep topping your mothers? Why not take a clone from the lower branches, instead of constantly taking the main colas? Just wondering what your reasoning is.... Also, you mentioned your clones dying off...are you keeping their environment humid enough, and warm?