How tall should I let plants get?

It's too late for this grow, but I am growing 6 medical plants and would like to know how tall I should let them get in vegi stage to get 5 oz per plant. I have almost 6'x6'x 9' framed room in garage with 2 600 watt hps lights.
Portable AC and 440 cfm carbon filter also. I grow in 7 gallon grow bags and this are dimensions of plants on last day of vegi last Sunday:
THC Bomb1: 18" tall/ 30" wide
THC Bomb2: 16" tall/ 27" wide
THC Bomb3: 18" tall/23" wide
BigBlueCheese: 21"tall/25" wide
BigBlueCheese2: 17" tall/23" wide
White Widow 18"tall/ 22"wide

All plants have been tied down using LST technique on advanced growing forum. ThcBomb2 has been trimmed using FIM technique on advanced growing forum. I have been giving second feeding after nutrients from soil have been used up. Last feeding was 3/4 strength fox farm nutrients.

Anything I should consider to move from 3 oz to 5 oz yield?

id let them veg for 8 weeks with ur mh then go with hps. don't know how tall that will get ya but u should be near 5 dry each

tomascat said:

id let them veg for 8 weeks with ur mh then go with hps. don't know how tall that will get ya but u should be near 5 dry each

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If the plants weren't tied down, they would likely be much taller. They are pretty wide and fill my space pretty well. My clones and seedling usually get 8 weeks under crappy T8 lighting until grow room is empty. I vegi usually two weeks in MH lighting before 12/12 flip. I wonder where I can push size without having room too full. Big Blue Cheese can stretch 3x it's vegi size. Could deal with two plants above 50"-60" tall. Might be interesting

If you vegging your plants till the nodes are alternating stops the strech aswell...id say if your nodes are alternating 2 weeks onwards they should only double in size if even that..you need to watch the height of your light aswell..i mean a 600 watt from my experience from the bulb will penetrate know futher than 4foot for solid nugs..so that's 18" from the plants and there 18" now and the strech say another 18" thats 5 foot...so by right U should be flowering them now...to make full use of your light or U will end up with a lot of b grade buds down futher on your plants...just my thought...happy growing

scarecrow77 said:

If you vegging your plants till the nodes are alternating stops the strech aswell...id say if your nodes are alternating 2 weeks onwards they should only double in size if even that..you need to watch the height of your light aswell..i mean a 600 watt from my experience from the bulb will penetrate know futher than 4foot for solid nugs..so that's 18" from the plants and there 18" now and the strech say another 18" thats 5 foot...so by right U should be flowering them now...to make full use of your light or U will end up with a lot of b grade buds down futher on your plants...just my thought...happy growing

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Thanks for your advice. My plants have filled in really well after tying stems down awhile ago. Hopefully I'll get lots of colas. Tons of tops especially on plant I tried FIMMING guide on. Not sure how it will end up, but I'm guessing maybe too many tops. Probably needs to spread energy out a lot. Plant is so even it looks almost like a azalea