MY PLANT IS STRETCHING WAY TOO MUCH!

Okay so, I started this plant on the 12/12 cycle at 6 inches, just so it could be able to fit my grow box. But I guess it serves true that even if you start 12/12 early, the plant will not bud until about 30 days. Now I have a 3 foot plant that is too big for my grow box. The strain is Himalayan Gold. I need to know what do I need to do to get this plant to fit?
 
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