Catching-Up a Girl That is a Week Behind?

How do i "catch-up" (katsup for some of you) a girl that i didn't hatch until one week after the other? The one that needs to catch up is a Sativa (Honey B from Barney's Farm) and the other which is doing fantastic and really bushy is the Indica (Blue Cheese from Barney's Farm -- it may be LSD though, but i think it's Blue Cheese). What would be the best way to "catch-up" the hindered/lagging girl?

The only way I can think of is give the smaller one 24 hours of light. This will work only if the other is on 18/6 or 20/4 though, and may not even work being that sativas take much longer to grow.

If the small one is sativa it will likely catch up the indica anyway based on how stretchy they can. Check peoples journals for how many times stretch to expect. You could apply some lst as well.