Can they use 2700k light late into vegging? I have lots of room to add some spare 2700k CFLs, but I don't want to put them in there if it's just going to increase my electric bill w/o much help to my plant. Should I just wait until flowering?
you don't mention how old your plants are. although, it doesn't really matter. your cfl is hardley gonna burn up your plant. i'd suggest getting some sort of hid lighting set-up. cfl's won't net you enough weed to last very long. at least not enough to warrant growing it for 3 plus months.
Enough 42watt CFLs can grow less than a handful of plants very well. I'm not looking to grow a massive amount anyway. I'm going to keep one mother and just put her clones into a flowering box at 2inches tall and hope they grow around 1ft each full of buds. Below is a link to my flowering box. http://forum.grasscity.com/grow-room-design-setup/181994-pc-flowering-box.html I'm 1 month into vegging now. I just want to know if my plant will benefit during veg if I add some 2700k lighting along with my 6500k lighting.
The 6500k is much more important during Veg but the 2700k does help. If you can afford to do it, you might want too. Either way so long as you have sufficent other lighting you wont need to if you feel the need not too. But do hook those up during flowering