Red vs Blue

Are red bulbs necessary to bud? I have a 2ft T5 light with 4 blue bulbs and didnt want to go spend more money on red ones if they aren't needed to bud.

short answer is no, you can bud under what ever you have. will the results be optimum? no.

spend the money

I take it the outcome of red is well worth it then?

as with life, you get out what you put in. Yes, they are worth it

I have 2 T5's same as yours, I use mine for seeds, there great for starting but I get more big leaves than hieght so I switch to MH. But I'm thinking the T5's would make an excellent light for late/mid budding, I think you need more watts with florescents the temp should high also, plus the UV in the MH is a big bonus for me. By themselves would be worth trying but more to compact the bud growth to for hieght.

Yes you could bud, but you need red for better results. Blue lights are like early to mid summer sunshine, and red lights would represent late summer/early fall sunshine. The plants want to bud later in the year, so by moving to red you replicate that time of year with the proper light spectrum.