Cool temps and low humidity. What will happen?

Despite my best efforts, the room remains susceptible to changes in weather. During the cold months, the temps stay in the 55f-65f range, and RH is around 35%-50%.

While I realize this isn't exactly ideal, my hunch is that it also isn't going to be devastating either. I'm more concerned about the cool temperatures.

Anyway, what sort of effect does this kind of cool temps and low humidity have on the finished product?

slower growth, smaller buds, if you can keep it around 65 during day and night then it wouldnt be as bad but 70-80 are the temps you want.

are space heaters out of the question? i have my house 50f day and night and i gave up both my heaters to keep my babies alive, being cold is one of the costs if you live in a cold region.

I would think that your RH is fine in that range my room stays really low like 10 to 30 percent low and as of now no problem i think your gravy on that i have a little oil filled heater just looked it up on walmart site for $38.00 it is digital with a thermostat i have not used mine but it will work great i think check it out http://www.walmart.com/ip/Optimus-Portable-Oil-Filled-Radiator-Heater/15162311 I dont know if this link will work for you still not familiar with all thats on this site sorry.

Just seen that one is not digital like the one i got but im sure it would still work