Bleaching shortish hair?

With the caveat that I've never bleached my own hair when it was long, so I've never done separate roots/lengths anyway, I just slapped bleach all over when I had grown-out pixie hair. I think if you keep it warm while it's developing (rather than worrying about the temp of the room you apply it in) it shouldn't make much difference.

What end result do you want?

Make sure you go to a warm place while it's processing. Cold is the death of bleach! Be careful using a hair dryer. I had a friend who did that and held it in one place a bit longer than anywhere else. Not only did she have horrible breakage in that bit, she had really nasty burns on her scalp too 🙁

Yikes I'll be careful with the hairdryer!

I'm not sure what colour to aim for yet, maybe green.

IT kind of depends how much you want to avoid hot roots and how long your hair actually is. Green can show hot roots really badly because it's not the most forgiving colour.

My hair is currently about 4" or 5" at the longest bits, down to 2" at the shortest. 
I'll probably get it cut again before I do anything though, either way it'll be after christmas.

You probably will get hot roots then.

Haircut update!

It's all less than 3" long now.

Edit:  Yeah hot roots happened  :/  oh well.