Combing hair extends it OK so I'm trying to make a feather by using scaled cube as a base, and i use 2 edges as a vertex group for particles, now when i try to comb it it either rises towards me or on the very top when I try to comb it - it extends ridiculously (see images)

after some combing here i already had to cut off top because it went too much


after I try to fix the top a little bit 


keep lenghts and root are checked, any advice?
You may need to apply scale in Object mode (CtrlA > Scale). 

The hair length will be affected and probably all the combing already done will be damaged, so I'd suggest starting with a fresh particle system after applying scale.