Hill Climbing with Asthma

Hello,

I have asthma since I was kid. I haven't had a full blown asthma attack for over 40 years though. It get bad (ish) when I have a cold or flu - but thats about. When cycling, especially in the winter months I have to take it easy for the first 20 mins or so - but then Im ok - except when it comes to hills - where it absolutely kills me ! - I really grunt up the hills - and ain't good for much when i get to the top ! My peak flow tests are pretty poor - Im nearly always asked to repeat them ("Im sure that can't be right - lets try again") I use brown and blue inhalers. Anybody else struggle like this ? - what can be done ? - if anything !

Thank you