all depends on the hard build of your garage,ie if rendered or brick,refrain from using ivy or self clinging climbers,this will in time cause problems to the brick or rendered ,by drawing all the moisture out of the brick work,making the morter joints britttle,patiance is the key,you have not mentioned whether it is south facing or not,if north facing this will limit your option's,so passion flower will be no good,also passion will only do wll in sheltered positions,and do not like early morning frosts on them,remember passion flower is really only semi hardy,
so there for mild winters of late in sheltered positions have allowed this wonderful climber to thrive,but on a severe
winter you will lose it,i would suggest you go for a multiple choice giving you variation of colour,thus giving you interest.
will grow well except north facing
1 pyracantha red berry
2 montanna clemetis
3 pyracantha yellow berry
4 jassmin
5 weisteria
north facing
1 climbing hidayadranga
2 russian ivy vigorous growing