There was an article by an ex Euro racer in Bicycling mag (whohoo!!) a few years ago that described a hill climbers training technique: after getting an adequate basis,which you have done, find a hill of at least a mile length and 5% or so grade. Do a series of rides in a high enough gear that your cadence is 45-60 range and push it on up that hill. This builds strength and hill climbing conditioning. It is not easy either.
It is not used except as a training method. It can be hard on knees so adjustments may be necessary. People in Florida, Kansas and Okla will have to find a headwind to substitute. Steve