Sometimes it takes a few years for them to bloom after they become established.....I'd try a general fertilizer 10-10-10 or hydrangea food....but becareful not to put on too much.....stay away from high nitrogen fertilizers.....it will give you too much green growth at the expense of flowers.

Ian

Climbing hydrangeas are notorious for being slow to bloom after planting.......4 years is actually on the short end of the time range. Typically the estimated time period before blooming is stated at 5-7 years, depending on the maturity of the plant at planting.

Fertilizing will NOT help it bloom any sooner. Good soil conditions, adequate light and watering and time is all that is necessary.