So...there are two Hydrangea plants? What type is the first one? How long have you had it? Have you ever pruned it? Does it grow in sun/shade/part shade?
Edited to add:
I learned the hard way that pruning correctly is important to enjoy blooms. Some Hydrangeas bloom on "old" wood: H. macrophylla (Mopheads and Lacecaps), H. quercifolia (Oakleaf), and some bloom on "new" wood: Hydranges paniclates, Hydrangea macrophylla 'Endless Summer' series, Hydrangea arborsescens 'Annabelle'.
For the second plant, the Strawberries and Cream plant, it is not the fertilizer but the pH of the soil that could have an effect on the bloom color. The plant prefers a neutral or slightly alkaline pH to maintain the desired pink color.
