After getting smacked by another winter windstorm in our area, I am truly in the mood for for spring. Shooting ice and snow definitely not my thing, but when the spring flowers peak, I'm out there for a few days. There are no real secrets to shooting beautiful blooms, just some planning and common sense.
Know where and when your best opportunities are. The best shots will not happen on a whim. Over the past few years, I have kept a casual "bloom calendar" of when some flowers and shrubs will peak. For heavily trafficked public gardens, go at an off peak time, and at the earliest viewing window you can get. If beds are unguarded, people will just walk where they may, trampling edge blooms and perhaps even picking their own.
Learn the language of light, and study its nuances. Early morning is my favorite, but late afternoon will work too. The light angles are lower, and in addition to the beauty of the flower and its surroundings, you will also have the bonus of more dramatic light and shadow. If shooting mid day in bright sunlight, look for flower beds under trees where you can get a mottling of light instead of direct overhead sunlight. Overcast days also provide great opportunities for closeups. Clouds will act as giant softboxes and provide gentle diffused light.
Try new angles. The front on shots have been done, and done again. Find the perfect bloom and angle it.
For maximum productivity, try making a deal with your local nurseryman. Shooting privileges in exchange for some promo shots. Even small locals have websites these days. One small outlet here is thrilled to use their own flower shots on their website instead of the mundane canned variety seen on every other website.
I wish you all success in your spring flower shooting.