The Washington Park bistro Bittersweet is in full bloom. Alongside the climbing roses and the hydrangeas, the restaurant now grows edible blossoms like society garlic, chives, and even Parisian micro marigolds (inspired by chef Olav Peterson’s recent European adventures). Peterson snips the flowers daily and works them into his menu. Tonight, they may add sweetness to a crunchy salad; tomorrow, a delicate finish to a dessert.