The classic pairing
Flowers and chocolate go together on Valentine's Day, anniversaries and birthdays. Some florists keep chocolates on hand, others partner with a candy shop, and some do not offer them at all.
Ask on the call. If they do, ask what kind and how they are packaged. In summer, heat can be a problem for chocolate, so delivery timing matters.
If chocolates are not available, a romantic bouquet with a heartfelt card is just as good. Or deliver the chocolates yourself and let the florist handle the flowers.