What not to plant next to hydrangeas?
Sunflowers are similar to lavender in that they need full sun to grow and bloom. Most hydrangeas will wilt and suffer in full sun, so they shouldn’t be planted together. Some types of hydrangeas, like panicle hydrangea varieties, actually prefer more sun. But sunflowers are tall and might shade them too much. Brighten up the shady base of your hydrangeas with annual flowers and foliage plants. The nice thing about adding annuals is that you can mix it up and try different plant combinations or flower colors every year. Good shade-tolerant options include begonias, coleus, browallia, euphoria and impatiens.