The idea of pairing a Hydrangea's (Hydrangea macrophylla) deep blooms with gardenia's creamy, white flowers is enough to make us swoon, so it's good that they're so compatible as neighbors.

Fruit trees shouldn't be grown near gardenias, however. These sweet-scented flowers (Gardenia jasminoides) are tricky enough to manage without the extra hurdles that fruit trees create.

Summersweet ( Clethra alnifolia) blooms in the late summer, says Irish-Hanson, but it's wise to plant it during the spring.