Rhododendron is the genus for both the plants that explode like happy, colorful fireworks this time of year. In our parts, rhododendrons are evergreen, have larger leaves and fuller flowers. They actually provide an interesting winter specimen. They bloom earlier.
Azaleas lose their leaves come fall, have a slightly more delicate appearance and bloom a little later.
Want to be sure? Count the stamens. Rhododendrons have 10 and azaleas have five, though when in doubt and in a crowd of gardeners, call it a rhododendron.
The Northern Lights Series of hybrid azaleas is being developed and released by the University of Minnesota Landscape Arboretum. Any azalea released and included in this series will have flower bud hardiness of -30 degrees to -45 degrees F to withstand Minnesota winters.
Whichever you plant, these shrubs bring unparalleled color to the garden as they erupt in neon, fluorescent and yummy pastels. Companion planting with another shrub or in the perennial border works well; these shrubs visually recede into the landscape as their flowers fade in summer.
- Azaleas and rhododendrons do well in full sun to part shade.
- They crave an acid soil. The University of Minnesota recommends incorporating acid peat, sulfur or ferrous sulfate into the surrounding soil to lower the pH. (A pH of 4.0 to 5.5 is optimum.)