Gumpo White and Gumpo Pink Azalea are really good friends, they look like twins all year until the blooms open in late May. When I have a spot with moist soil, I choose Gumpo because they like a little more moisture in the soil soil than any azalea I've ever planted. I still use soil conditioner as with any azalea.
Be sure to use a well drained soil medium when planting any Azalea, Rhododendron, Mountain Laurel, or Camellia as they all prefer fall planting with less watering than you might think. In NC our soil is clay so we prefer to use pine bark soil conditioner when planting these varities.