Location is important. The east and north sides of the house are the best sides to plant Rhodos. South and west sides would do fine also if they are shaded from 12:00 on.
Another major requirement for these plants is a distinctly acid soil (Ph 4.5 to 5.5). It should be well drained but supplied with ample moisture at all times. This soil environment can easily be produced at the point of planting or created for an established plant.
When planting dig a large oversized hole, three times wider than the plant’s root ball and twice as deep. Back fill this with peat moss, shredded bark, and one third of the original soil, all the while mixing in a cup of Aluminum Sulfate. This with produce an environment perfect for this acid loving plant.
To maintain this level of acidity year by year switch over to Iron Sulfate if your ground tends to be on the sweet side. Coffee grounds are also an excellent source of food and will keep the Ph down into those acid levels they love.
If you find that your location is a struggle for them remove the spent flower clusters. By removing them, the plant is spared wasting energy trying to produce seed.
But Acid soil is the key to their success; keep it down there at the levels they like and you will be rewarded with flowers unmatched throughout shrubdom.