This section is from the book "Beautiful Gardens - How To Make Them And Maintain Them", by Walter P. Wright. Also available from Amazon: Beautiful Gardens: How To Make And Maintain Them.
The best soil for Rhododendrons is either peat or fibrous loam. Limestone and chalk are fatal. The soil should be cultivated at least 2 feet deep. April is the best month for planting. The plants may be put in fairly close to give immediate effect, but thinning should be done before they overcrowd each other. Old plants going bare at the base may be cut hard back into the old wood after flowering. Fading flower trusses should be pinched off.
The following are beautiful varieties of Rhododendron: -
A. B. Freeman Mitford, crimson.
Baroness Schroder, white, spotted purple.
John Waterer, crimson.
Lady C. Mitford, peach.
Michael Waterer, rosy red.
Mrs. John Clutton, splendid white.
Old Port, plum purple.
Pink Pearl, magnificent pink.
Fig. Rhododendron Pink Pearl.
Sappho, white, marked magenta.
Sigismund Rucker, magenta.
The Queen, blush.