Hi Dax, Some rhododendrons need some shade to keep lacebug down. Those that are reputed to do well in full sun include: Rhododendron Anah Kruschke  (ponticum seedling) 6Â, -15oF, ML-L, 3-4/3. A good looking rhododendron that grows well in sunny, hot locations. Its reddish-purple flowers are held in medium sized, tight trusses. Dense and lush foliage with dark green leaves. Rhododendron ÂBlue Angel  (Sappho seedling) 6Â, -15°F, M, 4/2. This angel comes from Gene Cockram of Florence, Oregon. It has lovely purple flowers with a contrasting yellow blotch. With strong green, sun tolerant, foliage the growth habit is much like its parent. Rhododendron ÂBlue Ensign  (probably a ponticum hybrid) 4Â, -15oF, M, 4/3. Very hardy, sun tolerant, lilac blue with a striking purple blotch. Its truss is similar to ÂBlue Peter and while they both become huge plants, ÂBlue Ensign is more compact. Rhododendron ÂCadis  (ÂCaroline x fortunei ssp. discolor) 5Â, -15oF, ML, 3/4. Long, narrow leaves and the fragrant, light pink trusses of this plant genuinely deserve the recognition afforded this cold hardy hybrid from the eastern U.S. A sun tolerant selection. Rhododendron ÂCounty of York  (ÂCatawbiense Album x ÂLoderi King GeorgeÂ) 6Â, -15oF, M, 3-4/3. Vigorous growing plant with large, upright white trusses of good substance. Here is hardiness, good flower and large foliage, all in one hybrid. Apple-green, somewhat shiny foliage. Sun exposure and cold are well tolerated. Rododendron ÂCunninghamÂs White  (caucasicum x ponticum var. album) 4Â, -15oF, ML, 2/3. An attractive, compact plant with small, white flowers enhanced by a greenish-yellow blotch. These lovely and numerous flowers open from buds which are flushed with pink. It will tolerate sunny locations but partial shade is best. Rhododendron ÂFastuosum Flore Pleno  (catawbiense x ponticum) 6Â, -15oF, ML, 3/3. Double, lavender-blue flowers with a large golden flare on the upper dorsal lobe give extra interest to this hardy, sun tolerant hybrid. The growth habit is somewhat open but round on this fine plant. Its good foliage is dense and green. Rhododendron ÂGomer Waterer  (catawbiense hybrid) 6Â, -15oF, ML, 3/4-5. This old standby is one of the best whites ever hybridized. Flower buds are a delicate pink that open to blush white blossoms containing a freckling of soft green in the throat. Large deep green leaves make this an outstanding foliage plant. Very sun tolerant. Rhododendron ÂTrilby  (ÂQueen Wilhelmina x ÂStanley DaviesÂ) 5Â, -15oF, ML, 3/4. Beautiful flowers of deep crimson with black marking. Matte green leaves are set off against red stems to beautify the plant even when not in flower. Sun tolerant. Rhododendron ÂWissahickon  (parentage unknown) 5Â, -15oF, ML, 3-4/3-4. A good choice if you are looking for a vigorous growing variety that is sun tolerant. The bright rose flowers, with a deeper throat, have brownish spotting. A plant of good reputation in the East. Rhododendron ÂWyandanch Pink  (unknown) 5Â, -15oF, M, -/-. This is the rhododendron for that sunny spot in the yard as it does best in the sun. Excellent foliage highlight the vivid pink flowers spotted darker on the upper lobe. The above descriptions came from the Greer Gardens Website. They are very dependable.

You face several problems in the Denver area. There are some areas with natural wind drainage from the mountains where hurricane force winds are not uncommon. I am familiar with one such area between Boulder and Denver. Also, when Littleton was a new community, people were having trouble getting any kind of tree started. You will be facing several problems. 1) Alkaline Soil. Raised beds are the best solution for this. Rhododendrons and azaleas have shallow roots, so a raised bed that is 12 to 15 inches high is normal. Use a good acidic soil that is well drained. 2) Alkaline Water. The raised bed won't help if you use alkaline water. Use only rain water including water collected in cisterns or neutralized water. 3) Winter wind and sun. These are serious problems. A wind break and some winter shade are necessary. Summer sun is not trivial either. Some summer shade is necessary. 4) Hardy plants. Being from Idaho, you are probably familiar with this problem. All azaleas and rhododendrons have a characteristic hardiness. Winter hardiness and summer hardiness are both important. They usually go together. Here are some interesting references: Gardening challenges for newcomers to Colorado (Colorado Extension) Iron chlorosis (Colorado Extension) Growing Azaleas and Rhododendrons (Missouri Extension) Azalea and Rhododendron Care and Culture (Oregon State University) Here is a link that might be useful: How to grow rhododendrons and azaleas.

It depends on the cultivars. Some will take full sun while others get lace bugs or sunburn. A few will take shade but this tends to hamper the setting of flower buds and, hence, blooming. Most like partial sun and partial shade. In general, the east facing exposure is ideal for more plants since the morning sun will remove the morning dew and help prevent disease. However, the west facing exposure is near ideal and most plants should be OK there. The other consideration is winter hardiness. Winter sun and wind stress rhododendrons and azaleas. That is why you see some people put burlap around their plants (not over them). I personally don't like this except for new plants the first year or two. Small evergreen azalea plants especially need some protection the first two or three years. More tender plants will do better on the north side near the east or west side if you give them wind protection. Ideally you will put in some trees on the south side to provide high shade. This means partial shade. I have had good luck with red oak and meta sequoia that I planted. They both grew rather quickly for me. Sweet gum and sour gum are said to be good also. Also, ideally you will put in some wind breaks on the northwest side. At least, for me, that is the predominant direction the winter winds come from. You don't say where in PA you live. In general, the best rhododendrons for the south facing side are the iron clads, very hardy varieties such as Nova Zembla, English Roseum, Roseum Elegans, Boule de Neige, Catawbiense Album, Mrs. Charles S. Sargent, Purpureum Elegans, and PJM. Evergreen azaleas aren't as hardy. The hardier ones are: Bixby, Helen Curtis, Hino-red, Hino-white, Karens, and Marie's Choice. Here is a link that might be useful: How to grow rhododendrons and azaleas.

The oaks and your liquidambar are both compatible with azaleas and rhododendrons. They generally provide filtered shade not dense, their leaves decompose slowly providing a long lasting acid mulch, and they are normally not surface rooted. I can't answer your questions on specific spacing though - here in this maritime climate I can grow rhododendrons in full sun. Is rainfall normally an issue for you or is it just this year in particular? Ideally, open sky above them would allow them to benefit from what rainfall you do have, while still receiving enough shade from adjacent trees as light patterns change during the day.