Both are tough and adaptable choices, but there are, of course, no absolute guarantees for your specific conditions. If there is a local chapter of the American Rhododendron Society it might be a good idea to see if members are having success.

Heat and humidity often encourage fungal root diseases, so excellent drainage will be very important. Rarefind Nursery in NJ is worth checking as a source. Theoretically at least, it shouldn't matter as hardiness and adapatability are genetically determined. Fall planting may have some advantages, especially root establishment under cooler and less dry conditions.

Hi...I agree that in your area fall planting might be better as roots will grow til ground freezes hard, getting you a better start come spring. Both Yak Angel and Ken Janeck are thought to be yak hybrids, the first with the species makinoi, and the latter with the species smirnowii....all good things. Angel is essentially white in bloom, and Ken Janeck has pink in bud and when starting out. Enclosed is pic of Ken Janeck. I have old plants of both that are now eight feet tall...they are dwarf..for a while, but given time and if they are happy, ultimately they get big..just slower. Work in plenty or leaf mold from oaks if you can and if your soil is heavy clay, add some gravel or coarse sand. If they are pot bound it would be essential to break up the edges of the root ball. I would avoid the yak hybrid called Yaku Princess, I see it all over and its inferior to many other yak types. The heat is the limiting factor for you. Morning sun then afternoon shade is your best location.

HHhhhhmmmm. I know a landscaper in the DC area who says he won't bother with rhododendrons even if clients request them. That isn't to say specialists don't successfully grow them in their gardens - there is a DC chapter of the ARS after all - but it does mean they start to get more difficult. Big old ones are at least an order of magnitude more common in the suburbs of Philadelphia. I hardly ever see them in Piedmont NC.

So, you're right on the border. If you have your heart set on these varieties, by all means try them. But you might save yourself a lot of trouble just by planting some of the new hyperythrum hybrids including the new highly commercialized southgates, which you can be sure won't have a root rot problem. It's worth observing that in low elevation Japan, most forms of R. yakushimanum are considered ungrowable.

BTW...as far south as Richmond it's better to plant almost any tree or shrub in fall, definitely including rhododendrons. Unless it's something very borderline in hardiness like a "hardy citrus". But if we have an August hurricane next year and Richmond gets dumped on with 6 inches of rain in one day following a spell of temps in the mid 90s for two weeks, fall planting isn't going to magically keep a yak hybrid from dying of phytophthora root rot.
The non-Southgate but similar 'Charles Loomis' is by far the toughest rhododendron I've ever grown, thriving in almost full sun here with almost no coddling.
Look at Southgate Brandi...looks similar to my eyes:

Here is a link that might be useful: http://southernlivingplants.com/shrubs/plant/southgate_brandi_rhododendron

This post was edited by davidrt28 on Tue, Sep 23, 14 at 20:57

Thanks for all your thoughtful replies. Sadly the yaks turned out not to be available from Greer Gardens after all, so even though the sites were ready nothing went in last fall. Still thinking about it, though your posts give me pause... Perhaps a more southern-adaptable rhodie... Perhaps an oak leaf hydrangea that I just saw called ruby slippers... But, I sort of needed something evergreen... And there is not that much space... 3x3 would be ideal, but 4x4 could work... That's why I thought of the yaks, but then someone mentioned they had huge ones? Hmmm... Our summer heat and humidity concerns me too, and the garden is small, so whatever goes in has to be a real workhorse and look decent most of the year. Sorry... I'll keep thinking it through, but thanks again for you expert advice!

Greer Gardens in Eugene, Oregon is closing. Harold Greer is retiring from the nursery business to pursue his hobbies including rhododendrons full time. My oak-leaf hydrangea is much more robust than any rhododendron I have. It has to be severely cut back every year. Ruby slippers is not as tall but still grows quite wide and pruning would be required every year.

The yaks would be practical if you could provide good acidic soil, high shade, a raised bed to assure good drainage, and a mulch layer to keep the soil cool. Also, some people in the west use a misting system in hot weather, but their climate is very dry in the summer. That would be problematic in our damp east climate.