I made some notes recently when doing some research. Here are a few names that you can check in alphabetical order. Capistrano is a 4' tall late mid-season bloomer. Goldkrone is a 4' tall mid-season bloomer. Hotei is a 3' tall mid-season bloomer; blooms after 5 years so ck how the plant is before buying. Jenny Tabol is a much taller bicolor, around 5', with pinkish edges. R.austrinum, a native deciduous azalea, also has yellow varieties such as Admiral Semmes. Check with vendors like A Sandy Rhododendron and Carlsons Gardens.

Be aware this was a quick research thing so plenty names are definitely missing. I was looking for rhododendrons only (no azaleas) with mid-to-dark yellows so I omitted ones with light yellowish colors. I also omitted some bi-color yellows because I simply did not like them. For example, Azalea Golden Lights is also a good mid-May 6' candidate and so is Azalea Yellow Cloud (late May bloomer, about 8' high).

Luis

Capistrano appears to have become the reliable yellow standard for the northeast. Hotei cannot take the heat.

Here is one of my favorite yellow rhodies. It is called Horizon Lakeside. This is a photo of the one currently blooming in my yard. There are many types that I saw today when touring a rhododendron nursery. Enjoy. Jim

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There is a decidous azalea cultvar named 'My Mary' which is reported to grow 8-10 feet tall. Its flowers look more like a lot of Rhodie flowers I have seen when compared to most azalea bloom types.

I definately like the 'My Mary' almost golden yellow trumpet form of flower with deeper red throats. They flower in late April to early May in USDA Zone 8. In USDA zone 6 it is mostly they would bloom in early to mid May due to winter conditions taking longer to break enough for the 'My Mary' to break dormancy.

There are 4 different types of rhododendrons:

1) Deciduous Azaleas: Bold Yellows are very common and very hardy. Some of the hardiest (-25F) bold yellow deciduous azaleas are: Apricot Surprise, Girard's Yellow Pom Pom, and Marion Merriman. There are some pale yellows also like Weston's Lemon Drop. My Mary (0F) is not hardy in Zone 6.

2) Evergreen Azaleas: There are no good yellow evergreen azaleas. I am not aware of any in the trade.

3) Lepidote (small leaved) Rhododendrons: There no good yellow lepidotes. Jericho is pale yellow and hardy to (-20F).

4) Elipidote (large leaved) Rhododendrons: They are many yellow elepidotes, but not many are very hardy. The most common true yellow is Capistrano, but it is only hardy to -15F. The hardiest is Casanova which is hardy to -25F, but it is only a pale yellow. Horizon Lakeside (+5F) is not hardy in Zone 6.

Here is a link that might be useful: Rhododendron (elepidote) Capistrano

they have been selling hong kong in my area as a yellow
rhodie-- but I haven't seen it in bloom yet-- I think it is supposed to be paler than capistrano

diggerb

Hong Kong is slightly more cold hardy than Capistrano.

It is not considered as good a yellow, but close.

Lots of good info here.

Not to forget the species yellow Rohdie:

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Snasxs, that is a deciduous azalea which is a rhododendron.

Strong yellows are very common with deciduous azaleas.

Yes, rhodyman, you are right.

I like this one:

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Rarefind nursery is marketing some very nice hardy yellow rhodies. I can tell you that "My Jane" is more spectacular in real-life than the picture indicates, and too me seemed to be a better yellow than Capistrano.

Here is a link that might be useful: http://www.rarefindnursery.com/index.cfm/action/productdetail/product_id/3451.htm

stanettetn6, I agree with davidrt28. I saw My Jane and Capistrano side by side
at Rarefind and thought My Jane to be a nicer plant. Got a three footer from Eastern Plant Specialties. They might have some left.

They are also selling large specimen plants from their Maine location. I visited and saw a six foot Hong Kong which was for sale.

At Rarefinds "dog" sale in August, I putchased a six foot Goldfort, a cream color, well branched, for $50.00!

Other yellows and creamy yellows that I have had success with: Unique (elepidote: pink buds, pale yellow),
Klondyke (decidous, true Exbury, intense golden yellow, be careful with this one: it's a show stealer), narcissiflora (old Ghent hybrid, very rare in the trade, very much sought after by enthusiasts, beautiful decidous yellow).

some lepidotes: kieski (low growing pale yellow, parent of some of the Guyencourt hybrids by Guy Nearing ), Mary Flemming (pink and cream mix)

I strongly advise staying away from Hotei; East Coast nurseries are selling it probably because it blooms young. But it simply cannot take our hot humid summers.

Here is a link to eastern, I see they still have many karge specimen sized plants for sale: http://www.easternplant.com/

The OP is in Zone 6 and wants to have a yellow Rhody. A lot of the plants mentioned aren't hardy in that zone.
ezlivin1, you don't mention your zone or where you live. A person's location is vital to the validity of the post. Without it, the post is almost useless. Even just the zone is of limited value. I live in Zone 8 Seattle. A lot of Texas is Zone 8. Not much in common when it comes to growing Rhododendrons. Soil, humidity, heat, it's all different. More info from some posters would help a lot.

Read this thread, it mentions most of the yellow rhododendrons. In Zone 6, the deciduous azaleas are a more saturated (deeper) yellow. The yellow rhododendrons tend to be on the tender side and more creamy-yellow rather than deep yellow.