Some rhododendrons will grow tall, but unfortunately, they may not fill in to the ground. Other evergreen plants will fill in better and could be good planted in the back with rhododendrons in front of them. Then you have the best of both worlds. No evergreen plant is going to quickly grow to the size you desire and stop growing. That isn't the way plants work. The PNW has lots of different climate zones. Here are some possibilities and their cold hardiness rating:

Some good tall rhododendrons are:

Roseum Elegans – 6’, -25F. You can depend on this vigorous hybrid in any climate. The rosy lilac flowers are rated down because of their small size, but they are still beautiful. The medium olive green foliage is produced in abundance and does well in hot climates.

Catawbiense Boursault – 6’, -20F. A hardy selection with rose-lilac blossoms on a plant of good, sturdy habit. It has pleasant, medium-green foliage.

A. Bedford (Arthur Bedford) – 6’, -5F. This large growing, vigorous rhododendron tolerates exposure to full sun. Its funnel shaped flowers with ruffled edges are pale mauve to lavender-blue with a distinctive dark blotch. This is a good selection for a more upright habit.

Anna Rose Whitney – 6’, -5F. Here is a vigorous plant which typifies all that is good about rhododendrons. This plant grows quickly to form a very large, densely foliaged, well shaped rhododendron. Deep rose-pink flowers are held in large, open trusses.

Horizon Monarch – 6’, 0F. This hybrid is really fantastic. It is the most upright, cone shaped truss of any yellow. Red buds open to a mellow, warm yellow flower with small vivid red flares. Gigantic trusses of 15 or more flowers are very showy. Large, leathery, deep green leaves clothe this spreading plant.

Loderi King George – 6’, 0F. Known as the best white form of the ‘Loderi’ group. The huge flowers open pale pink and then become white. Deliciously fragrant. A magnificent plant that will some day approach the proportions and size of a small tree. Allow plenty of room and give wind and sun protection.

Loderi Venus – 6’, 0F. Deepest pink of the ‘Loderi’ group and one of the most anticipated. Extremely fragrant. In flower, the sight and fragrance is something you will not soon forget. The plant can become rather tall.

Mrs. G. W. Leak – 6’, 0F. Tall, vigorous plant with olive-green leaves. Clear, light pink flowers have a dark blotch in an upright compact truss. Grows in sun or shade. It has a good upright growth habit.

Here are some recommendations for good privacy plants for the PNW.

Privacy hedges: Pick plants that suit your style and space; six evergreen options (The Oregonian)

Hide behind your plants instead of a fence (The Seattle Times)

7 Great Hedging Plants For Northwest Gardens (Vancouver, BC)

Instant Privacy (Snohomish, WA)

Thank you both for the great information! Rhodyman, I am familiar with Roseum Elegans - it was one of the few that I grew successfully in Alabama. The other links are helpful. Right now, there is a hedge of various large plants - cherry laurel mostly, and an unknown deciduous tree in the problem corner. The neighbor says that it drops seeds that sprout all over the place. I have yet to ID it. I would like to cut it down and replace it with a tall privacy plant and like you said, layer in front.

Miketann, what color are the King George blooms?

Loderi King George has pink buds and blooms white on large trusses and mildly fragrant. A very nice fragrant, I might add.

Below is a rhody called Purple Splendour. Mine is in quite a bit of shade so it's growing more open than it might if it were in more sun.

Pieris japonica and Kalmia latifolia are two other plants with a lot of varieties that do well here also.

Mike

Lem's Monarch is one of my favorites. This one is growing up into a Japanese Maple. My friend's dog is for scale.

Stunning!

Another one that grows fast and tall is Cynthia.

Nowadays many of these are spoiled in this area by foliage mildew. This was becoming prevalent here by the 1990s - many people appeared to think that their rhododendrons had been made gaunt by the 1990 winter, when in fact they had been losing leaves to mildew. Not only does this make them sparse but it can be fatal on some kinds - 'Anna Rose Whitney' and 'Purple Splendour' for instance tend to be badly affected. So I definitely would be very careful with selection if I was going to attempt to rely on a rhododendron for screening. Unfortunately it often appears to be the worst on the most flashy kinds, with the old workhorse types like 'Roseum Elegans' being the ones that have been able to maintain a normal appearance.

Also they are all slow-growing, you are typically talking about perhaps decades to end up with a rhododendron 10 ft. tall.

The fastest growing, most large-parted ones will also be those with the coarsest foliage texture that is the least suitable for background planting. The suggestion to use some other kind of shrub for this particular position will probably turn out to be the most apt.

Yes, a woman at a nursery was just telling me yesterday to go with species rhododendrons.

A lot of people are enthralled by species rhododendrons, but you have to consider each species or each hybrid on its own merit. To completely avoid the foliage mildew which has been determined to be powdery mildew, is to avoid red, purple and yellow rhododendrons. That just about eliminates everything except white and pink. Nova Zembla and Vulcan are 2 reds that are resistant to powdery mildew, but are not especially tall growing. Where I live in SE PA, powdery mildew is only a problem on lilacs, peonies, and deciduous azaleas. We have very hot and humid summers, but we also have frequent summer rains. Perhaps the rain keeps the spread of powdery mildew in check. Some horticulturists recommend hosing the visible signs of powdery mildew off plants. Perhaps our summer rains along the East Coast do just that.

After hearing so many positive comments about King George, I have been looking online for one and the only place that seems to have it is Thompson Nursery which is located 3 hours south of where I live. They do not do mail order. Is this variety difficult to find? I know that not all nurseries are online.

I have some that are well rooted branches that I'm going to remove to showcase the parent plant. I might need some help. :-)

Where are you located?

Mike

I am in Vancouver (Wa)

This is not the best time of year to be hunting for rhodies :-) Most retail outlets other than the few nearby rhododendron specialty nurseries are very low on stock now and won't be bringing in fresh stock until late February or March. Loderi King George is such a standby selection, you should be able to find it anywhere - even at HD - at that time.

Personally, unless you were looking for a very rare or unusual selection, I wouldn't bother with mail order living in the PNW - in season, rhodies are offered for sale everywhere and probably larger and cheaper than by mail order and without any shipping costs. And there are so many great retail nurseries in th southwest Washington - northwest Oregon area, you shouldn't need to travel far to find one.

Or you can always take up Mike's offer for help and maybe snag a start for free :-)

Ok thanks! I just assumed that Fall was the best time of year to plant but that does not seem to be the case here. I will wait until later toward February.

Darn, I was hoping for some help. ;-) I should have dug them earlier, but I wanted them to be well rooted. Now they're over 5 feet tall and it's going to be a job.

Like GardenGal says, they should be available in the Spring almost anywhere. It will save you a trip and a lot of digging. :-)

Fall is an ideal time to plant here but that does not necessarily coincide with the best availability of plants. Most retail nurseries bring in plants seasonally, usually late winter and early spring, and once they are sold out, that's pretty much it for the season. That is certainly true for B&B stock and bare root however containered plants can be brought in any time if the growers have them available. IME as a longtime nurseryperson, rhodies are generally featured and available in late winter and through their bloom season but because demand drops off so much after bloom season, they are seldom restocked. So now all that is left is the leftovers.

You will have much better luck locating in spring.

I am learning! A few weeks ago I was looking for new shipments of trees to choose from and was told basically the same thing from that particular nursery. A different nursery did tell me that they would have new trees after the first frost.

Miketann, don't give up yet! :)

I am also trying to find Loderi King George or Venus anywhere and no luck. No retail mail order nurseries offer it

Not sure those two would grow in NC anyway.

Here the least mildew affected types are Sec. Pontica derivatives like 'Roseum Elegans' so I don't see how the previous comment about flower colors applies.

F.W.I.W. I found out last year or otherwise recently some of what I had been calling foliage mildew effects was apparently actually lace bug infestation.

Not that I don't often otherwise see the pale mildew growth on heavily affected leaves.

Lacebugs have become a big problem in my garden the last 2 years. Some rhododendrons are affected, some not. Smaller leaved varieties seem to be more susceptible...so far. Four years ago it was a non issue in my garden. I'm concerned.

I have been reading about lacebugs and it is a big concern here. Apparently the "hairier" leafed varieties (Impeditum??) are less susceptible. I was talking to a woman last week and she said that she has managed to keep them at bay by keeping a close watch on the leaves and washing the undersides of the leaves if she sees evidence of their presence. A rhododendron garden in Portland is using some type of sprinkler system to spray upward from underneath the leaves.

So far my Impeditums are untouched by the lacebugs. I'm going to move a couple today.

Hi mike, I can help dig those rhodies if you are ready to part with them, several of mine have been affected by drought and mites.

LOL!! Richard, I doubt Mike needs much help digging up the impeditums :-) You do realize that they are tiny, dwarf shrubs, seldom exceeding 2'x2'?

Here's that Impeditum I moved. :-)

If you look into it you may find that "impeditum" was actually fastigiatum.