I would think Pink Simplicity should be an OK landscape rose for your climate, where blackspot isn't much of a problem. Some roses drop buds sometimes. We haven't figured that one out.

Phosphorus for bloom is probably a gardener's myth. Roses use much more nitrogen than phosphorus. You want maximum growth for maximum bloom, and that means you give them all the nitrogen they want. This could be around 1/4 cup of 10-10-10 or 12-4-8 per square yard per six weeks.

Slightly too much water doesn't inhibit bloom. But are you sure they are getting enough? Roses need less water than turf if both are to grow at the maximum rate; however, you want roses to grow at the maximum rate, and you don't want the grass to do so (at least I wouldn't), so probably they should get about the same amount. As a rough guess, 3/4" twice a week in your summers. There is a web page that gives realtime evapotranspiration data for Utah cities that I would use if I were irrigating there.

If alkaline soil is a problem, it shows up as iron deficiency-- new growth pale or yellow between dark green veins.

Aphids are normally not a significant problem. I usually ignore them.

When you prune in spring, look for winter damage which shows as darkened center pith. The previous year's growth (at least) should show white center pith. Prune to white pith except for barky old canes.

Here is the evapotranspiration page showing how much water is recommended for turf according to recent weather.

Here is a link that might be useful: Utah ET net

All Roses do best in slightly acid soil. A PH of around 6.5 is ideal. You might want to fix the soil first. in well drained soil too much water is not a problem. If you have lots of clay where water stands you'll want to fix that also.

Pink Simplicity does well for me. Almost always in bloom. The self cleaning blooms means less deadheading.
Have you tired trimming them back a couple of inches to promote new growth which may produce blooms? If the growth is all blind it'll not produce flowers. Just use a hedge trimmer.
{{gwi:289867}}

Mine are getting about 1/2" of water twice a week, so 1" a week. Perhaps it's a little less, since their at the end of the rotor sprinklers' range. They do their best flowering (what little it is) in July, when it's hottest, so I'm not sure it would be low-water stress. Then again, could low moisture be the cause of tiny flowerbuds that fall off?

A few years ago, when I posted about this, several rose gardeners told me they might be getting too much nitrogen by picking up some of the nutrients from the lawn fertilizer, since they're right next to the lawn. I think they said this because of the vigorous, healthy green growth I described.

I did a soil test this spring and it said I had adequate ranges of all three main nutrients, and it even said my ph wasn't that bad. I don't know, though, if those home tests are very accurate. Anyway, I suppose I should fertilize again soon, since it was March when I did it last.

Karl, what does blind growth mean? I haven't seen that term before.

These had been trimmed back to about 3' last fall to avoid snow damage to the branches, and I was going to trim them again this spring but decided maybe I had trimmed too much in past year, so I let them just be the way they were. They've put out two feet of new top growth since March.

If I trim them several times through the season, will I be cutting off what would be flowering branch tips?

How much are they growing? I've seen PS but haven't grown it. I would think with adequate water and nitrogen they would grow around a foot a month, or more than that if they set few buds. Trust me, there are scientific findings that high N is good for repeat-blooming roses. I give mine a little Turf Builder once in a while.

I wouldn't put much stock in the home test kits. I did it once, but didn't really trust the NPK results and couldn't interpret the pH test at all. I could have gotten a real test by the state for less money than the kit cost, including postage. Since this seems a puzzling case, a real soil test might be in order. One inch of water per week might be suboptimal some weeks, but not enough to prevent bloom.

A blind shoot is one that terminates without a flower bud. If the new growth is normally a different color than the old leaves, when the top leaf turns to normal green, you know the shoot has gone blind. Compare the tip with the tip of a growing shoot and you see that it has hardened off with no more embryonic leaves. Blind shoots should be rare on a repeat-blooming rose. They indicate lack of water, root disturbance, or some other inhibitor of growth. It would be useful to go see how many blind shoots the roses have.

I guess you've already thought to consider whether the one blooming rose has different soil or watering than the others.

Blind growth is that which doesn't produce flower buds. Most often the growing tip aborts due to insect or some other damage. It could be caused by insufficent water if that occurs at a critical stage of growth.
Blind growth most often appears on the lower portion of the canes and on damaged canes.
On self cleaning plants, insufficent water when the buds are very small could cause them to abort. Should that happen the result could be blind growth. Normally though, new growth will appear with buds.
Get that soil checked. That area may be worse than the rest of the garden. PH can play a big role as too high or too low PH locks up many nutrients, some which may promote bud development.
Adding more will not help if the plant cannot use it.
Blind growth most often appears on the lower portion of the canes and damaged canes.

By the way, happy birthday, Karl! (I saw the other thread). And thanks for helping, too. You too, Michael. I'll take a closer look at these when I get home, and I'll see if I can post some photos of what they look like right now.

Michael, the one that flowers well gets the same water, sunlight and as far as I know, the soil was the same when I planted them.

I should tell you that the native soil is somewhat rocky and clayish. But when we had the yard done from scratch in 2001, we had about 6" of "topsoil" added on top of the native soil here. The "topsoil" is really a blend of sandy loam (excavated soil -- not exactly topsoil, but there isn't any real topsoil in Utah) mixed with some compost and composted manure. One of the areas where roses are blooming better in my yard is a place that received much more fill dirt after construction, so it probably has better drainage. But the roses in that area are wonderful Meidilands that I think are just a lot more carefree than these Simplicities.

Sandy loam is good topsoil. If you should ever replant the area, I'd advise mixing the sandy loam with 6" of the native soil and some more manure to get a deeper topsoil layer and a less abrupt transistion. Layered soils are considered problematic, for reasons I try to explain in the nearby thread, "Primer of Soil Moisture."

I, too, tried pink Simplicity from Jackson Perkins. After the second year of no blooms, I called them up to find out what I was doing wrong. The only suggestion I got was that I had given them too much nitrogen (foliage was very healthy). This was before I was on the web, so I gave them another two years of grace, and then pulled them out! I had probably a dozen flowers in 4 years from all 6 plants!

Fast forward another couple of years to the era of the Web, and I read somewhere that Jackson Perkins' Simplicities often don't bloom...

Daphne in Tacoma

I have only once seen a hedge of Simplicity that actually looked like a HEDGE. They marched with an impeccable black wrought-iron fence, surrounding the front yard of a small 1940's era bungalow on Laurel Canyon Blvd.
I bet they planted them no more than 10 inches apart, but they formed a thick hedge some 5 ft tall, trimmed off flat at the top and in full bloom.
I nearly drove my car off the road.
A few months later, the whole shebang was bulldozed, to make way for a very tacky apartment building.
Every other Simplicity "hedge" I've seen was uneven and "spotty," with some vigorous, tall plants, and some real wimps.
Clearly, it can be done, but I think it takes dedication, perseverance, and LUCK.

Jeri

I have a hedge of 10 PS that I am trying to grow. This is year 2 and most of them are about 4 tall, but I am having major problems with BS and losing leaves. Had the same problem last year, which was the first year. I didn't spray at all last year, lost tons of leaves, but they all came back strong this year. They were covered with buds, but then got hit by the frost and I lost the entire spring flush. I was devasted. I called J&P and asked them what I should do. They suggested a mild pruning which I gave them, and around Memorial Day, I was fortunate to receive a fairly good flush. Now they are covered with BS and I've lost most of my leaves. Didn't spray last year, but started spraying about 2 weeks ago with bayer advanced disease contrl and have noticed a redution in leaves lost, but haven't seen any new buds. If I remember correctly, I did have a nice flush last fall, but only sporadic blooms throught last summer. Of course, that was year one, however. I'm fertilizing and spraying regularly now, so am looking forward to many more blooms now that I'm controlling the BS. If not, I'll be sp'ing them and replacing them with carefree beauty.

And btw, I have noticed that PS loves the sun! The more the better - Even 1-2 addl hrs of sunlight, seems to make a huge difference among my PS.

I wouldn't call Pink Simplicity a hedge rose. It is actually your run of the mill pink floribunda. It should be treated as such. When it first came out on the market folks in my home town (Green Bay, WI) planted these and most of the bushes did not survive that first winter because the roses were cared for like a hardy shrub (not!). :-\

Stevation,

There is a house by Northridge Elementary in Orem (I think it's about 1800 N and Main) that has a Pink Simplicity hedge that knocks my sock off every year in the spring. After that I never notice it blooming again. For our area, I have had much better success with Nearly Wild and Betty Prior. I had some Pink Simplicities once, but I shovel pruned them several years ago and never looked back.

I think it's a beautiful simple rose that has been marketed badly. We have 7 for at least 6 or 7 years now they never would make a hedge. Yet i love the blooms in Spring and Fall

I'll tell you what makes a hedge . . .

In the right conditions, R. rugosa or R. rugosa alba. There's a monster hedge of it at The Hermitage, east of Nashville, TN, and it's lovely. There's also a rugosa hedge at Shore Acres, in Oregon.
And I've seen pix of Archduke Charles planted as a hedge, in TX. With the way that looks, I wouldn't even consider bothering with any of the Simplicities if I wanted to make a rose hedge.

For California, for a TALL hedge, my DH wants to make a Grandmother's Hat hedge.

Jeri

Mine got the shovel years ago. The purple has the best bloom here, still have 1 out of 3 bushes.

Outta the Blue would make an awesome hedge.

Here is a link that might be useful: Outta the Blue

I have seen two gardens where Pink Simplicity was grown as a great hedge. I have seen far more gardens where Simplicity was attempted and looked terrible. Either one must have a very green thumb or very good soil. I never had any luck with that sick sister, and would prefer Betty Prior to it anyday.

I also would be inclined to try Betty Prior, but that's because I haven't seen anyone try it and only know it from old gardening books. Pink Simplicity does nothing for me, and where I've seen it it suffers horribly from black spot.

I agree with the comment that it's a poorly marketed floribunda, not really a hedge rose. When it was released there were not yet any Knockout roses, which seem to more fully meet the goals J&P markets Pink Simplicity as meeting.

Bonica would be a good choice.

OK, so at first, it seemed like the consensus (Karl and Michael) was that Pink Simplicity is not that bad of a rose for me. I thought maybe I'm just not giving it enough water after hearing that perhaps lack of water makes self cleaning roses abort their young buds. I think I'll try more water and see what happens. But the more recent posts clearly make me think I should rip them out and try something else. I really like the pink color of these (how manly of me, huh?) and I want something that will flower well all summer. I see a few suggestions above, including Rosa Rugosa, Betty Prior, and Bonica. Any other suggestions that would knock my socks off most of the summer?

By the way, here's what mine looked like last July. It was OK, but that's the best they ever get and it took until mid-July to flower that much (no spring flush) and it didn't last long enough:

{{gwi:293304}} {{gwi:293305}}

The closer ones look pretty "hedgy" from that angle, but you can see the ones right of the arbor haven't really grown together very well. Perhaps I do need a different variety to make a good hedge that will bloom long.

Please keep the advice coming. I think I'll keep trying on these for the summer, but make contingency plants to replant the whole hedge in September if it doesn't get better. Someday this will be our daughters' wedding reception place (we hope), and we need to make it look good!

If you really love that particular shade of pink, rather than try Rosa rugosa I suspect you may prefer the color of one of its more famous varieties, Fru Dagmar Hastrup.

(Oh, the one downside of the rugosa roses is that you can't cut them to put in a vase indoors. The stems are incredibly thorny, but beyond that the flowers drop their petals in hours if you cut them to bring indoors.)

I inherited a J&P PS hedge with my last house in Southside Virginia. The tenants had done nothing and it was pretty scraggly looking, but basically healthy. I pretty much hacked it into a hedge form (I didn't really know what I was doing) but they responded magnificently and bloomed their heads off for the next several years. Blackspot was a misery and they needed constant spraying (while next to them Climbing Old Blush just laughed at it), but otherwise they made a perfectly attractive if unexciting hedge.

Stevation--I have Bonica here in Utah County, and they grow and bloom beautifully in the spring. After that they bloom sporadically for the rest of the summer. They want to spread out more than grow tall. Mine are easily 6 feet wide by about 3 1/2 to 4 feet tall. They have been in since 1999, and they never have any winter damage at all. Their spring flush is much nicer than Pink Simplicity, and they do rebloom some. (I used to not get such a nice spring flush, but then I heard somewhere that Bonica hated to be pruned back much, so I stopped giving them much of a haircut in the spring.) Pink Simplicity is a much more upright growing rose than Bonica. If I had to pick some of my roses that I am growing right now for a hedge, I think I'd pick either Graham Thomas or Abraham Darby. Both of those roses get big, stay beautifully healthy, and bloom a lot. But, as always, YMMV.

Because I'm in a dry climate, blackspot has never been a problem for me. But I'm wondering if these roses do better with more humidity or richer soil. The foliage on these is pretty healthy, with only a minor spot of powdery mildew here or there.

So, solicitr, what would you consider a more exciting rose hedge? I would think these were pretty darn impressive if they would just bloom well.

Hey Down and Dirty -- I looked at your page and it looks like you have a *lot* of experience with roses here in Utah. Your description of Bonica makes it sound like it might work, because I actually don't like how tall these PS roses get. They're actually six feet tall right now, because I haven't done any pruning this year while trying to figure out what I've done wrong. I'd be happier with something that stayed 3-4 feet tall. But blooming *sporadically* through the summer isn't exactly what I want. I want the best all-summer bloom I can get.

What's your opinion of Knockout? The pink or pink double variety might suit my needs.

Also, I could consider colors other than pink, but in other parts of my garden, I keep noticing that I pick too much purple and yellow, so I think I'll avoid those colors.

Down and Dirty, you mention on your page not needing to spray your roses at all. What about aphids? I'm noticing even more aphids on my PS roses today, and I think I'll be spraying this week. What do you do?

Stevation -- Aphids you can get rid of with a strong hard blast from a garden hose. It's easy to do, and pleasant on a warm day. Also helps to prevent spider mite problems, or eliminate them if they have started.

Jeri

Hmmm--I just typed a response and it seems to have disappeared. Hope I'm not double-posting here.

I think you might be happier with one of the pink Knock Outs if a "knock your socks off" effect is what you are aiming at. They are colorful and very easy care and have good rebloom.

I can't tell from your picture, but is it possible that the lesser-blooming roses on the right side get more shade than the roses on the left? That could account for the difference in blooming.

For that matter, do all your roses get at least 6 hours of sun? Sunny roses usually bloom more than partially shaded roses.

Good luck--looks like you have a lovely garden going there.

Kate

Do you have any red? If not consider Showbiz & or Trumpeter

Other favorite roses that make a statement:

Pinkish - Passionate Kisses
orangy - Morden Fireglow
Pinkish orange - Banjamin Britten

Most of the roses in this hedge are probably getting 8-10 hours of sun a day. I should try noting the times next weekend to be sure I'm right. They only get very brief morning shade from some tall Swedish aspens behind that arbor, but those are columnar trees and don't cast much shadow. Further around the crescent to the right (not in the photo) are the last few roses in the hedge, which are starting to get shaded by a nectarine tree. There's also a fence several feet behind them that casts shade on their roots, but the tops get sun.

Anyway, if I rip them out, I won't replace the two that are closest to the nectarine tree -- it's a little crowded there now, and they probably can't get enough sun as that tree grows.

I don't have much red in my garden, but I'm not sure I want 15 red roses as a hedge -- it may a little intense. I think the pink makes a softer, more pleasing impact. It's possible that a lavender color would be OK, but not far away is a short hedge of lavender-to-purple hibiscus shrubs, and I'd like to avoid repeating purple so much, even though you'd think it was my favorite color from the number of large purple perennials in my garden!

I like Passionate Kisses from what I just saw online about it. Is it a strong rebloomer in your experience?

Is it possible to add fragrance to my list of desires on these hedge roses? It seems like the more profuse repeat bloomers aren't usually fragrant -- am I right?

So, here's my list of attributes I'd love to find:
* Pink blooms, can be single or double -- don't have to be just like Pink Simplicity
* STRONG repeat (or constant) blooming from May to frost, if possible, preferably without constant pruning or deadheading
* 4' height or so, with enough spread to look like a healthy hedge
* Some amount of good fragrance -- doesn't have to be incredible, just pleasing
* Can handle somewhat alkaline soil, hot summer, and dry weather

Any other ideas with those criteria?

Also, any other ideas for making my current roses perform better? Here are the ideas I have so far (to see if I can make these work out better and not have to buy all new ones):
* Give supplemental water every week to ensure they're getting enough
* I think I'll use a liquid fertilizer every two weeks during that watering (I'll get one with more nitrogen) -- is every two weeks OK or too much? Is there a fertilizer you recommend that has important micronutrients as well as the macronutrients?
* Shear them back a bit now to promote some new growth again that may produce more buds

Anything else? Thanks!

I'd return to my question about blind shoots. Are the shoots stopping and then starting out with new growth buds, or are they making continuous vegetative growth with no flower buds? If the latter, probably it just doesn't want to bloom much in your climate.

It's probably unlikely that a desert soil would have a micronutrient deficiency. It's more likely there would be an excess of something. A serious problem with nutrition would produce symptoms visible in the foliage or growth tips.

Just follow the instructions on your soluble fertilizer. These are usually generous amounts. I would try a bit more water, splitting the 4-day interval. It's possible your layered soil is causing problems with water availability in the top layer. But then again, if they are growing continously, that should be enough for bloom.

Michael,

They appear to just be growing continuously (and they were really six feet tall, not five, like I said at first). At the end of winter, they were about three, maybe three and half feet tall. Anyway, it looks like they do produce tiny little flowerbuds that dry up and fall off and then the branches just keep growing.

I really do think the aborting flower buds could be related to insufficient water. I had originally thought I was giving them too much water, but I've changed my mind on that.

So, when a rose has self-cleaning flowers, is there a little joint in the stem just at the base of the flower bud that allows the mature spent flower to just fall off? If that's how it works, that would explain how these tiny little flowerbuds just fall off sometimes when you touch them. Many of them appear to be dried up and brown. Seems to me that insufficient water could be making that joint weak and allowing them to abort. Or perhaps there's a nutrient deficiency that makes them weak. Anyway, I'll try more water and fertilizer.

There is a visible joint called the abscission layer partway down the flower neck and another between the neck and the stem. If the plant decides to abort a bud, it hardens off the abscission layer so the part above dies and drops.

Passionate Kisses does pretty good - in my garden it was getting afternoon sun. The best bloomer is Outta The Blue. OTB is very fragrant, it's purple but lightens as it ages. I'm pretty sure PK has scent. It just finished blooming, not sure if there are any blooms left for me to smell.

OK, I know a lot of you have already responded, and I appreciate that! I just want to show you a few photos so you can see what I mean about my roses' current condition.

Here's what the one looks like that is blooming well:
{{gwi:293306}}

Here's what the others look like -- stark difference! Sorry for the sun glare on the lens, but at least you can see how they haven't flowered at all yet this year:
{{gwi:293307}}

And here's a closeup of one of the withered tiny flowerbuds. When you click on the thumbnail photo below and go to my Picasa online album, be sure to hit the magnify button so you can see this little bud up close. These tiny buds just fall off when you touch them. They're on otherwise healthy branches.
{{gwi:293308}}

So, any more advice after seeing those photos? Like I said before, I think my problems are probably partly caused by not giving enough water. Hopefully more water will make the shrubs stop aborting those little buds! And those aphids are probably weakening the tiny buds, since the buds are so little right now.

Steve, go to the link and see Buford's picture. This is what I think of as mysterious bud drop. The rose has cut off circulation at the abscission layer midway up the neck, so it drops with a clean-cut end.

I am not sure what I'm seeing in your bottom photo. Are the black spots dead buds? Is the green pointy thing just above them a bud or vegetative growth?

We could think about rose midge. To my knowledge, this terrible pest has not been reported in Utah. However, you seem to have too much new growth for that. And why is one plant excused from damage? For info, use the search string: robin rosetta midge. You could repeat your pics in a thread referring to rose midge to see what people think. More pics showing the structure of non-blooming shoots might be helpful, closeup of any dead stuff, etc.

That is a lot of aphids, but I've never known aphids to prevent bloom. Most roses will repel aphids when buds are about to open, but PS appears not to know that trick.

Deficiencies of calcium and zinc can cause death of growth tips, but I'd expect to see other foliar symptoms. You could get a soil test.

I was asking whether you had continuous growth or stop-and-restart. The third picture is not continuous growth.

Here is a link that might be useful: bud drop

Hey Michael, thanks for sticking with me on this problem! I appreciate your time and help. Let me try again with the photo, and I'll make it bigger so you don't need to click and view it somewhere else. The dead flower bud is brown and thin, very small. See it inside the yellow circle below.
{{gwi:293309}}

I may not have understood your question about continuous growth versus stop and start. I thought of it as continuous because I haven't noticed the shrubs not growing for any period of time. But perhaps when these buds form on the branch tips, they pause for a while and then continue growing upward after the bud aborts. You can see that this branch is growing up past this aborted bud. But some of the aborted buds are at the tips of other branches. This one was just easy to photo at the moment.

When these fall off, they don't include any piece of stem like the photo in the other thread you linked to. They just break off right at the base of the bud. Sometimes they're still green, and I touch them and they fall off, leaving those three skinny leaves that would have framed the flower (are they sepals?) behind.

The sepals are still enclosing the dead bud.

OK, about "stop and start," I see the rose makes trusses or panicles with multiple necks carrying blooms, and in the picture one of the necks has turned black (?) and atrophied, killing the bud. Maybe it was a lateral bloom rather than a terminal bloom. I can't tell whether the growth continuing above it is neck growth or secondary cane growth.

If a bud aborts at the tip of a branch, and a new vegetative growth bud starts just below that, do these growth buds sometimes turn black and abort like the bloom buds?

I'm not sure what you're seeing as a black neck. Are you referring to the very small area just below the withered bud (within the yellow circle) and above the three leaves that frame it? That could just be shadow. I'd have to look closer at some of these when I get home this evening.

I'll have to look at some more aborted buds and see how growth has behaved around them. But I haven't seen anything turn black on these shrubs. The flowerbud itself turns brown as it dries up, but not black. And these buds are only about 1/2" long when they abort. They're very slender, too. Tiny little things. But I haven't noticed any vegetative growth falling off or withering at all.

I'll do some more inspecting tonight and perhaps take some clearer photos of the problem, too. I should have something more to post tomorrow.

I had the same experience. The neighbors planted a hedge of Pink Simplicitys complete with their J&P tags, then they divorced and moved like a month later. The new owners took them out and they were on the curb for the garbage. So I planted them on the HOA property to color it up some. They got great care, good soil, good sun, and they grew like crazy and never bloomed, blind shoots and blind shoots and blind shoots galore.

I decided it must have been bad budwood somehow. They were ALL doing it consistantly for several years.

OK, I went out and inspected some more this evening. I found quite a few small new terminal flowerbuds, so I think I'm going to get a flush of blooms soon. These little buds are really getting sucked by aphids (and I saw a few brown beetles or weevils, too), so I sprayed all the shrubs with an Ortho systemic spray.

I noticed that on the shrub that flowers well, the blooms come in groups of three to five. On the shrubs that aborted the buds, you can see where a bud used to be, and one or more of the three to five stems in that cluster just kept growing and sort of turned into branch growth rather than a flower stem. This may explain why the good bloomer is shorter -- it's stems turned into flowers instead of morphing into more vegetative growth. At first glance, it might look like just a bunch of blind shoots, but I think these shoots had flowerbuds on them, but the buds withered and then the shoots just kept on growing upward. I don't know if that's possible, but that's what it looks like to me.

Anyway, I was going to cut their height back tonight, but when I saw quite a few flowerbuds that weren't falling off, I decided I'd better let this flush bloom and then cut them back.

I think what happened is that my spring flush tried to happen, but some deficiency, either in water or nutrients, caused all the flowerbuds to abort, so they just kept producing more vegetative growth. Now they're getting ready for a summer flush and perhaps that mysterious deficiency is not so bad now, and they're going to bloom. They are definitely getting more water now than they did earlier in the spring. I didn't turn on the sprinkler system until late April, and it was a dry spring. But then again, I've had some wet springs in the past six years, and they've never bloomed well even then.

I'm betting on some kind of mineral or nutrient deficiency. I think I'll need a more comprehensive soil test than the do-it-yourself one I tried this spring. I can send a sample to the local extension for testing. Anyway, if I can figure out what deficiency is causing weakness in a joint where the the flowerbud attaches to the stem, perhaps I can save the spring flush from fall off next year and I'll get to see these roses in all their intended glory.

Well, a guy can think big, right? :-)

'Lavender Simplicity' is a really bad rose as well. Just planted some and they immediately dropped all of their leaves with blackspot after a meager bloom. Flower color is lovely but plant is terrible. I have grown 'Carefree Wonder' for years and it is a beautiful shrub almost always in bloom. 'The Fairy' is a joy. Has anyone ever grown 'Scentimental'? It looks nice. I need 2 frontyard-worthy shrub roses.

I've never had that problem with my Pink Simplicity.
That said, spent blooms often fall off at the slightest touch after a couple of days
Being self cleaning like that, not enough water could cause the tiny buds to abort if they were allowed to wilt just a tiny bit, especially in your dry high altitude. That magnifies water loss.
Your other roses that do not self clean won't be so affected.

Karl,

I think one question can help me settle my mind on this. Does self-cleaning mean that the whole flower structure falls off somewhere below the sepals after it's spent, or does it just mean that the petals fall off, leaving behind the ovary, style, etc?

Because if the whole flower falls off at the stem, then that could explain the mechanism that's prematurely kicking in to abort these buds. But if it's just the petals falling off, then I'm not sure my problem is related to the self-cleaning attributes of this rose.

Thanks to everyone for the help on this thread!

Well, I'll try to answer my own question if anyone else out there has the same questions.

Looking last night at my one shrub that has been blooming well, some of the older spent flowers have stems that are drying out (they're about 3" long). If I wiggle them just a little, they fall off at the base of the stem. So, I suppose that's what self-cleaning means, and YES, this seems like the answer to my problem.

These self-cleaning roses have a joint at the base of the stem that will separate from the branch a number of days after the rose is done blooming. My little rosebuds appear to be separating right at that joint but they're so small they haven't even developed any stem length yet.

As Karl said, my non-self-cleaning roses won't be affected like this, and they're not. They bloom just fine. And I do live in a place with nearly no humidity when it isn't raining, so that dry air probably adds to or creates this problem.

So, the final conclusion of this long, long thread (thank you again everyone) is that I'll be giving them more water and probably a foliar fertilizer early in the season -- as soon as they leaf out -- to try to avoid whatever deficiency these plants have that is making them abort their spring flush.

By the way, I'm finally starting to get a summer flush of blooms, and it looks like it's going to be pretty good. The shrubs are way too tall (6-7', since I never pruned them this spring while trying to figure out what I was doing wrong), which makes them look a bit funny, but I won't be cutting them back until after this flush.