I'd be more than a bit leery of both. Morning glories, at least around here, are so confoundedly vigorous that they tend to choke and overwhelm everything in their vicinity. Sweet peas may look delightful now, but they are a complete nightmare at the end of their season. (Again, this is just my experience here in inland southern California) When the heat comes (sometimes May, sometimes June), their delightful green shoots and leaves cook in a heartbeat, and the blossoms fry an ugly death. Worse yet, the plants quickly become beset by spider mites and powdery mildew.
Now I have no idea if this is the same kind of PM that affects roses, but I do know that spider mites can be equal opportunity predators. As delightful as the idea of interplanting sounds now, I fear it will all come to a bad end for your roses.

Interesting points, and very possibly why I haven't seen anyone proposing these particular "companions" before.

Of course I have no problem with hacking the Sweet Peas out/down the minute they finish doing their pretty part, but that still might not be soon enough to save the roses from ....

In my old neighborhood morning glories completely swallowed a two story house. They finally got a tree trimming crew in to remove everything. The stuff was also creating two story tall curtains on the electrical wires and moving into surrounding yards. It was a sight to see. When the house finally emerged, it was a surprise. There were truckloads of plant material to haul away.

I think morning glories are very invasive and difficult to get rid of. My roses don't seem to like competition from anything. Two years ago I had a volunteer petunia come up at the base of a Belinda's Dream that was in a grouping of four. I thought it was charming and left it there. It ended up climbing up into the rose. Some of the canes actually died from the competition of the petunia. Two years later that rose is half the size of the other three. I know some people love clematis in their roses, but I've been hesitant to try them because of the petunia incident.

I grow sweet peas, and I haven't had problems with spider mites or mildew, but their season ends very quickly here due to the heat. I haven't actually grown them up a rose, but up structures or plants near them.

I sure appreciate all this input, and I see that my fledgling idea wasn't a very good one. I'm glad I asked before I headed off into dangerous territory. I still love both the Morning Glories and the Sweet Peas, but I will make sure I give them their own areas to colonize (or not). With the possible exception of one perennial MG that I planted with the express wish that it hide an ugly shed, I've never had any of them be terribly vigorous, much less invasive. Of course now that I've said that, and now that I've started a dozen + of them way early, I'm sure I will live to rue the day...

Susan

Morning Glories: Nay! they are highly invasive where I live, and snails are drawn to them.

Sweetpeas:Yay!!!
I love growing sweet peas near my roses.
If your climate is cool from c. May 1 through June, with temperatures averaging in the 60's and 70's rather than the 80's and higher, the flowers do not brown.
There are also sweet pea cultivars that are more tolerant of heat.
My favorite varieties of sweet peas are the ultra fragrant Spencer types, they are highly perfumed and frilly and lovely.
I grow sweet peas in their own row, c. 2-3 feet in back of my roses.
when the sweetpeas stop blooming it is easy for me to knock them down, so they lie on the ground to be hid by the rosebushes, because it is only as the sweet peas go to seed that they add nitrogen to the ground, through their root system.

Luxrosa

If snails are a problem where you live, I suggest buying sweet pea plants as large as you can find, they have tougher leaves and the snails are less likely to chomp them down to the ground as they did my 2-3 inch tall seedlings last year.

Snails? Snails? Sheesh, they are almost as big as the gophers here..... Thank goodness for Sluggo which makes them slightly less problematic than they used to be.

Lux, I'm just about 50 miles north of you in Santa Rosa; our climates are pretty similar, although I think here it gets a bit hotter when it's hot and colder when it's cold. I have not been aware of the difference in the culture of different varieties of sweet peas, so thanks for the heads-up on that. Mostly what I have grown are just always seeds that I save from one year to the next, but I did pick up a new plant this year and will check the label to see if it's possibly a Spencer strain. In any case, I will keep my eyes open for some of those in future.

I believe there are two kinds of Morning Glories, the perennial, which is a purple-flowered house-eating pest unless you have a house you want it to eat (I learned this the hard way), and the annual, which is easy to control and a nice clear blue.

I think Lux is right that sweet peas are legumes, which are nitrogen fixers. If you cut them back once they've flowered, but leave the roots in the ground, I believe you're feeding your roses' roots, aren't you? Ditto with clover?

Do NOT plant morning glory. I did that and it nearly ate my entire yard. I now have to pull up dozens of seedlings year after year from just one plant. I do have some wild morning glory that behaves itself nicely, but I have no idea what it is.

The English call morning glory bindweed.

AARRgghh!!! I have been fighting morning glories in my mother's roses for 10 plus years. NEVER NEVER NEVER do that on purpose. Hers came from a neighbors house. Moreover, most people are at least slightly allergic to the sap in those morning glories, so you can get a nasty itch from pulling them out. And the roots NEVER die, but come back year after year, rivaling bermuda grass in their ability to avoid anything that might conquer them.

I grow sweet peas, and I think you would want to put them somewhere where the dead vines are easy to pull out.

There is an ideal plant for vining through climbing roses, however. Plain old vining geraniums. They look good year around, bloom alot and don't try to take over. I use the dark lavender one. Clematis also does well for that purpose, but it doesn't bloom as continuously.

This is a shot of a 6x6 plant of Mme. Plantier with the lavender vining geranium winding through it from last spring. But the best thing is that the geranium continues to bloom even after the once blooming rose has stopped.

{{gwi:238020}}

beautiful picture; thanks for sharing your garden.

Also MG put out a lot of seeds and they are prolific. Each flower makes a seed pod with dozens of seeds. You can see them after the flowers die. I try to pull out any MGs I have before they seeds set.

It's almost as bad as kudzu down here.

Ipomea (sp?) -"Blue Dawn Flower" is a nightmare from which you will never awake. It will tangle and overtake everything, and I can imagine how nasty it would be to try to untangle it from thorny rose canes.

BUT, I have been planting ANNUAL morning glory seeds (Grandpa Ott) for years, and they never even reseed. I have to buy a new pack every Spring. The look great with nasturtiums, but I have never tried them with roses. They are very well behaved and trouble free.

I love sweet peas mixed in with my roses. I have never seen any ill effects from this combo

wow k_strong, very beautiful!

Same corner, yesterday. The Mme. Plantier rose, which only blooms one month out of twelve, just disappears into the background when not in bloom. Common pink jasmine is in bloom there now, along with those vining geraniums, which bloom twelve months out of twelve. But most of the greenery in this pic is the non-blooming rose.

{{gwi:238021}}

Definitely there is a difference between the perennial morning glory, a fiercely invasive plant, and annual varieties.

Same goes for sweet peas. There is a perennial that can be a problem. I grow an annual, Cupani's, which also colonizes in the Santa Rosa Rural Cemetery, and it's sweet as can be. I let it clamber up and through the roses - it grows to no more than 4 to 5 ft tall - and cut it back when it's done. It's not hard to pull it out, it self-seeds, and I collect seeds to give to my friends. Lovely stuff. I took it to the Sacramento cemetery and have it growing through some Perle d'Or roses - very pretty. I wrote about the sweet peas in the last Cemetery Rose newsletter, along with photos.

I haven't had any trouble with clematis overtaking the roses, but my garden is a bit hot and dry so they probably aren't as vigorous as others would experience. My favorite is Rooguchi, a very modest one that climbs with support and has darling blue bell-shaped flowers. I have it growing with a climbing mini, striped red and white Roller Coaster, and the combo makes me happy all summer long.

So, I think that the trick is to find MODEST sized climbers. I think that the idea of vining geranium is inspired, although I'd be afraid of pink jasmine smothering the roses in my climate.

MODEST companion plants work well, too. I couldn't live without companions to my roses at home - true geraniums and heuchera and alyssum, to name a few - and have been working hard to add more companions to the cemetery, too.
Anita

Here is a link that might be useful: Cemetery Rose Newsletter

DO NOT NOT NOT ever plant Morning Glories in Southern CA.!!!
You will never rid yourself of them, and the $##@@## things will grow like Kudzu!

Sweet Peas? Do THEY do that?
I love Sweet Peas, but have come to hate morning glories, despite the loveliness of their color.

Jeri

k_strong, really beautiful picture. thanks. how is the fragrance on the pink jasmine?

Jeri, the perennial sweet peas have been a problem in some of the foothill cemeteries. I remember hearing about that on that first rustle that we took. Some roses were practically hidden until they cleared the sweet peas away.

The annual morning glories aren't the same monster as the Blue Dawn Flower, but I still would rather not have to untwist their growth from the roses. I think it's better to plant climbers that don't wrap around what they are growing through.
Anita

I also grow the jasmine that is in the photo, which is named Poets Jasmine, or J. officinale, and I grow it because it is very sweetly fragrant. It is the type of jasmine that is used in making perfume. The blooms are white, it is the flower stems that are pink; a charming combination.

Poets Jasmine can become invasive in warm climates, I planted it by a border fence in my last home and my neighbor complained about it coming over and rooting on his property and covering his Himalayan blackberry plants.
It is a plant that is easy to grow in a pot.

Luxrosa

Jeri, the perennial sweet peas have been a problem in some of the foothill cemeteries.

*** OH, THAT sweet pea!
Now I understand.

Jeri

Luxrosa, your former neighbor should have THANKED you for covering his Himalayan blackberry plants -- talk about ingratitude! -- Debbie

One of the things I list as a Major Regret is that I planted Morning Glories once in my yard. :( The previous owners also planted a substantial amount of perennial sweet peas... :((. And of course it wouldn't be Oklahoma without that Insidious Trumpet Vine...
Give those MGs to someone you don't like!
:D
albin

my last post should read "flowers are tubular, the long tubes at the bottom of the flower are pink, the petals white"

I consider this plant a must have for any fragrance garden.

I felt that I had fallen into a heavenly dream the first time I saw this jasmine and smelled its lovely scent.

lux.

I take all of your cautions about Morning Glories to heart, and I won't plant them so that they actually use the roses as trellises, but I do think that those of you who rail against them are thinking of the perennial version and not the annual versions that are available. I am well aware of the shed or house-eating qualities of the perennial Morning Glory; I planted one because I wanted it to hide an ugly shed, and it does a pretty good job of that. But the annuals are....just that....annuals which die back (at least here in Zone 9), and occasionally (only occasionally) reseed and even then only minimally.

To get MG's to do well here I have to start them indoors because they like more heat than we get.

Still, I do think you are all right that they would be too big and too heavy and block too much air if planted as a true companion to roses, and so....I'm just not gonna do it.

Gee, it's so much fun to have been able to log on at all that I'm just going on and on....

Susan