You do realize that Knockout roses mature at around 3'x3' while photinia will grow (and rather rapidly) to 12-18' and 8-12' wide? Seems a rather ill-suited combination to me :-( The photinias will soon shade out the roses and then - pretty much inevitably - eventually succomb to leaf spot themselves, which is decimating these shrubs throughout much of the southeast.

And in general, alternating plantings of two different plants is not a great look - very contrived. If you wish to use the plants on hand, remove the roses and locate a few more photinias to fill in. You could use the roses in front of the photinia, but I doubt you will have enough room - they will rapidly consume that 4' width (especially since they should have been planted at least in the center, if not at the outer edge of the raised bed, to allow for mature spread).

You sure don't need any more permanent plants in that area but you could fill in with annuals or a few temporary perennials or groundcovers until the shrubs put on some size.

Actually left to their own and well cared for knockout roses will grow to 5' x 5' or even bigger--there are some that large where I work. And the photinias can be shaped to whatever habit works in the landscape, it seems to me.

As for the look, I happen to like it.

"Left to their own" and "well cared for" are contradictory terms. The growth rate of the photinias and roses is not equal - one (the photinia) will grow faster than the other, requiring ongoing maintenance to keep sizes similar. There is also evidence that supports frequent pruning of the photinias encourages the leaf spot, which is another consideration.

If you like the look, go for it - it's your garden. But I doubt you will need any companion plants other than something very temporary until the shrubs and/or roses fill in.

Photinia get huge; even if you prune constantly the trunks and limbs will get huge. These are used for major screening and hedges. They could be used as a very tall backdrop hedge for a border in front, but not really part of the border. Run away if you are trying to create a nice shrub and flower bed. Do not use them just 'cause you like the red new growth. There are other things. You would never "alternate" them with roses.

Seems to me that we are in one of those double-jeopardy situations where Joe wants outsider advice on how to enhance a planting whose appeal is somewhat personal, or idiosyncratic.

This may represent a mis-planting or over-planting, but it is one of the tenets of DIY design that everyone is allowed to do this, since it is only ourselves we burden with the outcomes, be they impractical, dangerous, or merely ugly. I am spending the next week taking out a Chimonanthus praecox that I planted in a narrow bed between a concrete wall and a sidewalk; its trunk has now reached the maximum capacity of the space. That was forseeable from the time I planted it and experts would have dissuaded me. On the other hand, I've enjoyed the tree for 10 0r 12 years and am ready for a change.

Joe may enjoy this planting for at least that long, and if he's good at pruning maybe for longer. But anyone who isn't keen on the original planting isn't going to enter into its enhancement with any enthusiasm.

There was a recent discussion about a little shrub planted at the end of a driveway and asking what to do till it grows in... you might look for that.

KarinL

Planting the photinia in groups on the ends, sort of like bookends with the roses all together in a middle section would solve the problem of the photinia overwhelming and shading the roses. There would need to be a fence behind this layout to provide screening and backdrop behind the roses.

If the photinia gets all spotty and starts defoliating at some point you will be liable to find yourself choosing another kind of shrub anyway.

The planting would be a lot more interesting if it was made up of more than two kinds of shrubs.

My super red and super bronze photinias are being eaten alive by something in my garden. I also have a weeping cherry which it too seems to be being eaten too HELP I want try something before I try pesticides. We live in NSW never had this problem before. Some of the plants have just gone nothing left of them??