Knock out roses can grow up to 3-4 feet high and as wide. It seems to get to its max height in the warmer zoned climates. If the beds are 4 foot wide, and your knock outs grow to say 3 foot in width, it doesn’t give you much room to plant the other upright plants. Check the width measurements given for them on the labels to see if they will fit. If they don’t grow too wide, you could probably put one of them next to the roses.