I am using a Grandiflora rose named Prominent (Kordes) as a foreground planting; a climber (Autumn Sunset) is in the background. I love the color and the shape of Prominent’s blooms, but the blooms are sparse and plants are spindly compared to the healthy climber. Is there anything wrong with planting a new Prominent bush a few inches from each existing bush, to create fuller looking plants?
Below are some general guidelines on spacing for roses. Since you are planting a Grandiflora near a climbing rose which I am assuming has a structure to climb, you could probably get away with planting a bit closer than the 30″-36″ spacing recommended between two Grandifloras, but if you plant right up against the other rose, I imagine it would be problematic due to inadequate air circulation, which could lead to diseases. Here is what a publication of the University of Illinois Extension has to say:
“A general rule of thumb suggests that roses should be planted about 24 inches apart. This spacing will vary depending on the type of rose you are planting. Old garden roses will need wider spacing, while miniatures can be planted closer. Sufficient space between plants allows for good air circulation, an excellent first step in disease control.”
Suggested Spacing for Roses, from Jackson and Perkins:
Hybrid Teas & Grandifloras
Space: 30″ -36″ apart
Coverage: 6 -10 sq. ft.
Floribunda
Space: 24″ -30″ apart
Coverage: 4 -6 sq. ft.
English Rose
Space: 36″ apart
Coverage: 10 sq. ft.
Climber
Space: 4′ -5′ apart
Coverage: 12 -15 sq. ft.
Hedge
Space: 24″ apart
Coverage: 4 sq. ft.
Shrub
Large
Space: 30″ -36″ apart
Coverage: 6 -10 sq. ft.
Small
Space: 24″ -30″ apart
Coverage: 4 -6 sq. ft.
Miniature
Space: 12″ -18″ apart
Coverage: 1 -2 sq. ft.
Tree Rose
Standard
Space: 3′ -5′ apart
Coverage: 10 -15 sq. ft.
Patio
Space: 3′ -4′ apart
Coverage: 10 -12 sq. ft.
Miniature
Space: 2.5′ -3.5′ apart
Coverage: 6 -11 sq. ft.