Rose bushes are garden staples known for their varied colors and fragrances. They do spread, but the degree and method of expansion depend entirely on the specific variety and how the plant was propagated. Understanding a rose’s growth habit is key to predicting its mature footprint in the garden.
Defining Lateral Growth in Roses
A rose bush expands laterally through distinct biological mechanisms. The most desirable form of spread involves the emergence of new, thick canes called basal breaks, which sprout directly from the crown or the graft union. These new shoots, often reddish when young, are a sign of vigor and contribute to a wider, healthier shrub.
Another mechanism is suckering, where shoots emerge from the root system away from the main plant base. Suckers on an own-root rose are genetically identical to the main plant. However, they become problematic on grafted roses because they arise from the rootstock, not the desired variety.
Some specialized varieties, such as true groundcover roses, spread through rhizomatous or stoloniferous growth. Here, roots or horizontal stems spread underground, rooting wherever the cane touches the soil to create a dense mat.
Expansion Based on Rose Classification
The tendency of a rose to spread is linked to its classification and breeding purpose. Groundcover and landscape roses are intentionally bred for aggressive lateral spread, covering several square feet. These types are valued for their ability to form a dense, low-maintenance carpet of foliage and bloom, often rooting themselves along the length of their canes.
Shrub roses, including many popular English varieties, are known for moderate lateral expansion. They expand by continually producing strong basal breaks, resulting in a dense, wide, and rounded clump. Hybrid Tea and Floribunda roses exhibit the least natural spread, focusing energy on vertical growth. These types maintain a tight, upright profile, making them clump-forming rather than spreading bushes.
Grafted Roses and Rootstock Suckering
The most common source of unwanted spread is the rootstock of a grafted rose. Most commercially available roses are created by budding a desirable ornamental variety (the scion) onto a hardy, vigorous root system. The swollen area where these two parts join is called the graft union.
Suckers emerge from the rootstock below this union and represent the original, often less attractive, variety. If left unchecked, these suckers divert energy, weakening the cultivated rose above the graft and causing it to decline. An own-root rose, grown directly from cuttings, does not have this issue since any new shoot is genetically identical to the main plant.
Managing Unwanted Spread and Containment
Controlling lateral spread requires specific actions tailored to the type of growth. Rootstock suckers must be removed precisely to prevent regrowth, which involves tracing the shoot back to its origin below the soil level. Instead of cutting the sucker, it should be pulled or torn off sharply at the point of attachment to the rootstock. This tearing action removes the dormant buds at the base, preventing them from regrowing.
For roses that naturally form dense clumps, such as Hybrid Teas and Floribundas, size is controlled through annual renewal pruning. This involves removing the oldest, woodiest canes entirely at the base to stimulate the growth of new basal breaks.
For vigorous or groundcover varieties, placement is the best containment strategy. Ensure they have sufficient space to spread without encroaching on paths or neighboring plants. If needed, a physical barrier, such as a buried root barrier or edging material, can restrict the outward expansion of aggressive root systems.