Rosa (genus)

Japanese name: バラ（木立ち・ブッシュ）
Scientific name: Rosa

[Overview]
A type of garden rose cultivar that grows as an upright bush.
Among modern roses it includes the Hybrid Tea group, and among old roses it includes the China group and the Tea group.
The trunk stands up firmly.
Many have thorns on the trunk, branches and leaf axes.
The leaves are alternate and odd-pinnately compound, with serrated leaflet margins.
Most are repeat-blooming and flower from spring to autumn.
The size, shape and color of the flowers vary by cultivar.
Some flowers are fragrant.

[Cultivation]
Propagate by cuttings or grafting.
It prefers a sunny, well-drained, well-ventilated, fertile soil.
Avoid dry places and places exposed to strong afternoon sun.
The optimum temperature for growth is 20–25 °C; growth declines above 30 °C, and in direct midsummer sun the leaf temperature rises and weakens the plant.
In midsummer, place potted plants where they receive sun only in the morning, or provide shade.
Plants in the ground may be planted where they will sit in the shade of deciduous trees.
For potted plants, water thoroughly when the soil surface dries; for plants in the ground, rainfall is sufficient unless summer brings a long spell of sunny weather and the soil becomes dry.
Apply organic fertilizer in winter, and apply slow-release fertilizer after spring flowering and after summer pruning.
When deadheading, cut off about 1/2–1/3 of the flower stem after the flowers have finished.
To prepare for autumn flowering, cut back lightly to about 3/4 of the original height in August–September; around February, remove old and diseased branches and prune to 2/3 of the original height just above a strong outward-facing bud so that the plant takes on a cup shape.
Basal shoots (new growth), which grow vigorously from the base of the plant, are strengthened by pinching the tips once they have grown to a certain length.
If shoots emerge from the rootstock, remove them as early as possible.
Pests and diseases include black spot, powdery mildew, aphids, rose sawflies and longhorn beetles.

View this page in Japanese (日本語)