A deciduous and potentially large upright shrub with slightly glossy mid-green leaves. In mid-summer Hydrangea paniculata 'Kyushu' produces upright pyramidal panicles of creamy-white flowers and is noticeably earlier into flower than other varieties..
Botanically speaking, the flower heads mainly comprise the larger and more showy sterile florets that surround the small fertile flowers. There is good evidence to suppose that these large sterile flowers act as 'honey guides' to attract pollinating insects.
Generally speaking the more mature and larger the plant, the larger the flower panicles. Hence, hard pruning, in spring, will tend to produce a more compact plant with smaller flower heads, whilst light or no pruning will result in not only a larger plant overall but one proportionately large flower heads. As a guide, an established plant could be cut back to about three feet in height, just above the pairs of buds you will find on each stem, some time during March.
Hydrangea paniculata grows wild in Japan, where it has been seen growing as a quite substantial tree, as well as Sakhalin, and eastern and southern China. It was introduced into the UK in 1861. The variety 'Kyushu' was collected on Kyushu Island in 1926.
Hydrangea paniculata 'Kyushu', in common with other hydrangeas will appreciate quite cool and shady conditions, so plant in soil that is rich in organic matter, which does not get aggressively dry in summer, and in a position which offers some shade from the full heat of the mid-day sun. If you are planting in full sun you will tend to get a more compact plant, and you may need to water the plant during a mid-summer heat wave - otherwise, full sun will be tolerated.
Probable height in the UK will be in the region of 2 to 3m, depending on the pruning regime. Hydrangea paniculata 'Kyushu' can be confidently considered fully hardy, but the young spring growth may be prone to damage from cold winter winds or a sharp frost. Consequently plant in a slightly sheltered part of the garden and avoid a frost pocket, such as the bottom of the slope where cold air cannot flow away.