Spiraea cinerea Grefsheim

Spiraea x cinerea 'Grefsheim', also known as the Acute-leaved Spiraea, is a graceful and compact bush with flexible and drooping branches. In spring, it is completely covered with a multitude of white flowers. Not demanding, it will suit all gardens. Its compact and spreading habit makes it suitable for the front of borders, rockeries, and cultivation in pots or containers. It will adapt to all climates except for excessively dry conditions.

Spiraea x cinerea 'Grefsheim' belongs to the Rosaceae family. It is a hybrid obtained by cross-breeding Spiraea x multiflora (another hybrid) and the species Spiraea thunbergii. This bush, with compact growth and long upright branches which eventually droop at the ends, reaches a height of 1.2 m (3.9 ft) with a width of 1 m (3.3 ft).
The spectacular and abundant flowering takes place in April-May. The white flowers, grouped in bouquets, appear along the branches of the previous year. They are followed by fruits with no horticultural interest, but interesting for attracting and feeding birds. Spiraea x cinerea 'Grefsheim' has a bluish grey-green foliage, which turns yellow tinged with purple in autumn. The leaves are narrow, acute, finely dentate, and measure from 2 cm to 3 cm (0.8 in to 1.2 in).

Plant in moist to dry, well-drained, neutral or limestone soil, even poor soil. This undemanding bush will thrive in full sun or partial shade. In order to maintain the plant's vigour, it is important to remove old branches at the base in spring. Prune lightly after flowering if necessary, removing half of their length from faded shoots. This plant blooms on the branches of the previous year. Apply a complete fertiliser every year in March.

Spiraea x cinerea 'Grefsheim' can be used in borders, as a standalone plant, in groups, as an edging plant, or in pots. It can also be used as a small flowering hedge with other undemanding plants, such as Spiraea prunifolia, Prunus x cixtena, Prunus tenella, Ribes sanguineum, and white, pink, orange, or even red Cytisus x praecox.

Note: This variety has more arched and vigorous branches than the famous Spiraea arguta. In addition, the flowering occurs earlier than that of the latter.