Spiraea ‘Grefsheim’, or spiraea x cinerea ‘Grefsheim’ as this hybrid is called in botanical terms, was bred in Norway, which is probably where it has learned to withstand harsh winters. Spiraea ‘Grefsheim’ is hardy to -20C and is therefore suited to all areas in the UK. This deciduous shrub of garden origin has simple, lance-shaped, grey-green leaves which develop a blue-tinted hue in summer, subsequently turning reddish brown in autumn. Spiraea 'Grefsheim' has arching branches which are covered in large panicles of small five-petalled flowers, white in colour, and only 8mm in width.
The shrub itself is of similar stature, with its compact habit of growth it is considered a dwarf shrub. Spiraea 'Grefsheim' can reach a mature height of 1.5m tall at an average growth rate of 30-50cm p.a., so it will reach its final height in just a few years. Spiraea ‘Grefsheim’ is generally the first to flower of all spiraeas, adding plenty of interest to the spring garden. Spiraea 'Grefsheim' will make a stunning display in both small as well as larger gardens, in borders, informal hedges or as a specimen shrub. Flowers appear on previous year’s growth, so prunings may impair the plant’s ability to flower.
This is normally not an issue, as spiraea ‘Grefsheim’ will make a beautiful garden decoration without requiring any pruning. It tends to remain compact and small and does not need to be kept in check, unless garden planning requires otherwise. Grow spiraea 'Grefsheim' in full sun or partial shade in moist well-drained soil. It is tolerant of much and will not suffer from extended dry periods. As a final bonus, spiraea ‘Grefsheim’ offers wildlife interest by providing plenty of nectar and pollen for bees and other pollinators.