Grey Spiraea 'Grefsheim'

Grey spirea 'Grefsheim' (Spiraea × cinerea 'Grefsheim') is the shrub gardeners call May snow. Its slender branches arch almost to the ground and in spring are smothered in white flowers about 8 mm across, gathered into small clusters along the whole length of last year's shoots. The fine grey-green leaves only sharpen that white foam.

In April and May the bush becomes a white cascade, which is why it goes into informal hedges, onto banks and into cottage borders. At 10-20 years it holds 1-1.5 m in height and width, more compact than Van Houtte's spirea, and it flowers earlier than any summer spirea. Prune straight after flowering, before the new buds are set.

Key characteristics:

• What makes it special: The flowers carry a light honey scent, so in May the bush hums with bees, while pests and diseases barely touch it.
• Dimensions: Over 10-20 years it forms a rounded shrub 1-1.5 m tall and just as wide.
• Flowering: In April-May the branches are covered with pure white flowers about 8 mm across, gathered in neat clusters along them.
• Light: Grows in sun or partial shade, but the most generous flowering comes in an open, sunny spot.
• Soil: Takes readily to any garden soil - chalk, loam or sand, acid, neutral or alkaline - as long as it is moist and well-drained.
• Watering: Moderate watering without drying out; the one thing it dislikes is excess moisture and standing water.
• Care: Prune right after flowering; an overgrown bush is rejuvenated with a hard cut at the same time.
• Landscape use: Lovely in cottage and informal gardens, on banks and slopes, in flower borders and free-growing hedges.
• Origin: The cultivar holds the RHS Award of Garden Merit (2003).