Grefsheim spirea

Sun

Full sun gives the best flowering; tolerates partial shade with fewer flowers.

Water

Water regularly while establishing. Once established, water during prolonged dry spells, especially in hot weather.

Soil

Well-drained soil, from sandy loam to clay, provided it does not stay waterlogged; tolerates acidic, neutral and alkaline conditions.

Height

4-6 ft (1.2-1.8 m)

Spread

4-6 ft (1.2-1.8 m)

Flowers

Small white flowers cluster along the previous year's arching stems in early to mid-spring, before or as the leaves emerge.

Foliage

Small, narrow, grey-green leaves; autumn colour is usually yellow and can be modest.

Growth

Moderate to fast.

Care needed

Low

• Pollinators
• Deer resistant
• Drought tolerant
• Cold hardy
• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1.6 ft (0.5 m)

2. After 1 year

   2.5 ft (0.75 m)

3. After 2 years

   3 ft (1 m)

4. After 3 years

   4 ft (1.3 m)

5. After 5 years

   5 ft (1.5 m)

   full size

About 4 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Growth rate

Fast

• Water deeply through the first growing season whenever the root zone begins to dry.
• Apply 2-3 in (5-8 cm) of organic mulch, keeping it clear of the stems.
• Add a thin layer of compost in spring; routine heavy feeding is unnecessary.
• Allow enough space for the branches to arch naturally without obstructing paths.
• Avoid planting in low spots where water stands after rain.

Pruning. Prune immediately after flowering, shortening overlong flowered shoots to a strong side shoot and removing up to one-third of the oldest stems at ground level when the shrub becomes crowded. Avoid autumn or winter shearing, which removes the following spring's flower buds.

Early spring

Renew mulch and add a thin layer of compost if growth has been weak.

Spring

Enjoy the flowers; leave healthy stems uncut until flowering finishes.

Late spring

After flowering, thin crowded older stems and shorten branches only where needed.

Summer

Water young plants during dry weather and check tender shoot tips for aphids.

Early summer

Take softwood cuttings from healthy, non-flowering shoots.

Autumn

Plant while the soil is workable and moist, then water thoroughly; in very cold climates, spring planting is also suitable.

• Plant as a loose flowering hedge where its arching branches can develop without shearing.
• Use at the back of a mixed border, with later-flowering perennials masking the quiet summer foliage.
• Set above a low retaining wall or on a bank so the flowering stems can cascade.
• Combine with spring bulbs and blue-flowered perennials for a white-and-blue spring display.

Garden styles it suits: English country, Cottage garden, Romantic rose garden, Traditional, White garden and Low-maintenance.

Plant it with: Daffodils, Grape hyacinths, Catmint, Hardy geraniums, Peonies and Lady's mantle.

Wildlife: The spring flowers provide pollen and nectar for visiting insects, including bees. Dense branching offers cover for small birds.

• Aphids can distort young shoots: wash small colonies off with water and encourage ladybirds and other predators.
• Powdery mildew may coat leaves in crowded or shaded conditions: improve airflow and avoid drought stress.
• Poor flowering often follows winter pruning or deep shade: prune only after flowering and provide more sun.
• Waterlogged soil can cause root decline: improve drainage or move the shrub to a better-drained position.

Not known to be toxic to cats, dogs, horses or people; no part is recognized as a significant poisoning hazard. It is an ornamental plant, not a food crop, and eating plant material may still cause stomach upset.

• Vanhoutte spirea (Spiraea × vanhouttei)

  Usually flowers later in spring and has broader, often shallowly lobed leaves rather than Grefsheim's narrow grey-green leaves.

• Thunberg spirea (Spiraea thunbergii)

  Also flowers early on fine arching stems, but its leaves are typically brighter green, more finely toothed and less grey.

• Bridal wreath spirea (Spiraea prunifolia)

  The commonly grown double-flowered form has tiny rosette-like flowers and broader leaves; Grefsheim has single, five-petalled flowers.

The botanical epithet cinerea means ash-grey, referring to the greyish foliage.

Propagation. Root softwood cuttings in early summer or semi-ripe cuttings later in summer. Layer low, flexible branches; vegetative propagation preserves the named cultivar.

Accepted botanical name

Spiraea cinerea

Sources: GBIF (CC BY 4.0). The care and design notes are LandscapeGPT's own.