Rowan 'Joseph Rock'

Sun

Full sun or light partial shade; autumn colour and fruiting are usually best in sun.

Water

Moderate; keep the root zone evenly moist while establishing and water during prolonged dry spells.

Soil

Moist but well-drained, moderately fertile soil; slightly acidic to neutral conditions are ideal. Avoid compacted, waterlogged ground and very shallow, drought-prone soil.

Height

25-40 ft (7.5-12 m)

Spread

15-25 ft (4.5-7.5 m)

Flowers

Late spring to early summer; flat clusters of small creamy-white flowers, followed by yellow berries in autumn.

Foliage

Pinnate leaves with narrow, toothed green leaflets; turns orange, red and purple in autumn.

Growth

Moderate

Care needed

Medium

• Pollinators
• Wildlife
• Low allergen

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

Difficulty

Moderate

Toughness

Fairly tough

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

1. Planting day

   7 ft (2 m)

2. After 1 year

   8 ft (2.4 m)

3. After 2 years

   9 ft (2.8 m)

4. After 3 years

   10 ft (3.2 m)

5. After 5 years

   13 ft (3.9 m)

About 20 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

Mildly toxic: may upset a stomach

Growth rate

Moderate

• Plant with the root flare at soil level, allowing enough room for the mature crown.
• Water deeply through the first two growing seasons whenever the surrounding soil becomes dry.
• Apply 2-3 in (5-8 cm) of organic mulch over the root zone, keeping it away from the trunk.
• Stake only if the young tree is unstable; use a flexible tie and remove the support once roots hold it firmly.
• Feed in spring only if growth is weak and soil fertility is poor; avoid heavy nitrogen feeding.

Pruning. Prune lightly in late winter while dormant, removing dead, damaged or crossing branches and maintaining a well-spaced framework. Avoid topping or heavy crown reduction; remove suspected fire-blight infections promptly in dry weather.

Autumn

Plant while the soil is moist and workable, or wait until spring in regions with severe winters.

Late winter

Check branch structure and remove dead, damaged or crossing growth.

Early spring

Refresh mulch, keeping the trunk clear, and check stakes and ties.

Late spring

Inspect new shoots and flowers for aphids and signs of fire blight.

Summer

Water young trees deeply during dry spells and watch for scorched leaves.

Late autumn

Leave healthy fruit for birds; collect fallen leaves if leaf disease has been troublesome.

• Use as a lawn specimen where its yellow berries and autumn foliage can be seen from the house.
• Plant at a woodland edge above ferns and shade-tolerant groundcovers.
• Combine with ornamental grasses and late-flowering perennials for an autumn border.
• Use as a small canopy tree in a mixed wildlife planting, allowing space for its eventual spread.

Garden styles it suits: English country, Woodland, Wildlife garden, Autumn colour, Cottage garden and New perennial (prairie).

Plant it with: Japanese anemones, Hardy geraniums, Hellebores, Male fern, Tufted hair grass and Snowdrops.

Wildlife: Flowers provide pollen and nectar for insects. Birds eat the berries, often later than red-fruited rowans, and the crown offers cover and nesting sites.

• Fire blight: blackened flowers and shoots may bend into a hooked shape. Cut back into healthy wood in dry weather, disinfect tools between cuts, and avoid high-nitrogen feeding; seek local advice for extensive infection.
• Aphids: colonies can curl young leaves and leave sticky honeydew. Wash off small infestations with water and encourage ladybirds and other predators.
• Leaf spots and scab: remove fallen infected leaves, avoid wetting foliage when watering, and maintain airflow around the crown.
• Drought and heat stress: scorched leaf edges and early leaf fall are common on hot, dry sites. Water deeply, maintain mulch and avoid planting where reflected heat is intense.

Not known to be seriously toxic to cats, dogs or horses. Raw berries can cause stomach upset in people or animals if eaten in quantity, and the seeds contain cyanogenic compounds; treat the fruit as ornamental and discourage children and pets from eating it.

• European rowan (Sorbus aucuparia)

  Has similar divided leaves and creamy-white flowers, but the usual fruit colour is orange-red rather than the yellow of 'Joseph Rock'.

• Kashmir rowan (Sorbus cashmiriana)

  Usually has pink-tinged flowers and conspicuously white fruit, rather than creamy-white flowers followed by yellow fruit.

The cultivar name commemorates Joseph Rock, the botanist and plant collector who worked extensively in China.

Propagation. Usually propagated commercially by grafting or budding onto a suitable Sorbus rootstock. Seedlings do not reliably retain the cultivar's characteristics; remove shoots arising from below the graft.

Accepted botanical name

Sorbus

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