Joseph Rock Rowan Trees

• Latin name: Sorbus 'Joseph Rock'
• Sold as: Bareroot standard (6/8 and 8/10cm girth), bareroot half-standard, pot-grown 12 litre
• Mature size: 8 to 12m tall and 4 to 8m wide
• Habit: Upright
• Berries: Butter-yellow, held on the tree after the leaves fall
• Autumn colour: Orange, red and purple
• Roots: On its own roots, not grafted
• Best soil and site: Moderately fertile, humus-rich, acid to neutral soil. Sun or partial shade. Tolerates city air
• Hardiness: H6, hardy through the British winter
• Delivered: Bareroot, November to April. Pot-grown, all year when in stock. Collection from Castle Cary also available

Joseph Rock is an upright Rowan with butter-yellow berries that show against leaves turning orange, red and purple, and then against the bare branches. It grows on its own roots, tolerates city air, and makes an ideal specimen tree for a small garden.

Joseph Rock Rowan Trees

An excellent ornamental variety, Sorbus Joseph Rock has smaller, lighter coloured leaves than most other Rowans, giving the tree a more open look. The flowers come in plain clumps of creamy white before turning into masses of glorious golden-orange berries. He really stands out in autumn, when the leaves take turns to flush with reds, coppers and purple-brown tones.
The maturing berries are held through autumn and show well against both the foliage and then bare branches as they mature from milky yellow to rich amber.

He will reach about 8-9 metres, 25-30 feet high (or approximately 4 metres tall as a half standard), with an upright growth habit, well suited to avenues or smaller gardens.

Browse our other Rowan trees, Whitebeam & Wild Service trees.

Delivery season: Rowan trees are delivered bareroot from late autumn to early spring, November to April.
Choosing a size: Small trees are cheaper, easier to handle and more forgiving of less than ideal aftercare, so they're best for a big planting project. If instant impact is your priority, or if you are only buying a few plants for use in a place where it's convenient to water them well in their first year, then you may as well use bigger ones. Our standard trees are measured by the girth of the trunk in centimetres, one metre above the ground, not by their height.

Growing Sorbus Joseph Rock

He will be happy in any well-drained, neutral to acidic soil, but not chalk. He needs close to full sun to flower and fruit well. Tolerates urban pollution
We recommend mulching well in late spring and, if your soil is on the dry side, giving him a weekly soaking in a summer heatwave.

History & Trivia

Joseph Francis Charles Rock (1884-1962) was an Austrian botanist and ethnographer who became an American citizen in 1913, and the first curator of the U.S. Department of Agriculture's herbarium at the University of Hawaii. He travelled extensively in Western China for close to three decades, collecting plants for the USDA at a time when China was in turmoil, and it was necessary to employ large caravans with plenty of armed guards to deter bandits. He bequeathed his photographs and diaries to the Royal Botanic Garden in Edinburgh.

The tree is probably one form of the variable species Sorbus rehderiana, taken from the mountainous forests of the Chinese province of Yunnan in the 1930's, but because of its pinnate leaf structure, it is usually classed as an S. aucuparia.

Standard trees are measured by their girth in centimetres 1 metre above ground level: their trunk's waist measurement. Unlike sapling trees and hedge plants, standards aren't measured by their height, which will vary quite a bit both between and within species.
So, a 6/8cm standard tree has a trunk with a circumference of 6-8cm and an 8/10 standard has a trunk 8-10cm around. This measurement makes no difference to the tree's final height.
On average, standard trees are 2-3.5 metres tall when they arrive, but we cannot tell you precisely how tall your trees will be before we deliver them.

Planting Companions

Put yellow next to yellow with Sunshine, or set it against the best red autumn leaf in the genus, Embley. For more autumn colour, see our Maples and our trees for ornamental interest. Dust bareroot roots with Rootgrow as you plant.

Why Ashridge?

Ashridge has sold trees since 1949 and is a Which? Best Plant Supplier 2025. Your Joseph Rock comes bareroot, lifted while dormant, or pot-grown for planting in any month. Bareroot trees are guaranteed for 12 months, and so is a potted tree delivered leafless between November and March.

Frequently Asked Questions

How big does Joseph Rock grow?

8 to 12 metres tall and 4 to 8 metres wide. Our own experience is 8 to 9 metres, with an upright habit that keeps it narrow for its height.

Will it grow on chalk?

We advise against chalk. It wants acid to neutral soil that is moderately fertile and rich in humus. Mulch it in late spring and water it in a summer heatwave if your soil is dry.

Is Joseph Rock grafted?

No. Our Rowans grow on their own roots. There is no rootstock to throw suckers, so any shoot from the base is Joseph Rock itself.

Where does Joseph Rock come from?

Nobody can say for certain. It is a hybrid of uncertain origin, named for the plant collector Joseph Rock, and it won a First Class Certificate in 1962.

Is it a good tree for a small garden?

Yes. It is an ideal specimen tree in a small garden, and it tolerates atmospheric pollution, so it suits a town plot too.

When are the trees delivered?

Bareroot trees are delivered from November to April, while they are dormant. Pot-grown trees can be delivered and planted in any month when you find them in stock.