The rowan tree (Sorbus aucuparia), also known as a European Mountain Ash, is a fast-growing tree that reaches heights of 9 m (30 feet) with an equal canopy spread at maturity. Healthy specimens produce oblong green leaves that turn to red in autumn. Showy white flowers bloom in the spring, giving way to tiny orange fruits that attract birds and other forms of small wildlife.
Prepare the soil for spring planting by breaking it up with a pitchfork and testing the pH with a soil-testing kit prior to planting. Rowan trees prefer soils with a pH between 4.5 and 7.5.
Amend the soil if the pH is out of range. Add lime to the soil for a pH below 4.5 or peat moss for soil with a pH above 7.5. Add the required amendment according to manufacturer's recommendations.
Dig a planting hole for the rowan tree that measures twice the width of its nursery container. The depth should match that of the nursery container, ensuring that the tree grows at the same height it has been in the container.
Remove the rowan tree from its nursery container and set it in the centre of the planting hole. Fill the hole with water from a garden hose and backfill. Tamp the soil down around the trunk of the rowan tree to release trapped air after backfilling.
Water the rowan tree deeply after planting using a soaker hose. Supply the tree with at least 2.5 cm (1 inch) of water per week in lieu of rain. Maintain moist soil to a depth of 2.5 cm (1 inch) at all times during the first growing season. Once the tree is established, supplemental watering is only necessary when the weather is especially dry.
Rowan trees planted in well-amended soil do not require fertilising. Remove dead or damaged branches using a pruning tool during early spring. A 7.5 cm (3 inch) layer of bark chips spread under the canopy of the rowan tree will improve drainage, suppress weeds and protect roots.
Do not overwater the rowan tree. Soaked soil promotes root rot, a disease that can kill the tree. If the soil feels moist 2.5 cm (1 inch) down, do not add more water.