Tree heather, a beautiful evergreen shrub, offers year-round structure and seasonal charm to any garden. Its abundant blooms attract pollinators, contributing to garden biodiversity.
Understanding Tree Heather
Tree heather (Erica arborea) is a large evergreen shrub characterized by its upright, often candelabra-like or columnar stems. It can reach heights of 12 to 15 feet with a spread of half that size. The foliage consists of small, needle-like leaves, providing a dense, green backdrop throughout the year.
In bloom, tree heather produces an abundance of tiny, bell-shaped flowers, typically white and often highly perfumed. The flowering period generally occurs from autumn through spring, with specific timing varying by location. Tree heather thrives within USDA hardiness zones 7 to 9, demonstrating resilience to temperatures as low as 14°F (-10°C). Popular varieties include ‘Albert’s Gold’ with its yellow-green foliage and ‘Estrella Gold’, known for its slow growth and gold-tipped leaves.
Planting and Initial Establishment
The optimal time to plant tree heather is during spring or autumn, though potted plants can be introduced any time the ground is not frozen or waterlogged. Tree heather prefers full sun for vigorous growth and abundant flowering. While it can tolerate some partial shade, particularly when sheltered by taller trees, protection from strong winds and harsh winter conditions is beneficial.
Tree heather requires acidic soil, ideally with a pH between 4.5 and 6.5, and it must be well-draining. Heavy, wet, or alkaline soils are not suitable and can impede growth. Amending the soil with compost, ericaceous compost, or sand before planting improves drainage and acidity.
When planting, dig a hole that is twice as wide as the root ball and deep enough so the top of the root ball sits level with the surrounding soil surface. Gently tease apart the roots from the root ball before placing the plant in the hole. Consistent watering is necessary during the first year, with approximately one inch of water per week, to ensure the plant establishes a robust root system. After two to three years, tree heather typically develops drought tolerance.
Ongoing Care and Maintenance
For established tree heather, full sun promotes vibrant blooms and foliage, though partial shade is tolerated. In regions with intense summer heat, providing afternoon shade can help protect the plant. Maintaining acidic (pH 4.5-6.5) and well-draining soil is also important. An annual application of an acidic mulch, such as pine bark or leaf mold, helps to retain soil moisture and maintain acidity.
Plants grown in containers or in warmer climates may still benefit from occasional irrigation. Tree heather generally does not require heavy fertilization; excessive nutrients can lead to leggy growth. If the soil is alkaline or the plant shows signs of nutrient deficiency, an ericaceous fertilizer can be applied annually in early spring to support healthy development.
Pruning is beneficial for maintaining the plant’s shape and encouraging healthy growth and blooming. The best time to prune tree heather is after it has finished flowering. For the first two years after planting, pruning back by approximately two-thirds can encourage a bushier habit. Subsequently, minimal pruning is needed, primarily to remove any diseased or damaged shoots. While many heather varieties do not regenerate from old wood, tree heather can be cut back hard and will typically regrow vigorously.
Common Issues and Solutions
Yellowing leaves can indicate a nutrient deficiency, often lacking nitrogen, iron, or magnesium, or improper watering. Insufficient sunlight or alkaline soil conditions can also contribute to yellowing foliage. Addressing nutrient imbalances with an ericaceous fertilizer, adjusting watering schedules, and ensuring adequate sunlight exposure are effective solutions.
Browning foliage typically points to drought stress or winter burn, especially in areas exposed to harsh winds. Ensuring consistent watering during the initial establishment phase and providing shelter from strong winter winds can prevent browning. If the plant fails to bloom, it may be receiving insufficient sunlight, the soil pH might be incorrect, or it could be due to improper pruning. Providing at least six hours of full sun daily and confirming acidic soil conditions can encourage flowering.
Tree heather can also face issues with certain pests and diseases. Root rot is a prevalent problem, usually resulting from soggy, poorly draining soil. Improving drainage by amending the soil is the primary preventive measure; in severe cases, affected plants may need to be removed and the surrounding soil replaced. Pests like mites can cause distorted, yellowed, or stippled leaves, while scale insects appear as small bumps on foliage and stems. These can often be managed with forceful water sprays, insecticidal soaps, or horticultural oils. Fungal issues such as rust, characterized by orange powdery spots, can be addressed by removing infected leaves and ensuring good air circulation.