Diana Althea Tree Form

Diana Althea Tree Form brings refined beauty and a soft, timeless presence to any landscape. Growing to approximately 8 feet in height and 5 feet across, it produces an abundance of crisp white flowers from spring into summer, creating a striking contrast against its dark green leaves. Its tidy, upright structure makes it a perfect focal point for patios, courtyards, or narrow beds, blending seamlessly into both classic and contemporary designs. Easy to maintain and versatile in placement, this tree offers elegant blooms and seasonal transitions that enhance small spaces.

• Deciduous flowering tree 
• Moderate growth rate
• White flowers blooming in spring and summer
• Green foliage turns yellow in fall
• Ideal for patios, walkways, and compact landscapes

Hardy in USDA zones 5-9, Diana Althea Tree Form thrives in full sun. It performs best in well-drained soils. Its graceful blooms and subtle seasonal color shifts bring enduring elegance to North Texas and beyond.

The Diana was one of the first major sterile Altheas released by the U.S. National Arboretum. They are triploids, meaning they are genetically incapable of producing seeds.

Once established, Diana Althea Tree Form is a low-maintenance favorite. Its sturdy trunk and consistent blooming habit make long-term care straightforward and manageable. Here’s all it needs:

• Watering: Provide regular, deep watering during the first growing season to ensure strong root establishment. Afterward, this tree-form althea tolerates moderate dry periods but performs best with supplemental irrigation during extended summer heat.
• Pruning: Prune in late winter or very early spring before new growth begins. Maintain the defined trunk by removing any shoots that emerge below the canopy and lightly thin interior branches to preserve airflow.
• Fertilizing: Apply a balanced, slow-release fertilizer in early spring as growth resumes. Avoid excessive nitrogen, which can produce vigorous leafy growth at the expense of flowers. In established landscapes with average soil fertility, feeding needs remain moderate.
• Mulching: Apply a 2-3 inch layer of mulch around the base to stabilize soil temperature and retain moisture. Keep mulch a few inches away from the trunk to prevent moisture accumulation against the bark. Organic mulch also helps suppress competing weeds.
• Winter Care: Mature specimens are reliably cold-hardy and typically require no special winter protection. In colder climates, young tree-form plants benefit from temporary trunk protection during their first few winters.

Diana Althea Tree Form is generally durable, though occasional pests and environmental stressors may arise.

• Aphids: Clusters of small insects may gather on tender new growth, causing curling leaves and sticky residue. A strong water spray or insecticidal soap application effectively reduces infestations.
• Japanese Beetles: Skeletonized foliage during summer may indicate feeding damage. Hand removal or traps positioned away from the tree help manage populations.
• Leaf Scorch: Browning along leaf edges can develop during extreme heat or inconsistent watering. Deep, consistent irrigation during prolonged hot periods minimizes stress.
• Root Stress from Poor Drainage: Yellowing foliage and slowed growth may signal overly wet soil conditions. Improving drainage and adjusting watering practices restores root health.