The Sweet Olive tree (Osmanthus fragrans) is an evergreen shrub or small tree, cherished for its exceptionally fragrant, unassuming blossoms. These small, typically white flowers release a powerful apricot-like scent, often described as a blend of apricot, jasmine, peaches, or orange blossoms, that can perfume a large area of the landscape.
Planting Your Sweet Olive Tree
For sweet olive trees to thrive, select a location with full sun to partial shade. In hotter climates, afternoon shade can protect foliage. While sweet olive tolerates various soil conditions, well-drained soil is ideal to prevent root issues.
Before planting, incorporate organic matter into the soil to enhance fertility and drainage. Dig a hole two to three times wider than the root ball, but no deeper. Position the tree so the top of the root ball is level with or slightly above the surrounding soil, then backfill and gently firm the soil. After planting, water thoroughly to settle the soil and establish roots.
Routine Care
Consistent watering is important, especially for newly planted sweet olive trees. Infrequent, deep waterings that thoroughly saturate the soil are more effective than frequent, shallow applications, encouraging deeper root growth. Once established, sweet olives are moderately drought tolerant but benefit from supplemental watering during prolonged dry periods. Check soil moisture a few inches below the surface to determine when watering is needed.
Fertilizing sweet olive trees supports healthy growth and encourages abundant blooms. Apply a balanced, slow-release fertilizer, such as a 10-10-10 formula, in the spring. Avoid fertilizing after late summer or early fall, as this can stimulate new growth vulnerable to cold weather. Applying organic mulch around the base of the tree helps retain soil moisture, suppress weeds, and regulate soil temperature. Keep mulch a few inches away from the trunk to prevent moisture buildup and rot.
Pruning
Sweet olive trees do not require extensive pruning, as they naturally develop an attractive, dense shape. Pruning can maintain a desired size, shape, or remove dead, damaged, or diseased branches. The best time for significant pruning is late winter or early spring, before new growth begins.
Light pruning for shaping or removing stray branches can be performed at any time. Since sweet olive flowers primarily on old growth, heavy pruning can reduce the floral display for the upcoming season. If a substantial size reduction is needed, prune after the main flowering period, allowing the plant time to produce new growth for future blossoms. When pruning, make clean cuts just above a leaf joint or an outward-facing bud to encourage desirable growth.
Common Issues and Solutions
Sweet olive trees are robust and not prone to serious insect or disease problems. However, they can encounter issues. Common pests include scale insects, mealybugs, and aphids, which can be managed with horticultural oil sprays or insecticidal soaps.
Fungal issues like powdery mildew or leaf spot can occur, especially in humid conditions or areas with poor air circulation. Ensuring good air circulation through proper spacing and occasional thinning of dense growth helps prevent these problems. Leaf scorch, caused by Xylella fastidiosa, can lead to leaf yellowing and necrosis; adequate watering and fertilization help maintain plant vigor.
Environmental factors also cause issues. Yellowing leaves may indicate nutrient deficiencies or overwatering, while a lack of blooms could stem from insufficient light or improper pruning. Adjusting watering schedules or light exposure usually resolves these problems.
Winter Care
Sweet olive trees are hardy in USDA Zones 7 to 10, tolerating temperatures down to about 10 degrees Fahrenheit. In these zones, they can remain in the ground year-round. For trees in marginal zones or during unusually harsh winters, some protection is beneficial.
Apply a thick layer of mulch, such as shredded bark or straw, around the base of the plant to insulate the root zone from freezing temperatures. For container plants, move them to a sheltered location, like a cool garage or bright, unheated room, when temperatures consistently drop below freezing. If kept outdoors in colder areas, wrapping the plant in horticultural fleece provides additional protection from frost and cold winds.