The ‘Mr. Bowling Ball’ Arborvitae (Thuja occidentalis ‘Bobozam’) is a unique dwarf cultivar prized for its compact, globe-like form. This evergreen shrub naturally develops a nearly perfect spherical shape, reducing the need for manual trimming. Its foliage is notable for its soft, fine, and almost thread-like texture, contrasting with traditional arborvitae varieties. This selection is a low-maintenance option for year-round structure.
Site Selection and Soil Preparation
The ideal location for establishing ‘Mr. Bowling Ball’ Arborvitae is one that receives full sun to partial shade exposure throughout the day. Locating the shrub in a spot with at least six hours of direct sun encourages the densest foliage growth and best color retention, while too much deep shade can cause the plant’s growth to become sparse and leggy. In hotter climates, a position that provides some light afternoon shade can help protect the foliage from scorching during intense summer heat.
The Thuja genus prefers soil that is consistently moist yet remains well-drained, as the plant is susceptible to root rot if water lingers around the base. While the cultivar is adaptable to a variety of soil types, including clay and sand, amending poorly draining areas before planting is beneficial to its long-term health. A slightly acidic to neutral soil pH is preferred, though this variety tolerates a moderate range.
When planting, dig a hole that is at least twice as wide as the root ball but no deeper than the root ball itself. The shrub should be positioned so the point where the trunk flares out, known as the root collar or root flair, is level with or slightly above the surrounding grade. Planting too deeply is a common mistake that can compromise stem health and lead to moisture problems that encourage fungal diseases.
Watering and Nutritional Requirements
Consistent moisture is necessary for newly planted ‘Mr. Bowling Ball’ specimens to successfully establish a robust root system during their first year in the ground. During the growing season, a weekly deep watering is recommended, ensuring the top few inches of soil become moist but not saturated. This practice encourages roots to grow downward rather than remaining near the surface, which improves the plant’s resilience.
Once the arborvitae is established, its watering needs decrease, and it exhibits a moderate tolerance for brief periods of drought. Instead of frequent, shallow applications, established shrubs benefit most from deep, periodic watering only during extended dry spells. Overwatering can quickly lead to yellowing foliage and root damage, while persistent under-watering may manifest as browning or desiccation at the leaf tips.
The ‘Bobozam’ cultivar is naturally slow-growing and is not a heavy feeder, seldom requiring supplemental fertilizer. If the soil is poor or lacking nutrients, apply a balanced, slow-release granular fertilizer formulated for evergreens once in early spring. Applying too much fertilizer can easily harm the plant, so follow product instructions carefully.
Maintaining Form and Seasonal Protection
One of the main advantages of ‘Mr. Bowling Ball’ is its genetic tendency to maintain a dense, spherical shape without intervention, requiring little to no pruning throughout its life. If shaping is desired or if a stray branch disrupts the globe form, trimming should be done lightly in late winter or early spring before the appearance of new growth. This light pruning, or tipping back, should only remove new growth to maintain the plant’s size or clean up the shape.
It is important to avoid cutting back into the older, leafless, brown wood of the arborvitae, as this type of tissue does not regenerate new foliage. The shrub’s dense habit can make it susceptible to damage from heavy snow or ice loads, which can cause the branches to splay open and deform the shape. Gently brushing heavy accumulation from the branches can prevent this structural damage.
The evergreen foliage is vulnerable to desiccation, or winter burn, especially when exposed to harsh, drying winds and intense winter sun. Applying a protective layer of mulch around the root zone helps regulate soil temperature and moisture, which is important heading into winter. In exposed or windy sites, temporary burlap screening or an anti-desiccant spray can offer protection against moisture loss.