Jackman’s Blue Rue (Ruta graveolens ‘Jackman’s Blue’) is an evergreen shrub known for its striking blue-green foliage and aromatic qualities. Its unique appearance and drought tolerance make it a resilient and appealing choice for garden designs.
Key Characteristics of Jackman’s Blue Rue
Jackman’s Blue Rue is a compact, bushy evergreen shrub, typically reaching 2 to 3 feet in height and width. Its most notable feature is the aromatic, steel blue to blue-green foliage, finely divided into rounded segments, giving it a frilly texture. A glaucous, or waxy, coating contributes to their distinctive color, enhancing their visual appeal.
During summer, the plant produces muted acid yellow or greenish-yellow flowers. These flowers attract pollinators like bees and butterflies. The plant’s mounding habit provides consistent presence in the garden year-round.
Growing and Caring for Jackman’s Blue Rue
Light Requirements
Jackman’s Blue Rue thrives in full sun, requiring at least six hours of direct sunlight daily. This promotes robust growth and helps maintain its vibrant foliage color and characteristic compact form. While it can tolerate partial sun, insufficient light may result in leggier growth and reduced flowering.
Soil Preferences
Well-drained soil is important for Jackman’s Blue Rue, as it is sensitive to waterlogging. The plant adapts well to various soil types, including average, sandy, gritty, or clay soils, provided they offer good drainage. It prefers average to poor fertility and can grow in a wide pH range, typically between 6.0 and 8.5, from slightly acidic to neutral or mildly alkaline. Avoiding overly rich or water-retentive soils promotes compact, bushy growth.
Watering Needs
Jackman’s Blue Rue is drought-tolerant once established. For newly planted specimens, consistent moisture is beneficial during the first year to establish a strong root system. After establishment, it requires minimal watering, often thriving with hydration about twice a week in dry conditions. Overwatering should be avoided, as it can lead to root issues.
Pruning for Health and Shape
Pruning Jackman’s Blue Rue helps maintain its shape, promotes bushiness, and encourages new growth. The best time for pruning is in early spring or late winter, before new growth begins. Remove dead or damaged stems at the base. The plant can be trimmed back by about one-third to encourage a fuller appearance. Removing spent flowers after blooming can also prevent aggressive self-seeding.
Fertilization Needs
Jackman’s Blue Rue has low fertility requirements and generally does not need much fertilizer. If the soil is poor, a balanced, slow-release granular fertilizer, such as a 10-10-10 formula, can be applied once in spring. Avoid over-fertilization, as it can lead to excessive, leggy growth rather than the desired compact form.
Ideal Landscape Applications
The striking steel blue foliage of Jackman’s Blue Rue adds color and texture to garden designs. Its compact, mounding habit makes it suitable for various landscape uses, including rock gardens, xeriscaping, and mixed borders. As an evergreen, it provides year-round interest.
Its ability to tolerate heat and dry conditions makes it a fitting addition to water-wise gardens. It can be utilized in containers, where its unique foliage can be highlighted. The blue-green color contrasts well with plants featuring golden foliage, such as oregano or thyme, creating visually interesting combinations.
Propagating Jackman’s Blue Rue
Jackman’s Blue Rue can be propagated through softwood or semi-hardwood cuttings. Take cuttings during summer from healthy, non-flowering shoots. Cuttings should be 4 to 6 inches long, with lower leaves removed.
Plant these stem segments in a well-draining rooting medium, ensuring the base is firmly in contact with the soil. Applying a rooting hormone can enhance the process. Maintain consistent moisture without overwatering, and provide dappled sunlight until roots establish. Gradually transition them to brighter conditions.
Potential Challenges and Safety
Jackman’s Blue Rue is generally robust and rarely troubled by common pests or diseases. However, it can be susceptible to root rot in poorly drained or overly wet soil. Proper soil drainage is important to mitigate this risk.
Handling Jackman’s Blue Rue requires caution. Its sap contains compounds called psoralens that can cause phytophotodermatitis, a skin reaction to sunlight exposure. Symptoms include redness, burning, blistering, and hyperpigmentation. Wear gloves and long sleeves when pruning or handling the plant to prevent skin irritation. The plant is also toxic if ingested, so it should not be consumed by humans or animals.