Creeping juniper (Juniperus horizontalis) is a resilient, low-growing evergreen conifer. It forms a dense, wide-spreading mat, making it an excellent, low-maintenance choice for ground coverage. Its primary benefit is providing superior soil stabilization and erosion control on banks and slopes. The fibrous, spreading root system anchors the soil effectively, which is important on inclined surfaces where rainfall causes rapid water runoff. Establishing this plant correctly ensures a long-term, attractive solution for preventing soil loss.
Selecting the Right Variety and Site Preparation
Success starts with choosing a cultivar adapted to the site conditions. Creeping juniper requires a minimum of six hours of direct sunlight daily; planting in shade will result in thin, sparse growth that compromises its groundcover ability. Cultivars such as ‘Blue Rug’ (Juniperus horizontalis ‘Wiltonii’) are recommended for slopes because they maintain a low profile (4 to 8 inches high) while spreading widely (6 to 8 feet).
Proper site preparation is necessary before planting to ensure establishment. The area must be cleared of existing perennial weeds, as competition for water and nutrients will stunt the new plants. Juniper requires well-drained soil, so loosen the top six inches of soil where the plants will be placed. If the slope consists of heavy clay, lightly incorporating organic matter like compost or aged pine bark will improve aeration and drainage, preventing root rot in the young plants.
Step-by-Step Planting on Inclines
Planting on an incline requires specific techniques to ensure the root ball establishes securely and receives adequate moisture. For effective erosion control, plants should be spaced closely (typically 3 to 5 feet apart) so their mature spread overlaps. Closer spacing accelerates the formation of a continuous mat, which stabilizes the soil.
The planting hole should be dug approximately twice as wide as the root ball but slightly shallower. When placing the juniper, the top of the root ball must sit level with or slightly above the surrounding soil grade to prevent the crown from becoming buried, which can lead to rot. For maximum stability on the slope, gently angle the root ball slightly uphill, ensuring the plant is not positioned to wash out during heavy rain.
A crucial step is creating a water-capturing basin for each plant. Using the removed soil, form a crescent-shaped ridge or berm on the downhill side of the juniper. This low, temporary soil wall acts as a dam, slowing water runoff and directing rainfall toward the root zone where it can soak into the soil.
After placing the plant and backfilling, lightly firm the earth around the root ball to eliminate air pockets, which can dry out the roots. Care must be taken to avoid packing the soil too tightly, as this can impede root growth and drainage. Following these steps ensures the juniper is both physically stable on the incline and positioned to maximize water absorption during the establishment period.
Essential Post-Planting Care for Slope Establishment
The first year after planting is important for establishing a robust root system capable of stabilizing the slope. Newly planted junipers require consistent, deep watering to encourage roots to grow outward and downward. Utilizing the crescent-shaped berms, water deeply but infrequently, aiming to saturate the soil to the depth of the root ball.
Once the initial watering is complete, apply a 2- to 3-inch layer of mulch around each plant, keeping it pulled a few inches away from the crown to prevent moisture buildup and potential fungal issues. On a slope, shredded bark or pine straw is preferable to lighter materials like wood chips, as their interlocking nature helps them resist being washed downhill. For steep banks, biodegradable erosion control netting can be secured over the planting area with landscape staples before mulch application, offering added stability.
During the first growing season, the goal is root establishment, not rapid foliage growth, so fertilizer should not be applied. Minimal pruning is necessary, typically limited to trimming back dead or damaged branches. After the first year, the plants will become highly drought-tolerant, and the dense, spreading foliage will begin to knit together, providing a permanent and effective barrier against soil erosion.