Pachysandra terminalis (Japanese Spurge) is a widely used, low-growing evergreen perennial that establishes a dense groundcover in shaded areas. While valued for its minimal maintenance once established, successful coverage requires a deliberate planting strategy. Proper spacing dictates both the time it takes to achieve a uniform carpet and the overall project cost.
Determining Optimal Spacing for Coverage
Spacing depends primarily on how quickly a solid mat of foliage is desired. Most Pachysandra terminalis varieties are typically spaced between 6 and 12 inches apart. Planting 6 to 8 inches apart ensures the fastest coverage, often filling the area within two to three growing seasons. This denser planting provides a quicker aesthetic solution and is useful on slopes where rapid soil stabilization is beneficial.
Choosing a wider spacing of 10 to 12 inches between plants is a more economical approach that requires fewer plants. While this saves on initial cost, it extends the time needed for the groundcover to mature, potentially taking three years or more to fully coalesce. The native Pachysandra procumbens (Allegheny Spurge) spreads more slowly, and a spacing of up to 24 inches is sometimes recommended. Conversely, planting too closely reduces air circulation, increasing the risk of fungal diseases like leaf blight as the plants mature.
Preparing the Soil and Planting Method
Successful establishment requires attention to the planting environment. Pachysandra thrives best in slightly acidic soil (pH 5.5 to 6.5). Preparing the bed by breaking up the soil structure and ensuring excellent drainage is necessary, as the plant will not tolerate standing water.
Before planting, incorporate organic amendments like compost or peat moss to improve moisture retention and fertility. Dig the hole slightly wider than the root ball to allow for root expansion. The top of the root ball must be set exactly level with the surrounding soil surface to prevent the crown from being buried or exposed. After backfilling the hole, water thoroughly to eliminate air pockets and settle the soil around the roots.
Long-Term Growth and Encouraging Density
Pachysandra achieves its dense, carpet-like appearance through its characteristic growth habit of spreading via underground stems called rhizomes. These rhizomes grow horizontally beneath the soil surface, sending up new shoots that slowly fill the gaps between the initial plantings. This colonization process is what eventually creates a solid, uniform groundcover, regardless of the initial spacing chosen.
To support growth and encourage a thicker mat, apply a light application of a balanced, slow-release fertilizer in early spring. Pruning the tips of the plants can help promote a bushier growth habit and enhance air circulation. Maintaining consistent soil moisture during the first year of establishment is important for young plants to develop a robust root system. Applying a thin layer of organic mulch around the new plantings helps regulate soil temperature, conserves moisture, and minimizes weed competition until the Pachysandra fills in.