Pachysandra, Japanese Pachysandra, or Spurge

(Buxaceae - Box Family)

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• Form
  • medium-sized, herbaceous perennial evergreen groundcover
  • about 10" tall, always used as a groundcover in group or mass plantings, with each plant slowly spreading via a combination of its basal shoots and leaning top growth
  • procumbent mat growth habit
  • slow growth rate

• Culture
  • partial shade to deep shade
  • prefers a moist, well-drained, acidic, rich soil in full shade, but is tolerant of periodically dry soils as long as they are well-drained, and is tolerant of soils of neutral to slightly alkaline pH
  • propagated primarily by rooted stem cuttings, but also by clump division, or harvest of the rooted stolons or daughter plants at the clump perimeter
  • Boxwood Family, with leaf blight, stem cankers, and leaf spots being the principle cosmetic or serious diseases, and scales and nematodes being the primary serious pests
  • commonly available in flats, with individual plants being in individual cell packs or peat plugs, or with roots matted together in a solid mass of soilless media in the flat
  • plant 6" to 12" apart (depending upon the size of the transplant and how quickly you want the groundcover to fill in) and mulch lightly at transplanting; if peat plugs are used, tear apart or tear off the outer peat covering to facilitate rapid root establishment in the soil
  • plants will become very chlorotic and will die out in patches if improperly sited in full sun or partial sun, or if sited in periodically wet or poorly drained soils
  • a typical planting will take about three years to fully establish a solid carpet of groundcover; in the interim, a light mulch will retain soil moisture and reduce the invasion of weeds
  • leaves that fall upon the groundcover in Autumn should be gently raked and blown out, as vigorous or quick raking will shear off individual plants at ground level, especially in mature plantings, where the semi-woody basal stems with heavy top growth tend to snap
  • mature plantings can have their dense foliage (and the resulting poor air circulation to the stems) as their own worse enemy, as prolonged Spring or Summer rains (or periodic irrigation) may cause outbreaks of Volutella pachysandrae, leading to brown patches of severe leaf spot, leaf blight, and stem canker
  • dense foliage can also be a severe impediment in trying to eradicate infestations by scale (an insect with a white "shell" that attaches to the lower leaf surface and looks like a white "dot"), as it is very difficult to apply sprays to leaf undersides at ground level

• Foliage
  • leaves emerge medium green, mature to dark green, and are glossy to waxy evergreen, obovate, and dentate at their apices
  • the broadleaf, alternate leaves become clustered at the stem apices

• Flowers
  • creamy white, from late March to mid April, on 1" to 2" terminal inflorescences, but almost insignificant from an ornamental perspective

• Fruits
  • white terminal fruits are rare and ornamentally inconspicuous

• Twigs
  • new vertical shoot growth (about 2" to 4" per year) occurs in two forms: from new basal shoots arising from the underground stolons, and from vertical extension of the pre-existing but procumbent old stems (these are the two ways by which each parent plant of the groundcover slowly expands in diameter and fills in the planting)
  • the light green new shoot growth is herbaceous in the Spring, but becomes semi-woody by Winter

• Trunk
  • not applicable

• ID Summary
  • the shiny dark green foliage yields a glossy broadleaf evergreen mat of groundcover, which is topped by small creamy white inflorescences in early Spring

• Function
  • evergreen groundcover for group or mass plantings at the northern or eastern foundations of buildings, or under the moderate to dense shade of shrubs or trees

• Texture
  • medium texture
  • thick density (once established)

• Assets
  • forms an attractive dense carpet of glossy evergreen foliage
  • excellent performance in partial shade, full shade, or very deep shade

• Liabilities
  • slow to establish as a solid mat of foliage
  • can have serious disease or pest problems with maturity
  • retains blown leaves in Autumn and Winter, and their removal sometimes causes the older and larger stems to break off
  • absolutely requires at least partially shaded conditions for acceptable performance

• Habitat
  • zones 5 to 8
  • native to Japan

• Alternates
  • evergreen groundcovers (Euonymus fortunei 'Colorata', Hedera helix, Vinca minor, etc.)
  • groundcovers for either partial shade or full shade conditions (Aegopodium podagraria 'Variegatum', Hedera helix, Hypericum calycinum, Lamiastrum galeobdolon 'Variegatum', Liriope spicata, Vinca minor, Waldsteinia ternata, etc.)

• Variants
  • Pachysandra terminalis 'Green Carpet' - the most popular cultivar, selected for its cold hardiness, compact habit, and dark waxy green color
  • Pachysandra terminalis 'Variegata' (also known as 'Silver Edge') - foliage has a creamy-white variegation around the leaf margins

• Translation
  • Pachysandra translates as "thick stamens", referring to the pollen-bearing floral structures.
  • terminalis translates as "terminal," referring to the location of the inflorescences at the stem termini.

• Purpose
  • Pachysandra is probably the most exquisite of the evergreen groundcovers.

• Summary
  • Pachysandra terminalis is perhaps the best evergreen groundcover for moderately- to deeply-shaded sites, forming dense mats of glossy dark green foliage.