Chapter 116 Pieris japonica
116.1 Japanese pieris
Flowers, red spring foliage, and mature green foliage of Pieris. Link to original image.
116.2 Soil: Ericaceous Mix
Ratio: 3 parts bark, 1 part peat, 1-2 parts grit
Add-ins: dolomitic limestone (MAX of 2 lbs/yd), Tree-Tone (15 lbs/yd)
pH: ~5.5-6.0 (acidic)
Moisture: Moist
116.3 Light
Routine: full sun to partial shade. If in sun, provide some shade midday in summer.
116.4 Cultivation Notes
Growth habit of pieris shrubs. Link to original image.
116.4.1 Potting & Root Pruning
Schedule: repot every 3-4 years in early spring.
116.4.1.1 Top & Branch Management
Heavy pruning: hard and formative pruning can be carried out after flowering in early spring.
Fine pruning: trim back new shoots throughout the growing season. Deadhead after flowering.
Leaf pruning: do not leaf prune.
116.4.2 Feeding
Use an ericaceous fertilizer (organic or soluble) formulated for acid-loving plants. Holly-Tone is a good organic choice for incorporating into soil; MirAcid works well as a soluble food for routine feeding every 2-3 weeks in summer. Feed at full strength for trees in development; reduce to half strength for trees near their final size, or in show pots. Wait until the flowering period ends to fertilize, and stop fertilizing about a month before frost.
Begin fertilizing fall-blooming types in mid-spring, and stop about 2 weeks before the blooms are expected.
116.4.3 Pests & Problems
Leaf spot and Phytophthora root rot can be a problem. Chlorosis occurs at times; use Ironite or chelated iron to treat it. Lace bug infections can be a serious problem, particularly in the eastern U.S. Watch for mites, nematodes and scale.
116.4.4 Winter Storage
Reliably hardy to 25°F. During colder periods or late spring frosts, provide frost protection.
116.5 Propagation Notes
Shrubs with decent sized trunks are available routinely from nurseries. I have picked up nice shrubs ready for training at the end of the season for less than $10. I have never tried growing Pieris from liners or cuttings, but they supposedly can be propagated by greenwood cuttings in early summer or semi-ripe cuttings in mid- to late summer.
116.6 Artistic & Styling Notes
Does best in informal upright forms and cascades in small to large sizes.
This article has photos of several Pieris in various stages of development.
116.7 Additional Information
116.7.1 Natural History
Pieris is a genus of seven species of evergreen shrubs occurring in forest and on hillsides in the Himalayas, E. Asia, North America and the West Indies. They are hardy in USDA Zones 5-8.
Pieris japonica and Pieris ‘Forest Flame’ are both commonly available and are also suitable for bonsai.
116.7.2 In Cultivation
Pieris requires a fair amount of ongoing maintenance, even when planted in a garden.
It grows best in locations sheltered from wind with some afternoon shade. Remove spent flowers immediately after bloom.
Bead-like flower buds are set in late summer for the following year and provide winter interest and contrast to the evergreen foliage. Many cultivars are available featuring flowers in various shades of white, pink and deep rose.
Sometimes sold as Andromeda japonica.