Good Things Growing…In The Gardens

More information on growing Pieris…

While working in the northeast, I ran across (and planted) hundreds of Pieris japonica , including a number of cultivars. ‘Dorothy Wycoff’ and ‘Valley Valentine’ were the two most often encountered, with screaming red new growth, and pinkish flowers, respectively. ‘Variegata’ is a very handsome form with creamy-white leaf edges that grows even slower than the species. I imagine the performance of all these cultivars to be like the species in Birmingham: iffy, but not impossible if given perfect growing conditions and a dose of patience. We have several small plants of ‘Variegata’ planted in dense shade in the Hosta Walk and they look fine two years after planting. One plant each of the previous two cultivars are languishing in the McReynolds Garden, probably due to excess soil moisture.

Pieris japonica (and its hybrids and cultivars) grows slowly with an elegant, upright and layered habit, slightly taller than wide with age. Landscape size is generally 5’ tall x 4’ wide after about 15 years; a 10’ tall plant would be very old, especially in the southeast. The semi-erect to drooping, 3-8” long racemes of flower buds emerge in late summer-fall at the branch tips, and open over a long time period – up to two months – in early winter in Birmingham. The flowers are white, bell-shaped, fragrant enough to wake up the bees on a cool winter day, and are quite frost-tolerant.

The flowers look like lilies-of-the-valley, and lily-of-the-valley-shrub is sometimes listed as a common name, which does no good if one does not know what a lily-of-the-valley is. Also confusing is the common name andromeda, which is also the common name for Andromeda polifolia , bog andromeda, or bog rosemary, a related, diminutive relative of cold mountain and maritime bogs.

The difficulty with growing Pieris japonica and kin here is directly related to excess heat and soil moisture. Protection from heat and direct sun is critical; locations against structures with northern exposures are well-advised if shade from trees is not available. Soil must be acid, high in organic matter and very well-drained. Frankly, if you’re not able to supply all these ingredients, you probably should grow something else.

Lacebugs can attack pieris, often in large numbers. These insects feed from underneath leaves, piercing the leaf cuticle and sucking out plant juices. Lacebug damage appears as rusty stippling on leaf surfaces and lasts until the leaves fall off (several years). Contact sprays are ineffective as controls, unless leaf undersides are sprayed – which is not easy – in a timely manner; expensive systemic treatments provide more long-term control. However, plants sited in deep shade typically show far less lacebug damage than those in sunnier positions because lacebug predators, primarily small spiders, are present in greater numbers in shadier spots, and plants are generally less stressed (stressed plants being prone to attack). If you successfully grow Pieris , even healthy and vigorous ones, you will have a few lacebugs; this should not be a cause for concern or spraying. Finally, don’t confuse lacebugs with lacewings, which are beneficial insects.

Pieris floribunda , mountain pieris (or mountain fetterbush), has not been historically tried at BBG, and for good reason, as this is a plant of cool, high elevations in the southern Appalachians. Nevertheless, it has transferred some heat tolerance (and lacebug resistance) to the hybrids named in the main article. Flower racemes tend to be shorter than P. japonica , and flowers appear in early spring. If you have a vacation home in the mountains, perhaps it’s worth a try, but not in Birmingham. The lack of broad adaptability of this species and the next may be due to the need for specific associations of symbiotic mycorrhizal fungi, which are seldom found outside of native habitats.

We have another native pieris, Pieris phillyreifolia , or climbing fetterbush. It is restricted to raised hummocks and well-drained stream banks in extreme coastal MS, AL, GA and SC, and through the panhandle and into central Florida. According to the literature – and the common name – the plant often climbs up the trunks of trees (baldcypress, water gum) in shaded, swampy areas, which would lead one to believe it prefers moist soils. Examination of plants in the wild, however, shows this climbing tendency to be very weak, and that the plants are above water in well-drained, sandy to organic soils (leaf humus). The predominant growth habit is of a low (10-15”) stoloniferous groundcover. Flowers are not heavily borne, but are typical for Pieris , although shorter (1-4” racemes) and smaller. Leaves are dark green with a matte finish. We planted (and lost) several P. phillyreifolia in the wetter areas of the Barber Alabama Woodlands before obtaining a plant of the cultivar ‘Baldwin’, introduced from Tom Dodd Nurseries in Loxley, AL. This taller form was found growing in Baldwin County, in a sunny location in sandy soil. We grow it in the Hosta Walk, where it seems pretty happy in half-sun.

Pieris taiwanensis , sometimes listed as P. japonica var. taiwanensis , appears somewhat confused in both the literature and the trade. Most commonly, it is represented by the cultivars ‘Snow Drift’ and, perhaps, ‘Prelude’. Obviously hailing primarily from Taiwan, it is said to be found only at higher elevations there and may not confer the heat tolerance of many Taiwanese endemics. Minor taxonomic and geographic differences aside, it seems to be smaller than typical P. japonica , and our young plants of ‘Prelude’ in the Hulsey Woods are very compact (15” in all dimensions). They are in a dry location in half sun and although they flower well, they appear washed-out-green in winter and half- baked in summer.

Lastly, the plant masquerading through the southeast (albeit in very limited numbers) as Crabiodendron yunnanense , is probably Pieris ryukyuensis , and likely the same as the cultivar ‘Temple Bells’ (mentioned in the main article). We have one near the wishing well in the Curry Rhododendron Garden and another in the Asian Glade, near the vegetated swale. Despite their slow growth, both seem happy enough and do flower nicely. To me, their fragrance is not as strong as P, japonica , but overall, they are very healthy. Further trials with ‘Temple Bells’ will help us to determine if our Crabiodendron are true to name or mere imposters.