The Lesser-known Hardy Ericaceous Shrubs, Part 1: Andromeda to Gaylussacia
(Editor's Note: This article was originally published on January 1, 2009. Your comments are welcome, but please be aware that authors of previously published articles may not be able to respond to your questions.)
Many gardeners are familiar with Ericaceous shrubs, or the Ericaceae family. This family is among the most important in regards to flowering shrubs. Members of this family include rhododendrons, azaleas, mountain laurels, Japanese andromeda, heaths, heathers and of course, blueberries! As a group, all require organic-rich, moist, yet well drained soil that has an acidic pH. Dappled shade seems to be the best lighting conditions (except blueberries which need full sun). Many of these are broad-leaved evergreens so can provide year-round interest in the garden landscape. Florally, they have five fused petals which make the flowers appear bell-shaped, saucer shaped or urn-shaped.
If you have an acidic site, you can grow the above genera and they will provide you with a wonderful display throughout the seasons. However there are several other lesser well-known members of this large family which are welcome additions to the acidic garden. These literally encompass an A to Z of plants, from Andromeda to Zenobia. Because there are quite a few plants to discuss, I will break this article into two parts. In part 1 I will cover Andromeda to Gaylussacia. Part 2 will describe Ledum to Zenobia.
Andromeda are commonly known as bog rosemary. There are two species typically grown, A. polifolia from Europe and A. glaucophylla from North America. The two are very similar with narrow, evergreen, blue to grey-tinted foliage reminiscent of rosemary (hence the common name). They bloom early in the season with pink to white urn-shaped flowers. Plants form compact buns about 20 cm tall. They do require consistently moist soil to perform at their best. This species is useful in zones 2-6 and do best in areas with cool summers and snowy winters. Three named selections include ‘Kiri Kaming', a dwarf selection with green foliage, ‘Blue Ice' with exceptionally blue foliage and ‘Macrophylla' with larger-than-normal flowers and grey-green foliage. In winter, the foliage often becomes a unique plum-grey tone.
Details of Andromeda glaucophylla
Arcterica nana is virtually unknown in North America but is often represented on the alpine show tables in the UK. This Arctic-affinity evergreen hails from the Bering Sea of Siberia south to the mountains of Japan. The small leaves are thick and leathery, deep grene in summer but tinted reddish-purple in winter. Terminal clusters of sweetly fragrant, white, urn-shaped flowers are produced in late spring-early summer. Plants only reach 10 cm and need cool, moist soil in full sun to thrive. It is a challenging plant to grow outside its natural habitat. Rated for zone 1.
Bearberry, Arctostaphylos uva-ursi, is commonly grown as an evergreen groundcover for shady to sunny slopes. This is one of the few ericaceous shrubs that can tolerate drought and alkaline soils. This tough (zone 2) plant is also one of the few members of this family that can thrive in the mid-west and prairies. The pink to white urn-shaped flowers are produced early in the season and become bright red berries by autumn. Winter foliage often adopts reddish to purplish tones. This plant is native throughout North America. There are three named selections called ‘Vancouver Jade', ‘Emerald Carpet' and ‘Massachusetts'. There are many taller Arctostaphylos species, commonly called Manzanita, found throughout western North America south into mountainous areas of central America. All of these are rated for zone 7 or warmer so are outside the focus of this article.
Details of Arctostaphyllos uva-ursi
Bruckenthalia, Cassiope, Daboecia and Phyllodoce are all close relatives to heaths and heathers and have been previously discussed in an earlier article, "Heaths and Heathers for UDSA zones 4-6".
Leatherleaf, Chamaedaphne calyculata, is a relatively unknown (ornamentally-speaking) evergreen shrub from eastern North America and across northern Canada and Alaska. In my area (Newfoundland, Canada) they are quite common and the earliest native shrub to bloom. Small axillary clusters of cream-white, urn-shaped flowers are produced along the upper portions of the stems. This shrub has bronzy-green foliage in summer that turns distinctively brownish in winter. The leaves have the curious habit of being held erect, similar to praying hands. They reach 1 5. M and prefer sunnier, moist locations. Rated hardy to zone 3.
Empetrum nigrum or black crowberry, is a prostrate evergreen from northern and Arctic regions of the northern hemisphere. Virtually unknown as a garden ornamental, this plant superficially looks like a creeping Erica. The flowers are insignificant but develop into black, edible berries by mid-summer. The bright green summer foliage turns bronzy in winter. Rated for zone 1, this plant is only suitable for cool summer regions, where they can be used as a ground cover in sunny areas. This species can actually support light foot traffic.
Details of Empetrum nigrum
Enkianthus is one of the few ericaceous shrubs that are deciduous. This genus is found throughout China and Japan. The genus contains several species that look quite similar. Most are relatively tender (zone 7 or warmer) but E. campanulatus is hardy to at least zone 5. This latter species may reach 4 m and is a lovely addition to any garden, especially planted in the dappled shade under taller deciduous trees. The elliptical leaves are often arranged in whorls. They are dull green with hairy margins, but turn brilliant scarlet in autumn. The flowers are produced in nodding, terminal clusters in mid to late spring. The bell-shaped flowers are off-white with pinkish veins or pinkish-red. There are several named selections with ‘Showy Lantern' and 'Red Bell' being among the most popular. These selections have reddish-pink flowers. Enkianthus cernuus and E. perulatus are also recommended species, rated for zone 6.
Some variations possible in the fall colour of Enkianthus
Flower details of Enkianthus: on left is the standard flowers while on the right is the cultivar 'Red Bell'
Trailing Arbutus or Mayflower, Epigaea repens, is a native prostrate shrub found in shady woodlands of eastern North America. They have relatively large, leathery, heart-shaped leaves and tubular flowers in white to pink shades in early spring. The flowers are sweetly fragrant. This hardy (zone 3) shrub is not easy to cultivate. Soil, moisture and light levels must be quite exact. Plants should be covered in a loose layer of leaves in winter as exposure to excess winter winds and sun can blast the foliage.
The white and pink forms of Epigaea repens
There are many different Gaultheria or wintergreen species, found worldwide primarily in mountainous and cool, woodland regions. Only a handful are hardy to zone 5 or 6. All are evergreen with white urn to bell-shaped flowers. These are early summer bloomers. Fruit colour can vary tremendously depending on the species. Many have edible berries with a distinct wintergreen flavour. All require moist but well-drained soil. In eastern North America we have two native species. Creeping wintergreen, G. hispidula, forms prostrate mats of tiny, rounded leaves. The flowers are rather insignificant but they develop into white, egg-shaped berries. This species makes an admirable groundcover in shady to partly shaded sites north to zone 3. Nearly as hardy (zone 4) is the common wintergreen, teaberry or checkerberry, G. procumbens. This common woodland species inhabits shady to partly shaded sites where it suckers forming shrublet colonies to 15 cm tall. The leaves are glossy deep green and often turn purplish in winter. The flowers develop into bright red berries that remain on the plant all winter and often well into the next summer! In zone 5 you can try the Japanese species G. miquelliana. This one has a habit like G. procumbens but is denser thus better for use as a groundcover. It also prefers more sun. The glossy leaves are rugose and also turn purplish in winter. Its flowers develop into white berries. This species is usually quite prolific in its berry production. In zone 6 (well protected zone 5) there is the western North American species G. ovatifolia and G. shallon. The previous appears quite similar to G. procumbens of the east. The latter is a shrub over 1m with large, rounded, dull green, leathery leaves. Where happy, it will sucker freely and form dense colonies but in my zone 5b it is more well behaved. The flowers develop into red berries. This species is very important as a filler for floral arrangements.
Examples of Gaultheria include (left to right) G. hispidula, G. miquelliana, G. shallon and G. procumbens
Huckleberries and dangleberries are members of the genus Gaylussacia. They are not often grown as garden ornamentals but do have some lovely attributes. In eastern North America we have 5 native species. Of these, three grow in partly shaded, dry pine forests of the eastern US. These include dangleberry or blue huckleberry, G. frondosa; dwarf huckleberry, G. dumosa, and box huckleberry, G. brachycera. The first two are deciduous, reach 1.5 m and 40 cm respectively, with bright red fall foliage while the latter is evergreen with a groundcover habit 20-40 cm tall. All produce white, bell-shaped flowers in spring that develop into blue to blackish berries in autumn. They are rated for zone 5. Our other two native species are black huckleberry, G. baccata and northern dwarf huckleberry, G. bigeloviana. These two deciduous species prefer consistently moist soil in full sun. The former has coral-pink flowers while the latter white. Both produce blue to blackish fruit and have leaves that turn brilliant scarlet in autumn. Both extend their eastern North American ranges into NE Canada and are rated for zone 3. In regards to edibility, G. frondosa and G. baccata have the tastiest fruit.
Details of Gaylussacia dumosa (left) and G. baccata (middle, right)
Next week will be part 2, covering Ledum to Zenobia.
I would like to thank the following people for the use of their pictures: alph (fall foliage Enkianthus), carkeekfish (fall foliage Enkianthus), growin (Gaultheria shallon), mgarr (Enkianthus 'Red Bell' and white-flowered Epigaea) and triodastra (pink-flowered Epigaea)