For many gardeners, acid-loving plants are the ultimate experience, and the height of garden beauty. Rhododendrons, Azaleas, Camellias – these names conjure up profusions of gorgeous blooms on thousands of different varieties. Fortunately, large parts of eastern North America have those kinds of soils, making growing them easy. Those ‘big names’ are all highly-desirable plants, but they are not the only plants that enjoy acid soil conditions. Japan has acid soils in its forests, and there we find a plant that is not as well known, but equally desirable – the Pieris, also known as Japanese Andromeda, or Lily-of-the-valley Shrub. The hanging bunches of bell-shaped flowers do indeed look a lot like lily-of-the-valley, and the bush itself, with glossy evergreen leaves and a rounded form, looks beautiful in every season. The new growth is often colorful too, making this plant a great all-round garden shrub. New varieties have been developed in the last few decades, bringing different forms and newer colors, so from being a slightly obscure specialist plant, the Pieris has stepped onto center stage – plant some soon.
The natural home of Pieris is in open woodlands, so it looks right at home in any natural or semi-natural garden setting. Beneath deciduous trees, or open evergreens, it will thrive, and if scattered at strategic locations along a winding path through the trees it will look perfect and bring beauty and interest over a long period. It is the perfect companion and complement to the flamboyance and more vibrant colors of the Rhododendrons, and it makes the perfect background behind drifts of Azaleas.
You don’t have to have your own woods, though, to grow Pieris, and such obvious places are just the beginning of where and how you can grow this plant. Its attractive foliage holds its own among any broad-leaf evergreen you might use to plant around your home. The substantial bonus of a beautiful display of flowers makes it a top choice for the shady corners around your home, such as on the east or northern sides. It doesn’t need any clipping to keep its neat, mounded form either, and depending on the variety you choose it can be a larger plant or smaller, foreground material. As well, coming from Japan, Pieris is a natural choice for the shadier spots in an Asian or Japanese style of garden, and its refined beauty will be completely at home.
Every garden, even the smallest, usually has some more shaded areas, and beds there can be difficult to fill. Here the Pieris steps right up and takes on the job, working well with evergreens like yew or hemlock, and with other shade-loving plants. If you plant it with hydrangeas it will bring early flowers while those shrubs are just getting started, and then step gracefully back while they put on their mop-headed performance through the summer months.
With newer, smaller varieties becoming available, Pieris is also a great plant for planter boxes and pots. If you don’t have suitable soil it is also the easiest way to grow these plants well, although they are not as demanding of very acid soil as some other plants. Planters and pots in shadier spots of the garden are often just filled with evergreens, which may be attractive enough, but they have no seasonal highlights. Replacing them with small Pieris means interest through winter and spring, as well as handsome foliage for the rest of the year – a win-win for your landscape. In larger planters they can be mixed with other acid-lovers, to bring year-round beauty to a shady terrace or patio.
These plants are evergreen bushes, growing between 2 and 15 feet tall, depending on the variety, although most as in the 2 to 6-foot range. It forms a rounded bush, with many upright branches, so it is typically about as broad as it is tall. Older stems show rough bark with long grooves. The bark is tan to reddish-brown, and slightly stringy. Plants usually remain leafy to the ground until quite old, when they can eventually show a woody base.
The leaves of Pieris are long and oval, between 1 and 4 inches in length, and ½ to 1 ½ inches broad. They are smooth, softly glossy, with a thick, leathery texture. The leaves grow in a spiral around the stems, creating attractive rosettes of foliage beneath the flowers, which form at the ends of the branches. New spring growth is almost always pink to reddish, and some varieties have bold, bright red new foliage. This attractive young foliage adds a second ‘flowering’ after the real one and extends the color this plant brings to your garden by several weeks more.
Flower buds form early on this plant, and by late summer they begin to show in clusters, arranged along thin stems growing in a bunch from the top of each branch. These grow slowly through the winter, and they add lots of interest during those months. These immature buds are usually greenish-white, but in some varieties they can be pink. By spring the bud clusters are large, and there can be hundreds of buds at the ends of each branch. They open as the warmer days arrive, and the cluster of flowering stems arches over in all directions, hanging downwards very gracefully. Each stem is 6 inches or more in length, with many flowers along it, creating a display that is both graceful and spectacular. The individual flowers are between ¼ and ½ of an inch long, and they are white or shades of pink, depending on the variety you are growing. The flowers are sweetly fragrant, adding another dimension to the pleasure they bring. Blooming extends for 2 or 3 weeks, depending on the temperature, and as the flowers fade, they begin to form seed heads. These are not very attractive, and they are normally removed, to encourage more flowers for the following year.
Pieris is hardy from zone 5 to zone 8 or 9, doing best in zones with moderate temperatures and moist summers. In zone 5 it is best to grow varieties that have shown good hardiness – ‘Cavatine’, for example, is a variety with good cold resistance. Plant in sheltered spots, protected from cold winter winds. Extra attention is needed in zone 9 to shade and moisture, and hot, dry parts of the country are not so suitable.
This plant will grow in both sun and shade, and more sun is desirable in cooler zones. Locations with a few hours of morning sun, followed by afternoon shade, are ideal, and so are spots with light, dappled shade, or in shade from walls and fences, such as against a north-facing wall with clear sky overhead. In colder areas some winter shade will help protect against sunburn on cold days, and this often comes naturally from the longer shadows of winter.
If you are already growing azaleas, rhododendrons or camellias successfully, then you will have no problem growing Pieris. They need similar soil conditions, which should be moist but well-drained, and rich with organic material. The soil should be acidic, with a pH of 6.5 or less, although this plant is less ‘fussy’ about acidity than other acid-loving plants, and it will often grow well in neutral soils, if they are rich and moist. If you don’t have suitable conditions (or even if you do and want to place them in planters anyway), grow Pieris in planter boxes or pots, using soil for acid-loving plants. Make sure the pots you use have drainage holes.
Although poisoning is rare, it should be mentioned that all parts of this plant, including the leaves, are toxic. Don’t allow livestock or horses to eat it, and it can cause vomiting and sickness in dogs and cats – although they will rarely show any interest in eating it. Most animals recover, and this kind of poisoning is also seen from Rhododendrons. Human poisoning has sometimes happened from eating honey made from the flowers. For most gardeners this is of little concern, and despite many garden plants being toxic to different degrees, actual cases of poisoning remain very rare.
Good soil preparation is valuable when growing Pieris, so dig the area well, adding plenty of lime-free compost, rotted leaves, or peat moss to it as you dig. Soak the pot the night before you plant, and plant into moist soil. Place your plants in the ground at the same depth as in the pot, firm down the soil around the root ball, and water well. Water twice a week for the first few weeks, especially if you are planting during warmer weather, and don’t allow the soil to dry out. Until the roots spread out, water close to the stem, as well as further out, and water deeply.
If the light conditions and soil are suitable, Pieris is an easy plant to grow, needing minimal attention. Make sure plants don’t dry out in summer, and watering is the main care needed during dry seasons. Fertilizer in spring is beneficial in keeping plants vigorous, healthy and growing strongly, and especially in containers plants should be fed regularly. Use a blended fertilizer for acid-loving flowering plants, such as is used for azaleas.
The only trimming needed is to dead-head the plants after flowering. Do this by snipping off the spent flower clusters rich above the top leaves. Don’t remove the tip of the stems, or any leaves, and trim as soon as the flowers fade. New shoots grow from directly below the flowers, so over-trimming will remove them, reducing growth and flowering. The seed heads are not attractive, but they do take energy from the plant, and allowing them to develop will reduce flowering in the following year, especially in young plants. When plants become too large to dead-head they will probably be vigorous enough to carry seeds, and they will be mostly hidden among the new growth, so this job can be reduced or ignored on large plants. Other pruning is not needed, and plants develop best if left to grow naturally. Any long, very vigorous stems can be shortened back to encourage bushier growth, but regular pruning is not beneficial.
Pieris do not normally suffer from any pest or disease problems. Yellowing of the foliage is sometimes seen, but this is a nutritional problem. If the soil is strongly acidic, increase fertilizer, making sure you are using something blended for acid-loving plants. In neutral or only slightly acidic soil, using chelated iron in early spring and again in fall will usually restore a healthy rich green color to the leaves.
Pieris are a group of plants in the same family as rhododendrons and heaths, the Ericaceae. Most of these plants grow naturally in acidic soils. There are just seven species in this group, with four of them coming from China, Japan or Korea. There is one species from Cuba and two from North America. Only two species are grown in gardens, and the Japanese Andromeda, Pieris japonica, overwhelmingly provides the garden varieties.
This is because the main American species, the mountain andromeda or fetter bush, Pieris floribunda, is difficult to grow in gardens, and also difficult to propagate in nurseries, so it remains very rare. It is an attractive plant, with more upright or arching flower stems than in Japanese andromeda. It grows chiefly in the southern Appalachian Mountains through the Carolinas into Georgia, and in Virginia and West Virginia. The second American species (Pieris phillyreifolia) is very rare, growing only in swamps, climbing into Pond Cypress (Taxodium).
Japanese Pieris, Pieris japonica – This is the only species normally grown in American gardens, and this plant grows wild throughout Japan, Taiwan and eastern China. It is variable, usually growing as a shrub less than 10 feet tall, but sometimes making trees up to 30 feet tall. It grows on the floor of forests, especially among Japanese cedar (Cryptomeria japonica), whose open shade creates ideal conditions for it. It was probably introduced into Europe and America during the 19th century, and since then its many valuable varieties have been developed. Some of the best are:
‘Cavatine’ – a compact, bushy plant no more than 4 feet tall, and more reliably hardy in zone 5 than other forms. Grown in the Netherlands from seed collected on the Japanese island of Yakushima. ‘Award of Garden Merit from the Royal Horticultural Society of Britain.
‘Temple Bells’ – another compact form that is ideal for garden planting, with very long-lasting flowers on long stems.
‘Brouwer’s Beauty’ – a hybrid between the Japanese and American andromeda, with the advantage of sterile flowers, meaning dead-heading is not needed.
‘Forest Flame’ – bold new shoots begin red, turning pink and then yellow before turning green.
‘Flamingo’ – pink new shoots and bright pink flowers.
‘Variegata’ – white edges on the leaves give year-round interest.
Although not so widely known or grown, Pieris have all the features to earn a place in any garden. They are valuable for their unique flowering and charm, and they deserve to be more widely grown. You can help they become more well-known by planting some in your garden – once seen they are always loved.