With fewer flowers in the garden during the wintertime, attention is more readily drawn to bark and foliage, and plants with variegated foliage can provide a great deal of prolonged interest. The author returns with more suggestions for the winter garden.
The appropriately named cast-iron plant (Aspidistra elatior) is a quiet, subtle foliage plant. Extremely tough and accommodating, it will tolerate strong sunlight (with ample watering) or the deepest shade. Bait for snails and slugs to keep the leaves from being eaten, but they are otherwise relatively pest free and durable subjects (even as house plants). Partial to full shade will enhance the deep green foliage color. The variegated forms are spectacular. ‘Variegata’ will vary from highly striped to almost no stripes, so be sure to select a good form. Bright white stripes alternate in varying patterns on the green leaf and run lengthwise from base to tip. ‘Asahi’ has leaves wondrously tipped in white. There is a rare form with the reverse pattern of variegation: white leaf with green tips. ‘Okina’ is striped and dotted with white. ‘Milky Way’ (syn. ‘Milk Spot’) has dotted leaves. One form has rolled leaves, another has broad leaves. There is a selection (not yet named) with a central stripe running the length of the leaf. And still another selection has leaves miraculously marked half white and half green!
Aspidistra yunnanensisis is a dwarf grower and is also subtly variegated with a center stripe of lighter, creamy green. Its leaves are smaller than on the typical cast iron plant.
All aspidistras prefer regular watering (though they are drought tolerant in shade) and will respond to frequent feedings during the growing period. They are not fussy about soil, but better soil will result in more lush growth. They can also be used as houseplants, and in difficult garden situations where there is only minimal light, such as under stairways or inside enclosed entryways. [Sunset zones 4-10, 14-24]
Among the most common of carefree evergreen plants for shady conditions is Japanese aralia (Fatsia japonica); in its variegated form (‘Variegata’), it is stunning. In any form, Japanese aralia provides a bold accent with its deeply lobed leaves, which can be as much as sixteen inches wide. [Sunset zones 4-9, 14-24]
The evergreen holly-leaf osmanthus (Osmanthus heterophyllus) is particularly showy in its coloredleaf forms: ‘Aureus’ (yellow edged), ‘Goshiki’ (cream and bronze), ‘Purpureus’ (new growth purple red), ‘Variegatus’ (creamy margins). As an added bonus, their tiny flowers are delightfully fragrant, and the shrubs are tough and dependable. [Sunset zones 4-10, 14-24]
Conifers also show off best at this time of year, when relatively little is flowering. Colored foliage (yellows, blues, silvers, whites, and all the variations in between) and a great variety of greens, as well as the many textural forms, provide endless choices for the gardener.
Many woody plants have showy bark colors, and the colors are often more obvious during the cooler months when their leaves have fallen. Redtwig dogwood (Cornus sericea) offers brilliant red twigs, or yellow twigs in the cultivar ‘Flaviramea’; they are best in slightly moist situations in the garden. Likewise, willows (Salix) provide subtle tints of red, yellow, green, and purple in their winter bark; all are easily grown in moist soils. Shrubby forms of both dogwood and willow benefit from being coppiced (cut to the ground each spring before new growth begins) to encourage the fresh young shoots that will develop the most colorful bark in the following winter.
Among deciduous trees, the maples (Acer) provide the most bite from their bark. Striped-bark maples are too seldom grown, given their stunning bark patterns. Some, such as ‘White Tigress’ (a hybrid of A. tegmentosum), are relatively slow growing, so it may take a few years for the most dramatic display of white-striped green bark to develop. The coral bark group of Japanese maples (Acer palmatum) offer red winter twigs and bark, not unlike the redtwig dogwoods. ‘Sango-Kaku’ is the best known cultivar, but ‘Beni-Kawa’ is an improvement with red young stems and yellow older branches and trunks. Acer rufinerve is showy in itself but absolutely stunning in the selection ‘Winter Gold’. Colder temperatures enhance its bark color, which is school-bus yellow on a tree reaching at least thirty feet tall. It screams for attention from a distance with just its brilliant yellow branches.
All maples like good drainage. The addition of organic compost to the soil and planting the crowns high will increase the chances for success with this group. They tend to be somewhat sun shy, but, in time, the canopy will shade itself provided the plants are well watered.
For a more exotic touch, the bamboos often have variegated leaf or culm (stem) colors. Foliage colors can be light to dark green, with either white or yellow stripes along the margins or in the middle of each blade. Culms may be even more varied: yellow, blue, pink, black, purple, dotted, blotched, or striped. Some have a white powdery ring at each node on the jointed culms. These are foliage plants for textural effects in the landscape, and many make exceedingly graceful specimens.
Bamboos need good drainage but ample water—especially during the beginning of each growth period, when culms are shooting up from the roots. Soil should be reasonably rich. Sun or shade exposure varies with each species and selection, but all appreciate some relief from the sun if they are on minimal watering regimes. The low-growing forms usually prefer part sun to enhance their foliage, but will grow in full sun with ample watering. Wind protection, especially during the young shoot growth stage will benefit all bamboos since the young shoots are tender and easily damaged if they bump into each other or into other branches in windy situations.
It should be understood that many bamboos spread by long rhizomes, and this will affect the site chosen for planting. However, some bamboos are noninvasive, their rhizome structure only growing a short distance from the main clump of stems so they can be planted anywhere. There are good noninvasive bamboos! With careful selection, bamboos will add immensely to the winter garden.
This is just a sampler of what can be added to provide more visual interest in winter. Venture out this winter to see what’s available at your local nursery, or in a nearby botanical garden.
See Pacific Horticulture, January ’08, for the author’s first installment on plants for the winter garden, wherein he focused on flowers and berries.