Foliage – the Mainstay of the Garden
Every year as the first of February rolls around, the bleakness of the winter landscape stares back at me from the window. Under gray skies, the garden appears desolate. Murky, muddy grays, browns and tans are the colors of late winter; the light and life of even these neutral colors seemingly drenched right out by dark cloudy skies and freezing air. During the dreary season, the landscape in our foliage challenged region makes us long for the warm days of summer. First shoots and bulbs are beginning to appear; hope is kept alive by the promise of swelling buds on the barren twigs of shrub and tree. I’ve come to know this landscape melancholia as foliage deprivation. (Mahonia repens with winter-reddening and frost tipped leaves.)
Foliage is a term used to denote all the leaves and twigs of a plant or even a cluster of leaves, flowers and branches. Collectively, we think of foliage as meaning the leaves, or even narrower, a plant whose leaves are its main attribute in advancing the design of the landscape, as in a plant with grand leaves in some fashion. Regardless, winter is the time of year when foliage is at a premium in the landscape.
I long for green. Green tips of tender baby leaves, green blades of grass and stems. I yearn to see plants of spring green, lime green, mint green, chartreuse, jade, moss, olive and sage green leaves. Waves of green rolling in the wind. Great swaths of green where now only crisp dried debris remains in shades of brown – from sandy beige to buff, burnt umber, camel, chestnut, chocolate -- longing for even a russet, burgundy or bronze blade or leaf among last years remains.
We bring foliage into the home, potted greens, in hope of brightening our lives. We feel better when green is around us. Winter holidays are based around bringing ever-greenery into the homes. It’s a hopeful thing – we have hope the world will warm again and fill the landscape with green.
How we take soothing green for granted as soon as flowers appear, denigrating greens by calling them filler plants, or background. One can view a green landscape as what is expected, or worse, as boring, if all the same, or so it seems when there is so much of it. A color to take for granted, until it is gone. But really, so much variation in this sobriquet. We attach the common plant names as adjectives to name the green: clover green, grass green, fern green, ivy, laurel and myrtle green, pear and apple green, pine green, tea green and so on. Avocado green – the green of the inside or outside?
Green is much more. Green is soothing, exciting and thrilling, especially when paired with leaves sporting pigments of crimsons, burgundies, golds and variegated creams and whites. Green is dependable. We depend on green to make the landscape. Green is indispensable. Indispensable to animal life on earth, including us humans.
After one has been gardening for a few years, or perhaps, a number of years, green becomes beautiful. Green becomes beautiful at the moment when in thinking about a plant, the leaves become the main draw instead of some expectation of flowers. Plants either have showy flowers or foliage, although sometimes both. A foliage plant flourishes, rather than flowers.
Benefits of Leaves
Plants are unique living organisms. They are the only photosynthetic organisms to have leaves, essentially, solar collectors composed of photosynthetic cells. Plants are at the base of the first trophic level that synthesize sugar and oxygen from sunlight. A really remarkable feat. And of special interest to us today, is the ability of plants to pull carbon dioxide from the atmosphere. This planet of green supports all other life. (OK, some bacteria and protozoans use energy from sunlight to do this too.) (Photo at left is Jeffersonia diphylla, twinleaf, named after Thomas Jefferson; photo at right is Persicaria 'Red Dragon', avoid afternoon sun.)
Usually it is within the leaves this remarkable chemical reaction takes place (in some plants, stems contain chlorophyll cells, such as the palo verde trees). The conversion of sunlight energy into sugar and water happens within the green pigment chlorophyll. Technically, six molecules of water, plus six molecules of carbon dioxide produce one molecule of sugar plus 6 molecules of oxygen. This has gone on for millenniums, 24/7 to produce the food and oxygen we need. (Photosynthesis, Estrella Mountain Community College Bio Book.)
Carbon fixation within the photosynthesis process can be performed by three processes, C3 carbon fixation, C4, and CAM (used by most succulents). Plants using C4 and CAM pathways are more heat and drought tolerant, than those using the C3 carbon fixation pathway. C3 plants are normally native to the cooler regions of the world. C4 and CAM are adaptions in plants found growing in hot, dry areas. Knowing the photosynthesis process of a plant can aid the gardener in making a better choice for its location in the landscape within the context of water use.
Seeing Green, Mainly
Useful, too, are the clues the color of the leaves give gardeners in their placement in the landscape.
The Greens. Why are leaves green, in the main? In short, the green color is the portion of the light spectrum unused by plants. Leaves are composed of the green pigment chlorophyll. Simply, as white sunlight passes through the chlorophyll pigment, the pigment absorbs all the other visible light wavelengths (the blue and red wave lengths) except for green, which is reflected back. Leaves also contain carotene pigments that absorb orange-yellow wavelengths and xanthophylls pigments absorbing yellow to almost colorless light. Anthocyanin, a purple-red pigment is present in some species, however, it isn’t involved in photosynthesis. (Botany for Gardeners.) Chlorophyll in the leaves masks the orange-yellow and purple red of the carotene, xanthophylls and any anthocyanin also present. We think of chlorophyll as green in color, though it is the color not used. Think of green as waste light leftover by the plants. Lucky for this, otherwise they’d all appear black.
Variegation. The interesting yellow, cream or white markings, stripes, ribbons, edgings, dots or splotches we call variegation are the result of a lack of green chlorophyll pigmentation that is caused by a random or genetic mutation. Variegated plants are less robust than non-variegated of the same species, and are more prone to die out under stress. This is one reason why yellow and variegated cultivars perform better in afternoon shade, rather than full sun, especially in our climate. This lack of vigor is due to decreased chlorophyll, thereby reducing food/energy production for the plant. (Viral disease is also a cause of some variegations.)
Red Foliage. So what about trees with reddish or mahogany leaves? A metabolic disorder causes a few plants to have a higher concentration of anthocyanin. Leaves that appear purple, blue or red contain a higher concentration of anthocyanin than chlorophyll. Anthocyanin is a pigment adept at absorbing green light, but less skilled at absorbing red, blue or purple light. In some plants, new leaves first appear red, or tinged with red. This anthocyanin protects the tender leaves from ultraviolet light waves. As the leaves mature, an enzyme breaks down the anthocyanin, allowing the leaf to absorb this spectrum of red-blue-purple light. In mature trees, the leaves then appear green. (Photo at right is of the purple smoke tree.)
Leaves of plants with reddish leaves lack the enzyme to break down anthocyanin, and reflects the red portion of the light (along with the green), using less of the light spectrum than the “normal” green-leaved plants.
Descriptions of plants with red leaves will often include a statement that advises for best leaf color, plant in a sunny location. This is also said of evergreen plants that experience winter leaf reddening. Additionally, some shade plants with green leaves, when planted in sunny locations, will turn red or reddish, such as some nandinas.
Winter reddening of green leaves. Another variation of leaves is the winter reddening of some evergreen leaves. Evergreen plants that exhibit winter-red are admired and sought after for the winter landscape. Winter-reddening in plants is a term used to describe the accumulation of red pigments beginning in fall or winter and continuing on until spring in primarily broadleaf evergreen species. (Photo at left is of winter-reddening of a penstemon, most likely Penstemon pseudospectabilis, snapdragon penstemon.)
So far, there is no definite explanation as to why some evergreen plants bearing either leaves or needles tend to tint red in the winter, or not. This color change is not due to the leaves senescence, that is changing color in the autumn. Basically, few studies have been done to determine the underlining causes of winter reddening, as there never appeared to be an agricultural or economic need to find out.
Although scientists don’t know for certain, they have a few ideas. Photo protection – sunlight attenuation and antioxidant protection – is the favored hypothesis for this yearly occurrence. One theory is, that, in certain species in winter, under high light and cold conditions, excess energy is captured relative to the plants energy expenditure. To avoid photooxidative damage in these plants, it ramps up production of photoprotective anthocyanin, thus decreasing the amount of processed energy, a function called photoinhibition of photosynthesis – reactions that decrease the efficiency of photosynthesis when plants are exposed to light in winter. Perhaps the plant decreases photosynthesis due to a decrease in need and use of energy.
Other thoughts on winter reddening of green leaves of some plants of the same species of plant is that in plants with winter-reddening, the leaves suffer from reduced nitrogen, photosynthetic capacity, and/or chlorophyll content. (Support for a Photoprotective Function of Winter Leaf Reddening in Nitrogen-Deficient Individuals of Lonicera japonica, Molecules, 2014, 19.)
A less popular and untested theory called the co-evolution hypothesis of winter reddening is that the change to a redder pigment acts to reduce leaf damage by making them less palatable and/or less visible to herbivores, as many mammals continue to forage for food in the winter and lack a functional red receptor. (Winter leaf reddening in ‘evergreen’ species.)
There are cases in nature where the same species will exhibit both winter-red and winter-green leaves when occupying the same light exposures and soil conditions. So far there are no explanations as to why a plant would exhibit differing winter colorations in the same time and space.
Whatever the reason, I’ll continue to look for plants plants that transform their evergreen foliage to winter-red, such as certain geraniums, erigoniums, penstemons, mahonias, junipers, Japanese honeysuckle, Texas Red Yucca, and sedums that add a bonus level of winter interest to the garden (for other areas, certain rhododendrons and azaleas too). Bergenia ‘Flirt’ is a cultivar with medium green warm weather foliage that turns nearly black in winter. (Photo of Arizona rosewood, Vaquelinia californica at right.)
Silver and Gray – the Other Green. Gray, interspersed with green foliage plants, increases the interest of a bed or border, although all silver or gray gardens can be dull, gloomy and unappealing. How is it that most gray and silver plants thrive, and often require full sun and dry locations?
Gray and silver foliage plants contain tiny hairs that reflect solar radiation, cooling the surface of the leaf by several degrees, offering protection from the wind, and slowing evaporation. Having adapted to extreme growing conditions, gray and silver leaved plants make excellent companions in gardens with our climate and soil conditions. The color of the foliage, is in fact, most often due to the density, color and length of the hair on the leaf. Underneath the gray or silver appearance, more often than not, is a green leaf. The chlorophyll in the leaves give plants the green color. Gray and silver leaved plants do contain chlorophyll as do nearly all plants. In some cases, actual leaf color (hairs not withstanding) may vary as it does in the typical green world. For the leaf matter we perceive as gray, it's easy-peasy being green. (Artemisia 'Sea Foam' photo at left.)
Gray leaf color exhibits itself in many shades of gray – dull gray to shiny silvery white, hues of blue-green and gray-green colored leaves. They come in all sizes from thin and tiny (Cerastium tomentosum, snow in summer), to large, flimsy (Salvia argentea, silver sage), tough and fleshy (Stachys byzantina, lambs ear) and thick succulent (Agave parryii, Parry's agave and Echinocereus reichenbachii albispinus, white spined lace cactus), both smooth and prickly. Regardless of the form and appearance, silver and gray leaved plants found in nature (as opposed to white, hybridized variations) can usually be relied upon to be more drought tolerant and sun adaptable than their green relations.
Right Plant, Right Place
For best results and lower maintenance, the choices one makes should be dependent on the micro-niche the plant is placed. Country gardens with full exposure to the wind and sun is the most trying environment, while protected city gardens are kinder to plants. This time of year, new plant introductions may entice us. In our climate, it is prudent to wait a few years before trying the last new thing to see how they perform. If your location is challenging, stick with the tried and true. They have withstood the test of time. Growing plants with big or unusual foliage in containers will help save on water usage.
Leaves are shaped in many ways from very tiny (Apache plume, Faluga paradoxa, ) often found on xeric plants to very much larger leaves (Bananas, Musa, and Elephant ears, Colocasia species) of sub tropical and tropical plants. Leaf shapes form in countless ways. Common shapes include acute, eliptic, lanceolate, linear, cordate, lobed, ovate, palmate, spatulate, and whorled. Most leaves are flat, some are cylindrical, are simple, compound or attached to the stem in leaflets. Compound leaves can be pinnately compound, bipinnate, trifoliately compound and palmately compound, among others. (Photo of the ginko leaf at right.)
Veining (longitudinal, palmate, pinnate, reticulate) and edge margins (ciliate, crenate, dentate, lobate, serrate and double serrate, spiny and undulate, etal.) are also used to differentiate between genus and species. The combination of size, shape veining, surface texture, leaf arrangement, colors and colorations provide endless foliage possibilities for gardeners. (Manual of Leaf Architecture.)
Foliage in the Landscape
Gardeners are rarely interested in the amount of photo protection, co-evolution with mammalian or insect predator species, carbon capture, oxygen and sugar output of a plant’s leaves. Gardeners are more interested in the leaf variations of size, shape, thickness, texture, color and duration through the seasons as tools in creating pleasing landscapes. As a xeriscape gardener, I came late to the lush foliage world. Gardening with the big and the bold usually means gardening with more water. In home city landscapes packed with buildings and trees, we are faced with the challenge of gardening in shade, at least for parts of the landscape.
The allure of flower color is enhanced by its fleeting nature, in contrast to the stability of green foliage. Anticipation and excitement builds as each week passes and new plants come into bloom, supported by the continual presence of season long blooming annuals and perennials. I consider many plants foliage plants even though they bloom. Some blooms last longer or are showier than others. Some plants take years to bloom even once, then die, yet are exceptional focal points in the landscape for many years (agaves). By June, color slows and the brilliance of one’s garden is noticed more for its foliage. Or not noticed. With foliage as the work horses of the garden and the planet, a deft ability to compose one’s garden with a pleasing mix of foliage colors, shapes, sizes and textures among the fleeting floral display is helpful.
Gardening with foliage is a necessity in shady areas, and a challenge in hot, dry, sunny climates. I know, I’ve struggled. Plants growing in shade have different characteristics than plants in full sun. Shade plants generally have leaves that are larger, green and or greener, with thin cuticles and are thinner overall. These features allow shade plants to capture the filtered sunlight for photosynthesis below tree canopies where competition for the sun’s rays is fierce.
There are fewer shade-requiring plants native to the Southwestern areas of the U.S. and the Great Plains in comparison to sun-requiring natives, more likely due to the abundance of regional sunny days and absence of tall trees that create a shade ecology. Therefore, native big foliage plants are rare. Plants native to our region adapted to survive its environment.
Although we bask in sunlight, the lack of humidity and copious rainfall are two factors that challenge foliage in our gardens. Strong winter sunlight, as we often experience, and severe temperature fluctuation are other conditions to surmount in growing beautiful foliage. Not to mention the wind and hail – known foliage shredders. Cold hardiness and soil alkalinity is often a factor when it comes to basic suitability of plants for our climate and conditions.
Even so with all the drawbacks we can think up, there is a surprising amount of green that is growable on the Texas High Plains. Gardening well with foliage is an art, but one that is easily mastered over time with study, thought and research. We can grow plants with unique and brilliant foliage, some for a season, some for several years, some effortlessly, some with more attention and care. We can borrow plants native to more shaded areas that are adaptable to our conditions when specific needs of the plants are addressed.
There are too many terrific foliage plants to mention in a definitive list, and it would be too time consuming to do so. But I will mention a few plants and plant groups that are among my favorites. Foliage is the key or strong point of the plant, although many of them flower. Two other considerations for me is whether they are native or not (a term I use in the broad sense, whose boundaries expand and shrink as needed) and the amount of water required by them. I have linked each of these plants to its page in Plant Profiles
Mahonia repens, Creeping Oregon grape holly, is always at the top of my list as a four-seasons of interest plant. Evergreen with winter reddening, native to the Rocky Mountains from New Mexico into Canada, it features yellow flowers for about a month in spring. When inter-planted with daffodils, it makes a complementary backdrop. Creeping Oregon grape holly thrives in shade, will take some sun. There are many times I smile at my stand that borders the south and west side fence. Today, in winter, mahonia’s winter-red leaves provide a gratifying groundcover. (Mahonia repens in flower at upper right.)
Heuchera sanguinea. Coral Bells are low mounding herbaceous plants that are evergreen in our region, native to higher elevations of New Mexico, into Arizona and northern Mexico, that attract hummingbirds. They grow well and flower well in part sun to shade, with afternoon shade preferred. Established clumps flower mainly in spring and will continue on through the summer if adequately watered every other week. They are welcome as understory plants and look attractive lining a border. There are many cultivars of H. sanguinea, and other species in the Heuchera genus. The leaf color of cultivars range from apricot, white, cream, silver, green, lime, burgundy, maroon, bronze, red, to plum and purple, although they may all not be cold hardy. They make attractive container plants either singly or in combination. Their attractive foliage is indispensable for the shade garden. (Photo of H. sanquinea foliage at left.)
Geraniums, cranebills. These are known by the common name hardy geraniums, to distinguish them from the red, pink and white geraniums (Pelargoniums) bedded out and used in containers each summer. They belong to the same family, but not the same genus. Hardy geraniums should be planted in areas of morning sun to part shade.
Geranium maculatum, is our U. S. native geranium, although most cultivars are of G. sanguineum. Reliable cultivars to try include ‘Alpenglow’ and ‘New Hampshire’, good mounders requiring moderate watering (every other week). ‘New Hampshire’ will produce seedlings that are easy to be transplanted. Geranium x cantabrigiense 'Biokovo' is a light pink bloomer. One of the most loved is ‘Johnson Blue’ geranium, but it is not evergreen. They are loved as much for their intricate cut leaf patterns as they are for their flowers. Geranium sanguineum ‘Album’ is a very pleasant white hardy geranium that enhances any area with afternoon shade. It features five-petaled, clear white flowers and small, deeply-lobed, dark green leaves. Flowering in May and June, it is more cold and heat tolerant than most. A few geranium varieties will be evergreen through the winter with winter leaf reddening. For a good list of geranium varieties, click here. (Photo at right is G. 'Johnson's Blue' with winter reddening.)
Columbines. Another plant with the sterling quality of thriving and flowering in shade are the columbines. Aquilegia chrysantha has golden yellow flowers from May into June, and A. canadensis has the striking combination of yellow and red flowers. Most people may remember the blue columbine as the state flower of Colorado, A. caerulea, otherwise known as Rocky Mountain columbine, often seen when hiking the Rockies. Columbine’s foliage is delicate and lacey, adding a fairy-like appearance for weeks on end in spring and again in fall. Columbine is a tough, versatile plant that brightens in sun or shady locations, requiring twice a month water, more or less. (Photo of A. chrysantha foliage at left.)
Nandina domestica, known as heavenly bamboo or just nandina. Although not native to the United States, nandina is a foliage plant with multiple attributes – clusters of small white flowers in spring and striking red berries in fall and into winter. Although not a bamboo, it is a good look-alike and suited to Japanese and Asian style gardens. It thrives even in deep shape, it will take the heat and sun. As an added benefit, in Amarillo, the leaves remain until spring when they are quickly replaced, and in the winter some of the leaves display their winter-red color. An all-around must have plant with a number of varieties/cultivars to choose from. Suitable for containers. Nandina domestica is the rare plant with only one species in the genus.
Nandinas pair magnificently with mahonias, heucheras and geraniums in the foreground of a shaded or understory area. (Winter photo with berries of N. domestica.)
Agave harvardiana, Harvard’s century plant. A. harvardiana is the largest agave that will winter over in the Texas Panhandle and one of the most cold hardy. Next in size is A. neomexicana. I prefer the look of the New Mexican agave – a rounder, and to me, prettier rosette shape. Long lived to 15-20 years before they flower, they contribute a strong architectural element in the landscape. Their big, thick succulent leaves beg one to touch, just be mindful of the sharp black spines. Several other agave species are cold hardy in Amarillo, and many are eminently suitable for containers (be sure to bring inside as needed). Agaves thrive in part to full sun locations. Read more about agaves here.
Yuccas. It is hard to go wrong with the liberal use of yuccas in the landscape. Many species of yucca are cold hardy in the Texas Panhandle, whether small in size, or tall tree form species. Yuccas can be easily worked into nearly any style perennial bed or container. They can have great presence in the landscape. Often thought of as a xeric plant, many yuccas, particularly yuccas native to the southeastern U. S., can fit into more conventional higher water beds. Yuccas prefer part to full sun areas.
Some of the more useful yucca varieties and cultivars belong to Yucca filamentosa and Y. flaccida. ‘Color Guard’ is a gold-centered variegated form. 'Golden Sword' has more upright leaves, photo at left. ‘Bright Lights’, 'Bright Edge', ‘Blue Sword’. ‘Hairy’ are a few other cultivars. Previously they were shown as Y. filamentosa cultivars, now they appear as Y. flaccida. It doesn’t matter; the plant is the same. Every year more forms of the Adam’s needle appear. Any of these work well in containers or in part shade that require every other week watering. Another attractive specimen is Yucca x gloriosa 'Variegata', a hybrid between Y. aloifolia and Y. filamentosa. Afternoon shade is best for any of these gold leaved and variegated cultivars.
Drier, sunnier areas beg for a tree form yucca, such as Y. aloifolia, Y. rigida, Y. rostrata and Y. thompsoniana. They are the species one would most likely be able to find. Read more about yuccas here. Yuccas, along with agaves above and cactus, are three of our Southwest Evergreens.
Ornamental Grasses. There are countless ornamental grasses, both native and non-native that provide superb foliage for sunny areas. Ornamental grasses are bunch grasses, that form a clump, rather than runs, like buffalograss or bermuda grass. I include in the grasses category, rushes and sedges. Ranging in size from a few inches to over ten feet, there are grasses for every condition, bed and style. Grasses also make outstanding container plants, either in combination, or as the sole specimen. Native grasses I like to use include little bluestem, the switchgrasses (Panicums), and blue gramagrass, Bouteloua gracilis. For non-native, Miscanthus cutivars are popular, Karl Foerster Reed Grass, and many of the Penisetums for containers. Blue ovena grass, Helictotrichon sempervirens, and ornamental blue fescue, Festuca ovina glauca are two evergreen grasses that are not drought tolerant, but work well on the edge of lawns that receive weekly irrigation. Sedges and rushes work well in moister areas like ponds and water gardens. Papyrus, Cyperus papyrus, is a trendy container sedge, that come in the taller standard size, and also a dwarf version for small containers. Grasses are the predominant plant type in the world’s grasslands, so it only makes sense to make copious use of grasses in our landscapes on the High Plains. (Photo of blue avena grass at right with calamint and solidago.)
Elephant ears (Colocasia and Alocasias), Caladiums and cannas. Tropicals and semi-tropical foliage plants are some of the most used tropicals and semi-tropicals for shady landscapes and containers. Coleus, gingers, and bananas are a few more large-leaved plants used as annuals that contribute to the lush look of foliage for shady spaces. These are not native to our area and are useful as summer annuals that are either discarded after the season or properly stored for use the following summer. Tropicals in containers, ponds and annual beds add the look of the exotic foliage lushness without breaking the water allowance, when one’s use is kept in check. Containers of tropicals take no more water than a container of bedding impatiens and begonias, especially when the soil mix is rich with compost. (Photo at left of elephant ears and coleus.)
Leopard Plant, Farfugium japonicum was previously in the Ligularia genus. I have only had a leopard plant one year, this native to Japan. I paired it in a container with dwarf papyrus and dwarf elephant ear. The leaves are round and sporadically spotted with yellow dots. It’s lovely. This first year, it sent up a yellow daisy-like flower but briefly. Still, I loved the foliage. Even better still, I kept the pot outside this winter, covering it twice when our temperatures fell to near zero. The foliage still remains, even as I write this at the first of February. Even if the foliage freezes, it will come back from the roots. I will buy a few more for the ground and see how much extra attention it requires during the summer. Plantdelights.com carries several cultivars, but I got mine locally from Sutherlands in Amarillo off the pond plant rack. For me, this plant is a keeper. (Photo at right shows leopard plant, Fargugium japonicum, as the lower plant in the container.)
It was love at first sight after seeing Ligularias at the Denver Botanical Gardens, even though I've yet to use them. They are big leaved and water-thirsty, but if you have a shaded spot where water runs to and keeps the soil soaked, yet with good drainage, you could do no better than choose a Ligularia. ‘The Rocket’ is the one I fell for at DBG. In mid summer when the weather is the warmest, it sends up spires of daisy-like flowers that appear in dense racemes. It’s not for every garden, but if you have a boggy spot, give this perennial a try. Not a native, there are about 150 species native to mostly Asia, with a few in Europe.
Artemisias, etal. No landscape can be complete without a little silver and gray intermingled with the green. If we follow nature, where a mound of gray or silver punctuates the landscape, we cannot go wrong. Gardens of all gray and silver can be blinding, be judicious in its use, but do use them. Important to note when choosing plants, if it is gray or silver leaved, most likely it is drought tolerant. Silver and gray foliage contributes to a sense of place for our region. Click on my most viewed page, Fifty Shades of Gray, for a list of 50+ terrific gray and silver leaved plants to use in the landscape. (Photo at left of Kintzley's Ghost honeysuckle, Loncera reticulata.)
Foliage provides a permanence that give context to our garden and background to many flowering plants. With careful, thoughtful plant choices, we can experience more of the lush look of foliage lusted after by many, without draining the water budget. Banish the landscape blues with prudent plantings of some of these top rated foliage plants.
Botany for Gardeners, Brian Capon, Timber Press, 2005.
Support for a Photoprotective Function of Winter Leaf Reddening in Nitrogen-Deficient Individuals of Lonicera japonica, Molecules, 2014, 19, Kaylyn L. Carpenter, Timothy S. Keidel, Melissa C. Pihl and Nicole M. Hughes, www.mdpi.com/1420-3049/19/11/17810/pdf.
Winter leaf reddening in ‘evergreen’ species, Nicole M. Hughes, New Phytologist, 2011
Angie Hanna, February 5, 2018