Simple old fashioned New Zealand flax, Phormium tenax, has been popular on the West Coast for as long as anyone can remember. Big specimens are prominent in old pictures of Victorian era gardens. The upright and olive drab foliage gets as high as ten feet, and as broad as fifteen feet. Bronzed and variegated cultivars stay somewhat more compact.
Modern cultivars of New Zealand flax might be Phormium colensoi, or hybrids of the two species. They are generally even more compact, with more colorful foliage. Foliage may be olive green, greenish yellow, brownish bronze, rich reddish bronze or striped with like colors. Some bronze sorts are striped with tan or pink. ‘Yellow Wave’ has floppier foliage.
New Zealand flax is a tough evergreen perennial. Its long and narrow leaves can be too fibrous to cut without scissors. These leaves grow as tall as they do from clumping basal rhizomes. Interestingly rigid floral stalks stand slightly higher than the foliage, with yellow or red bloom. After bloom, these floral stalks can be a delightful and bold dried cut flower, and work well with pampas grass bloom.
It may not grow too rapidly, but Japanese aralia eventually gets nearly eight feet high and wide, and commands a bold presence. The deeply and symmetrically lobed leaves can get as broad as a foot and a half, on long petioles (stalks). The foliage of ‘Vairegata’ emerges with a yellow border that turns pale white. ‘Moseri’ stays quite compact.
Plants grown for their foliage can be maintained by cutting the oldest stems to the ground as they begin to deteriorate, so that newer stems can replace them. Alternatively, lower growth can be pruned away as it develops to elevate the canopy and expose interior stems. However, individual stems do not last indefinitely, and will eventually need to be replaced by any convenient watersprouts.
Ferns are an odd group. They lack the color or fragrance of flowers, or the branch structure of shrubbery, trees or vines. Very few turn color in autumn. They provide only green foliage. Yet, as simple as this seems, the generally evergreen foliage that ferns provide is some of the most distinctive foliage that can be found in the garden.
With few exceptions, ferns are richly deep green. Only a few are lighter green or almost yellowish. The leaves, which are known as ‘fronds’, can be soft and papery, or coarse and tough. The fronds of most ferns are pinnately divided into neatly arranged leaflets; and many ferns have leaflets that are intricately lobed. Some ferns have leaves with more palmate symmetry. A few ferns actually have undivided leaves.
(Pinnate symmetry involves a central midrib or midvein to each leaf, or a central rachis that supports lateral leaflets. Radial symmetry involves multiple midveins or rachi that radiate outward from the centers of individual leaves.)
The Australian tree fern is the largest of the common ferns. It develops a broad canopy of long fronds on top of a trunk that can launch it as high as a two story home. Both the fronds and trunk of the Tasmanian tree fern are shorter and stouter. Other tree ferns are rare. The trunks are not really stems, but are thick accumulations of roots dispersed through decomposed stem tissue.
The staghorn fern is an epiphyte that naturally clings (nonparasitically) to trunks and limbs of trees. The flared upper fronds collect foliar litter that falls from the trees above to sustain the roots within. In home gardens, it is popularly grown on wooden plaques or hung like hanging potted plants, but without a pot.
Some ferns can be grown as houseplants like the classic Boston fern, which cascades softly from a hanging pot. Maidenhair fern is popular for intricate foliage on wiry rachi (leaf stems). Squirrel foot fern has lacy foliage and interestingly fuzzy rhizomes that creep over the edge of a pot.
Since almost all ferns are understory plants that naturally live on or near a forest floor below a higher canopy of trees, they are generally quite tolerant of shade. In fact, most prefer at least some sort of partial shade. This is quite an advantage for spots in the garden that are too shady for other plants. Also, many ferns can disperse their roots into soil that is already occupied by more substantial plants, even if the more substantial plants happen to also be making the particular spot too shady for other plants. In other words, they play well with others.
However, many ferns are more demanding than other plants are in regard to soil quality and watering. They perform best with rich and well drained soil, and regular watering. Sickly ferns generally respond well to fertilizer; but too much fertilizer can burn foliage. Old leaves may need to be groomed out if they do not naturally get overwhelmed by new foliage.
Out in the garden, coleus, Plectranthus scutellarioides, prefers partial shade where the foliage is less likely to get roasted during arid and warm summer weather. It is grown as a warm season annual instead of as a perennial, because it gets so tired through winter, and can be killed by even a very mild frost. Its sensitivity to exposure in the garden is probably why it is more familiar as a houseplant.
The flashy and sometimes deeply lobed foliage is variegated with any combination of green, chartreuse, yellow, orange, red, burgundy, pink, white, brown and almost black. Flower spikes should be snipped as they develop to keep foliage dense. The tiny purple flowers are not much to brag about anyway. Large plants can get to two feet tall and broad. Cuttings root easily in rich and regularly moist potting soil or just plain water. Seeds need sunlight to germinate, so should only be pressed onto the surface of damp potting soil without getting covered, and misted daily.
There is someplace in the world for the brethren of each and every houseplant to grow wild. All houseplants do not originate from the same regions, and many were bred in cultivation, but all originate from somewhere. They are houseplants only because they are plants that can live in a house.
Most houseplants are from tropical regions, and many are understory plants that grow in the partial shade of taller trees. They are naturally tolerant of the mild temperatures and partial shade within the home. Not many deciduous plants will be happy without a winter chill.
Confinement is also a concern, since houseplants need to be potted, and stay below ceilings. Plants that need to disperse their roots will not work. Neither will plants that can not be pruned down as they grow. Some palms that work well in malls have leaves that get longer than the distance between the floor and ceiling in the home!
Most houseplants are grown for foliage instead of flowers, not only because a lack of seasons inhibits bloom, but also because their foliage is naturally so appealing. African violets are one of the more notable exceptions. Amaryllis is all flower with almost no foliage, but typically gets discarded when done blooming.
Coleus and caladiums have such colorful foliage that there is no need for flowers. Bloom actually compromises their foliar quality anyway, which is why flower spikes get snipped from coleus. Mauna loa lily is grown for excellent rich green foliage, but sometimes adds clear white blooms as a bonus.
All sorts of ferns are very good houseplants. However, a few, including the popular Australian tree fern, produce coarse fuzz that can be irritating to the skin. A few others, like sword fern, produce messy spores that can permanently stain fabric and carpet. Just because they can live in the home does not mean that they should.
The various ficus are excellent houseplants because they can grow quite large, but can also be pruned to fit into their particular situations. The popular weeping fig (Ficus benjamina) has an abundance of small glossy leaves. Rubber tree and fiddle leaf fig have big thick leaves. Creeping fig is even more distinct from the others, as a wiry vine that is popularly grown in hanging pots.
Does anyone really know what a ‘perennial’ plant is? It is obvious that it is not an ‘annual’ plant that lives only a single year. A ‘biennial’ plant produces vegetative (non-blooming) growth in the first year, and then blooms, develops seed, and dies in the second year. A plant only needs to live more than two years to be a perennial plant, or simply a ‘perennial’. Well, that does not narrow the definition down much. Bristlecone pine can live for thousands of years, but is not often thought of as a perennial.
In simple home gardening terminology, a perennial not only lives for more than two years, but does so without producing significant woody stems. Yes, this also happens to include palms and trunk forming yuccas (which are known as ‘perennial trees’), but that is another topic. Some perennials live only a few years. Some can live indefinitely by replacing their stolons, rhizomes, bulbs, tubers or whatever they regenerate from as their old growth gets left behind.
For example, bearded iris spread by fleshy stems known as ‘rhizomes’. As they grow from the forward tips, the older ends that get left behind will rot away. They are constantly replacing themselves, without leaving evidence of how long they have been doing so. (In other words, it is impossible to cut one down to count the rings.)
Many plants that are known as annuals are actually perennials, but get removed and replaced during their respective dormant season. Busy Lizzy can regenerate each spring if their roots do not succumb to frost in winter. Begonia, chrysanthemum, cyclamen and primrose are just some of the many other annuals that could technically survive as perennials.
Lily-of-the-Nile, African daisy, daylily, canna, penstemon, New Zealand flax and various grasses and ferns are some of the more familiar perennials. They are too diverse to generalize about, but happen to be among the most reliable of plants for bloom and foliage. Because form and mature size is somewhat predictable, properly selected perennials are unlikely to outgrow their particular situations.
Foliar color is not limited to autumn. Some deciduous plants display colorful foliage from spring to autumn. Then, some of these change color for autumn. Some evergreen plants display colorful foliage through the year. Variegation of foliage can be more colorful than associated bloom. So can unvariegated bronze, purple, red, yellow, blue or gray foliage.
All sorts of plants exhibit variegation or other variations of color of their foliage. They can be annuals, perennials, shrubs, vines, trees, or houseplants. Although many are popular primarily because of their foliage, some provide appealing bloom as well. Blue and gray foliage is a natural advantage in harsh climates. Other colors are selections of mutations.
Because variegation deprives portions of foliar surface area of the chlorophyll needed to perform photosynthesis, it inhibits growth. This can be an advantage for plants that grow too vigorously otherwise. However, many variegated plants occasionally develop growth that is not variegated. If not removed, it can overwhelm and displace desired variegation.
New Zealand flax, dracaena palm (Cordyline australis), gold dust plant, euonymus, coral bells and hosta are some of the many plants that are more familiar with colored foliage or variegation than without. If simple unvariegated coleus, croton or caladium are available, they must be notably rare. Blue spruce is always blue. Purple leaf plum is always purple.
Although both gold and gray junipers are popular, the most common are green. Bronzed and variegated cannas are likewise not quite as popular as those with simple lush green foliage. Pittosporum tobira is so much more vigorous without variegation than with it, that the two distinct types of this same species perform different functions within landscapes.
Golden honeylocust supposedly produces lighter shade than darker green honeylocust. ‘Ruby Lace’, a bronze cultivar of honeylocust, supposedly produces faintly darker shade. Some golden or variegated foliage is more susceptible to scorch; although sun exposure enhances foliar color and variegation. Fresh new spring growth gets the best foliar color, but is likely to fade through summer.
Wispy billows of pinkish or tan blooms through June and July are what the smoke tree, Cotinus coggygria, is named for. It probably should have gotten more recognition for brilliant foliar color in autumn. It reliably turns bright yellow and orange, and if the weather is right, it can turn rich red and even purplish. Until then, the popular modern varieties have either dark purplish or light yellowish foliage. Some of the older plants have slightly bluish green foliage. The nearly circular leaves are about two or three inches long. Yellowish varieties tend to be shortest. Those with purplish or bronze foliage get larger. Old fashioned green plants are the largest, and can get twelve feet tall and broad. Smoke tree can be large shrubbery, or pruned up as small trees. Aggressive pruning in winter promotes better foliar color through spring and summer, but inhibits smoky bloom. Slightly distressed plants have better color in autumn. Plants that are watered too much are likely to succumb to disease within only a few years.
Flowers get all the credit for color. They certainly are the most colorful features in the garden, as well as the most fragrant. However, foliage can do so much more than simply provide green. It can be hued with yellow, red, blue, purple, bronze, gray, or variegated with white or yellow. Plants with colorful foliage can range in size and function from small annuals and perennials to shrubbery, vines and even trees.
Hydrangea, hosta, ivy, English holly and various pittosporum are some of the more popular plants for white variegation, and are often variegated with yellow. Euonymus can conversely be variegated with white, but is usually variegated with yellow. New Zealand flax can be variegated with pink, bronze, brown or gold. Box elder is a good sized deciduous tree that can be variegated with white, or alternatively frosted uniformly with gold as new foliage emerges in spring. There is even a variety that has slightly purplish or smoky colored new foliage.
Silver mountain gum, silver Mediterranean fan palm, lamb’s ears, artemesia and the various dusty millers have remarkably silvery foliage. Silver mountain gum can grow into a mid-sized tree with a stout trunk. Lamb’s ears is a low perennial. Olive trees, some junipers and the various lavenders have gray foliage. Colorado blue spruce and some agaves have striking blue color.
Various purple leaf plums and Japanese maples are famous for their purplish foliage. Smoke tree and some beech have even darker purplish foliage. Some New Zealand flax and cannas can be just as purple or comparably bronze.
Actually, New Zealand flax and cannas, as well as junipers known for blue or gray foliage, can alternatively be bright yellow. Golden arborvitae, golden honeylocust and golden Monterey cypress really stand out nicely against darker green.
Colorful foliage tends to be most colorful as it develops freshly in spring, and tends to fade somewhat through summer. Gold junipers can actually fade to basic green by autumn. Shade inhibits most types of coloration, but can show off variegation better. There really is so much variety with colorful foliage that it is impossible to generalize.
Too much of a good thing eventually gets old. That is how so many of the good junipers that were so popular half a century ago became so unpopular. They became too common, and many were planted into situations that they were not appropriate for. As they matured, many became overgrown or disfigured. Only recently have a few newly introduced modern cultivars restored the appeal of both new and traditional junipers to a generation that is less familiar with their former stigma.
Even though all junipers are evergreen and somewhat similar in regard to foliar texture and their lack of interesting bloom, they demonstrate considerable diversity. Some are low and sprawling ground covers. Others are dense low shrubbery. A few develop as small trees. Branch structure may be densely compact, gracefully arching, rigidly upright, or sculpturally irregular.
Some junipers have yellowish new growth that eventually turns to a more typical deep green. Others are bluish gray throughout. A few rare types are variegated. Almost all junipers have scale-like leaves (like those of cypress). A few have needle-like leaves.
‘Blue Arrow’ and more traditional ‘Skyrocket’ junipers are like short and plump Italian cypress with bluish or gray foliage. ‘Wichita Blue’ juniper is even shorter and plumper, with more sculptural branch structure. However, it is not nearly as irregular and sculptural as the old fashioned ‘Hollywood’ juniper. Modern ‘Gold Star’ and the older ‘Old Gold’ junipers are shrubby types that exhibit arching stems with gold tips.
‘Icee Blue’ is like an improved version of the classic ‘Blue Rug’ juniper, that matures as a shallow bluish ground cover. ‘Blueberry Delight’ juniper is one of the few junipers known for conspicuous fruit, with pretty powdery blue berries against grayish needle-like foliage on trailing stems. ‘Limeglow’ juniper gets a bit deeper, and exhibits chartreuse new growth that turns rich green.
Just because junipers can be shorn certainly does not mean that they should be! Shearing deprives junipers of their naturally appealing texture and form. Instead, junipers should be selectively pruned only where necessary to eliminate growth that is beginning to become obtrusive. Stems should be cut back deeply into the main stems from which they originate, in order to avoid leaving stubs or disfigured stems. Tree junipers like ‘Hollywood’ juniper, as well as overgrown shrubby junipers, can be pruned to expose bare trunks and stems. The gnarly stems and shredding bark can be as appealing as the foliage that obscures them.
Otherwise, once established, junipers do not need much attention or water, and are remarkably resilient. They only rarely get infested with spider mites or scale insects, or get damaged by disease. They only want good sun exposure.