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Holly Fern

60601This is one of those perennials that has mixed reviews. Although relatively tough once established, holly fern, Cyrtomium falcatum, is susceptible to rot and fungal leaf-spot. It likes to be watered somewhat regularly, but rots if the soil is constantly saturated. Leaf-spot is not as dangerous as it looks, but can be unsightly. Too much fertilizer (to correct the damage) can burn the foliage too.

Individual fronds might get as long as a foot and a half, with half a dozen to a dozen pairs glossy and irregularly toothed pinnae. Foliar texture (remotely) resemble that of some types of holly. Because they disperse their roots so efficiently, mature specimens do not like to be transplanted. Small plants can grow as houseplants for years, but eventually want to get out into the garden. Holly fern likes a bit of shade, and will tolerate rather dark shade.

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Ferns Are Shady But Cool

P90309+++++It could be either an asset or a liability. With few exceptions, ferns do not want to be too exposed to direct sunlight or wind, especially during warm and dry weather. However, as long as they get just enough filtered light, they can be quite happy in sheltered spots that are a bit too shady for other plants. Most like to be watered regularly, and perhaps lightly fertilized in spring and summer.

They provide neither floral color nor fragrance. They lack interesting branch structure and bark. Since they reproduce by spores, they do not even produce any fruit, either edible or ornamental. For those who do not know them any better, they might seem to be rather boring. Yet, those of us who grow them know how handsome their lush, finely textured and uniquely patterned foliage is.

Of the popularly grown ferns, only two develop ‘trunks’, (which are actually just clustered wiry roots growing downward through rotting stems). Two others are ‘epiphytes’ that naturally cling to trees or exposed stone, but in home gardens, are more popularly grown on wooden plaques. Most other ferns are terrestrial understory perennials that naturally live in the partial shade of larger plants.

Although mostly confined to the ground, some ferns can get quite large. Individual leaves, which are known as ‘fronds’, can get several feet long. Even before it develops a trunk, Australian tree fern produces huge fronds that can shade an atrium. Other ferns with smaller leaves can spread very efficiently, and can even become invasive. Fortunately, most ferns are relatively complaisant.

The two popular epiphytic stag-horn ferns have weirdly lobed but otherwise undivided fronds. Leaves of the odd bird’s-nest fern is neither divided nor lobed. Otherwise, fern fronds are intricately divided into small leaflets known as ‘pinnae’. These pinnae are neatly arranged on opposite sides of leafstalks known as ‘rachi’. Some ferns have silvery variegation, but most are rich dark green.

Ferns innately do well in pots. Boston, maidenhair, rabbit’s foot, holly and bird’s-nest ferns are actually excellent houseplants. However, Australian tree fern and a few others shed irritating fuzz that would be a problem in the home. Most of the popular ferns are evergreen. Many consume their own deteriorating foliage by covering it with new foliage. Some ferns need occasional grooming.

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Agave attenuata

60427Agaves are innately tough and undemanding. The main reason that they are not more popular in home gardens is that they are outfitted with nasty foliar spines. The worst of these spines are the distal tips of the large succulent leaves. Most agaves are also armed with shorter recurved spines on the margins of their leaves. Gardening with such well armed perennials can be dangerous.

A complete lack of foliar spines is what makes Agave attenuata such a deviant. The relatively pliable foliage forms big grayish rosettes that can get as broad and tall as four feet. Groups of these rosettes can slowly cover quite a bit of area. The plump stems below may eventually become exposed as they shed old foliage, but are they usually obscured as newer rosettes develop and grow.

The cultural preferences of Agave attenuata are also somewhat unusual. Unlike other agaves, it wants occasional watering and a slight bit of shade. If too exposed, it can get frosted in winter, or roasted in summer. Agave attenuata is also known as foxtail, lion’s tail or swan’s neck agave because its fluffy yellowish flower stalks curve downward, and maybe up again, to about six feet tall.

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Mirror Plant

90227Classic but simple mirror plant, Coprosma X kirkii, was a utilitarian shrubby ground cover for many years before all the colorful modern cultivars that are so popular now were invented. Individual plants can cover quite a bit of ground without getting any deeper than two feet. It is particularly useful in coastal landscapes, because it is so resilient to wind and exposure, as well as sandy soil.

Modern cultivars are remarkably variable. Some are variegated with white, yellow or bronze, either as foliar margins or blotches. Others are very dark purplish bronze. One cultivar is dark bronze with pink foliar margins. Most of these modern cultivars have nicely rounded and undulate leaves, although some have narrow leaves that are comparable to those of the now rare original cultivar.

The more colorful modern cultivars do not grow quite as large or as efficiently as the original, so are not quite as practical as ground cover on large areas. However, they should work just as well for smaller areas, and are even better in conjunction with other plants. Some types of mirror plant are shrubbier. Yet, others cascade nicely from terraces and big planters, and over retaining walls.

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Colorful Foliage Needs No Bloom

90227thumbThere is no shortage of color for the garden here in our mild climates. If we want to, we can grow various flowers to bloom at various times throughout the year. If that is not enough, we can grow plenty of colorful foliage too. Evergreen sorts can stay fresh and resilient to minor frost all winter. A few deciduous plants and warm season perennials with colorful foliage will refoliate in spring.

Besides the various shades and hues of green, foliage can be variegated with white, cream, gray, chartreuse, yellow, gold, red or pink. Such variegation can be stripes, blotches, spots, margins or lacy patterns. New spring growth of some variegated plants is blushed with pink or red. Plants with blue, gray, silvery, bronze or purplish foliage are mostly monochromatic, without variegation.

Just as most popular flowers became less efficient at their primary function of attracting pollinators, as they were bred and developed to be bigger and more colorful than they naturally were, most colorful foliage is not an an advantage to the plants that produce it. After all, foliage needs chlorophyl for photosynthesis. Variegated portions of leaves lack chlorophyl, so are much less efficient.

In fact, many variegated plants originated as mutant growths, known as ‘sports’, that appeared on unvariegated plants, and were cloned. Many try to revert back to green by producing their own unvariegated sports. These green sports grow faster with more chlorophyl, so can overwhelm variegated growth if not pruned out. Monochromatic blue or gray foliage is not mutant growth, but is instead a natural adaptation to extreme exposures, mostly at high elevations, so is not prone to reversion.

English holly, English ivy, euonymous, silverberry, New Zealand flax, mirror plant and various pittosporums are some of the more popular variegated plants. Purple leaf plum, purple smokebush and a few cultivars of Japanese maple are popular plants with purplish or bronze foliage. Blue spruce, American agave, Arizona cypress and various junipers have exquisite bluish or gray foliage.

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Conifers Have A Woodsy Style

81205Conifers are the most prominent forest trees in North America, but are notably scarce in home gardens. Except for compact varieties of juniper (which were probably too common years ago) and arborvitae, most conifers are trees that get too big for residential gardens, and few adapt to regular pruning that might keep them contained. Almost all are evergreen, so block sunlight in winter.

Gingko (maidenhair tree), bald cypress and dawn redwood happen to be deciduous conifers; but gingko is typically thought of as a ‘broadleaf’ (not coniferous) tree, and bald cypress and dawn redwood are quite rare. The various podocarpuses are useful coniferous trees that happen to be very complaisant to pruning, but like gingko, they are typically thought of as broadleaf trees.

Junipers and arborvitaes are just as practical for home gardens as they ever were, and the many modern varieties that have been introduces over the years are even more interesting than the old classics. Modern arborvitaes are more compact. Modern junipers exhibit more colorful foliage, and more distinctive forms and textures. Foliage can be lemony yellow or blue like a blue spruce.

Simply speaking, conifers are cone bearing plants. They are typically outfitted with needle or scale leaves. Of course, it is not that simple. Juniper seeds are contained in fleshy structures that resemble berries. Gingo and podocarpus seeds actually come with a squishy mess. So, ‘cones’ are not always as easy to recognize as pine cones are. Neither are the wide ‘needles’ of gingko.

Redwoods, pines, cedars, cypresses, Leyland cypresses, spruces and firs are the more familiar of the larger coniferous trees. Bunya bunya, Norfolk Island pine, western red cedar, incense cedar and the various yews and chamaecyparises are somewhat rare. Larch and hemlock are very rare because they do not like the climate here. With few exceptions, these larger conifers have dominant central trunks that can not be pruned down without ruining the structure of the trees as they develop.80516

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Secret Lives Of Christmas Trees

90102thumbPeople really stress out over Christmas trees. Some do not want a cut Christmas tree because it involves killing the tree. Some do not want an artificial Christmas tree because it is . . . artificial. Some do not want a living Christmas tree because it is too expensive for a tree that is too small. There are so many myths and misconceptions about Christmas trees, yet everyone wants one.

As mentioned, artificial trees are . . . artificial. Obviously. They are not a horticultural commodity, so are not an appropriate topic for a gardening column. What can be said about them is that they are not a more environmentally responsible option to disposable cut real trees. Countless dinosaurs died to make the petroleum for the plastic that these non-biodegradable trees are made of.

Cut trees are still the most environmentally responsible option. They are not harvested from forests, but from plantations, just like any other cut foliage, cut flowers or vegetable crops. Many are grown from the branched stumps of previously harvested trees, by a process known simply enough as ‘stump culture’. It works like coppicing, and allows some stumps to produce for many years.

Potted living trees are the most misunderstood type of Christmas trees. There is nothing environmentally friendly about them. They are exotic (non-native) trees grown in synthetic media (potting soil) in vinyl pots. They get synthetic fertilizer, artificial irrigation and very unnatural pruning while growing within artificially regulated environments that are designed to promote efficient production.

Only a few of the more compact types of living Christmas trees, like Colorado blue spruce and dwarf Alberta spruce, can survive confinement in pots for more than just a few years. Austrian black pine and dwarf limber pine need a bit of trimming as they grow, but also have the potential to work for a few Christmas seasons. The common small potted Christmas trees that are already decorated are Italian stone pine and Canary Island pine, which do not survive confinement for long, and get too big for home gardens.

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Asparagus Fern

51209The softest and laciest of the asparagus is the asparagus fern, Asparagus setaceus. The extremely small ‘leaves’ (or ‘cladodes’) are less than a quarter of an inch long. The tiny and mostly unnoticed pale white flowers that bloom sporadically in warm weather make it obvious that asparagus fern is not really a fern. (Ferns do not bloom.) If any green berries develop, they are toxic.

The wiry perennial stems can climb like vines to almost reach upstairs eaves, although most get less than half as high. Individual plants produce only a few stems, rarely more than ten. Pruning out old deteriorating stems stimulates new growth. Potted asparagus fern eventually gets crowded with swollen roots, so needs to graduate to larger pots. As a houseplant, it needs regular watering.

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Sweetgum Color

P81117KWe may not get much foliar color in autumn here, but we get enough. Sweetgums do not need much cool weather to color well. They would probably have colored better and held their foliage a bit better if the weather got cooler faster, but we can not complain about what we got. Most of the crape myrtles are still completely green. Cottonwoods are defoliating, but without much color. Maples are rare here. The three best trees for color in autumn here are sweetgum, pistache and flowering pear. Of these, we happen to have several sweetgums here.P81117K+
Sweetgum is not the sort of tree that I would recommend for home gardens. They are innately very likely to develop structural deficiency. By the time such problems are identified, they are difficult to correct without disfigurement. Aggressive roots are likely to displace pavement, and sometimes invade septic systems. Then there are all those nasty maces; those hard and prickly round seed pods that stick into lawns and make pavement dangerous to walk on. They are too abundant and heavy to rake away as easily as fallen leaves. There are not enough squirrels in the entire forest to take them all!P81117K++
In some of our unrefined forested landscapes, where maces and falling limbs can fall into the forest without damaging anything, and roots can not reach concrete pavement, sweetgums can be allowed to go wild. (Unfortunately, most of ours happen to be near concrete within refined landscapes. That is another story.) Their tall and somewhat conical form happens to work very well with the native redwoods and Douglas firs, which provide the perfect rich green backdrop for their exquisite autumn color. Those of us who do not know better might mistake them for a native species. They look right at home here.P81117K+++

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Heavenly Bamboo

51111Good old-fashioned Heavenly bamboo, Nandina domestica, which can almost reach the eaves, can be difficult to obtain nowadays. More compact modern cultivars do not get much more than six feet tall, and some stay less than three feet tall. Foliage is airier in partial shade, but more colorful where more exposed.

As it begins to emerge in spring, new foliage is pinkish or reddish before greening. It slowly bronzes by autumn. Some cultivars turn ruddy or orangish, or even burgundy. Individual leaves are actually quite large, but are divided into many small, diamond shaped leaflets. Some cultivars have very narrow leaflets. Tiny white flowers bloom through summer. Bright red berries ripen through autumn.

Although unrelated, Heavenly bamboo grows like bamboo, with vertical canes developing from creeping rhizomes. Overgrown or deteriorating canes should be cut to the ground as they get replaced by newer canes. Otherwise, they become top-heavy and inhibit development of new canes. Foliage should not be shorn, since it is not much to look at without its naturally intricate texture.