Hedges – Living In The Background

90918thumbPretty soon, as autumn weather starts to get cooler, some deciduous plants will develop brilliant color before defoliating for their winter dormancy. Throughout the rest of the year, evergreen plants with gold, silver, bronze, bluish, purplish, reddish or variegated foliage are more colorful than common green foliage is. A few deciduous plants with colored foliage turn different colors in autumn.

Such colorful foliage is generally appealing in the garden. However, there are reasons why not all plants in the garden are so colorful. There really is the potential for too much of a good thing. If all foliage was always colorful, landscapes would look cluttered. Flowers would not be so prominent. There are many situations for which plain and simple evergreen foliage is likely the best choice.

That is why simple evergreen hedges of the various species and cultivars of pittosporum, privet, holly, arborvitae and laurel are still so popular. Some are formally shorn. Where space is sufficient, others are informal screens in which the shrubbery is more or less allowed to assume its natural form and size. The various boxwoods are useful for smaller evergreen and formally shorn hedges.

Most contiguous hedges and screens are intended to separate spaces or obscure fences or buildings. Some sporadic sorts might only expected to disrupt the expansiveness of large buildings or partially deflect prevalent breezes. What they have in common, is that they are in the background. Some are behind or next to lawns, patios or decks. Others are behind more prominent plants.

Shearing hedges that are adjacent to lawns, patios and decks is of course much easier than shearing those that are behind other plants. Screens or hedges behind rose gardens, dahlias, flower beds, or anything that might be damaged by the process of shearing a hedge, should be of the sort that do not need to be shorn regularly. Nor should they be so colorful that they steal the show.

If possible, maintenance of hedges should be scheduled to coincide with the off season of plants in their foreground.

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Fake Six on Saturday

P90824K‘Six on Saturday’ is a weekly tradition for many of us who enjoy sharing six horticulturally oriented pictures on Saturday. I just did it earlier this morning.

This is not ‘Six on Saturday’. It is just one picture of six arborvitae. What’s worse is that there is an indistinguishable seventh at the far end of the row. It blends into the sixth in this picture. There are seven barberry between them, with the seventh beyond the last arborvitae. This picture was taken more than a week ago, so most of the amaryllis are done blooming now.

This row of arborvitae and barberry was installed early last winter, after a grungy hedge of photinia was removed. It would have been nice to salvage the photinia, but they were such a mess that the process would have taken more than two years, and even then, would have been patchy.

These arborvitaes will not grow into a contiguous hedge like the photinia were, but already soften the otherwise uninviting visual impact of the plain and uniform fence behind. They will grow taller and broader, but will never get so big that they will be difficult to maintain. It should be easy enough to get behind them to prune away parts that get too close to the fence.

I happen to be pleased that we were able to incorporate this sort of formality into an otherwise completely informal landscape. The irregularity of the terrain, as well as the randomness of the big forest trees that were here before landscapes were installed, make such formality nearly impossible. Even if it were easier, formality is not exactly fashionable in landscape design.

Despite their imposed formality and exotic origins, both the arborvitae and the barberry are remarkably compatible with the native flora of the surrounding forest landscape.

Oriental Spruce

60127If it got as big as it does in the wild, Oriental spruce, Picea orientalis, would not fit into many home gardens. It can get more than a hundred feet tall! Fortunately, it does not often get much more than twenty five feet tall locally. Trees that compete with taller trees in forested landscapes might get to forty feet tall. Their symmetrically conical canopies get about fifteen or twenty feet broad.

The tiny needles of Oriental spruce are less than half an inch long, so are smaller than those of any other spruce. Relative to the finely textured deep green foliage, the densely arranged and neatly angular stems are notably stout. Like other spruces, Oriental spruce is best where it has sufficient space to retain lower stems down to the ground. It can look rather silly with a bare lower trunk.

Garden varieties are more common and stay smaller than the straight species. ‘Skylands’ has yellow foliage, although it fades in warm situations. ‘Aurea’ has paler pastel yellow new foliage that matures to green. ‘Gowdy’ has a narrow columnar form, and grows very slowly. ‘Nana’ develops as a plump low mound that stays less than three feet tall. All like to be watered somewhat regularly.

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

‘Red Star’ Atlantic Whitecedar

60106Is it red or white? Actually, it is neither. ‘Whitecedar’ is the common name for Chamaecyparis thyoides, which is a formidable coastal conifer from Maine to Mississippi. ‘Red Star’ is a much smaller garden variety. Its finely textured foliage is bluish green when it first emerges in spring, and can turn slightly purplish or bronzed gray if it gets cold enough in winter, but never turns red.

In more humid climates, ‘Red Star’ Atlantic whitecedar can eventually reach second story eaves, and can get half as broad. It rarely gets half as large locally, and can take quite a few years to do so. The slightly aromatic evergreen growth is densely conical, almost like a lumpy dwarf Alberta Spruce with an upwardly rounded underside. It can be a bit more sculptural if partially shaded.

Even without pruning, ‘Red Star’ Atlantic whitecedar is symmetrical enough for formal landscapes. Alternatively, it can add a bit of formality to relaxed landscapes. Although it is slow to provide privacy, it works nicely as an unshorn hedge. If somewhat crowded in a row, it grows taller faster. Shorn hedges lack natural form, but can recover their natural texture between shearing.

Boulevard Cypress

51230Between New England and the Pacific Northwest, the boulevard cypress, Chamaecyparis pisifera ‘Cyano-viridis’, is classified as a small tree, even though it gets no bigger than large shrubbery. Locally, only very mature specimens reach the eaves, without getting much more than half as broad. Trunks and limbs remain concealed by fluffy evergreen foliage. Warm and dry air limit growth.

The handsome foliage is strikingly silvery blue, comparable to that of Colorado blue spruce or blue Arizona cypress, but with a surprisingly soft texture. It is really quite distinct from other evergreens, even other closely related chamaecyparis.

Boulevard cypress prefers cooler climates, so does well locally in light shade sheltered from wind. During warm weather, it can get roasted if too exposed. Although it does not require much water when mature, it is happiest if watered somewhat regularly.

Living Christmas Trees Grow Up

81031All around town, there are Italian stone pines, Canary Island pines, Monterey pines and Aleppo pines that are much too big for the home gardens that they live in. Some are too close to pavement or foundations. Others are under utility cables. Many are shading or crowding out other more desirable plants. What most have in common is that they started out as living Christmas trees.

Because they seem to be so cute and innocent when they are decorated in a small pot, living Christmas trees very often get planted where they really do not belong. Not much consideration is given to their true potential. Pines are innately difficult to contain, and can not easily be pruned back for confinement once they get growing in a space that is not spacious enough for them.

Living Christmas trees simply are not often the horticulturally responsible option for Christmas trees that we would like to believe that they are. Very few end up in good situations where they have room to grow. Planting them in the wild is not practical, since their roots are too confined to survive without watering. Because they are not native, they should not be planted in the wild anyway.

Contrary to popular belief, the most popular of the living Christmas trees do not do well in containers long enough to function as Christmas trees for more than just a few years. Some spruces and small pines can be happy in containers for many years, but can be demanding. If their roots get too disfigured, they are less likely to adapt to the landscape when they outgrow containment.

Ironically, cut Christmas trees are usually more practical than living Christmas trees. They may seem to be expensive, but they are less expensive than living Christmas trees of good quality (unless a living Christmas tree functions for a few years.) Even though they are bigger, cut Christmas trees are not as heavy and unwieldy as the big tubs of soil needed to sustain living trees.

Cut Christmas trees are not harvested from forests, but are grown on farms like any other horticultural commodity. There should be no guilt associated with bringing one into the home. In the end, they can be composted or otherwise recycled like green-waste. There is no long term commitment, and no need to provide accommodations for an eventually humongous tree in the garden.

Those who insist on procuring a living Christmas tree should choose responsibly, and be ready to accommodate a growing young tree. Although not big enough to be real Christmas trees, dwarf Alberta spruce like those in the picture above are sometimes decorated as a small live Christmas tree. They happen to be conducive to confinement in proportionate pots. One in the ground, they grow like strictly conical shrubs that do not get big enough to cause problems.

My First Tree

71108Calocedrus decurrens. Incense cedar. The first tree that I ever planted was a small incense cedar, like the tree in the picture here. Of course, it was not this big when I planted it.

It came from my maternal grandparents’ cabin near Pioneer, in the foothills of the Sierra Nevada. It was a wild seedling that might have been pulled up because it was where the cabin was to be built. My grandmother planted it into a small wooden planter in the backyard. Once it recovered and started to grow, she gave it to my parents, who had me plant it on a small hill in the back yard. Although not native to the Santa Clara Valley, it did well, and grew tall and lean. I tend to compare all incense cedars to my first tree.

Almost all are older and bigger, with plump trunks. I can guess from their age that most were planted during the Victorian Period. Quite a few were planted half a century later, during the 1950s, when Monterey pine and Monterey cypress were too commonly planted. Not many incense cedars are young. It is as if they had been available in nurseries until the early 1970s, and were not grown much after that. I planted a few in Scott’s Valley back in the 1990s, on the southern margin of what is now Sky Park, but only because my colleague happened to grow them.

Because it was less expensive to transport ‘relatively’ local lumber than to import Eastern red cedar lumber from the East, incense cedar provided the veneer for closets of old homes here, as well as cedar chests. Small groves of incense cedar were grown in the Santa Cruz Mountains as a local source of cedar wood. Now that cedar closets and chests are no loner necessary to repel moths from woolens and furs, the naturalized groves are abandoned, and now grow wild. I know that they are technically not locally native, but I still like to see a few of them around. They look so much like my first tree.

Dwarf Alberta Spruce

81031It is so tempting to dress up a densely conical dwarf Alberta spruce, Picea glauca ‘Conica’, as a garden gnome for Halloween. They are so symmetrical that they seem to have been shorn that way. They are too small to be classified as trees, but are not as shrubby as most shrubbery either. Their practicality is rather limited to formal situations where their strict symmetry is desirable.

Dwarf Alberta spruce is very different from the straight (not dwarf) species that can get to almost fifty feet tall. It instead grows very slowly, and stays quite small, although it can eventually reach downstairs eaves. The finely textured evergreen foliage is soft but slightly bristly. The tiny individual needles are only about half an inch long. The aroma of crushed foliage might be objectionable.

Dwarf Alberta spruce is popularly grown as a potted Christmas tree, and happens to be one of the few coniferous plants that can stay potted long enough to functions as such for a few years. In the ground, it wants rich but well drained soil. It can rot if the soil stays too damp. Red spider mite can be a potential problem. Although it likes full sun exposure, it can get roasted in hot situations.

Plan Ahead For Coniferous Evergreens

81031thumbWe all know what autumn is for. Planting, of course. Yes, it is a recurring theme; but there are so many different things to plant. Dormant bulbs need to get into the ground before cool and rainy winter weather. Deciduous plants that should be planted while dormant prefer an early start if planted as soon as they defoliate in autumn. Believe it or not, most evergreen plants are no different.

Evergreen plants do not experience the degree of dormancy that defoliated deciduous plants do, but they too are significantly less active during autumn and winter than they are during warmer weather. Therefore, if possible, they should also be planted in autumn, so that they can begin to slowly disperse roots through winter, to be ready to resume growth as weather warms next spring.

All planting should be planned. This is more important for trees, big shrubbery and other plants that are difficult to relocate once they have dispersed their roots. Some broadleaf evergreens that get bigger than expected can be pruned into submission. However, most coniferous evergreens are notoriously difficult to contain if they get too big for the situations into which they get planted.

‘Coniferous’ plants are those that produce cones. Cypress, pine, fir, spruce, cedar and redwood are the more familiar coniferous trees. Most coniferous trees, except for most of the various cypress, have excurrent branch structure, with lateral limbs extending from a central trunk. They can not be pruned down without disfiguring their central trunks. Lateral limbs can be disfigured if pruned back. Such trees should therefore be planted where they can grow unobstructed to mature size.

Juniper and arborvitae are some of the more familiar of coniferous shrubbery. They can be shorn even into formal hedges, but only if shorn very regularly. Their dense foliage shades out interior foliage. If they get too big for the respective situations, they can not be pruned back into submission without exposing their bare interiors. Once exposed, bare interior stems may never recover.