Pittosporum tobira

90925A surplus of common names seems to be a common theme for many plants that we thought we knew the names of. The simple Pittosporum tobira, which might be known here by its Latin name, might instead be known as mock orange, Australian laurel, Japanese pittosporum, and Japanese cheesewood. Its native range is about as diverse, including Greece, Japan, Korea and China.

Back in the 1990s, the compact cultivar known as ‘Wheeler’s Dwarf’ was common enough to be as cliché as tam junipers were in the 1950s. There are actually a few other dwarf and variegated cultivars that do not share that reputation. Most are low, dense and mounding. ‘Variegata’, although not a compact dwarf, grows slower and stays smaller than the unvariegated straight species.

Otherwise, Pittosporum tobira gets about ten feet tall and wide. It can eventually get significantly taller, especially if lower growth is pruned away to expose the sculptural trunks within. If shorn as a hedge, it should not be shorn so frequently that the dense foliage is always tattered. Leaves are delightfully glossy and convex. Small trusses of modest pale white flowers are sometimes fragrant.

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Waxleaf Privet

90918Here on the West Coast, privets had traditionally functioned like hollies had in the East. They are conducive to shearing into the big formal hedges that were popular during the Victorian period. Since then, as gardening space became more limited, the common glossy privet became less popular than the more compact and complaisant waxleaf privet, Ligustrum japonicum ‘Texanum’.

Since it does not get much higher than ten feet, and typically stays less than eight feet tall, waxleaf privet is proportionate to urban gardening. As a formal hedge, it can be shorn to stay less than two feet from front to back, although taller hedges look better if allowed to get bulkier. As an unshorn informal screen, it should not get much broader than six feet, with an appealingly billowy form.

Foliage is evergreen and remarkably glossy, sort of like that of holly, but without the prickles. Regularly shorn hedges should not bloom, but might produce a few trusses of tiny white flowers inside of the shorn surfaces. In sunny situations, unshorn glossy privet blooms profusely enough to be mildly fragrant in spring. Bloom sometimes produces floppy clusters of tiny but messy black berries.

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.

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.

A Hedge Between Keeps Friendship Green

70517thumbIf good fences make good neighbors, what about hedges? If only it were that simple. There are all sorts of evergreen hedges to provide privacy, obstruct unwanted views, disperse wind, define spaces, or muffle noise. They can do much of what fences do, and muffle sound better. The problem is that they are composed of living plants, shorn into submission and very unnatural shapes.

Unlike fences, hedges need to be shorn very regularly. Otherwise, the shrubbery that they are composed of tries to grow into its natural forms. Slow growing plants like Japanese boxwood may only need to be shorn twice annually, especially if no one minds if it looks somewhat shaggy. Old fashioned glossy privet is so vigorous that it likely needs to be shorn a few times before autumn.

Even if the work of shearing is not a problem, accessibility might be. Hedges are popularly planted between properties. The outsides of such hedges are therefore accessible only from adjacent properties, which might have other plants or landscape features in the way. There is also the risk that the neighbors might not want anyone coming over to shear such a hedge! Beware of the dog!

Hedges in conjunction with backyard fences are easier to maintain as long as they are kept below or at the same height as their fences. They only need shearing on the inside and on top. Fences might be needed to keep dogs in or out anyway. When planning for a new hedge, other plants and garden features that might obstruct access within the same landscape must be considered too.

Taller hedges should be shorn so that they are slightly narrower on top, and wider at the bottom. This promotes more uniform growth, and hopefully prevents basal baldness. Upper growth gets more sunlight than lower growth, so grows faster, and too often shades out lower growth while becoming distended up high. Hedges should also be watered and fertilized evenly from end to end.

It is important to remember that hedges work for the landscape, and should not be allowed to dominate. Fat hedges waste space. A well groomed hedge that is only two feet from front to back works just as well as a hedge that is three times as plump. Feral plants that ‘volunteer’ within a hedge must be removed instead of shorn along with the hedge. They only compromise uniformity.