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Dusty miller is a popular perennial among garden enthusiasts, who often grow it for its soft, gray-green, lobed leaves. It is lesser known for its petite yellow flower clusters.
Photograph by Shari Kaplan
Hedges are the victims of improper shearing
By Tony Tomeo
I have always liked formality in landscapes, which is why I am so very rarely asked to design anything. I particularly like the way formal features may be used to enhance the appearance of informal specimens.
One of the most basic, utilitarian formal features of a landscape is a sheared hedge. Unfortunately, shearing is likely the most commonly abused gardening technique. This is most obvious in landscapes and gardens maintained by unqualified maintenance gardeners--commonly referred to as "mow, blow and go" gardeners or "hackers."
Hedges sheared with vertical sides generally produce more growth near the top and less near the soil level. This occurs because foliage near the top is exposed to more direct sunlight, whereas the lower foliage may be shaded for part of the day. Hedges that extend from east to west will be more evenly foliated on the south side, but may be sparse on the north side with almost all new growth on that side occurring at the top.
Very often, shearing does not compensate for the superfluous growth near the top, so, after shearing, the top is still wider than the bottom. This structure only enhances the problem of the lower foliage being shaded. Consequently, the top grows even wider past the bottom and is likely to be sheared the same way later. If this continues, the top extends slightly past the bottom with each additional shearing.
Hedges that face directly south may "creep" toward the south, even if sheared very evenly. If the south side is permitted to extend even a slight amount with each shearing, it will eventually reach beyond practical boundaries.
The north side, however, will be shaded by the dense superfluous growth on the south side and produce only minimal growth. Conversely to the south side, the north side may lose volume with each shearing. Eventually, the hedge will be closer to the south than when it was initially installed, often with exposed trunks on the north side.
The most effective structure for a formally sheared hedge is with the top slightly narrower than the bottom. Not only does this allow increased sun exposure to lower foliage, but compensates for increased growth higher up.*
Although the height of a hedge may be maintained with each shearing, some garden enthusiasts prefer to allow the height to fluctuate slightly to simplify shearing. Late winter or early spring shearing may be the most severe of the year and extend to where the hedge was sheared at the same time during the previous year.
Later shearing may allow a slight increase in height, so that the top of the hedge remains well foliated. An eventual severe shearing to the original height, during the following winter or spring, may be unsightly for a while, but will start the procedure from the beginning.
*Because of 'negative geotropism', plants prefer to grow against gravity. Consequently, even with very even sun exposure, growth is usually more active higher on formally sheared hedges.
Perennial of the Week: Dusty miller
Senecio cineraria is probably the most popular of the several perennial species known as dusty miller. Some garden enthusiasts enjoy the small clusters of yellow flowers that appear during warm weather. Most gardeners, however, grow it for the fuzzy, gray-green foliage, which grows more densely if the flower stems are pruned out before they bloom completely.
Individual leaves are pinnately lobed and only a few inches long. If permitted to bloom, plants should be sheared occasionally to maintain foliar density. Full sun exposure is preferred.
Mature plants may be as large as 2 feet tall and wide. New plants are easy to propagate from semi-hardwood cuttings, but even easier from division of basal stems from mature plants which have already rooted. Dusty miller is striking with brightly colored flowers or alone, particularly in evening light.
Horticulturist Tony Tomeo may be contacted at 408.358.2574, or at lghorticulture@aol.com.
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Sunnyvale, California Since 1994
