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Gardening in Difficult Places: A Tale of Two Median Islands

  • Julie Monson
  • by Julie Monson

    This column is dedicated to Claudia Alta (Lady Bird) Johnson, first lady and life-long champion of landscaped public spaces, from fields of Blue Bonnets in Texas to dogwoods in Washington, D.C. She died July 11, 2007.
    Median islands are those awkward spaces in a road that if ignored, look scruffy, and if nicely landscaped, look lovely, and give pleasure to all who drive by. I’ve admired several of Marin County’s colorful median strips, those middle-of-the-road urban embellishments that brighten a trip. One of my favorites, in the middle of Sir Francis Drake Blvd. in Greenbrae, provides a succession of handsome flowering shrubbery and perennials. Another favorite is in the access road into Corte Madera shopping mall, with less shrubbery but exuberant and colorful perennials and annuals. For the most part, these spaces are installed and maintained by public agencies. Sometimes, however, we (the home gardeners) have our own median island or parking strip, and face the difficult technical, horticultural and cultural challenges these spaces offer. I’ll describe here two very different median islands, one public and one private. Each has lessons that could be applied to these street-side spaces anywhere.
    I’ll begin with a median strip down the middle of Sir Francis Drake Blvd. in the tiny village of Inverness, a project I became involved with two years ago when the Inverness Garden Club was asked by the Inverness Association to design the landscaping for this median. The median, five feet wide and 80 feet long, had two main purposes: to encourage traffic to slow down and to beautify this block-long historic “downtown.” That experience taught me that landscaping a median island (or a parking strip, or any narrow space adjacent to foot and vehicular traffic) is more complicated than just selecting the plant material. On a public street, the curb has to meet county standards, and should be installed by experts. Automatic irrigation (a must for low maintenance) requires water and power lines beneath the street’s pavement and a safe place for the system’s controls. The layout of industrial strength sprinklers or bubblers is complicated because of the narrowness of median islands and the need to keep water from spraying the street. After determining these “hardscape” design elements, we were able to focus on what shows the most: the plants.
    Our plant choices were driven by criteria applicable to most “street” landscaping. Plants had to be hardy, low maintenance, drought and deer resistant, able to thrive in our coastal climate in full sun, to survive a rare frost and be attractive most of the year. We also had a 30” height limit and a directive against invasive roots, both mandated by Marin County’s Department of Public Works. The success of the venture was dependent on having the basics of curb, soil and irrigation done professionally. Then, after lengthy consideration, a committee of the Inverness Garden Club carefully selected 3 perennials and 3 grasses for the median strip. Planted by volunteers in the spring of 2006, this “garden” is now in its second summer and is stunning. (See photo).
    The three perennials were 1) Armeria alliacea (sea thrift), 2) Nandina domestica ‘Gulf Stream’ (heavenly bamboo), and 3) Lavandula intermedia ‘Grosso’ (lavender). The three ornamental grasses were 1) Helictotrichon sempervirens (blue oat grass), 2) Imperata cylindrical ‘Red Baron’ (Japanese blood grass), and Pennisetum orientale (fountain grass). We followed a simple planting scheme of placing three of the same plants in a triangular formation about 12 to 18 inches apart and repeating the pattern of 3s along both sides of the strip. These groups of the same plant material emphasize the character of each plant and make a stronger, more cohesive statement than if they have been planted in a random or purely alternating pattern. The sea thrift has bloomed almost continuously for the past year and a half, and the lavender is blooming profusely this summer. The lavender and fountain grass move gracefully with passing cars and local breezes. A stunning spot of bright red is provided during summer by the Japanese blood grass. All these plants are thriving in this sunny, busy spot, and while this narrow “garden” indeed beautifies this small commercial area, it is also slowing cars down.
    A very different median island, a slopping triangular space about 10 feet on a side, sits in the middle of our driveway in dappled shade. Ours is not a formal garden, and that part of it is mostly native shrubbery under bays and oaks. This island is out of range of our irrigation system, so the choice of plant material had to take into account not only shade, but limited water and poor soil, the result of grading the driveway. The solution: a “grove” of three Arbutus menziesii (madrone), under planted with Digitalis (fox glove) and Dicentra (bleeding heart) transplanted from the rest of the garden. The madrones, which we protected with deer fence for two years, grew very slowly for about four years, and then took off and have now created an irregular, glossy green, 25-foot canopy over our “island.” I particularly admire the reddish bark of the trunks and lower branches against the shady green of this area. Maintenance here is limited to monthly deep watering in the summer (a hose with sprinkler) and an annual layer of mulch. What had once been a weed-filled eyesore now provides a welcome vista to us and our visitors.
    Spaces like median islands and parking strips are the public face of our residential and commercial communities. Often, they serve a different purpose than the domestic gardens that enhance our homes and provide outdoor recreational and private space. Parking strips contend with foot and nearby vehicular traffic. They are visible to everyone passing by and if awkwardly planted or neglected, these spaces become not only eyesores but missed opportunities. If carefully planned (curb, soil, irrigation) and planted, they beautify their surroundings and bring pleasure to you, the gardener, and to all who pass by.