The Mountain Gardener: Cool your garden with a tropical makeover
by Jan Nelson
Jun 17, 2010 | 2112 views | 0 0 comments | 11 11 recommendations | email to a friend | print
Eye candy: Make a dramatic statement in your garden with tall canna lilies. Courtesy of
Eye candy: Make a dramatic statement in your garden with tall canna lilies. Courtesy of
eye candy: Broad-leaved Sum and Substance hosta, below can make a nice addition to the garden.
eye candy: Broad-leaved Sum and Substance hosta, below can make a nice addition to the garden.
Summer weather is finally here, and I find myself thinking of ways to stay cool. We know there is a cooling effect under the canopy of our forest trees. Extremes in air and soil temperatures are lessened. But any combination of perennials, shrubs and trees will help keep your garden cool, while also providing habitat for wildlife, decreasing energy use, absorbing carbon dioxide and supplying fresh oxygen.

Why not add some plants that have a tropical feel to make your garden feel and look soothing on a hot summer day?

Bold, large-scale plants with dramatic foliage evoke the jungle. Mixing the familiar with the exotic creates dramatic compositions. Hardy tropical gardens are based on rhythmic repetitions of plant form and foliage patterns, rather than on flowers. Flowers do play their part, but it is the flow and interplay of shapes and textures that form the design and create ongoing visual interest.

Start by adding a tree that is big and bold, like purple catalpa. Catalpas are among the few hardy deciduous trees that can compete in flower and leaf with subtropical species. Huge leaves, 10 to 12 inches long, emerge with a deep, blackish purple hue in spring, then turn purplish green in summer. At this time of year, the tree is covered with large clusters of white trumpet-shaped flowers lightly speckled with yellow or purple. At 30 to 40 feet tall, this beautiful tree is well adapted to extremes of heat and cold, as well as different soils.

You’re probably not going to be ripping out your old garden and starting anew, but you can revise your plant palette to include hardy tropicals. Even if your garden is small, using just a few outsize, textured plants can give a neutral, small space an immediate sense of intimacy. Emphatic foliage plants, such as Japanese aralia, philodendron selloum, black bamboo, red banana, windmill palm and canna lily, would make a dramatic statement in any garden. Canna Australia is especially showy. This burgundy-leaved cultivar is often grown for its foliage alone, though it bears spectacular orange-red flowers in summer. Plant it in full sun or part shade in average soil, and supply regular water during growth and bloom.

Sculptural plants instantly transport us to the wild. Richly colored foliage and bold shapes add a lush feeling to the understory of your tropical garden. Here’s where the chartreuse leaves of the Sum and Substance hosta really stand out. This 3-foot-high by 6-foot-wide variety can handle some sun. Pale lavender flower spikes are an added bonus. Combine it with the striking, creamy yellow variegated abutilon Thompsonii. It blooms almost continually, with pale orange bells veined with red. The hummingbirds will love you.

Underneath it all, plant some showy groundcovers, like black mondo grass, lysimachia Goldilocks, lamium Pink Pewter or Burgundy Glow ajuga.

Whatever you choose, see your garden anew and enjoy the summer in a cooler topical garden.

Jan Nelson, a California certified nursery professional at Plant Works in Ben Lomond, will answer questions about gardening in the Santa Cruz Mountains. E-mail her at
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