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10 Neat Things About Shade
by Shauna Dobbie
by Dorothy Dobbie

The Local Gardener magazines, Ontario Gardener, Manitoba Gardener and Alberta Gardener, are published by Pegasus Publications Inc.

Drawing on her 30 years' experience as a senior executive in the magazine publishing industry, Dorothy launched Manitoba Gardener in 1998, initially running the business out of her home. Two years later, Dorothy's daughter Shauna, living in Ontario, jumped into the fray with Ontario Gardener. And two years after that, they started Alberta Gardener. Visit us at and register for our "Ten Neat things" newsletter. Watch Shaw TV for garden tips and Listen to CJOB for the Gardener Sundays at 9:08

June 12, 2011

  1. Passive cooling. Remember back before air conditioning? In the summer, you closed the curtains during the day to keep the heat out and opened the windows at night to draw in the cooler air. That concept now has a fancy name: passive cooling. Gosh, and we thought it was just using your noggin.
  2. Trees. Plant shade trees to the south and west of your home, close enough to shade the house from the midday and afternoon sun. They'll drop their leaves in the fall so you'll still benefit from the light and limited warmth from the sun in winter. More "passive cooling" our grandparents called "common sense".
  3. Quality shade. It's cooler under a dense tree than under an awning or other shelter. The tree not only blocks the sun, absorbing the light for photosynthesis, it transpires, which creates a cooling effect.
  4. How much shade? The general rules for what constitutes full sun, part shade and shade are: full sun is six hours or more of direct sunlight per day; part shade is three to six hours; shade is less than three hours of direct sun per day. For an area with dappled shade, such as under an ash tree, think of it as part shade. Under a shadier tree, like a maple, it's probably shade, and under an airier tree, like a ginkgo, you may have pretty near full sun.
  5. Shade tolerance. Some plants that prefer sun will tolerate shade, performing adequately though with less growth and fewer blooms. These include iris, daylily and nicotiana. You might even get away with peonies in a spot that is marginally part shade.
  6. Small trees. Many trees that are naturally of rather short stature prefer some shade, including pagoda dogwoods and hydrangeas, because they developed as mid-storey trees in nature - trees that grow under the forest canopy.
  7. Shade plant adaptations 1. All plants (a mushroom is a fungus) need light to photosynthesis - to produce their energy for growth and reproduction. To survive in the under storey of a forest, where the big trees absorb most of the light, shade plants need to be extremely efficient at grabbing and using the limited light available. One method is to grow thinner, wider leaves, maximizing surface area. Those leaves tend to be arranged horizontally, as with Solomon's seal, rather than vertically, as with the sun-loving ornamental grasses.
  8. Shade plant adaptations 2. Some plants take advantage of the period before big trees leaf out. That's why so many shade plants bloom in the spring. After blooming, some shade plants will kind of just hang out for the rest of the season while others, like bleeding hearts and tulips, will die down until the following spring.
  9. Shade plant adaptations 3. Many shade plants have foliage of a deeper colour than sun lovers, enabling them to absorb as much light as possible rather than reflecting it back. The lighter yellow and silver foliage is generally reserved for plants that reside in the sun. Variegation, when naturally produced, is suspected to be an adaptation of shade plants to camouflage themselves from insect predators since shade plants need to use their limited energy for growth and reproduction rather than regeneration and healing.
  10. How much cooler in the shade? If there is an equation to determine how much cooler it is in the shade than in the sun, there are more variables to it than anyone has figured out so far. (To me, it's hard to imagine that they can't come up with something based on ambient temperature, angle of the sun, wind speed and so forth. What do these scientists do all day?) Suffice it to say that, on a hot summer day, you're better off under a tree with a tall cold lemonade, in your favourite lawn chair, reading your favourite magazine.

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