Beating summer's heat in the garden
 
By Urban Harvest

Although we have had a relatively mild spring, with our latest over 90 degree days and high humidity, it feels like summer is upon us. Many Houstonians believe the only way to flee the soaring mercury is to take shelter inside an air-conditioned structure.

For gardeners and those who need to be connected to the environment, this is a perfect setup for a bout with summertime “cabin fever.” Though our temperate climate provides pleasurable temperatures for most of the year, the summer months offer a challenge to how we enjoy our gardens and outdoor rooms.

To benefit from year round use of your garden space, incorporate elements that make it more user friendly. Here are a few ideas you might try.

Add Shade

Of course this is only common sense. If you want to stay away from the sun's heat block its rays. This can be done in two ways, planting trees or building a structure.

Trees not only provide a shady retreat in the garden, but if properly sited to screen your residence from the south and western sun angles, they also significantly reduce the utility costs for cooling it. Large, deciduous (so they can allow sun in winter) canopy trees are the best candidates for shading both garden and home.

Canopy trees tend to be slower growing trees, but there are three that outpace most others Mexican Sycamore (Platanus mexicana), Bald Cypress (Taxodium distichum) and Lacebark Elm (Ulmus parvifolia). Start with a 30-gallon tree and in two to three years, it will cast a fair amount of soothing shade.

Understory trees or large shrubs trained as trees are quicker to reach mature height and still supply considerable amounts of shade as they usually grow 15 to 25 feet tall. Sweet Bay Magnolia (Magnolia virginiana) and Chinese Fringe Tree (Chionanthus retusus) are spring flowering understory trees that work well in small urban gardens.

Training a large shrub into a small tree requires pruning to develop a trunk and branching system, but it is probably the fastest way of getting shade in the garden, especially if you start off with a 15 gallon plant. Typically we see Wax Ligustrum and Crape Myrtle as tree formed specimens, but Vitex (Vitex agnus-castus) or Almond Verbena (Aloysia virgata) are summer flowering shrubs that would be a welcome addition to any garden.

If you want to limit shade to the garden so that plantings such as prize winning roses or the prolific vegetable patch receive the sun they need, a shade structure may be an option. They can be simple or elaborate, depending upon your purpose and your budget.

A structure with a solid roof allows the installation of ceiling fans that not only create a cooling breeze, but also deter mosquitoes, which like calm conditions. Enclosing the structure with screening ensures a bug-free zone for garden enjoyment.

The structure can also be as simple as a few posts and beams that support utility panels (a farm fencing material). Any number of vines can be trained up the posts and over the panels to provide sanctuary from the summer sun.

Add Water

While adding water to the garden in our humid climate does not typically have the same physical cooling properties that it does in more arid climates, using water in the garden has a psychological cooling effect in our gardens.

The sound a water feature provides has a soothing quality. Water features range from gurgling bird baths to thundering fountains. Like any built element, they too can be simple or elaborate, depending upon your purpose and your budget.

Two ways water actually has physical cooling properties in Gulf Coast gardens are swimming pools and outdoor showers. While swimming pools may not be practical for most, it does not get any easier than an outdoor shower that hooks up to the garden hose. Many can be found online or through mail order catalogs.

Wait Until Dark

Average daytime temperatures for the summer months range from 91 to 94 degrees fahreinheit, but once the sun goes down, things begin to cool off nicely, with temperatures averaging 72 to 74 degrees. Equip your garden with elements that add nighttime interest.

Consider adding the outdoor lighting missing from the garden. Lighting allows usage of the garden after sunset, when summer temperatures are not only tolerable, but often pleasant. Moonlighting that is placed high in tree branches produces a soft wash over a large area and is best installed by lighting professionals.

However, low-voltage lighting can produce dramatic effects and is easily installed by a homeowner. Simply plug in the transformer, connect the electrical cable and snap the light fixtures onto the cable where desired. If the cable lies in a planting bed, simply cover it with mulch no need to dig. A variety of systems are available on line or at your local hardware store.

Finally, add plants to the garden that have an evening interest. Look for a place to plant some Four O'clocks (Mirabilis jalapa), Moonvine (Ipomoea alba) or Nightblooming Jasmine (Cestrum nocturnum). Their late afternoon/evening fragrance provides another reason to spend more hours in the garden after dark.

Any plant flowering white will shine in the garden at night and there are a number of annuals, perennials and shrubs that would make excellent choices. Plants with a crisp white variegation to the leaf, such as Variegated Pinecone Ginger (Zingiber zerumbet "darecyi") or Variegated Hydrangea (Hydrangea macrophylla "variegate") also add a sparkle to the evening garden.

This column is produced by Urban Harvest. Learn about gardening classes, community gardens and orchards, farmers' markets and more at www.urbanharvest.org. This article was written by Suzy Fischer, who is a co-founder of Urban Harvest and a registered Landscape Architect and principal of Fischer Schalles, a landscape design/build firm. Contact her at suzyinthegarden@urbanharvest.org.