Simple shade structure can help save plants

By Angela O'Callaghan

Thursday, May 28, 2009 | 11:08 a.m.

No one can miss the start of summer here in the Mojave. Starting with cool clear mornings, by the end of an afternoon, days can easily have become 30 or 40 degrees warmer. The cool evenings and mornings are a salvation to many landscape and garden plants, including vegetables, all of which suffer when it temperatures are more than about 85 degrees. From the end of May through the end of August, gardeners confront serious challenges trying to keep their plants thriving despite the cruel heat.

It is more than the extreme warmth that causes such problems for gardeners and their charges. The air in the desert is dry, which pulls water out of leaves. This obviously is a strain for them. As if that were not enough, sunlight in this region is far more intense than many other places, so much so that unless plants are acclimated, they will experience sunscald. The larger and thinner the leaves, the more susceptible they are to getting fried, especially when they are exposed to the afternoon sun.

Gardeners can adjust their irrigation systems to compensate for the lack of precipitation, but short of installing air conditioning (not an option outdoors), how can they help plants with the problems of heat and light? For some garden areas, especially vegetable gardens, there are a few steps that can prevent some of the worst damage our summer does to vegetable plants.

What do we do when we want to escape the sun? We go into a shady spot, first of all. Placing gardens so that most of the light comes from the east and southeast is ideal, but not always practical; one puts it where there is space and once the garden is installed it is not going to be moved. This begs the question, what to do for plants to ameliorate the effects of the summer's extremes?

We can provide shade for growing plants. Tomatoes often become sun bleached, turning a pale whitish green, in extreme light, especially when that light is accompanied by temperatures in the 100s. A little shade can protect them, thus extending the growing season.

Shade cloth can come in a number of colors, from beige or green to black. Each of them blocks a certain amount of light. A temporary shade structure does not need to be elaborate. It is possible to build large kite type affairs that look like diagonal sails over the garden, but for small plots, this might be overkill. In my very little garden, I have learned that upright rebar between three and four feet apart can make a reasonable support for shade cloth that I secure with plastic anchors. The result is a small area where the sun is diminished. It is cooler than its surroundings, but bright enough to maintain plant growth and production. Existing fruits – peppers, okra and tomatoes – ripen perfectly well. Removing the shade cloth is easy at the end of the season.

A structure like this may not be enough to keep a plant growing successfully throughout the worst of the summer, but adding a little shade can help it through at least part of it.

Angela O’Callaghan is the area specialist in social horticulture for the University of Nevada Cooperative Extension. She can be reached c/o the Home News, 2275 Corporate Circle, Third Floor, Henderson, NV 89074, or [email protected].