The Official Houston Zoo Blog

One of many big oak trees at the Houston Zoo

In the my last entry, I wrote about our dense canopy.  Shade is another important means of keeping plants happy during extreme weather.  It not only keeps the air cooler by preventing the intense sun from getting through, but it also helps the soil retain more water.  If it isn’t as hot, will the water evaporate as quickly?  Unfortunately even big trees that provide the shade also require additional water.  Especially when the temperatures are high and a fair number of trees throughout Texas haven’t been hand watered or irrigated because they haven’t needed it until now.  When we experience temperatures near 100 degrees and haven’t had rain, there just isn’t available ground water.  Another drawback to assessing the water requirements of large trees is that by the time they are showing that they need water it can be too late. 

Most plants appear to appreciate shade of whatever type recently.  We have a number of plants that desire full sun, planted in a fair amount of shade.  With the frequency and the intensity of the sun here, most plants will meet their required light needs.   A negative of planting where the light requirements aren’t met is that plants will become “leggy”, stretching towards the sun with a decrease in the amount of foliage.  We haven’t had a big problem with this.  

 Those of us that have attempted vegetable gardens this summer have seen signs of what the heat and sun can do.  Even when the garden is prepared and planted exactly as it’s recommended, our yield is greatly reduced and normally not as appealing.  There are a few vegetables like squash, corn and okra that don’t miss a beat, but plants such as tomatoes and peppers tend not to even set fruit when the temperature is near 100 degrees.  A method that can be utilized is putting some type of shade structure above your plants, so they are protect during the heat of the day.  This could be as simple as tarp on some type of post such as bamboo, 2×2 lumber or anything that keeps the tarp high enough that it doesn’t actually touch the plants.  Tarps are usable, but there are quite a few, very affordable, shade cloth options, which are available at most home improvement stores or garden centers. 

 In summation, when temperatures are this high, plants need shade.  Providing some means of protection from intense sun and heat for your plants could be just enough help to keep them alive and thriving.  Look for my next post, where I discuss irrigation and hand watering.

Article written by: Joe Williams, Manager of Horticulture at the Houston Zoo