Shade - The New Four Letter Word

We bought our first house in Tampa, in part, because of the stately oak trees that populated the yard. It was not until a year later that I noticed that most of the flowers I had planted had withered. I then switched to shade loving plants, but many of those barely survived. Limited by the number of plants that were colorful and yet could thrive in shade, I was forced to fall back on the staple of most Central Florida gardeners, impatiens. But even these plants shriveled up and died after a few months. I fought back every way I knew how, but with no success.

Finally, I realized that it was not the heavy shade that was responsible for the problem, it was the Oak trees, specifically their root systems. Previous to moving to Florida, we had lived in California. The Live Oaks in California have a complex root system that combines deep feeder roots that tap the water table along with a shallow root system. I just assumed that the oak trees in Florida would have a similar deep root system coupled with noninvasive shallow roots. It was not until I saw my first Florida Live Oak tree toppled by a tropical storm that I realized that all of the roots, even on 40 to 50 foot giants, were no more than four or five feet under the ground. In addition, those roots were highly aggressive and concentrated.

If that were not enough, with each year the tops of the Oak trees were responding in the same manner as the roots by spreading across the sky and choking out all the light. To the right is a picture of our first house in Tampa. Notice the small sliver of grass in the lower left of the picture? The rest of the property is covered with trees. This type of thick canopy creates other problems. You have to select shade tolerant St. Augustine grasses, such as Bitterblue or Palmetto. But even those grasses have problems when they compete directly with the oak tree root systems. You can compensate by spreading mulch outward from the tree trunks, but if your trees are big enough and numerous enough, you wind up virtually mulching the whole yard. The other challenge is fungus or Brown Patch that loves the cool, moist, stagnant air under oak trees.

It was then that I realized my problem - I would prepare a bed of Impatiens under an oak tree with new soil, fertilizer and loving care. For a few months the impatiens would explode with red, white and pastel colors. However, in time patches would begin the shrivel and then the whole bed would seem to wither. It took awhile to figure out that the oak roots had invaded the bed and were sucking all of the water and nutrients out of the soil. The impatiens could not compete.

Most people love Oak trees. But there is such a thing as too much of a good thing - and I have had my fill of Oaks.

Advice - shade is not a bad thing. It's the source of the shade that can cause problems.

Having spent this entire page whining about oak trees, I should note that there is at least one significant benefit to a heavy oak canopy - it provides significant insulation during frosts