Flood Tolerance of Tropical Fruit Trees

Southwest Florida's landscape is of the "flatwoods" type. The lack of any sloping in the land means that water does not have anywhere to run off too during the summer rains, bringing the water table up and often above the soil surface. Tree roots require not only water and minerals, but also air- the roots need to "breathe" just as much as the leaves do. This causes root growth becomes very restricted - for example, 99% of a mature citrus tree's roots are in the top two feet of soil in flatwood landscapes.

The high summer water table can kill trees if they are not flood tolerant. If you live an area that is prone to flooding during our rainy season, you may find the following chart helpful in choosing a tree for your yard. However, don't feel too restricted by this; with a little extra work you can also protect your trees from high water by planting on "turtle backs".

The principle involved is simple: build a mound upon which to plant. This will raise the roots of the tree out of the high summer water table.. One important key in building a turtle back is that the mound should not be constructed using organic matter (for example mulch or compostable material) as the primary component. The organic matter would quickly break down in our climate, and would subsequently lower the mound - possibly enough to bring the trees roots into the water table and drowning the tree.

For us, the primary material in South Florida is sand, and this is what we construct our turtle backs out of. If you would like to see an example of planting on a turtle back, please visit ECHO's Tropical Fruit Tree Arboretum. One caution is that you should avoid making the mound too high - then you run into the same types of problems that you might have growing a tree in a container (the tree becomes "root-bound" and the mound will not hold moisture very well, necessitating more frequent watering).

Table 11: Flood Tolerance of Tropical Fruit Trees.  Information from Florida Fruit by Lewis Maxwell and Rare and Exotic Tropical Fruit Trees and Palms, by Carl W. Campbell and Seymour Goldweber, published by the Caloosa Rare Fruit Exchange; and our own observations and experience.

*Please note that the citrus trees that we sell in our nursery are grafted onto flood tolerant rootstock. In fact, there are many properties of citrus trees that are rootstock-dependent. The rootstocks on the trees that we sell are Volkemer (for lemons and limes) and Swingle (for everything else). These rootstocks are particularly well-suited to the soils and conditions in SW Florida, so people residing on the east coast of Florida should purchase citrus from nurseries on that coast. As an example, Swingle rootstock does poorly on alkaline soil, common to the limestone soils on the east coast.