Why Did My Landscape Plants Die?
Guest Article for the Tallahassee Democrat
January 22, 2021, Release for the Tallahassee Democrat
It can be discouraging when a new plant placed in the garden doesn’t grow well. There can be many reasons for this, but there is a popular saying among horticulturists: “right plant, right place.” This means matching up the plant’s genetic requirements with the site conditions and constraints the plant needs to survive, and hopefully, thrive!
Matching up the plant requirements and the site conditions begins in the nursery. The label conveniently placed on many plants in the nursery gives clues as to where a plant will perform best. The label will show the proper lighting conditions, such as full sun, partial sun, shade, etc. What are the present lighting conditions at the site (shade, partial shade, or full sun)? Existing large trees and structures need to be evaluated for their shadow patterns throughout the day and for the various seasonal changes. Planting understory trees in too much sun can result in stress, sun scald, and even death. For grass to grow well, it requires at least five or more hours of sunlight, depending on the species.
The label will also indicate how much water the established plant will require. Remember that plants require more water during establishment than they will once they are stable fixtures in your landscape. Established plants can survive under typical environmental conditions, the exception being during periods of extreme drought. Soil requirements, including pH and drainage, typically are indicated on the label. Ask yourself: what is the soil quality? Has the topsoil been removed? Was the soil compacted by construction activities? Is the location dry or wet? Are you using reclaimed water? A common and useful practice to aid in water conservation is mulching. Mulch provides a buffer zone around plants, helping to avoid damage by mowers and other maintenance equipment. However, be careful not to have mulch in contact with the trunk of the plant. This can lead to increased disease and pest problems.
A very important factor when selecting the right plant for the right place is the mature size of the plant. Container plants typically are young, small plants and need room to grow vertically and horizontally. Is there adequate space for root development? This is especially important for trees to grow adequate structural support. While most root zones are less than two feet deep, with about 80 percent of the roots in the top foot of the soil, some roots may grow out as far as three times the mature height of the tree. Is there room to accommodate the mature canopy for large shrubs and trees? Trees and shrubs are often planted too close to structures or other plants when juvenile because many people are unfamiliar with the growth potential of the mature shrub or tree. Live oaks, for example, may reach 60 feet in height and over 100 feet in canopy spread. Sabal palms can easily exceed 50 feet in height. Some species of pine trees can grow to over 100 feet in height with a canopy spread of up to 50 feet or more.
It is important to make sure that the plants selected are of good quality and condition. Note, does the plant appear healthy? Does the plant have leaves of the proper color? Typically, healthy plants have foliage of an even green coloration, but, as horticulturists, we sometimes choose the plants that are different. Variegated foliage – having two or more colors or having atypical coloration – may be desirable and be normal for the species or cultivar that you have chosen. Consider obvious flaws when selecting a plant. Don’t use the attitude that you can “nurse the plant back to health.” Avoid plants with obvious problems like damaged limbs or trunk injury. Note any obvious signs of insects or disease and avoid these plants.
Look carefully at the structure of the plant above, as well as below, the soil line. Ask yourself if the plant has branching structure proper for the species. Are the branches symmetrically arranged around the trunk and somewhat evenly spaced top to bottom? Trees should have one main trunk, and most shrubs should have multiple trunks. Improper structure can lead to serious structural problems as the plant matures.
You need to examine the roots as well. A plant that has remained in a particular container for too long will often have roots circling the outside of the root ball. In severe cases especially, these roots can make it hard for the plant to grow a normal supporting root zone around the plant, radiating out in all directions. If this happens, the plant, especially trees, will likely be damaged in heavy storm winds due to inadequate root zone development.
Another common situation leading to plant failure is planting too deep. A plant planted deeper than it has been growing in the container has a decreased chance of growing a new root system able to sustain the developing plant. Another common situation is the improper application of weed control chemicals. Gardeners often rely on herbicides to control unwanted weeds in the landscape. The roots of your trees and shrubs extend out under the turfgrass and may be targeted by the herbicide application.
For more information on these and other plant growing requirements, please contact your local county extension office or look up relevant publications on the UF/IFAS Extension EDIS website (www.edis.ifas.ufl.edu).
Sam Hand, Jr. is an ISA Certified Arborist and an Associate Professor of Extension at Florida A&M University and Edwin R. Duke is an Associate Professor of Horticulture in the College of Agriculture & Food Sciences at Florida A&M University. They are both volunteer writers for UF/IFAS Extension Leon County, an Equal Opportunity Institution. For gardening questions, email the extension office at AskAMasterGardener@ifas.ufl.edu.