Common Problems to Avoid When Purchasing Trees from a Nursery
When you take the tree out of its container, you should not see circling roots on the outer edge of the rootball. Circling roots continue to grow in a circle even after the tree has been planted into the landscape.
Has the tree been in its container too long?
A very common problem with nursery stock is circling and girdling roots caused by trees having been left in the container too long. Roots grow outward until they reach the side of the container and then start circling along the wall of the container.
When a containerized plant with circling roots is planted in the landscape, the roots continue to circle. In the landscape roots must grow straight out from the base of the trunk in order to support the tree from tipping over in a strong wind. Circling roots may not grow outward and the tree can be prone to tipping over soon after transplanting or even years later as the tree increases in size.
Inspect the roots when purchasing a tree
Always inspect tree roots growing in a container by pulling a tree out of the container and checking the roots to see if they are circling. There may be some small diameter circling roots at the outer edge of the root ball. If these circling roots are small, less than 1/8-inch in diameter, they are not much of a problem. Small diameter circling roots can sometimes be corrected by slicing the outer edge of the root ball vertically in several places. But this type of root pruning treatment is not always successful. If there are many circling roots, it is best not buy that plant. See the next paragraph for the latest techniques on dealing with larger circling roots.
If you already have a tree with circling roots...
When you find you have alrady purchased a containerized tree with circling roots, take action to correct the problem. Working in a shady area or late in the afternoon when the sun will not dry out the roots, wash off the rootball to expose the circling roots that are on the outside of the rootball. Then take a sharp handsaw and cut the circling root back inside the rootball where the root is still growing straight outward. If you cut the circling root where it is growing along the outer edge of the rootball, the root will continue to grow in a circle. You must cut the root back inside the rootball where the root is still growing straight. Remove the circling root pieces. Plant the tree with the rootball that is now smaller.
To correct circling roots, wash off some of the soil to better expose the circling roots. The water will also keep the roots from drying. Work in a shady area not in the direct sun.
The circling root should be cut with a sharp saw an inch or two back from the edge of the rootball where the offending root is still growing straight out toward the container wall.
Here are pieces of removed circling roots from a single defective rootball.
This rootball has been fixed by removing the circling roots around the outer edge of the rootball. Many roots have been cut so it is very important that this transplant be irrigated daily at first and then less frequently as weeks pass according to the season, soil type and climate. In spite of the heavy root pruning in June in Florida, this tree did not drop a leaf because it was irrigated dailly through the summer.
Proper irrigation is critical for success
Removing circling roots will cause some additional stress for the transplant. Therefore the transplant will require regular irrigation right on the rootball daily at first and then less frequently as the tree becomes established. The establishment time depends on the size of the tree. A 4-inch caliper tree can take from six to nine months to become established. A 2-inch caliper tree can take three to six months. Soil type, season and climate will also affect how much and how often you should irrigate. And finally you should irrigate with a hose or dripper (bubbler) so the water is applied directly to the rootball. Sprinklers are for lawns and often do not put the water where it is needed most -- on the rootball.
Strangulation by circling roots
Circling roots remain circling roots even after planting in the landscape. Circling roots are caused by plants being kept in a container too long.
Another problem with circling roots is the roots girdle or strangle each other as they continue to grow in a tight circle causing retarded development. In the worst cases of circling roots, stem girdling roots form. Stem girdling roots are roots, which grow up and over the root flare and base of the trunk. These crossing roots will cut off the conductive tissue below the bark causing part of the tree to decline and branches to die. The carbohydrates produced in the foliage cannot be moved into the roots and the affected roots can die. Because the stem girdling roots block conductive tissue, water and nutrients absorbed by the fine roots cannot move into the upper part of the tree. Branches in the crown can starve and die.
Stem Girdling Roots
In the worst case a girdling root grows over the top of a root flare cutting off circulation in the conductive tissue. Notice the deep grove where the small girdling root (held in the gloved hand) was removed from the larger buttress root.
Stem girdling roots do not usually cause symptoms early in a transplanted tree’s life although sometimes growth is retarded. The girdling damage more commonly becomes apparent as severe retarded growth, branch death or general decline after five or 10 years when the tree starts to mature.
Too much soil over the root flare
Too much soil over the top of the roots in a container is a frequent problem with nursery stock. The tree root flare (the wide area at the base of the trunk) should always be visible and not covered with soil. To be sure too much soil is not placed over the top of the root ball, most researchers suggest that the topmost root of a transplant be visible at the top of the soil. If the topmost root is not visible, then soil in the container should be removed and the topmost root should be uncovered and left that way. If soil is placed over the root flare while the tree is in a container, small roots will begin to grow upward toward the soil surface. These small roots grow up not outward and can become stem girdling roots.
Planting too deep
Too many tree installers plant the trees too deep. The root flare should be place slightly above grade, which can be 10 percent or about 2 inches above the natural soil grade. If you cannot see the topmost first root, then there is too much soil over the root flare. Remove the excess soil and the small roots that are growing in this soil. Then plant the tree so the topmost root is visible slightly above grade.
This is a beginning stem girdling root that will, over time, begin to strangle the trunk. It should be removed.
A stem girdling root can strangle the trunk at the root flare restricting the movement of water and nutrients from the roots up to the foliage. Eventually this restriction may also impede the movement of carbohydrates from the foliage to the roots causing the roots to starve and die.
Remove strapping, wires, burlap and ropes
Straps and ropes are used to secure the rootball while moving to the site. Left in place, these ropes and straps will not degrade and can eventually strangle the growing trunk.
When balled and burlap (B&B) nursery stock is purchased for planting, be sure that all wire baskets have been cut back by removing the top 6 to 8 inches of the wire basket. It is not necessary to remove the entire wire basket but it is necessary to remove at least the top rung of the wire basket. Also, all strapping and nylon ropes that are used to secure the wire basket during transport and transplanting should be removed. These ropes do not degrade and if left in place, can girdle the trees as they grow. Also all burlap, especially synthetic burlap, should be removed from the root ball at the time of planting. Check out the two photos at the bottom of this article. They show a laurel oak that was planted 20 years earlier along the boulevard in Palm Coast. The wire baskets and synthetic burlap were left in place. Roots could not grow out of the original rootball. When Hurricane Floyd passed through the area in 1998, the laurel oak blew over.
Has the tree been planted in its container long enough?
It is important to begin with good quality nursery stock. Sometimes nursery trees and shrubs have been recently transplanted (called “bumping up”) into larger containers and the roots have not yet grown out properly. To test for this condition, grab the plant by the trunk about 3 or 4 feet above the top of the container and try to move the trunk back and forth. If the plant and container both move together, then the roots have grown into the new container soil. If the container does not move and the plant pivots at the soil line of the container, the roots have not properly grown out and the plant should not be purchased.
Purchase Florida Number 1 or better nursery stock
Florida Grades and Standards require that a Florida Number 1 grade tree has a single central leader like the tree on the left. The tree on the right is a Florida Number 2 grade tree. Drawing by Dr. Ed Gilman, University of Florida Environmental Horticulture Professor.
Florida leads the nation in providing standards for nursery stock quality. If Florida Number 1 grade or better are specified, then there are strict criteria for both the structure of the crown and the structure of the roots that must be met. Generally, a Florida Number 1 tree must have a single leader which research has demonstrated to be the strongest structure. Flush cuts, wounds and bark injury are not allowed. Circling roots and large roots growing out of the container are also not allowed for Florida Number 1 plants. Below is the matrix of nursery stock height and caliper for appropriate container sizes. Even if you live outside of Florida, you should still look for nursery plants that have the Florida Number 1 qualities. Good nurseries anywhere will carry good quality trees with the Florida Number 1 traits.
A laurel oak blew over in Hurricane Floyd because its roots did not grow out of the wire basket and synthetic burlap wrap.
A close up of the rootball shows very few roots were able to grow through the synthetic burlap and wire basket.
Matching Container Size to Transplant Size
Tree Caliper |
Min. Tree Height |
Max. Tree Height |
Min. Crown Spread |
Min. Ball & Burlap Root Diameter |
Min. Container Volume |
1" |
5' |
10' |
30" |
16" |
5 gal. |
2" |
8' |
15' |
48" |
24" |
15 gal. |
3" |
10' |
18' |
60" |
32" |
45 gal. |
4" |
12' |
22' |
78" |
40" |
95 gal. |
5" |
16' |
26' |
108" |
48" |
95 gal. |
Table 1 Matrix of appropriate tree size for each container size. This matrix applies to large shade tree species such as oaks. Matrix from Florida Department of Agriculture and Consumer Services Grades and Standards for Nursery Plants
How to use the Matrix: For example, if you purchase a 2-inch caliper tree, it should be between 8 feet and 15 feet tall and growing in a container that is at least 15 gallon.
