The Sweet Gum tree (Liquidambar styraciflua) is prized for its stately pyramidal form and brilliant autumn foliage, which ranges from scarlet to deep purple. However, this popular shade tree comes with a significant drawback: the persistent, spiky, and hard seed pods commonly known as gumballs. These small, woody fruits litter lawns and hardscapes, creating a frustrating cleanup challenge and a potential tripping hazard. Addressing this nuisance requires proactive strategies to stop seed pod formation or effective methods for managing the debris after it has fallen.
Preventing Seed Pods Through Growth Regulators
One of the most direct ways to prevent the production of gumballs is through the strategic application of plant growth regulators (PGRs). This chemical intervention works by disrupting the tree’s reproductive cycle, causing the developing flowers to abort before they can set fruit. The most common active ingredient used for sweet gum fruit reduction is Ethephon, a compound that breaks down to release the plant hormone ethylene inside the tree’s tissues.
The timing of this treatment is important for its effectiveness, as the application must occur during the tree’s brief flowering period in the spring, typically a one to two-week window in March or April. Applying the product too early or too late will lead to poor results, either by missing the flower stage entirely or by only partially reducing the fruit size.
Application can be done either by spraying the canopy or by using a trunk injection method. Spraying is generally difficult for mature, tall trees and carries a risk of chemical drift. Professional arborists often prefer trunk injection, which delivers the growth regulator directly into the tree’s vascular system for precise and localized effect. Since these specialized chemicals require specific training and equipment, consulting a certified arborist is the most reliable option for consistent annual treatment.
Pruning and Cultivar Selection Strategies
For a long-term solution, horticultural practices offer ways to manage or eliminate the gumball problem entirely. While general pruning is performed to remove deadwood and maintain the tree’s structure, attempting to significantly reduce fruit production on a large, mature tree through pruning alone is impractical. The sheer number of branches that would need to be removed would negatively affect the tree’s health and appearance.
Pruning should primarily be reserved for shaping younger trees and removing any structurally weak or damaged branches during the dormant season, ideally in late winter or early spring. If a homeowner is determined to reduce gumballs on a small tree, the goal would be to target and remove the previous season’s growth, where the new flowers will form. This kind of targeted pruning is resource-intensive and often only provides a marginal reduction in fruit.
Cultivar Selection
The most definitive long-term solution is to select a non-fruiting cultivar when planting a new tree or to replace an existing problem tree. Sweet Gum trees are monoecious, producing separate male and female flowers on the same tree, but specific cultivated varieties have been bred to be sterile. The cultivar ‘Rotundiloba’ is a popular choice, known for its distinctively rounded leaf lobes and its reputation as a nearly or completely fruitless variety.
Other seedless varieties, such as ‘Happidaze’ (also sold as ‘Hapdell’) and ‘Cherokee,’ are also commercially available. Choosing one of these fruitless selections provides a permanent solution, allowing the owner to enjoy the tree’s aesthetic qualities without the yearly cleanup.
Effective Cleanup Methods for Fallen Gumballs
When preventive measures are not an option, specialized cleanup methods can make managing the debris dropped by an existing tree much easier. The hard, spiky nature of the gumballs means they are difficult to gather with standard leaf rakes. Instead, using a sturdy garden rake with stiff, closely spaced tines can help to collect the pods into manageable piles for disposal.
For larger areas, mechanical solutions are available. Specialized rolling nut and seed pod harvesters, such as those that use a spring wire basket, are highly effective at quickly clearing lawns and patios. These tools are designed to collect the hard pods without picking up excessive amounts of leaves or grass clippings.
Many homeowners also find success using a lawnmower equipped with a bagger or a heavy-duty leaf vacuum system designed to handle hard debris. Running a mower over the area can shred some gumballs and collect the rest, but care must be taken to avoid damaging the mower blades. It is important to remove the gumballs promptly from walkways and driveways as they present a slip-and-fall risk, especially when wet.