Feature

Rehabilitating Flood-Damaged Landscapes and Inventory: Considerations for horticultural professionals after heavy rains and major flooding

By Andy Pulte and Bill Klingeman

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In the South, water is the constant variable; too much or too little is always a challenge. However, too much rain coming all at once has become a defining weather pattern in our region. If you search online for “rainiest cities” or “rainiest states” (and ignore any results from Hawaii), the most frequent results skew toward the American South. Unfortunately, flooding is no longer an occasional concern but is an increasingly familiar story for communities nationwide. For those who work in horticulture, particularly nursery and garden center professionals, floods not only disrupt operations but also put plant inventories and customer confidence at risk.

The devastating floods that followed Hurricane Helene in September 2024 were a reminder of how quickly weather can reshape both communities and horticultural operations. In parts of the Southeast, days of rainfall left container yards submerged and field blocks compromised. Many businesses reported significant losses of woody ornamentals and herbaceous crops. Beyond the immediate cleanup, Helene underscored the need for contingency planning, from drainage infrastructure to crop insurance.

Figure 1. Soil and roots of field-grown nursery trees were submerged for several days in 2019 (Photo by Gary Clendenon, TDA Plant Inspector).

Additionally, the importance of communicating with both customers and consumers about availability of materials and timelines for recovery came into focus.

Those helping customers with flood damaged plants may also be called upon to field questions about plant replacement needs. Being ready and understanding how flood waters can affect plant material in the landscape can be helpful for professionals. When plant material is underwater for more than a day, oxygen becomes severely limited in root zones. Plants in landscapes, containers, and in field production may appear wilted, not because of a lack of water but because they cannot physiologically access the water around them. The duration of flood stress to nursery stock and landscape specimens can lead to increase in plant diseases and woodboring beetle attacks. Recognizing that established and transplanted trees exposed to sustained flooding may require more frequent scouting and targeted management effort can help limit future damage and plant losses. These persistent challenges can be overlooked during recovery and may be difficult for some consumers and clients to understand.

Helping Customers and Clients at Home:

It is always good to think about how you will help your customers and clients. Having handy resources and a good working knowledge of how flooding impacts plants can help. Here are a few things to think about.

Figure 2. Hurricane Helene caused massive flooding and damage to nurseries and container stock in Western North Carolina in September 2024. During record breaking rainfall, stream overflows were deep enough to wash away propagation flats on top of production benches and destroyed buildings and structures at Carolina Native Nursery (Photo courtesy of Shelby Jackson).

Flooding reduces the oxygen in soils. It also impacts overall soil stability and how soil particles bind together. So, the story of recovering from flooding in a landscape is primarily a story of how to mitigate compaction and to revitalize a flooded soil. The balance of soil microbes will undoubtedly be impacted, and steps must be taken. First, encourage clients to let soil drain as naturally as possible. Rapid removal of water can lead to soil compaction in extreme situations. Channeling water away from the nursery, garden or landscape area may be necessary, but where water can drain naturally, that approach is often best. Also, try not to walk extensively or run equipment on waterlogged soil; this can also lead to more compaction.

Figure 3. Landscape shrubs, trees, and perennial plants will be stressed after days of flooded conditions (Photo by Tony Pernas, USDI National Park Service, Image 528006, Bugwood.org)

Flooding also removes nutrients from soils. Adding compost, manure, and mulch are a good way to return nutrients to the soil and encourage a healthy balance to a soil microbiome. When soil starts to dry, test it for pH level. Flooded soils may become more acidic, so soil test results may indicate a recommendation for adding agricultural lime to help bring your soil closer to a neutral pH.

Figure 4. Trees in a park picnic area in Kansas (Photo by Ryan Armbrust, Kansas Forest Service, Image 5549966, Bugwood.org)

After the Storm: Encourage Clients not to Rush into Recovery Activities

Encourage clients to not be overly anxious to replant after the water recedes. Working wet soil too soon can cause additional damage to soil structure and cause compaction that makes it difficult for existing specimens and transplants to survive and grow. If you turn a spade full of soil over and water is visible in the hole, the soil is not ready to work. If mower, tractor, or tires of other equipment leave deep depressions in turfgrass, or squeeze wet soil into standing water and puddling, the soil is not ready to work. Adding compost, manure, and mulch when reworking compacted soil is recommended, but you need to give these additives time to balance your soil biome. Also, don’t encourage immediate pruning of flood-damaged trees and shrubs. Yes, remove any broken, obviously dead, or hazardous limbs. But heavy pruning after flooding can cause even more stress to your plants. Be prepared for more disease and insect pressure on flooded plants. Fungal diseases and root rot are common after flooding and excess rain. Additionally, flood stressed plants will be more susceptible to insects in general. Landscape shrubs and trees including redbud and dogwood, maple, and oak species will be more susceptible to attacks by ambrosia beetles and other woodboring beetle pests.

For professionals, the challenges presented by flood are not just about plant losses, they are about operational resilience. Watching your business, nursery, landscape, or garden flood can be heartbreaking. For some, the damage may be small, but for others, the losses can feel overwhelming. Still, even in the face of these challenges, nature has a way of showing us its strength and resilience. Preparation for the possibility of floods in your area may pay dividends later.

Additional Reading and Resources

Clatterbuck, W.K. 2005. Shade and Flood Tolerance of Trees. UT Extension SP656. https://utia.tennessee.edu/publications/wp-content/uploads/sites/269/2023/10/SP656.pdf

Oliver, J.B., N. Youssef, J. Basham, A. Bray, K. Copley, F. Hale, W. Klingeman, M. Halcomb, and W. Haun. 2012. Camphor Shot Beetle – a new nursery and landscape pest in Tennessee. SP-742. TSU and UT Agric. Ext. Serv., The University of Tennessee, Knoxville, TN. https://utia.tennessee.edu/publications/wp-content/uploads/sites/269/2023/10/SP742.pdf

Poudel, A., A. Gautam, K. Addesso, J. Oliver, and G. Roper. 2023. Ambrosia beetles important to Tennessee nurseries. TSU Ext. Serv., ANR-ENT-02-2023. https://digitalscholarship.tnstate.edu/cgi/viewcontent.cgi?article=1177&context=extension