Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia
Dormant transplanting of trees and ornamentals in the Southeastern United States is a common practice; likewise, warm-season turfgrass sod can be successfully established during dormancy.
Research has shown that bermudagrass root growth is significantly reduced when average soil temperatures drop below 60 degrees F. In the Atlanta area, this would generally occur the first of November. Generally temperatures would not reach 60 degrees F. until the latter part of April. These observations generally agree with the normal dormant period of most warm-season turfgrasses and are commonly recognized as a risky period for sodding. However, substantial quantities of sod are transplanted during this period of slow growth or dormancy.
Off-season or dormant sodding (October-April) provides the following advantages:
- Provides for instant landscape;
- Improves the environment by reducing erosion, mud, dust and weeds around buildings;
- Increases occupancy rates of newly finished construction projects such as homes and buildings;
- Extends the producer’s and landscaper contractor’s production time, thus reducing the peak demand season.
Recommendations for normal sodding also apply to off-season sodding. Rootzone preparation is critical for success. During site preparation and prior to turf establishment is the best time to take a soil sample to determine pH and nutrient needs. Modification of soil pH is most beneficial when lime (used to raise pH) or sulfur (used to lower pH) can be incorporated into the soil. Loosening the soil to a depth of 6 inches by tilling is usually ideal for turfgrass establishment.
Also, corrections of soil nutrients deficiencies like phosphorus(P) and potassium(K) are more easily made prior to establishment. While all essential nutrients are required for turfgrass growth, there is inconsistent information on P and K needs during establishment and winter. Some studies report decreased winterkill and disease occurrence with the addition of P and K, while other researchers have reported no differences in cold hardiness or pathogen resistance due to increased rates of P and K.
Next, the tilled soil should be leveled, smoothed and moistened. The soil should be lightly watered, but not saturated. Ruts from foot traffic or equipment can occur when soils are excessively wet and are more difficult to repair after the sod is laid. To prevent drying and potential cold injury of roots, sod should be installed within 48 hours after harvest. Also, the radiant heat from the earth may offer some protection from cold injury when compared to turf exposed to the elements when left on a pallet. Sod should be laid tight and rolled to minimize creases. If creases are apparent once the turfgrass has been laid, the sod should be topdressed to fill low spots, conserve moisture and potentially retain heat near the soil surface.
The survival of off-season transplanted sod is dependent upon avoiding winter desiccation and low temperature injury. Due to a limited root system, desiccation can be a significant problem. The warm dry winds of late winter and early spring increase the demand for water, but the combination of low soil temperatures and a limited root system will reduce the plant’s ability to obtain water and nutrients. Direct low temperature injury can be a problem because the crowns, stolons and shallow rhizomes may be killed. Unfortunately, newly sodded turf lacks deep rhizomes and the expansive root system necessary to recover from winter stresses.
Research and practical experience has shown that warm-season turfgrasses may be successfully sodded during the off-season (October-April) when the grass is dormant or slowly growing. However, the cooler climates in and north of Atlanta may adversely influence some species. Increased winter injury has been observed on zoysiagrass and centipedegrass compared to bermudagrass sodded late in the year.
Nonetheless, successful transplanting is highly dependent on a healthy sod, which is difficult to determine when the sod is dormant or overseeded. Overseeding sod with ryegrass may reduce bermudagrass vigor and quality. While overseeded turf may look appealing during the winter months, during the spring the more heat-tolerant perennial ryegrasses can compete with the warm-season turf for water, nutrients and light, resulting in a poor transition and delayed green-up of the warm-season species. This is more common in ryegrass that has been heavily fertilized in the spring. To assist spring green-up and stimulate turfgrass growth, fertilize with 1.0 to 1.5 pounds of nitrogen per 1000 square feet once night temperatures consistently reach the mid 60s F. Also to further encourage warm-season species growth, the mowing height can be lowered. This practice opens the turfgrass canopy, allowing more sun to the permanent warm-season species while stressing overseeded grass. Resume accepted maintenance practices once conditions are favorable for warm-season turfgrass growth.
In summary, successful sod transplanting depends on proper soil preparation, good soil-to-sod contact, avoiding low temperature injury, and most important, proper water management to prevent desiccation.
Resource(s): Lawns in Georgia
Center Publication Number: 142