Looking Towards Fall: Overseeding in Southern Climates

Austin Grimshaw, Ph.D.
Product Manager, PerformancePack^®

With summer well underway, many turfgrass managers are focused on navigating heat, drought, and the day-to-day challenges of the growing season. However, August and September loom for the onset of fall conditions and prepping for winter playing conditions. One of those management practices is overseeding. Our warm-season areas look towards overseeding to maintain playability and color for the winter season. The decision on type of seed and cultivar can be a challenging decision for a superintendent or turf manager. I thought this article would be a nice change of pace to touch on my turfgrass breeding background and discuss improved genetics and resources that are available to aid in that decision.

When discussing overseeding most of the time we are concerned with ryegrass, and specifically Perennial ryegrass (Lolium perenne L.) as annual types usually are low in turf quality. Perennial ryegrass breeding led to turf-type perennial ryegrasses being first released in the USA in the early 1960’s. Since that time, it has become the most widely planted turfgrass with the Rutgers variety, Manhattan, released by Dr. C. Reed Funk in 1967, being recognized as the first cultivar to launch ryegrass as a staple in our industry. Perennial ryegrass is a cool-season (C-3 metabolism) perennial bunch-type grass best adapted to mild climate areas. As a bunch-type grass, it produces only tillers and has limited ability to spread. This is the reason for our heavy seeding rates as these plants cannot spread throughout the season. Continuing germplasm collection and population improvement programs at Rutgers and commercial breeding programs have resulted in a continued stream of better performing cultivars.

During my time at Rutgers, I collected ryegrass from pasture fields in Albania to bring back and incorporate into new cultivars. Collections from centers of origin every year allow the introduction of new traits that can relate to drought and heat tolerance, or disease resistance. With each new National Turfgrass Evaluation Program (NTEP) trial, the best performing cultivars of the previous test usually end up on the second page of the new test only four or five years later. This documents the effectiveness of the continued population improvement programs. They involve many cycles of phenotypic and genotypic selection and population backcrossing. Each cycle of improvement builds on the achievements of all previous cycles in these cross-pollinated species. This means as turf managers we need to be purchasing the newest verities and not be stuck on one we necessarily liked before. The elite ryegrass of a few years ago might be obsolete today.

Turfgrass Seed

Image courtesy of Turf Merchants, Inc.

Resources to evaluate new verities include the National Turfgrass Evaluation Program (NTEP) program as they publish quality, drought, and disease performance ratings of cultivars from locations across the country. Also, at Rutgers they publish yearly proceedings reports available at https://turf.rutgers.edu/research/. This document contains the yearly ratings of every variety and cultivar being evaluated at the Rutgers experimental station. My takeaway here is to source your seed from a reputable partner and seed supplier to ensure you are getting the latest in improved genetics as well as clean, weed-free seed. Simplot Turf & Horticulture works with suppliers such as Turf Merchants, Inc. to supply quality seed.

TMI Varieties for 2026

Gambler Perennial Ryegrass
Gambler Perennial ryegrass is a new addition, boasting rapid establishment and an unparalleled dark green genetic color. Its exceptional plant density ensures a robust and visually stunning turf, making it an ideal choice for high-performance applications. Renowned for its exceptional turf qualities, Gambler is perfectly suited for overseeding golf courses, where fine turf is paramount. Its elite characteristics also make it a preferred option wherever a top-tier perennial ryegrass is required. This innovative variety combines durability with versatility, proving to be a reliable solution for achieving lush, high-quality turf in demanding environments.

Voodoo Perennial Ryegrass
Voodoo Perennial ryegrass epitomizes excellence in both aesthetic appeal and functional performance. With its rapid establishment, genetic dark green hue, and unmatched density, Voodoo has redefined expectations for perennial ryegrass varieties. This remarkable variety is specifically engineered to meet the demands of high-performance applications, and its density is particularly beneficial for high-use areas where durability is critical, such as golf courses and professional sports fields. The dense growth also acts as a natural barrier to weeds.

TMI Paradox Baby

Paradox GLR Perennial Ryegrass, Seedling Stage. Courtesy of Turf Merchants, Inc.

Work with Your Simplot T&H Turf Advisor

Your Simplot Turf & Horticulture Turf Advisor can help you evaluate cultivars available in your market and assist with selection.

They can support you with:

Assessing overseeding needs
Developing a customized cultural and wetting agent program
Selecting the right solutions based on usage and budget

Learn more at th.simplot.com.

TMI Paradox First Year
Paradox GLR Perennial Ryegrass, Tillering. Courtesy of Turf Merchants, Inc.

Turf and Horticulture Resources