St. Augustine grass (Stenotaphrum secundatum) is a warm-season turfgrass highly valued in tropical and subtropical regions for its dense, carpet-like appearance. It offers excellent shade tolerance compared to other warm-season varieties. The search for St. Augustine grass seed often ends in frustration, as it is conspicuously absent from garden center shelves. This unavailability stems from a complex interplay of the plant’s genetics and the economic realities of large-scale seed production.
The Biological Reasons for Seed Scarcity
The primary obstacle to commercial St. Augustine grass seed lies in the plant’s reproductive biology. Cultivars like Floratam, which is widely popular, are virtually 100% sterile and do not produce viable seed. This sterility is often linked to the grass’s ploidy level, with many cultivated types being triploids, meaning they possess an odd number of chromosomes that severely impedes successful sexual reproduction.
Even in varieties that can produce viable seed, commercial seed production remains impractical because the overall yield is low. Furthermore, the grass’s seed is embedded within a thick, corky flowering structure known as a spikelet. This physical characteristic makes the mechanical harvesting and cleaning process exceptionally difficult and expensive compared to other turfgrass seeds.
When St. Augustine grass does produce viable seed, the resulting seedlings often exhibit high phenotypic variation and low vigor, making them unreliable for creating a uniform, high-quality lawn. Turfgrass breeders select for specific traits like color, density, and pest resistance, and these desirable characteristics are not reliably passed down through sexual reproduction. Therefore, relying on seed would compromise the consistency consumers expect from a premium turf product.
Vegetative Propagation: The Commercial Standard
Since seed is not a viable option, the industry relies entirely on vegetative propagation to establish St. Augustine lawns. This process bypasses sexual reproduction, ensuring that the new grass is a genetically identical clone of the parent plant. The most common method is laying sod, which provides instant coverage by transplanting a mature layer of grass and its root system onto the prepared soil.
Other methods utilize the grass’s natural ability to spread. Plugs are small squares of established turf planted at intervals, offering a more affordable but much slower establishment process than sod. Similarly, sprigs are pieces of stolons that are spread over the soil and lightly covered, taking the longest time to establish a full turf canopy.
These vegetative methods are commercially preferred because they guarantee the genetic purity of the cultivar being sold. The new lawn will exhibit the exact characteristics—such as shade tolerance or blade width—that the buyer selected. This certainty of performance and appearance is why sod and plugs are the standard for starting a St. Augustine lawn.
Selecting the Right Cultivar for Your Region
The necessity of vegetative propagation means that choosing the correct variety is a one-time, high-impact decision. Breeders have developed various St. Augustine cultivars to perform optimally under specific environmental conditions, and purchasing vegetative material is the only way to guarantee these traits. For example, the popular Floratam cultivar requires full sun, while varieties such as Bitterblue and CitraBlue are specifically bred to retain density in partial shade.
Other cultivars are selected for their defense mechanisms against common regional threats. Palmetto is known for its relatively good cold tolerance, while others may be bred for better resistance to the Southern chinch bug or fungal diseases like Gray Leaf Spot. Choosing a cultivar that is well-suited to the local climate, soil conditions, and light exposure is crucial for the long-term health of the lawn.