Zoysia Vs. St Augustine

In the quest for a warm-season turfgrass for your lawn, Zoysia grass, and St. Augustine are two common options that usually come up. They share some similarities, but they have differences, too. These differences help in deciding why you should choose one over the other.

The main difference between Zoysia grass and St. Augustine is a matter of texture versus hardiness. Zoysia’s soft feel and velvet texture feel great beneath your feet. However, St. Augustine holds up solidly to drought. However, if you choose Zoysia for your lawn over St. Augustine, keep your lawn mower well-oiled. You’ll need it a lot more. 

Here are some differences between these turfgrasses to help you decide the best grass for your lawn. 

What is Zoysia Grass?

Zoysia is a genus of warm-season grasses renowned for their excellent drought tolerance and durability even in high-traffic turfs. It resembles Bermuda grass in appearance but has stiffer leaf blades. Zoysia is a perennial that reestablishes itself under the right environmental conditions on turfs every season without replanting.

Zoysia grass has rolled vernation; the youngest grass blades are rolled inside the leaf sheath. It also has hairy ligules at the point where the leaf blade meets the leaf sheath, a common feature amongst warm-season grasses. Zoysia doesn’t have auricles extending from the collar.

Zoysia grass has a low growth profile and is both stoloniferous and rhizomatous. It forms an even, thick, fine-textured turf with a beautiful medium-green shade. However, Zoysia grass loses its color as it enters winter dormancy.

The leaf blade feels stiff to the touch and has a pointed tip. If left to grow without mowing, Zoysia grass produces a spike-type seed head, with seeds alternating on either side of the spikelet.

Common Zoysia grass species include Zoysia tenuifolia and Zoysia japonica. Recently, newer Zoysia cultivars like Emerald Zoysia, El Toro Zoysia, and Victoria Zoysia have gained popularity amongst turf experts for their improved establishment rate.

What is St Augustine Grass?

St. Augustine grass(Stenotaphrum secundatum) is a warm-season, perennial turfgrass species beloved for its excellent heat tolerance. This grass species thrives in different soils and grows in saline soil conditions.

St. Augustine grass blades are dark-green and smooth, with hairs around the collar region. The coarse-textured leaf blade is keeled/boat-shaped and has a rounded tip. A prominent, white midvein runs along the length of the leaf blade.

St. Augustine grass also has membranous, short-haired ligules at the intersection of the leaf sheath and the leaf blade. It, however, lacks auricles. Meanwhile, the leaf sheaths are distinctly compressed against each other and are difficult to pull apart.

If not mowed, St. Augustine grass produces seed heads of racemes containing 1-3 spikelets each. The flat purple-colored racemes are usually 3-5 inches long.

St. Augustine grass has a creeping growth pattern and spreads via stolons, which are above-ground offshoots that run lateral to the soil surface and develop new shoots and roots at intervals. This grass species grows relatively fast and can creep into neighboring flower beds if not controlled.

Common varieties of St. Augustine grass include

  • Floratam St. Augustine
  • Seville St. Augustine
  • Raleigh St. Augustine
  • Roselawn St. Augustine
  • Floratine St. Augustine

Zoysia Vs. St Augustine differences

Here is a summary table for differences between zoysia grass and St. Augustine grass.

St. Augustine grassZoysia grass
Dark-green, coarse-textured leaf blade, with rounded, keeled apex.Medium-green, fine-textured leaf blade, with sharp-pointed apex
Thrives in saline soil, but not compact or slow-draining soilThrives in compact or slow-draining soil but struggles in saline soils
Tolerate shade wellLess shade tolerant than St. Augustine
Spreads via stolons onlySpreads via both stolons and rhizomes
You can establish it via seedYou can grow it from seed, sod, sprigs, and plugs
Slow to recover from physical damageRecovers faster from physical wear
Has high maintenance requirements in terms of mowing, watering, and fertilizingNeeds closer monitoring to prevent frequent diseases
Tolerates a wider soil pH rangeTolerates a narrower soil pH 
Better at choking out weeds as it grows fasterSlow to fill in, bit crowds out weeds once it does

Zoysia grass and St. Augustine grass share many characteristics, such as excellent heat tolerance, hairs at the base of the leaf blade, and the absence of auricles. However, there are several differences between these two warm-season turfgrasses. You can compare Zoysia and St. Augustine by their physical features, growth habits, environmental preferences, and maintenance requirements.

Physical Features

The Zoysia leaf blade has a sharp tip, while St. Augustine grass has a rounded, keeled apex. Zoysia leaf blade also has a medium-fine texture, compared to the coarse-textured St. Augustine leaf blade.

Growth Habit

Both Zoysia grass and St. Augustine grass have a creeping growth habit. However, while the former spreads via above-ground stolons and underground rhizomes, St. Augustine is only stoloniferous.

The underground rhizomes remain intact if the Zoysia lawn is scalped, mowed too low, or aggressively dethatched. Meanwhile, the stolons of St. Augustine suffer considerable damage due to low mowing and invasive dethatching. Due to this difference, Zoysia grass recovers faster from physical injury than St. Augustine in such situations.

Propagation

You can grow a Zoysia lawn from seed, the most affordable way to establish a lawn. Yet, you can’t establish a St. Augustine lawn from seed. Grass seed suppliers don’t stock it due to the limited amount of the grass’s viable seed. To establish a St. Augustine, you have to go for costlier vegetative propagation options, sodding, plugging, and sprigging.

Drought Tolerance

Though both Zoysia and St. Augustine have exceptional heat tolerance, their tolerance to dry soil conditions differ. St. Augustine grass has moderate drought tolerance and will only withstand high summer heat if it receives enough moisture. Comparatively, Zoysia grass has a denser root system and stays green in prolonged periods of heat and drought in the summer.

Note: During a drought, Zoysia grass will go dormant and turn brown within a week, which may make it seem less drought-resilient than St. Augustine. However, when St. Augustine grass finally turns brown in a drought, it means the grass is dying and won’t recover even when watered. On the other hand, Zoysia quickly comes out of dormancy and greens up the first time you irrigate it after a drought.

Shade Tolerance

St. Augustine grass boasts better shade tolerance than Zoysia grass. The latter turfgrass is likely to struggle in shaded lawns and needs more sunlight exposure, while St. Augustine is able to thrive in less sunlight.

Salt Tolerance

St. Augustine grass has high salt tolerance and will still grow in the saline soils found in coastal regions. By contrast, Zoysia is only moderately tolerant of saline soil conditions and is likely to die due to salinity stress in excessively salty soils.

Weed Resistance

Both St. Augustine and Zoysia grasses form dense turf that easily crowds out weeds. However, St. Augustine forms denser turf. Zoysia grass grows slowly and takes a long time to fill in (6-8 weeks), giving fast-growing weeds a head start. On the contrary, St. Augustine grass establishes a bit faster and can effectively choke out most types of weeds.

Maintenance Requirements

Though both types of grass are relatively low-maintenance, Zoysia requires more care and maintenance than St. Augustine. For starters, Zoysia is more prone to diseases. However, it is a low-growing grass, thus doesn’t need to be mowed often. Comparatively, St. Augustine grass grows significantly taller and requires frequent mowing at a height of 2-4” for deeper root growth.

Note: You can mow Zoysia grass as low as 0.75 inches.

You need to water St. Augustine twice a week, with ¾ inches of water each time compared to Zoysia’s one inch of water per week. 

Soil Preferences

St. Augustine grass can grow in 5.0-8.5 pH soil and survive in highly acidic and alkaline soil types. However, Zoysia can only withstand 5.8-7.0 pH. St. Augustine grass is, therefore, the more versatile turfgrass of the two by this standard.

Zoysia beats St. Augustine’s intolerance for poor-draining soil and low-nutrient soil. Zoysia grows well in slow-draining, clay soils while St. Augustine grass struggles in such conditions. Zoysia also has lower fertilizer requirements than St. Augustine and will still thrive in nutrient-deficient soil where St. Augustine fails to grow.

Which is the best grass to choose?

You need to consider the soil conditions of your lawn, your commitment to lawn maintenance, the regional climate, the amount of shade on your lawn, and your budget when choosing between Zoysia grass and St. Augustine grass.

If there is shade

If you have a partially shaded lawn, go for St. Augustine grass. It handles limited sunlight exposure better than Zoysia grass. 

In case of drought

Opt for Zoysia over St. Augustine grass if you live in drought-prone regions like Nevada, Arizona, and Texas. Zoysia is more drought-resilient and comes back to life as soon as it’s watered again after a drought. 

Slow-draining, low-nutrient soil

In poor quality soil that’s slow-draining, compact, and low in nutrients, it’s better to go for Zoysia grass. It tolerates such poor soil conditions better than St. Augustine grass.

If you have pets

For pet lovers, Zoysia grass is the better choice, as it recovers faster from physical damage caused by pets. St. Augustine will be frustratingly slow to regrow after suffering damage to the stolons from pet paws and claws. 

Starting costs and maintenance budget

If you’re on a tight budget, Zoysia is the better option. It costs more to start and maintain a St. Augustine lawn. Zoysia can be established via cheap grass seeds. You can’t do the same with St. Augustine.

Can I combine Zoysia and St Augustine?

You can combine Zoysia grass and St. Augustine to mixed results. If the lawn is shaded or the soil is saline, St. Augustine might encroach into Zoysia. To reduce the chances of St. Augustine taking over Zoysia, we recommend planting a quick-growing Zoysia cultivar such as Palisades Zoysia. Meanwhile, Zoysia is only likely to overtake St. Augustine grass in dry soil conditions.

References

  1. Richard L. Duble, turfgrass Specialist- Texas Cooperative Extension: Zoysia Grass.
  2. The University of Missouri, Division of Plant Sciences: St. Augustine Grass- Stenotaphrum secundatum

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