Mixing Bermuda Grass & St. Augustine (Turf Tips)
Bermuda and St. Augustine can grow in the same yard, but they rarely make an even, stable mix. Bermuda favors full sun and close mowing; St. Augustine tolerates more shade and needs a taller cut. Before trying to maintain both, map the light and mowing needs. If they conflict, separate the lawn into zones or favor the grass best suited to each area.
Warning: A mower setting low enough for Bermuda can scalp St. Augustine, while a tall setting for St. Augustine can leave Bermuda looking coarse and weak. Scalping removes too much leaf at once, exposes soil, and can invite weeds. I recommend choosing the mowing plan before changing the lawn, not after the grass starts thinning.
Can Bermuda and St. Augustine Coexist?
Coexistence means both grasses remain present in the same lawn, not that they keep equal shares or look alike. Whether that works depends on sun, water, soil, and mowing. The grass better suited to those conditions and the chosen care routine may spread into areas where the other struggles.
Both grasses spread by aboveground runners called stolons. Bermuda also spreads by underground stems called rhizomes. These growth habits let each grass fill open ground, but they do not guarantee a balanced mix. Persistent shade often weakens Bermuda and favors St. Augustine. In strong sun, Bermuda may thrive, while St. Augustine can need more careful water and heat management.
Mowing is often the main conflict. St. Augustine is generally kept at 2.5–4 inches (6.4–10.2 cm). Common Bermuda is generally maintained around 0.5–2 inches (1.3–5.1 cm), depending on cultivar and mowing system. Follow the cultivar guidance or local extension recommendations when available.
| Condition or choice | St. Augustine | Common Bermuda | What it means for a mixed lawn |
|---|---|---|---|
| Usual mowing range | 2.5–4 in | 0.5–2 in | No one height suits both well |
| Light | More shade-tolerant; varies by cultivar | Usually best in full sun | Shade can favor St. Augustine |
| Spread | Aboveground stolons | Stolons and rhizomes | The better-suited grass may take over |
| 3-in mower setting | Within usual range | Generally too high | St. Augustine may look better than Bermuda |
A 3-inch cut may suit St. Augustine but leave common Bermuda too tall. Lowering the deck to suit Bermuda can remove too much of the St. Augustine leaf. If your yard needs one uniform appearance, a single grass suited to the whole area is usually simpler to maintain.
Equipment Setup and Safety Preparation
Equipment setup means checking the lawn and mower before cutting, then setting the deck for the grass you intend to maintain. A height-adjustable rotary mower with a sharp blade can suit many lawns, but it must be able to make the needed cut without scalping. A single setting cannot optimize both species.
- Inspect the site. Identify the grasses as best you can, then note sunny and shaded areas, drainage, soil condition, and irrigation coverage. If the grass is hard to identify, ask a local extension office or turf professional before making major changes.
- Check soil before feeding. A soil test can help guide fertilizer choices. Avoid fertilizing just because one grass looks weak; shade, poor drainage, mowing height, or uneven water may be the cause.
- Choose the cut for the zone. Set the deck for the dominant grass in that area. If the mower cannot safely cut Bermuda at its recommended height, do not force it to do so. Use equipment suited to the lawn or maintain a taller, clearly managed transition zone.
- Secure the mowing area. Keep people and pets away. Check the guards, discharge deflector, blade, tires, and deck-height adjustment. Wear eye and hearing protection, sturdy footwear, and close-fitting clothing.
- Adjust safely. Stop the engine and disconnect the spark-plug lead, or remove the battery on applicable equipment, before working near the blade or deck. Confirm the blade is secure and undamaged. Check actual cut height on level ground rather than relying only on the height label.
Do not lower the deck abruptly to make Bermuda shorter. If the lawn has grown tall, reduce height over several mowings. A sharp blade gives a cleaner cut; a damaged or dull blade can leave ragged tips.
Field Mowing and Mixed-Turf Management
Field mowing is the routine cut and follow-up that keeps turf healthy without removing too much leaf at once. The key limit is the one-third rule: remove no more than one-third of the leaf blade in one mowing. If the grass is too tall, raise the deck and lower it gradually over later cuts.
Mow dry turf when practical. Wet or very dense grass can be harder to cut evenly and may clump, though conditions and equipment vary. Do not push the mower through growth it cannot handle. If the engine strains or the mower leaves heavy clumps, stop and adjust the approach instead of forcing a low cut.
Use these steps for each mowing:
- Measure the current growth. Compare the grass height with your planned cutting height. If removing one-third would still leave the lawn too tall for the final target, make a higher first cut.
- Set the deck for the zone. Maintain St. Augustine in its recommended range and Bermuda within the guidance for its cultivar and mowing system. Verify the cut after a short test pass.
- Watch the boundary. A sharp line between species is not required, but note where the mix changes. Mow each distinct zone at the height that suits it.
- Stop if you see scalping. Pale or bare patches, exposed soil, and torn grass are signs the cut may be too low or uneven. Raise the deck and let the turf recover before making another height change.
If the two grasses need persistently different heights, manage separate zones. A simple boundary can follow a path, bed, or other existing feature. If there is no practical way to mow each zone correctly, consider favoring one grass that fits the light and use of that area.
Practical Site Scenarios
These are decision examples based on the grasses’ general light and mowing needs, not reports from named properties. Use them to compare your own yard’s conditions. Local cultivar guidance and site conditions still matter, especially where shade, drainage, or irrigation varies across a lawn.
| Site pattern | Likely pressure | Practical response |
|---|---|---|
| Open, sunny lawn with a low mowing target | Favors Bermuda | Keep St. Augustine separate or accept that it may not suit the cut |
| Part-shade lawn maintained tall | Favors St. Augustine | Let St. Augustine lead; do not lower the whole lawn to chase Bermuda |
| Sunny front lawn and shaded side yard | Different conditions by zone | Maintain separate mowing zones and heights |
| Mixed grass with thin or bare patches | Could reflect poor light, mowing, water, or soil conditions | Diagnose the cause before adding seed, sod, or fertilizer |
For example, on a property with a sunny front area and a shaded side yard, one uniform mower setting may not suit both. I would mark the zones, identify the dominant grass in each, and set the mower for that zone. This reduces the temptation to scalp St. Augustine just to improve the Bermuda’s appearance.
If your goal is a uniform lawn, decide which grass best fits the site first. Replacing or limiting one species may take more planning than simply changing the mower height, because both grasses can spread. Avoid promising a quick conversion; the outcome depends on conditions and follow-up care.
Mower Maintenance and Turf-Quality Checks
Mower maintenance means keeping the blade, deck, and height controls in working order so the machine cuts at the setting you chose. A sharp, undamaged blade and a level deck help prevent uneven cuts. They do not remove the underlying height conflict between Bermuda and St. Augustine.
After mowing, disengage the blade, stop the engine, wait for all motion to cease, and remove the key or isolate the battery before clearing clippings. Never reach under an energized mower. Secure the machine as directed by its manual before cleaning the deck.
Check the lawn and mower after each cut:
- Look for scalped spots, exposed soil, torn leaf tips, and heavy clumps.
- Confirm the deck is level and the height adjustment has not shifted.
- Clear grass from the deck only after the machine is shut down and secured.
- Check the blade for damage and follow the mower maker’s instructions for inspection and service.
If St. Augustine is thinning after a lower cut, raise the deck and avoid another aggressive cut while it recovers. If Bermuda stays tall under a St. Augustine setting, do not keep lowering the entire lawn. Separate the zones or change the long-term species plan.
Seasonal Care and Long-Term Species Management
Seasonal care means adjusting mowing and turf decisions as growth, light, and weather change through the year. The right timing depends on your region, grass cultivar, and local guidance. The core rules remain the same: match the cut to the grass, avoid removing more than one-third, and do not use mowing to mask a site mismatch.
Recheck the lawn when tree shade changes, irrigation coverage is adjusted, or one grass begins spreading into the other’s zone. A shaded area that once supported Bermuda may become less suitable as canopy grows. Likewise, a sunny, well-watered area may support a different balance than a dry or poorly drained one.
Before fertilizing a thin area, use a soil test and identify likely causes. Fertilizer will not correct a mower height that scalps St. Augustine or a shady site where Bermuda struggles. Keep notes on the cut height and areas that thin; this makes it easier to spot patterns rather than changing several things at once.
Conclusion and FAQ
The best plan starts with site conditions, not a compromise mower setting. Bermuda and St. Augustine can share a property, but their usual mowing heights differ enough that one uniform cut may stress one species. Map the zones, mow by the one-third rule, and choose a grass suited to each area.
Can Bermuda and St. Augustine grow together?
Yes, they can be present in the same yard. Their balance may shift as light, water, soil, and mowing favor one grass over the other.
What mowing height works for both grasses?
There is no single height that optimally suits both. St. Augustine is generally kept at 2.5–4 inches, while common Bermuda is generally kept around 0.5–2 inches, depending on cultivar and mowing system.
Is 3 inches too high for Bermuda?
A 3-inch cut is generally higher than the usual range for common Bermuda. Follow recommendations for your cultivar and mower system.
Will a low Bermuda cut damage St. Augustine?
It can. A low cut may scalp St. Augustine, remove too much leaf, expose soil, and leave the turf more vulnerable to heat, drought, and weeds.
How much grass should I remove in one mowing?
Remove no more than one-third of the leaf blade at a time. If the lawn is too tall, lower the height gradually over several mowings.
Which grass tolerates shade better?
St. Augustine is generally more shade-tolerant, though tolerance varies by cultivar. Bermuda usually performs best in full sun.
Should I use one mower setting for the whole yard?
Use one setting only if it suits the grass and cut goal across the whole yard. When the species need different heights, maintain separate zones or choose one grass for the area.
What should I check before fertilizing a thin lawn?
Check sun, drainage, irrigation coverage, mowing height, and soil condition. A soil test can guide fertilizer decisions; fertilizer alone will not fix a poor site match.
(This article was written by one of our staff writers, Victor Dempsey. Visit our Meet the Team page.)
