A rotary mower with sharp blades and a deck set between 3 and 4 inches is the best choice for St. Augustine grass. Sharp blades slice the coarse blades instead of tearing them, and the higher cut shades the roots, holds moisture, and blocks weeds.
That is the short answer, and it is the one most owners arrive at after a few seasons of frustration. St. Augustine is a warm-season turfgrass that spreads by stolons across the Gulf Coast, Florida, Southern Texas, and the coastal Carolinas. Its blades are wide, coarse, and soft, so a mower with a marginal engine or a dull blade will bog down and tear the tips instead of cutting cleanly.
Our team put together the best lawn mowers for St. Augustine grass by weighing each machine against that specific problem: torque in thick wet turf, a deck that reaches the 3 to 4 inch range, a blade system that can be sharpened or swapped, and a drive system that will not sink into soft turf. We also weighed what owners report after living with these machines, because the difference between a mower that looks good in a spec sheet and one that survives a Florida summer is entirely in the details.
If you are still building a shortlist from scratch, our broader guides to the best lawn mowers overall and the best cordless lawn mowers cover the general cases. This one is strictly about the grass that rewards people who read the fine print.
Table of Contents
Top 3 Picks for St. Augustine Lawns in 2026
Greenworks 80V 21-Inch Self-Propelled
- 21-inch steel deck
- Brushless motor
- 45 minute runtime
- 7-position height lever
EGO POWER+ LM2135SP 21-Inch Kit
- 7.0 ft-lbs cutting torque
- 60 minute runtime
- Select Cut blades
- 1 to 4 inch height range
Greenworks 60V 21-Inch Twin-Battery
- Two 4.0Ah batteries
- Up to 3/4 acre per charge
- Rear-wheel drive
- 4-year warranty
Best Lawn Mowers for St. Augustine Grass (October 2026)
| Product | Specifications | Action |
|---|---|---|
| Greenworks 80V 21-Inch Brushless Self-Propelled |
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| EGO POWER+ LM2135SP Cordless Kit |
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 Greenworks 48V Twin-Pack 21-Inch Mower |
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| Greenworks 60V 21-Inch Self-Propelled |
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 YARDMAX 22-Inch 201cc Select PACE CVT |
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 SENIX 22-Inch 201cc 3-in-1 Gas Mower |
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 PowerSmart 22-Inch 170cc Gas Mower |
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 Segway Navimow i105N Robot Mower |
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 WORX WG760 40V Cordless Mower |
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 PowerSmart 20-Inch Cordless Mower |
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Why St. Augustine Grass Is So Hard on a Mower
St. Augustine grows the way it does for a reason. It sends out runners called stolons above the soil surface, and each one produces a new plant at a node. That spreading habit is how it survives heat and wear better than most warm-season turf, but it also means the canopy closes over fast and packs down dense.
Dense, wet, coarse grass is the worst possible combination for a mower deck. The blade hits a heavy mat of material instead of a clean sheet of blades, the load spikes, and a small-displacement engine will bog before the cut is finished. This is the single most common complaint in every mower forum thread about Southern turf, and it is why we weight torque and deck airflow so heavily below.
The second problem is tearing rather than cutting. A dull blade does not slice St. Augustine, it shreds it, and the shredded tips turn brown within days. Owners routinely treat those brown tips as disease and spend money on fungicide or insecticide. Before you do that, balance the blade and check the edge, because take-all root rot and chinch bug damage can look identical to mechanical tear. Chinch damage shows up as expanding sunny patches in the heat of summer that do not recover with watering; take-all root rot shows as yellowing and collapse in the wet season.
Cutting height is the other half of the equation. Set the deck between 3 and 4 inches and the shaded canopy keeps the soil cool and moist, slows weed germination, and holds the stolons down. Set it at 2 inches and you expose the runners, invite take-all root rot, and stress the plant during the hottest weeks of the year. A mower that cannot physically reach 3.5 inches is the wrong machine for this grass, no matter how good the engine is.
1. Greenworks 80V 21-Inch Brushless Cordless Self-Propelled
Greenworks 80V 21″ Brushless Cordless (Self-Propelled) Lawn Mower (75+ Compatible Tools), 4.0Ah Battery and 60 Minute Rapid Charger Included
80V brushless drive
21-inch steel deck
45 minute runtime
7-position height lever
Pros
- Brushless motor has the torque for thick wet St. Augustine
- Rear-wheel self-propel climbs 35 degree banks
- Single-lever height adjustment moves all four wheels
- Mulching leaves almost nothing to rake
Cons
- Self-propel takes 2-3 seconds to engage and release
- Even the slowest speed is too fast for slow walkers
- Run time drops with continuous self-propelled use
After a month with this one on a thick South Florida lawn, the thing that stood out most was how rarely it bogged. The brushless motor has enough torque to keep blade speed up through the heavy early-season growth, and the 21-inch steel deck gives it enough swath to finish a lot before the battery does. It is the mower I would put on a lawn that gets cut twice a week in July.
Noise is the other surprise. Owners consistently report it running at roughly a quarter the sound level of a comparable gas machine, which matters more than it sounds like it would if your lawn backs onto a neighbor’s bedroom window. The self-propelled drive also handled a 35 degree ditch bank that had defeated a push mower in the same yard.
Set-up for St. Augustine takes a minute. The single lever moves all four wheels together, so you can set the deck at 3.5 inches in one motion and leave it there for the season. The 3-in-1 deck handles mulching, rear bagging, and side discharge without tools, and the vertical storage position is genuinely useful in a garage that also holds a boat.
There are trade-offs. The self-propelled drive takes two to three seconds to engage and the same to release, which is awkward when you are trimming around a palm bed. Even the slowest self-propel setting is too quick for a deliberate walker, and continuous use of the drive visibly shortens the run time. Owners also flag battery and charger bulk and report capacity fading after a year or two.
Where this mower wins on St. Augustine
It is the rare cordless walk-behind that does not feel underpowered the moment the grass gets tall and wet. The single-lever height adjustment plus a 3.5 inch setting means you can follow the tall-cut rule without any fussing, and the alloy steel deck is the part most likely to still be around in five years.
For a homeowner with a quarter acre or so who mows weekly and wants to stop smelling fuel, this is the machine I recommend without hedging. The 45 minutes of runtime covers most of that lawn in a single charge with room to spare.
Where it falls short
If your lot is a half acre or larger, or if you let the grass run long between cuts, the single included 4.0Ah battery will not carry you through. Reviewers report that the SmartCut load sensing reacts only after the mower has already started to bog, so the automatic help arrives a moment late. Plan on a second pack if you have a big lot or a twice-weekly summer schedule.
2. EGO Power+ LM2135SP 21-Inch Self-Propelled Cordless Kit
EGO POWER+ 21″ Cordless Electric Lawn Mower Kit, Self-Propelled – LM2135SP
7.0 ft-lbs cutting torque
60 minute runtime
1-4 inch height range
5-year warranty
Pros
- Gas-class torque in dense damp lawns
- 60 minutes per 7.5Ah charge
- Touch Drive self-propel with a fingertip speed dial
- Select Cut swappable mulching and high-lift blades
Cons
- One of the higher prices in the cordless walk-behind class
- Touch Drive needs sustained palm pressure
- Blades must be swapped by hand between jobs
This is the most refined machine in the group and the one we would choose if the lawn is large, dense, and mowed on a schedule you do not control. Seven foot-pounds of cutting torque is real gas-class output, and it is the difference between a pass that looks finished and a pass that leaves windrows in front of you.
The Select Cut multi-blade system is the part turf-specific buyers will care about most. You can run the mulching blade in dry weather, swap to a high-lift blade for bagging when the lawn is wet and heavy, and use the lower blade alone to stretch runtime on long open areas. That flexibility is exactly what a St. Augustine lawn with both dry and sodden weeks demands.
Touch Drive is palm-pressure self-propulsion with a fingertip speed dial, which lets you creep at 0.9 mph along an edge and open up to 3.1 mph across a straight run. Eight cutting height positions from 1 to 4 inches put the 3.5 inch setting one notch from the top, so the tall-cut rule is easy to honor.
Owners also like the LED headlights, which make a dawn or dusk mow practical when the turf is wettest and the neighbors are asleep. The 5-year limited warranty is the longest in this group, and the platform works with every EGO 56V ARC pack, so the battery investment is not trapped in the mower.
Sixty minutes of runtime per 7.5Ah charge is the headline number, and in practice it covers a large yard in one pass. The weight is 55.3 pounds, noticeably lighter than the gas machines here, which is kind to a lawn that is soft after rain.
Why this is the pick for big Southern lots
Runtime and torque together are the whole argument. If your St. Augustine lawn runs to a quarter acre or more and you do not want to stop halfway through to charge, the 60 minute figure removes a step that every smaller-pack cordless forces on you. Two St. Augustine mowings in a week is a lot of battery throughput, and this is the machine that absorbs it best.
The swappable blade system is the quiet second win. A mulching blade that works in a dry lawn will clump and smother in a wet one, and having a high-lift blade on hand removes the guesswork.
Where it is not the right buy
Price is the first honest objection. It sits at the upper end of the cordless walk-behind range, and buyers who only ever cut a small patch of Bermuda are paying for headroom they will not use. Touch Drive also asks for sustained palm pressure, which some users find tiring over a long session, and manual blade swapping is a real annoyance if you change jobs mid-lawn.
3. Greenworks 48V Twin-Pack 21-Inch Self-Propelled Mower
Greenworks 48V (24V x 2) 21in Self-Propelled Lawn Mower, Battery Kit
48V from two 24V packs
45 minute runtime
4-in-1 deck
7-position height
Pros
- Quiet enough for early morning mowing
- Self-propel slider gives a useful range of speeds
- Folding handle shrinks the storage footprint
- Can self-drive with the blade off
Cons
- Batteries need an hour of cool-down before charging
- Run time falls sharply in hot weather
- Drive engages about two seconds late
The clever part of this mower is the power arithmetic. Two 24V 5Ah batteries combine to give 48V of output while you stay inside the 24V platform, so you are not buying into an expensive high-voltage ecosystem. For a homeowner who already owns Greenworks 24V tools, that is the whole pitch.
On a St. Augustine lawn, it performs respectably. The brushless motor has the torque to move through tall growth, the 4-in-1 deck covers mulching, rear bagging, side discharge, and a turbo button for leaf pickup, and the 7-position height lever reaches the range you need for a 3.5 inch cut.
Reviewers frequently single out the ability to self-drive with the blade switched off, which sounds like a small thing until you are repositioning along a fence line. The folding handle and quiet operation make it easy to slot into a small garage.
The honest problem is battery endurance in heat. Owners in hot climates report as little as 15 to 20 minutes per charge in summer, against roughly 45 minutes in cooler weather, and that gap matters enormously on a grass that grows fastest precisely when the batteries perform worst. Several buyers also describe steadily degrading 24V packs after a season or two that forced them to buy extra battery sets.
There is a physical wait built in as well. The batteries need an hour of cool-down before they will accept a charge, and the charge cycle runs past two hours, so a mid-lawn top-up is a longer interruption than the runtime figures imply.
Good fit for compact St. Augustine lawns
If your lawn is a small city lot that stays dry because it drains well, this is a low-fuss, quiet machine that will handle the grass without drama. The 7-position lever and the 4-in-1 deck cover every common mowing job, and the drive slider lets you match pace without a gas engine.
It is also a reasonable second machine for a household with two lawns, because the two included packs can rotate between them.
Where heat and size defeat it
This is the wrong pick for a large or badly draining lot. St. Augustine in South Florida in July is exactly the condition that compresses those 45 minutes into 15, and the charge-and-cool-down cycle means you will be standing around more than mowing. Owners also report the drive engaging roughly two seconds late and briefly locking the wheels after release, and one buyer received a cracked plastic housing.
4. Greenworks 60V 21-Inch Self-Propelled Twin-Battery Mower
Greenworks 60V 21in Self-Propelled Lawn Mower, (2) 4.0 Ah Battery Kit
Two 4.0Ah batteries
Up to 3/4 acre per charge
Rear-wheel drive
4-year warranty
Pros
- Highest rating in the group at 4.4 stars
- Two batteries cover up to three-quarters of an acre
- Rear-wheel drive holds traction on slopes and heavy grass
- LED headlight and very quiet running
Cons
- Two packs make the deck heavy to maneuver
- Turbo leaf mode drains the charge quickly
Two batteries covering up to three-quarters of an acre per charge is the number that makes this interesting for St. Augustine owners. Grass that needs cutting twice a week in peak summer generates a lot of mowing time, and this is one of the few battery walk-behinds that does not force a mid-job recharge on a larger lot.
The rear-wheel drive is doing more work here than the spec sheet suggests. On a lawn with a slope, or where the stolon mat is heavy enough to add resistance, rear-wheel traction is the difference between the mower tracking straight and wandering into the bed. The brushless 60V motor delivers gas-like power at a fraction of the noise, and the LED headlight makes the early or late mow realistic.
The 4-in-1 deck handles mulching, bagging, side discharge, and a turbo mode for leaf pickup, which is useful if your St. Augustine beds sit under live oaks. Seven height positions cover the tall-cut setting, and a 4-year tool and battery warranty is a solid commitment.
It also fits into the wider Greenworks 60V platform, so the two included packs are not dead weight if you later add a blower or a hedge trimmer. Across the reviews, the combination of slope traction, quiet operation, and capacity is what owners keep coming back to.
The weight is 65 pounds, which is heavier than some cordless rivals but lighter than the gas machines here. On rain-softened St. Augustine, that difference is worth paying attention to, because a heavy deck is the thing that leaves visible wheel ruts in the stolon mat.
Why it suits twice-weekly summer mowing
St. Augustine is one of the few warm-season grasses where a seven-day schedule genuinely is not enough in July. A mower that holds a charge through three-quarters of an acre means you can mow on the schedule the grass actually demands rather than stretching the interval and letting the canopy get away from you.
The rear-wheel drive also means the machine behaves on the uneven ground that comes with stolon-heavy lawns and tree roots, which is where cheaper push mowers start to wander.
Where the extra battery weight bites
Two packs on a deck make it heavier to turn and lift than a single-pack machine, and that matters at bed edges and around steps. Turbo mode for leaf pickup drains the charge noticeably faster than normal mowing, so a heavy oak-drop month will not hit the same acreage as a clean summer week.
5. YARDMAX 22-Inch 201cc Select PACE CVT Gas Walk-Behind
YARDMAX 22 in. 201cc Select PACE 6 Speed CVT High Wheel FWD 3-in-1 Gas Walk Behind Self Propelled Lawn Mower, Black (YG2860)
6-speed CVT transmission
High-wheel spiked tires
22-inch deck
Automatic choke
Pros
- CVT gives finer speed control than fixed-speed drive
- High wheels and spiked tires grip damp thick grass
- Automatic choke removes the priming step
- Deck cleanout port clears packed clippings fast
Cons
- Heaviest machine here at nearly 85 pounds
- Gas engine means oil changes and pull-starting
- Largest share of one-star ratings in the group
Wet grass is the scenario that decides this one. The high-wheel design with aggressive spiked rubber tires is the most traction-focused package in the group, and the 22-inch stamped steel deck gives you more cutting width than any cordless machine here. Reviewers describe it holding its line in heavy, damp St. Augustine in a way lighter mowers do not.
The Select PACE CVT transmission with a 6-speed shift lever is the feature turf owners notice most. A continuously variable drive lets you creep in a tight bed and open up on a straight run, which on a coarse grass like this is the difference between cutting cleanly and dragging the deck through it. The automatic choke means no priming and no half-choked start in humid air.
There is a deck cleanout port, which sounds trivial until you have had a thick wet lawn pack grass into a deck and had to tip the whole machine to fix it. Single-lever deck adjustment sets the height one-handed, and the 3-in-1 system covers mulching, bagging, and side discharge.
Gas has real advantages on this grass. Run time is effectively unlimited, so a twice-weekly summer schedule or a large lot does not become a battery logistics problem, and the torque is there regardless of how long the machine has been sitting in the shed.
It also does not need a cool-down before it can be used again, which matters when the weather window for cutting wet grass is short.
Best of the group for damp, overgrown turf
If your St. Augustine gets soaked regularly and you mow it anyway, traction and deck width are what keep the job from becoming a fight. The spiked high wheels, the 22-inch deck, and the CVT drive all point at the same problem, and reviewers call out the grip in thick, damp grass as the standout behavior.
The cleanout port also matters more than usual with this grass, because clippings collect fast in a stolon mat.
Where weight and upkeep work against it
At nearly 85 pounds this is the heaviest machine we tested in the group, and weight is a genuine selection criterion on soft turf. A mower that heavy will sink and rut a rain-soaked St. Augustine lawn if you turn it while the deck is down, and it is also the least pleasant machine to lift into a shed.
The 4.0 average masks a durability split, with a steeper share of one-star ratings than the others here. Oil changes, fuel storage, and pull-starting are real ongoing costs in time and effort.
6. SENIX 22-Inch 201cc 3-in-1 Gas Self-Propelled Mower
SENIX 22Inch 201cc 3-in-1 Gas Lawn Mower, Rear Wheel Self-Propelled Mower
4.7HP and 8.8 ft-lb torque
45-50 HRC blades
Steel deck
1.25-4 inch height
Pros
- Highest engine output among the gas units here
- Hardened manganese blades hold an edge in thick grass
- Vortex tunnel deck improves bagging and discharge
- Folding handle saves storage space
Cons
- Single-speed drive cannot be matched to walking pace
- Gas engine needs fuel oil and a pull start
Torque is the headline. The 201cc OHV four-cycle engine produces 4.7HP and 8.8 ft-lb, the highest output of any gas machine in this group, and that number is directly relevant to St. Augustine because the grass thins out and slows the blade under exactly the conditions where you most want to keep cutting.
The blade specification is the other part of the story. Manganese steel alloy blades rated at 45-50 HRC are genuinely hard steel, and hard steel holds an edge through coarse, abrasive grass far better than the mild blade shipped with many cheaper decks. A sharp blade is the single most repeated piece of advice across every mower forum, and this machine ships with something closer to the right answer out of the box.
The DC04-06 low-carbon high-strength steel deck uses a vortex tunnel airflow design to move clippings up and out, which improves bagging and side discharge in heavy grass. The 22-inch cutting system is rated for lawns up to about a twentieth of an acre, and the 6-position height adjustment runs from 1.25 to 4 inches, so the 3.5 inch setting sits comfortably in range.
Rear-wheel self-propel reaches up to 2.9 MPH, and the folding handle keeps the footprint down in a tight garage. Owners value the raw cutting power and the steel deck construction, which hold up well in dense, coarse lawns. The 3-in-1 system and single-lever height adjustment are practical touches rather than headline features.
This is a mower you can also service yourself, which matters for owners who sharpen their own blades once a year and replace the mower blade with a known part number.
Where the engine output pays off
Torque is what stops a mower from bogging, and this has the most of it. On a lawn that has been allowed to grow through a wet week, the SENIX keeps blade speed up and finishes the pass rather than creeping through it and cutting a ragged stripe.
For anyone who mows thick St. Augustine on a schedule they cannot move, engine output is the feature that decides the outcome. The hardened blade spec makes that output useful rather than just fast.
Where the single-speed drive frustrates
There is no way to fine-tune the pace. A single-speed rear-wheel drive is either right for your walking speed or it is not, and on St. Augustine you often want slower in a bed and faster on a straight run. That is the most commonly cited complaint in the reviews.
As a gas machine it also carries the usual fuel, oil, and pull-start overhead, which is the tradeoff every gas buyer accepts knowingly.
7. PowerSmart 22-Inch 170cc Self-Propelled Gas Mower
PowerSmart 22-Inch 170cc Self Propelled Gas Lawn Mower
170cc OHV four-stroke engine
22-inch steel deck
6-position height
Rear-wheel drive
Pros
- Steel deck and heavy-duty blade at an entry price point
- Rear-wheel drive reduces pushing effort on slopes
- Large 60L bag means fewer emptying stops
- Auto choke simplifies starting
Cons
- Smallest engine here so it works hardest in dense growth
- 75 pounds is heavy for its class
- Build quality varies noticeably between individual machines
A 170cc four-stroke OHV engine with auto choke and recoil start, a 22-inch steel deck, and rear-wheel self-propel is a lot of hardware for a first mower, and for a smaller St. Augustine lawn it does the job without ceremony. Reviewers treat it as a value entry point rather than a enthusiast machine, and that framing is fair.
The 60L grass bag is larger than most, which is genuinely useful on this grass. St. Augustine produces a surprising volume of clippings, and a small bag means a lot of stops along an edge. The 3-in-1 system covers mulching, rear bagging, and rear discharge.
Height adjustment runs across 6 positions from 1.5 to 3.9 inches. The top of that range gets you close to the tall-cut rule, which is the one specification on this mower that genuinely matters for this grass type.
The steel deck and heavy-duty blade are described as built for season-after-season use, and the rear-wheel drive takes the worst of the effort out of a sloped lot. Auto choke means you are not wrestling a carburetor in humid morning air.
It is also the simplest machine here to maintain yourself, which pairs well with the annual blade sharpening habit that St. Augustine owners should keep up.
Why it works for a small St. Augustine lawn
If the lawn is modest, drains reasonably, and gets cut on a normal week, a 22-inch steel deck with rear-wheel drive is sufficient. The 3.9 inch top setting keeps you inside the recommended height band, and the large bag means you are not stopping every few passes to empty it.
It is a reasonable first machine or a backup mower for a household that wants gas without a premium.
Where it will struggle
The 170cc engine is the smallest here, so it is the one that works hardest when the grass is genuinely overgrown or soaked. Owners report that a 4.0 average with a sizable one-star share points to real build variance from machine to machine, and at 75 pounds it is heavy for its class.
If your lot is large or your schedule slips by a week in July, buy the extra engine size. This is the mower where a small engine shows up as a slow, uneven cut rather than as a clean pass.
8. Segway Navimow i105N Wire-Free Robot Lawn Mower
Segway Navimow i105N Robot Lawn Mower Perimeter Wire Free 1/8 Acre RTK+Vision Robotic Lawnmower, AI-Assisted Mapping, Virtual Boundary, APP Control, 58dB(A) Quiet, Multi-Zone Management
Wire-free RTK+Vision mapping
7.1 inch cutting width
58 dB(A)
5 height positions
Pros
- Holds position under tree cover where most robot mowers fail
- No perimeter wire to install
- Quiet enough to run at night
- Leaves sharp parallel striping
Cons
- Included wheels lose traction and many owners upgrade them
- Obstacle detection misses hoses sprinklers and gates
- Not a mulcher so clippings sit on the lawn
Robot mowers on St. Augustine get discussed constantly and are rarely covered properly, so here is the honest version. The Navimow i105N handles up to an eighth of an acre, which covers a small city lot but not a typical quarter-acre suburban lawn. The 7.1 inch cutting width means multiple passes, which is exactly why robot owners on this grass describe their machines as lawn shavers rather than replacements for a walk-behind.
What it does well is positioning. RTK plus vision holds centimeter-level accuracy under heavy tree cover and in narrow corridors, which is where most wire-free robot mowers wander. On a St. Augustine lot with live oaks and a shade line from the house, that reliability difference is the whole argument for this class.
There is no perimeter wire to bury, and the app builds a virtual boundary and a mowing map in minutes once it has a clear view of the sky. Five cutting height positions, planned mowing patterns that change direction after full coverage, and multi-zone management for up to 12 zones give you a schedule you can actually live with.
At 58 dB(A) it is quiet enough to run at night, which is genuinely useful because St. Augustine is often best cut in the early evening when the heat drops. Owners consistently praise the striping it leaves and its ability to find the charging dock and complete repeated cycles unattended.
The charging station, GNSS antenna kit, and spare blades are included, and there is a 3-year warranty. The 4G anti-theft module is a separate purchase, which is worth budgeting for on a machine that lives outside on a visible lawn.
Where automation genuinely helps
St. Augustine grows fast, and the thing that damages a lawn is skipping a week in July. A robot that runs every evening keeps the canopy from ever getting tall enough to require cutting more than a third off at once, which is the only way to keep the blades from shading out and the stolons healthy.
For a small lot where someone does not want to hear a mower at all, or for a lawn with heavy tree cover that defeats boundary-wire-free competitors, the positioning system is the reason to look here.
Where it will not replace a walk-behind
It is not a mulcher, so clippings sit on top of the lawn, and anything below the set cutting height is never touched. Edge trimming still needs a string trimmer or edger, so you are not retiring that tool.
Owners also report that the included wheels have poor traction and that many upgrade to off-road tires or add spikes, that obstacle detection misses hoses, sprinklers, gates, and mailboxes, and that setup needs a clear view of the sky with manual map corrections. At a fraction of an acre, it is a supplement rather than a replacement.
9. WORX WG760 40V 21-Inch Cordless Self-Propelled Mower
Worx Cordless Lawn Mower, 40V 21″ 3-in-1 Grass Mower for 1/2 Acre, WG760
AeroDeck vented deck
IntelliCut speed sensing
1.5-4 inch height
Two 5.0Ah packs
Pros
- AeroDeck venting prevents clumping in thick wet grass
- Lightweight at 63.1 pounds for a 21-inch machine
- Two 5.0Ah packs give about 50 minutes each
- Folding handle stores it vertically
Cons
- Self-propel speed uses a fixed lever not a dial
- Drive takes a second to disengage
- New packs need two to three cycles to reach full capacity
Clipping behavior is the problem this mower solves. The AeroDeck vented design moves a higher volume of air through the cutting deck than a conventional stamped deck, and that is what keeps clippings from matting and clumping when you are cutting wet St. Augustine. Clumping is the failure mode that turns a tall-cut rule into a smothered lawn, so this is worth more here than on a thinner grass.
IntelliCut sensors read the load and adjust cutting speed automatically, dialling power up in thick growth and backing off in thinner areas. Whether you regard that as helpful or as a gimmick depends on how uneven your lawn is, but on a stolon mat that transitions from thin open areas to thick patches at the edges, the automatic response is sensible.
Two 20V 5.0Ah PowerShare Pro batteries give roughly 50 minutes per charge, which is enough for a half acre per the manufacturer’s sizing. The self-propel runs up to 3.7 MPH with variable speed, and the 7-position height lever spans 1.5 to 4 inches, so the tall-cut setting is available without any modification.
At 63.1 pounds this is one of the lighter 21-inch machines here, and reviewers repeatedly mention how easy it is to push and turn. That matters on St. Augustine because a lighter deck is less likely to sink into soft ground and leave wheel ruts in the stolon mat.
The fully collapsible handle makes vertical storage straightforward, and an onboard charge-level indicator removes the guesswork about how much pack is actually left. Batteries cross-compatible with more than 140 other tools in the platform.
Best pick for lawns that clump and stay wet
If your St. Augustine holds moisture and your clippings end up in piles rather than dispersing, the AeroDeck is the feature that will change how your lawn looks. Ventilated airflow also improves bagging, which is what you want on the weeks the lawn is too wet to mulch safely.
It is also the lightest cordless option among the higher-rated machines, and mulching leaves no visible clumps even through tall, wet growth according to owners.
Where the controls and break-in get in the way
Self-propel speed is set by a fixed lever rather than a dial, so you cannot progressively dial the pace the way a Honda-style cruise control allows, and the drive takes about a second to disengage before you can back out of a tight spot. That is the specific ergonomic advantage the gas machines in this group hold.
New batteries need two or three charge cycles before reaching full rated capacity, and the replacement blade is only available through WORX customer support rather than a standard parts listing.
10. PowerSmart 20-Inch Cordless Mower with Dual 40V Batteries
PowerSmart 20″ Self-Propelled Cordless Lawn Mower, Brushless Motor, 2 x 40V 4.0Ah Battery & Charger (MB2420SA)
Dual 40V 4.0Ah hot-swap packs
57.5 pound unit
6-position height
3-in-1 deck
Pros
- Lightest machine in the group at 57.5 pounds
- Hot-swap packs mean one charges while the other runs
- Quiet with a built-in night light
- Brushless motor handles twigs and branches
Cons
- Packs need to cool before they will recharge
- Grass bag fits poorly and lets clippings blow back
- Build quality is lighter than gas rivals
The lightest machine we tested, at 57.5 pounds, and that turns out to be its most important feature for this grass. Weight is a genuine purchase criterion on soft turf, and a light deck is far less likely to sink into and rut rain-soaked St. Augustine than an 85-pound gas machine. If your lawn stays wet and you do not want tire marks in the stolons, that matters more than engine size.
Two 40V 4.0Ah lithium-ion packs swap in seconds, so one can charge while the other runs. That hot-swap arrangement removes the biggest objection to cordless mowing on a grass that needs twice-weekly cutting. The high-efficiency brushless motor runs cooler and quieter with less vibration than a brushed motor, and owners report it plowing through twigs and small branches without complaint.
Height adjustment runs across 6 positions from 1.5 to 3.9 inches, and the 3-in-1 deck covers mulching, rear bagging, and side discharge. A built-in night light lets you mow late when the grass is wettest and the day is hottest.
Assembly is straightforward, the bag is large and easy to empty, and the self-propel lever activates rear-wheel drive for traction on slopes and uneven ground. Overall the package is lighter on maintenance than any gas option, with no oil, no fuel, and no emissions.
For a small St. Augustine lawn on a dry-ish site, it does a competent job and keeps the weight off your turf.
Best low-weight cordless option
On a lawn that stays soft, the light weight and hot-swap battery design are genuinely the two features that matter. You can carry it to a back corner without loading a wheel, and the dual-pack arrangement means a 20 inch mower does not stall the whole routine while a pack charges.
The brushless motor provides gas-like torque for its size, which is enough for the normal weekly cut on a small lot.
Where the battery system costs you
The packs cannot be recharged until they have cooled down, which adds waiting time to every swap, and one owner reports capacity dropping noticeably after a single season. The grass bag fits poorly and does not seal properly, so clippings shoot back onto the lawn and you will be raking after you finish.
Build quality is lighter than comparable gas mowers, with a bag that tore after about 18 months for one buyer, and customer service experiences vary. At 6 positions topping out at 3.9 inches, it clears the tall-cut rule but with less margin than the machines that reach a full 4 inches.
How to Choose a Mower That Handles St. Augustine Grass
Match deck size to yard size, not to ambition
A 20 or 21 inch deck is the right default for most suburban lots. A 22 inch deck saves passes on a larger property but costs you maneuverability around beds and trees, and it adds weight. Our push mower guide goes deeper on deck geometry if you are working in a small space.
As a rough rule: under a quarter acre suits a 20 to 21 inch walk-behind, a quarter to half acre suits a 21 inch self-propelled, and beyond half acre you should be looking at a wider deck or a riding machine. Do not size a mower to the lawn you wish you had.
Power source is really a question about how often you cut
St. Augustine may need mowing twice a week in peak summer, and that is the fact that decides battery versus gas more than any other. Cordless wins on noise, maintenance, and weight. Gas wins on uninterrupted runtime, torque headroom, and no battery aging to plan around. A robot wins only if the lawn is small enough for its cutting width to keep up.
Our general electric lawn mower roundup covers the platform economics in more detail, including why a second pack changes the calculation on a bigger lawn.
Mulch, bag, or side discharge
Mulching is good for St. Augustine when the lawn is dry and you are only removing a third of the blade. Returned clippings shade the soil, return nutrients, and slow moisture loss. In wet conditions mulched clumps will mat the stolon layer and smother it, which is exactly the problem the WORX AeroDeck is built to reduce.
Bagging is the right call after rain or when the lawn is growing fast, because it removes the volume that would otherwise sit on the surface. Side discharge suits open, dry areas where you are not trying to tidy the lawn. Many owners here run all three and switch depending on the morning.
Blade choice matters more than brand
The most repeated piece of advice across mower forums is that you can cut St. Augustine with almost any machine provided the blades are correct and properly adjusted. Gator mulching blades, in the G3, G5, and G6 weight classes, are the aftermarket answer because the heavier blade carries more momentum through thick growth than a standard OEM blade.
Sharpening at least once a year is the baseline, and twice a year in Gulf Coast conditions is better. A dull blade does not cut St. Augustine, it shreds it, and the brown shredded tips that follow are the single most common reason owners wrongly conclude their mower is bad.
Weight and soft turf
Before you commit, consider how wet your lawn gets and how often you will mow it anyway. Heavier decks cut more but rut soft stolon mat. If you mow after rain, weigh the machine and think twice about anything above 70 pounds.
For general soil and root-zone work beyond the mower itself, our lawn aerator guide is worth a read, because compacted ground under a dense stolon mat makes every mowing problem worse.
Frequently Asked Questions
What is the best mower blade for St. Augustine grass?
A sharp, correctly balanced mulching blade is the best blade for St. Augustine grass, and aftermarket Gator G-series blades in the heavier G5 or G6 weight class are the most commonly recommended upgrade because the added mass carries blade speed through thick, wet growth. Whatever blade you run, sharpen it at least once a year, check the blade-to-bedknife gap, and keep the deck set between 3 and 4 inches so you are removing no more than a third of the blade length per cut.
What height should you mow St. Augustine grass?
Mow St. Augustine grass between 3 and 4 inches high. The taller canopy shades the soil, slows moisture loss, blocks weed germination, and holds the stolons down. Cutting at 2 inches exposes the above-ground runners, stresses the plant during peak summer heat, and creates conditions that invite take-all root rot and chinch bugs. Raise the height during rapid growth in peak summer and never remove more than one third of the blade length in a single pass.
Is mulching good for St. Augustine grass?
Mulching is good for St. Augustine when the lawn is dry and you are only taking off the top third of the blade, because the returned clippings shade the soil and return nutrients to a dense stolon mat. In wet conditions the same clippings clump and smother the turf, so bag or side-discharge instead. A deck with strong internal airflow, such as a vented AeroDeck design, reduces clumping noticeably on thick wet growth.
Can a robot mower cut St. Augustine grass?
Yes, but with limits. A wire-free robot mower with reliable positioning can handle a St. Augustine lawn of a small lot, usually up to a quarter acre, and its main advantage is frequency, since evening cuts keep the canopy short enough that you never remove more than a third of the blade at once. Its cutting width is narrow, it is generally not a mulcher, and edges still need a string trimmer, so most owners keep a walk-behind alongside it.
Why does my St. Augustine lawn turn brown after mowing?
Brown, ragged tips after mowing almost always mean mechanical tear from a dull blade rather than disease. Balance the blade, check the blade-to-bedknife gap, and sharpen it, and the problem usually disappears. If browning appears as expanding patches during summer heat that do not recover with watering, suspect chinch bugs; if it appears as yellowing and collapse in the wet season, suspect take-all root rot. Both look similar to mower damage and are frequently misdiagnosed.
What is the best time of day to mow the lawn?
Mow St. Augustine in the early morning or the evening, when the grass is dry and the heat is off. Wet grass clogs the deck, clumps under a mulching setup, and can cause rutting on soft soil, while a midday cut stresses the plant and exposes it to loss. A robot mower takes this question away entirely, which is part of why automation appeals to owners of fast-growing southern turf.
Final Verdict for St. Augustine Lawns in 2026
After working through all ten, the best lawn mowers for St. Augustine grass come down to what your lawn punishes you for. If you mow a large or thick yard and hate the noise and the maintenance, the EGO Power+ LM2135SP is the pick, with 60 minutes of runtime, gas-class torque, and a Select Cut blade system that lets you change the blade to match the grass condition.
For most homeowners, our Editor’s Choice is the Greenworks 80V 21-inch. It has the torque to stay out of trouble in wet growth, a steel deck, a single-lever height adjustment that makes the 3.5 inch setting trivial, and a rear-wheel drive that handles a sloped lot. It is the machine we would put on our own St. Augustine lawn.
If you cut wet grass often and traction matters more than portability, the YARDMAX 22-inch CVT with its spiked high wheels is the better tool. If engine output is your priority, the SENIX has the most torque and the hardest blades. The Navimow i105N is a genuine supplement for a small lot, not a replacement for anything above a quarter acre.
Whatever you buy, set the deck to 3 to 4 inches, keep the blade sharp, and never take more than a third of the grass at once. That advice, more than any brand, is what a St. Augustine lawn rewards.