RELEASED 2025.03REASSESSED 2026.08.06

Gardena

Gardena smart Sileno free 800

Name: Gardena smart Sileno free 800
Brand: Gardena

Removes the perimeter-wire setup barrier that kept robotic mowing a niche installation job. Satellite positioning with app-drawn boundaries holds roughly 10 to 30 cm, corrected over the internet through the included smart Gateway, so the dependencies move from buried copper to sky view and a working connection. It reached market in 2025, several seasons after consumer RTK mowers were already selling at comparable prices.

ReplacesGardena Sileno CityThe previous generation of this line.

Autonomy Ladder

Why Level III.

One five-rung scale, every category, from acting only on command to working unsupervised anywhere.

VGeneralized AutonomyAny task, any setting. No consumer robot has reached it.
IVEnvironmental AutonomyHandles new obstacles and re-plans in real time; rare in consumer products.
To reach Level IVSustained operation across sessions, including layouts and conditions it has not met before.
IIIConditional AutonomyThis robot

Gardena smart Sileno free 800 finishes whole jobs in a space it already knows, and still needs a person at the edges.

Navigation and control
GPS geofencing with automatic boundary learning; no RTK precision.
Why this level
- Satellite positioning with app-drawn virtual boundaries provides systematic, repeatable coverage without a perimeter wire, and the mower completes a full lawn unattended.
- Published positioning accuracy is roughly 10 to 30 centimeters, using GNSS supplemented by correction data pulled over the internet through the included smart Gateway, so boundary precision depends on both sky view and a working connection.
- Dense canopy degrades the satellite fix and returns intervention to the owner, which is what holds the classification at conditional rather than environmental autonomy.
Autonomy dimension 74 / 100 · 5 sources reviewed
IIAssisted AutonomyRuns preset routines; stalls at anything new.
IManual AutomationOne action on command; no independent operation.

How we assign a level →

Behind the classification

Sources we reviewed.

Verified5 sources reviewed

Sufficient public evidence across source types to publish a non-provisional classification.

Sources reviewed

Manufacturer documentation3 sourcesReviewed

Gardena smart Sileno free 800 product page, spec sheet, and app documentation; GPS boundary system technical overview.

Press & video reviews1 sourceOngoing

Press coverage and early reviews from gardening publications and robotics blogs; GPS accuracy and boundary-wire comparison pieces.

Let a Robot Handle the Lawn and Save $800 While You're …CNET

Longitudinal signal2 sourcesReviewed

Robovations dated log for this robot: 3 tracked entries spanning ~9 months.

How we evaluate evidence →

Robovations Score

How this number was reached

65of 100

CapableAt or above 41% of the 355 robots we scoreand 24% of the 79 scored robot lawn mowers

DeficientLimitedCapableStrongExemplary

What moved itpoints gained or lost against a typical robot

Carried by

Consumables97+2.2
Routine maintenance79+1.3
Support longevity70+0.7

Held back by

Field failure rate50−3.2
Edge-case recovery35−1.5
Operating envelope50−0.8

Capability40% of the score58What it does without you.

Task completion16% of the score68

Evidence

The Dutch besterobotmaaier.be review reports an even finish on open lawn with no visible tracks, but that grass is left standing along edges and in sharp corners "wat je handmatig moet bijwerken", and answers its own FAQ "Moet ik nog zelf de randen van het gazon maaien? Ja", a trimmer stays necessary. The Coolblue owner review is the counterweight: setup takes real effort and is "definitely not plug and play", but "once you've done that, you're done and don't need to touch it again".

Coverage and navigation10% of the score70

Evidence

Testberichte.de's editorial verdict of 21 Dec 2024 lists "navigiert zuverlaessig durch mittlere Gaerten" as a strength and "bei komplexen Hindernissen teils eingeschraenkte Funktion" as a weakness, and the Coolblue owner confirms zones defined in the app are kept. Set against that, a commenter on the nord-domotique test says mowing zones cannot be created, so "la tondeuse part dans tous les sens, ne fini pas la surface".

Edge-case recovery10% of the score35

Evidence

Two owner comments under the nord-domotique test describe the same stall: the first reports the mower takes over half an hour to leave its start point, that the GPS system cannot locate it, and that it "se retrouve regulierement hors zone et donc incapable de repartir, meme pour rejoindre sa base", with the app's assistance option ending in a 404. The second reports it simply stops for want of satellite. It is found stranded, cannot return to the dock on its own, and the in-app help path is broken, though besterobotmaaier.be and Testberichte report no rescues in open gardens.

Operating envelope4% of the score50

Evidence

The Coolblue owner is explicit that sky view governs whether it works at all: "it's VERY important that the view isn't obstructed. If you have large trees, the robot might lose its signal, making it unusable. Therefore, it's not suitable for every lawn." besterobotmaaier.be agrees that accuracy at the borders drops next to tall buildings or under trees, derates the official 800 square meters to a realistic 500 to 700 for a tidy result, and notes wet grass sticks underneath and marks the lawn in wet spells.

Dependability40% of the score60Whether it keeps doing it.

Field failure rate16% of the score50

Evidence

Testberichte.de aggregates 159 Amazon.de owner opinions at 2.7 stars, with 69 of them (43 percent) at one star against 46 at five, a split record rather than a sound one. The named mode in owner text is positional: the nord-domotique commenter reports repeated out-of-zone stalls the mower cannot recover from and is selling it ten months after purchase, while five Coolblue owners rate it top marks, so the mode is recurring and job-stopping where it occurs but not universal, and no hardware defect or recall appears in any source.

Software stability14% of the score65

Evidence

Updates ship over a channel that is unambiguously live, because positioning corrections themselves arrive over the internet through the smart Gateway; the vendor's service is in the path of the core function, not just the app. What is unestablished is behavior: the record's own con names firmware-update cadence as unproven, no independent account of any update's effect exists, and no owner reports an update breaking a working function. Updates ship, no regression pattern is reported, and there is no independent record either way.

Support longevity10% of the score70

Evidence

Gardena runs a genuine European parts and service operation inside Husqvarna Group, which vendor material properly establishes as a commitment. Against it, no support term is published for this model, it is a first-generation product, and the record notes that subscription or auto-shipping programs for consumables do not yet exist.

Ownership burden20% of the score86What it asks of you.

Routine maintenance12% of the score79

Evidence

The lightest published hands-on list among the wire-free machines here: roughly 10 to 15 minutes every two weeks on wheel wells and deck in heavy growth, monthly antenna housing and dock contact checks, and annual blade replacement. No perimeter wire to inspect, splice or re-lay, which removes the recurring chore that holds the wired machines down. Winter storage of mower and station is the seasonal item.

Consumables8% of the score97

Evidence

Annual blade replacement is the only scheduled consumable with no collector bag, no filters, no wire and no subscription. The qualifier the record supplies itself: on a rough or heavily seeded lawn, sets get bought on observation because Gardena publishes no mid-season interval.

middle half of the databaseits medianthis robot

Reported, not scoredneither measures how well the robot works

Five-year cost$2,300

Upper middle for robot mowers. $1,950 at purchase, roughly $150 of blade sets across five years at one set a year, an allowance for dock and antenna parts, and one battery pack toward year five. No subscription, no reference station and no wire to replace. The internet-delivered correction service is included with the smart Gateway and carries no stated fee.

Data postureCloud-dependent

Core function stops without the vendor cloud.

What leaves the homeNot documented

Read the full methodology →

FIT CHECK

Will the Gardena smart Sileno free 800 work on your yard?

Describe your yard using the controls. Each choice reads the spec sheet for you, flagging where the Gardena smart Sileno free 800 is built for your space and where it isn’t.

Yard size

Terrain

Grass type

Boundary setup

A classification of fit for the conditions you set, not a recommendation. Verdicts describe engineering design intent, not test results.

SPECIFICATION

The full spec sheet.

Manufacturer-published figures, measured against every robot lawn mowers we track.

Dimensions not publishedDimensional drawing

Key specificationsManufacturer-published

Wi-Fi: Supported✓

Official referencesProduct page

OWNERSHIP

Living with it.

First-generation GPS mower; boundary accuracy varies with satellite visibility.

Early reviews (Q1-Q2 2026) report 85-90% autonomous session completion in open yards; cloud cover and canopy shadow trigger manual recovery. No major firmware regression documented.

Owner effort~45 minhands-on per month

Consumables$85replaceable parts / yr

Reliability trendUnprovenowner-reported arc

What goes wrong · 4 documented · 0 self-recover

Occasional

GPS signal dropout under canopyMower halts; manual retrieval required.

Owner fixReduce canopy height or relocate dock.

Occasional

Blade dulling in thick grassRagged cut, slower progress, increased motor load.

Owner fixAnnual blade replacement (~$40-60).

Occasional

Dock charging contact corrosionCharging fails; mower returns to low-battery state.

Owner fixClean contacts quarterly with soft brush.

Rare

GPS boundary drift in magnetic interferenceMower may cross virtual fence near electrical wiring or metal structures.

Owner fixAdjust virtual fence boundary offset in app.

Step-by-step fixesWon’t Charge or Return to Its Base?Wet Grass or RainBlades Not Spinning or Not Cutting?All robot mower guides

Upkeep routine

Weekly52×/yr

Inspect wheel wells and cutting deck for compacted clippings if mowing in heavy-growth season; typical 10-15 minutes every 2 weeks in standard yards.

Monthly12×/yr

Inspect the satellite antenna housing for debris and clean the dock contacts if docking performance degrades.

Seasonal4×/yr

Clean charging dock contacts with soft brush to prevent corrosion; inspect for ant nests or water ingress. · Winter storage is clean the machine, charge the battery fully, and store the mower and its charging station somewhere dry and frost-free. The 18 V lithium pack is internal and stays in the machine. There is no fuel system and nothing to disconnect, and a lithium pack goes into storage charged rather than run down. Spring: check positioning and boundary behavior before the first cut of the season.

Yearly1×/yr

Replace the cutting blades. Robot mower blades are replaced, never sharpened: grinding weakens the protective coating and leaves an unbalanced part spinning unattended.

Safety notes

NoteBlade rotation during manual recovery: Blade does not stop automatically when mower is lifted. Power off via app before handling.

NoteGPS signal loss in electrical storms: Do not operate during thunderstorms. Manufacturer advises dock containment.

RECORD

How the assessment has moved.

Every announcement, release and reassessment behind the current classification.

Coming soon

Just launched

Active updates

Settled

Discontinued

Sep 2024 · AnnouncementGardena unveils smart Sileno free 800 wire-free GPS robotic mower
Mar 2025 · ReleaseReaches European retail in March 2025
Jun 2025 · NewsEarly press coverage highlights GPS accuracy limits in shaded residential yards
Jul 2026 · AssessmentRobovations Score recorded at 61 of 100
Jul 2026 · AssessmentRobovations Score revised 61 → 70
Aug 2026 · AssessmentRobovations Score rescored under v4.0: 70 → 65
Aug 2026 · AssessmentRobovations Score rescored under v4.2: 65 → 68
Aug 2026 · AssessmentRobovations Score revised 68 → 65
Aug 2026 · AssessmentRecord status: Provisional → Verified

Editorial comparisons

How Gardena smart Sileno free 800 compares.

All comparisons →

Ownership burden

Do robot mowers need a subscription or cloud connection?

Segway Navimow H1500E + 3 more

Read comparison

Common questions

What people actually ask.

5 answered

OperationDoes the Sileno free 800 need a buried perimeter wire?

No. Satellite positioning replaces the perimeter wire entirely. Boundaries are drawn in the app as a virtual fence; no physical installation is required.

OperationWhat happens if the satellite fix drops during a mowing session?

The mower halts and waits for the fix to recover. In a prolonged outage it has to be collected by hand. Gardena’s guidance is clear sky views for consistent operation.

OperationHow often do I need to replace the blades?

Gardena documents annual blade replacement for standard residential use. Sharpening is not an option: robot mower blades are replaced as a set, because grinding removes the protective coating and leaves an unbalanced part spinning unattended.

OperationCan the Sileno free 800 handle slopes?

Gardena publishes two figures rather than one: 30 percent (about 17 degrees) maximum incline inside the working area, and 15 percent (about 9 degrees) at the boundary. The boundary figure decides where the virtual edge can run, so a bank steeper than 15 percent has to sit inside the working area rather than along its edge. Wet clay and soft turf cost traction below both numbers.

OperationWhat is the difference between the Sileno free 800 and the wired Sileno+ line?

Sileno free replaces the perimeter wire with satellite positioning and app-drawn boundaries. Sileno+ is the conventional buried-wire line with no satellite positioning at all, which is why the wire is required. Gardena does not sell an RTK model in either line. Sileno free is first-generation wire-free; the wired line has been on the market since 2018.

Availability

Where it's sold

We may earn commission from qualifying purchases. This does not influence classification.

Amazon See current listings

Cite / Embed

Reference the Gardena smart Sileno free 800 classification.

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Citation

Robovations. "Gardena smart Sileno free 800: Autonomy Level III (Conditional Autonomy)." Autonomy Ladder™, assessed August 2026. https://robovations.com/robots/gardena-smart-sileno-free-800/

Where to next

Three ways to keep going.

For evaluators

Compare with a peer.

See the Gardena smart Sileno free 800 and Litheli Skope 800 AI-VISION side by side: autonomy level, Robovations Score, readiness, and price. Classification, not a verdict.

See the full comparison

Or compare with Kärcher RCX 4, HOOKII Neomow X, Goko M6.

For browsers

See every Level III.

Every robot we’ve classified at conditional autonomy. Sorted by readiness, score, and price. Filter by category, manufacturer, or release date.

Browse the database

Updated weekly with new entries and reclassifications.

Gardena smart Sileno free 800

Will the Gardena smart Sileno free 800 work on your yard?

The full spec sheet.

Living with it.

How the assessment has moved.

How Gardena smart Sileno free 800 compares.

Do robot mowers need a subscription or cloud connection?

What people actually ask.

Other robot lawn mowers we have classified.

Litheli Skope 800 AI-VISION

Kärcher RCX 4

HOOKII Neomow X

Goko M6

Where it's sold

Reference the Gardena smart Sileno free 800 classification.

Three ways to keep going.

Get the next reassessment.

Compare with a peer.

See every Level III.