There is a particular sinking feeling that comes from watching your new mower plow straight through a bed of freshly planted tulips. I have felt it. The fix is boring but effective: no-go zones, the invisible fences that tell the machine where grass ends and your prized plants begin. Every robot mower handles them differently, whether through a loop of boundary wire or a shape you draw in an app. Get them right during setup and the mower quietly works around your beds, ponds, and soft spots without you ever thinking about it again.

Step 1: Walk the Yard and Mark the Danger Spots

Before touching any wire or app, walk the whole lawn with a bag of marker flags or spray paint. Flag everything the mower must avoid: flower beds, vegetable patches, the pond, a delicate tree base, exposed sprinkler heads, and any dip that swallows a wheel. Do this on the actual grass rather than from memory, because the borders you picture indoors are rarely where they sit outside. This map of danger spots becomes your plan. Skipping it is the number one reason people find their mower parked in a hosta an hour later.

New to this? Start with our overview, How to Install a Robot Lawn Mower Step by Step, then come back here.

Step 2: Choose Wire Loops or App Zones

How you mark a no-go zone depends on your mower's navigation. Boundary-wire models use an island loop: you run the perimeter wire out to the object, around it, and back along the same path, keeping the two wires close together so the mower reads it as off-limits. Wire-free GPS models let you draw the excluded shape directly in the app, which is far quicker and easy to edit later. Some hybrid setups combine both. Confirm which method your model uses before you start so you buy the right amount of wire or update the right map.

Flower bed with a neat brick border separating it from the lawn

Step 3: Create a Boundary Wire Island

For wire models, an island is a there-and-back detour off the main perimeter loop. Run the wire from the boundary to the bed, loop it around the object, and return alongside the outbound wire. The two runs should sit within about a centimeter of each other so the mower treats the strip as a wall and never crosses. Peg it down snugly. If the wires drift apart, the mower may try to squeeze between them and get confused. Keep the island shape simple; tight curves and sharp points cause more misreads than a rounded outline.

Wire Spacing Is Everything: On boundary-wire islands, the there-and-back wires must run close together, within roughly a centimeter, so the mower reads them as a solid wall. Let them drift apart and the machine may try to slip between them into the very bed you were protecting. Peg them tight and check the spacing before you bury or cover anything.

Step 4: Draw and Edit App-Based No-Go Zones

On GPS and camera models, open the map in the app and add an exclusion zone by tracing the shape or dropping corner points around the object. Give yourself a small buffer, perhaps 8 to 12 inches, so the mower steers clear even if the signal wanders slightly. The big advantage here is editing: replant a bed or move a trampoline and you just redraw the zone in seconds. Save the map, then run a short test pass and watch the mower approach the zone to confirm it turns away cleanly rather than clipping the edge.

Spots Worth Fencing Off With a No-Go Zone

  • Flower beds and freshly planted borders
  • Vegetable patches and raised beds
  • Garden ponds, fountains, and water features
  • Exposed tree roots and delicate trunk bases
  • Pop-up sprinkler heads and irrigation valves
  • Soft, boggy ground that swallows wheels
  • Gravel paths and mulch areas near the lawn
  • Trampolines, play equipment, and sandpits
  • Steep drop-offs, steps, and retaining walls
  • Decorative rockeries and low garden lights
  • The dog's favorite digging corner
  • Any dip or hole a wheel could get stuck in

Our companion piece, The Tools You Need to Install a Robot Mower, picks up where this leaves off.

Step 5: Protect Soft Borders and Bed Edges

No-go zones stop the mower entering a bed, but they do not create a tidy edge. Where lawn meets a flower bed, a low physical border helps: a brick mowing strip, a shallow trench, or edging set flush with the grass gives the mower a firm turning surface and stops soil spilling onto the lawn. Aim to keep the wire or mapped line a few inches back from fragile stems. That small gap leaves a thin uncut fringe you trim by hand, which is a fair trade for never fishing the mower out of your dahlias.

Boundary wire pegged into the grass around a garden feature as a no-go zone

If you like to read around a topic, see the basics of robotic mower navigation.

Step 6: Test, Watch, and Fine-Tune

A no-go zone is only as good as its test run. After setting each one, start a supervised session and follow the mower to every excluded spot. It should approach, sense the barrier, and turn away without hesitation. If it nudges into a bed or ignores a zone, the wires may be spaced too far apart or the app buffer too tight. Adjust, then test again. Spend twenty minutes doing this on setup day and you save yourself a season of surprises, because a mower left to roam will always find the one gap you missed.

One last thing

No-go zones are unglamorous, but they are what let you trust a spinning blade to roam your yard unsupervised. Walk the lawn, flag the danger spots, then fence them off with tight wire islands or a few taps in the app, giving fragile borders a small buffer and a firm edge to turn against. Most importantly, test each one on foot before you walk away. Twenty careful minutes on setup day buys you a whole season of the mower quietly working around your beds while your tulips, and your peace of mind, stay exactly where you planted them.

If you want to go deeper, our guide to How Far to Keep Boundary Wire From Obstacles covers the details.