How to remove cat urine from artificial grass, and keep the cat from coming back

Cats evolved in dry country and concentrate their urine to save water, so each puddle carries more urea per ounce than a dog leaves. It also contains felinine, a compound that breaks down into sulfur-bearing molecules with the sharp, skunky note that lingers after the ammonia has faded. And cats are creatures of habit: one spot, every day, until the infill there is saturated. A neighbor's cat or a feral will also spray vertical surfaces at the boundary, which is why a yard can smell of cat with no obvious wet spot on the turf.

Wait for full dark and walk the yard with a UV flashlight, the inexpensive kind sold for pet stains. Urine residue fluoresces a pale yellow-green. Mark each spot with a golf tee or a bit of tape, and check the bottom foot of fence boards, posts, planter sides and the corner of the house, because sprayed urine runs down onto the turf edge. Treating the one spot you knew about and missing three others is the usual reason the smell survives.

1. Flush each marked spot with the hose on a shower setting for a minute or two, down through the turf.
2. Mix an enzyme cleaner labeled for cat urine at its strongest label dilution. Products labeled for cats generally include enzymes that handle the sulfur compounds; a general pet enzyme may leave the skunky note.
3. Saturate. Pour rather than spray on a small spot. The infill under it should be wet through; part the fibers and check.
4. Fence and post bases: spray the vertical surface and the turf edge below it until it runs.
5. Dwell overnight. Apply in the evening. Cover the spot with a piece of plastic if the night is hot and dry, so it stays damp.
6. Repeat every three or four days for two to three weeks. Cat spots take more rounds than dog zones because the residue is denser.
7. Check on a humid morning a week after the last round. The general enzyme method page covers timing and dwell mistakes that apply here too.

Treatment removes the smell. It does not change the habit, and a cat that has used a spot for months will refill it within a week of the treatment finishing. If it is your cat, put a litter box or a tray of loose, litter-type material in a quiet, sheltered spot the cat already likes, and keep it cleaner than the turf. If it is a neighbor's or a feral, the fix is at the boundary: a motion-activated sprinkler at the fence line is the one deterrent that works in our experience, because it makes the spot unpleasant without a smell that fades. Do not use an ammonia-based cleaner anywhere near the spot. To a cat it smells like another cat's urine and reads as an invitation.

• Vinegar. Neutralizes surface ammonia for a day and does nothing for felinine.
• Ammonia cleaners. See above. Worst possible choice.
• Covering with sand. Buries a small, dense, saturated spot; the smell is back after the first rain.
• Deodorizer sprays and citrus peels. Fragrance over sulfur. Cats are not deterred by citrus for long.
• Bleach. Lightens the turf and can react with the ammonia in the residue.

A cat spot that still smells after three weeks of full-strength enzyme has saturated infill, and because the spot is small, replacing it is a small job. Our pet odor removal extracts the infill in the spot and replaces it with an odor-control type, then treats the surrounding turf. On its own that is a pet spot treatment at $50 to $100; across a yard with several spots it is a Premium Restoration from $299 for up to 500 square feet with a heavy-odor add-on of $75 to $150. The honest answer page explains the three kinds of smelly turf and which can be fixed. Sanitizing afterward is covered on the disinfecting page.