I thought I would address a question I've had to answer many times this summer while showing homes.
On approach to the house, everything looks beautiful. Yard is cut, weeds are pulled, hedges are trimmed. Suddenly there is a waft of dank ammonia in the air. What is that smell? Cat pee, raw sewage, Tacoma aroma? Nope, it's the hedges, boxwoods to be specific. Those perfectly manicured boxwoods dotting either side of the home's winding walkway are the culprit. Many of the well kept, and I suppose not so well kept, homes in the PNW are adorned with boxwood hedges from road to door. Boxwoods are among the most commonly used ornamental plants in the world and for good reason. They're hardy, come in many different forms, and they're actually the oldest cultivated ornamental plant, dating back to some 4000 BC.
But why the smell!!?
When heated by the sun, some boxwood varieties release an oil that is often associated with the smell of cat urine. It's not your neighbor's cat, so stop blaming it.
If you own a home with boxwoods already established the most obvious solution is removal. A few small bushes that are more than 20 feet from the entrance of the home will probably be fine. But those big ones that require a ladder to trim, good luck. Odds are though if the bushes have been there long enough to get so big, then you're probably fine with the smell, maybe you even enjoy it. Weird.
English boxwoods are typically the culprit. There are Littleleaf Boxwood varieties that hardly ever smell. You could try replacing the stinky ones with these less offensive varieties.
If you're trying to sell your home and want to address the situation, but don't want to ruin curb appeal by ripping up half of your front yard, try adding small laminated cards on the bushes. Explain the smell without insulting it, "Ornamental English boxwoods may produce sparse aromas on warm summer days."
The unfortunate situation is that boxwoods prefer sun, lots of it in our climate. If you decide to decorate your yard with them, just remember to keep them a good distance from your doors and windows. Unless you like the smell, then I suggest a pot inside near a South facing window......