Q: Last fall, after we moved to our new house, our dog ruined various areas of the lawn with her urine. How do I rehabilitate these dead spots and keep more from forming?
—Jason Crownover, Westminster, Colo.
A: Roger Cook replies: Dog urine contains a high concentration of nitrogen, which kills grass the same way too much fertilizer in one spot will "burn" a lawn.
To repair these burned areas, remove any clumps of dead grass and loosen the soil with a hand-held claw tool. Level the damaged area with fresh topsoil, sprinkle seed and rake it in lightly, then water frequently to encourage germination. If there are lots of spots that need reseeding, buy one of the lawn-repair products that combine seed, fertilizer, and cellulose mulch in one bag. You can find them at pet stores and home centers.
To prevent future spotting, you have a couple of choices: Either follow your dog around with a hose to dilute her urine or train her to go only in one area, which you've covered with a thick layer of wood chips, mulch, or gravel. That's what I would do if it were my dog.