clock menu more-arrow no yes mobile

Why is This Lawn Patchy?

Ask This Old House landscape contractors Roger Cook and Jenn Nawada share DIY Smarts tips for killing weeds without hurting the lawn.


  1. Roger shares that the homeowner’s yard was patchy because she used a non-selective herbicide to treat for weeds in her lawn.
  2. Read labels carefully to ensure the proper weed killer is being used. On a lawn, a selective herbicide should be used. On sidewalks and walkways, a non-selective herbicide can be used.
  3. If there is a concern about the harsh nature of these chemicals, there are organic herbicides available that work pretty effectively.

Further tips from Jenn Nawada

  • Maintain optimum nitrogen levels. That helps grass to outgrow fungal damage quickly.
  • Keep mower blades sharp. Dull blades bruise grass, making it susceptible to fungal attack.
  • Avoid nighttime watering. Instead, water early in the morning, and only when the lawn is dry.
  • Aerate. A fall aeration reduces soil compaction and improves drainage, fertility, and turf vigor.
  • Overseed with fungi-resistant grasses. These include ‘Bilart’ and ‘Claudia’ fine fescues, ‘Chateau’ Kentucky bluegrass, and ‘Pennant’ perennial ryegrass. Consult your local cooperative extension service for other resistant varieties.


Roger and Jenn warned viewers to read the labeling on weed killers very carefully to make sure the correct product is being purchased, since they look very similar. They discussed both Roundup Weed Killer and Roundup for Lawns, which are manufactured by RoundUp.

Roger also pointed out that he’s been a fan of using organic weed killers and mentioned Avenger Weed Killer, which kills everything including the grass, and PureDefense Weed Shield, which is a selective herbicide that is manufactured by Purely Organic Products and is available at The Home Depot.

Expert assistance with this segment was provided by Nawada Landscape Design.

Shop Weed Control at The Home Depot