Brown lawns come back green, but with more weeds and moss. Here’s how to fix that.

DUE TO THE increasing costs of water, and environmental concerns over water supply, more and more homeowners have stopped watering their lawns in the summer.

The beauty of turf grass in our area is that it can be allowed to go dormant and turn brown during the summer months, and, as long as it receives one deep watering in July and another in August, the grass almost always will bounce back to active growth and green up again when the fall rains return.

Allowing the lawn to go dormant in summer year after year, however, can take a toll on lawn grass, causing it to thin out over time. It’s a problem because a thin lawn is much more susceptible to moss and weed problems than one with a thick stand of grass. Moss is opportunistic. It rarely takes hold in a healthy, vigorous lawn, but quickly colonizes thinned-out turf.

At the same time, the seeds of broad-leaved weeds such as dandelions, as well as undesirable weed grasses, germinate much more readily in thin turf, where the sun is able to penetrate to the soil surface. If you don’t do anything to solve the problem, before you know it, your lawn could become such a moss-covered, weedy mess, even the moles will be too embarrassed to live there.

Fortunately, renovating your lawn will get it looking and growing much better again, and from now until about mid-April, while the weather remains cool and moist, is the ideal time to do it. Just remember that the quickest way to ruin your soil is to work on it when it is sopping wet, so wait for a dry period, and allow it to dry a bit before getting started.

Begin by spraying out dandelions and other broad-leaf weeds with a liberal dose of straight white vinegar. Pick a sunny day; vinegar works only in warm, dry weather. The vinegar will kill any grass it hits, along with the weeds, but it doesn’t matter as long as you overseed as part of the renovation process.

If moss is a problem, controls are much more effective if applied after the moss is removed, so rent a power dethatching machine (verticutter), and use it to root out the moss, then follow up with a moss-control product.

The next step is to rent an aerifying machine and use it to punch gazillions of holes in the turf. Don’t worry about raking up the plugs. They’re practically impossible to pick up, and will quickly dry up and disappear.

Use a fertilizer spreader to apply a 50/50 mix by weight of perennial rye/fine fescue grass seed at about 2 pounds per 1,000 square feet, making sure none of the grass seed finds its way into adjacent garden beds. Rake as much of the seed as possible into the aeration holes; grass seed that germinates on top of the sod layer rarely survives.

Finish by fertilizing with an organic lawn food, and keep the soil surface constantly moist until after the first mowing. Be ready to mow the grass to 2 inches tall as soon as the seedlings reach about 3 inches high. That’s the height you should always mow, and when cutting the grass, always leave the clippings. Once the new seedlings fill in, you’ll be amazed how spectacular your lawn looks.

If you renovate your lawn every few years (or hire a company to do it), the grass will remain much thicker and better able to resist moss and weed problems, even if you continue to allow your grass to go dormant every summer. The only problem is that your lawn will be so attractive, those pesky moles will proudly move right back in to make new homes in your beautifully renovated lawn.