Lawns are one of those landscape features in need of fairly constant attention beyond mowing. You can slow the decline by fixing problems, but even healthy lawns will need some intervention sooner or later. We live in a region turf specialists call the transition zone, meaning we’re too far south for cool-season grasses to like our summers and too far north for warm-season grasses to do well in winter and early spring.
September and October are the best months for lawn fixing, especially for seeding preferred cool-season fescues. It may seem more intuitive to seed in the spring, when everything is growing, but spring seedlings can be too frail to handle the rigors of summer. Fall-started grass will have developed more fully before the stresses of next year’s growing season.
I talked to a number of turf experts — Debra Ricigliano of the Maryland Home and Garden Information Center; Dwayne Parris of Chapel Valley Landscape Co.; Murray Cook of the Brickman Group’s Sports Turf Services; Jody Fetzer of Hillwood Estate, Museum and Gardens; and Scott Steinfeldt of Chanticleer Garden — and also recalled my own lawn-repair adventures over the years.
If you are faced with a declining lawn and a desire to fix it yourself, you have three options: complete renovation, overseeding or patching bare spots.
Renovating the lawn
If your lawn is thin and overrun with weeds, it may be time to start again. A complete renovation gives you a chance to deal with perennial weeds and reverse soil compaction, improve the topsoil and switch to a better variety of turfgrass. The standard advice is that if your lawn is more than half weeds, complete renovation is in order.
The size of the lawn dictates the approach. A small urban lawn can be handled easily with manual tools, but once you are faced with anything more than 2,000 square feet, you need mechanical help.
You can spray your old lawn with glyphosate (most economically as concentrate diluted in a sprayer) and heed all the label precautions. It is too late to use more persistent herbicides, which would interfere with grass-seedling growth. This may include glyphosate with added herbicidal ingredients. After spraying with glyphosate, wait seven days, and then dig up or rototill the dead lawn. Alternatively, you can dig up the live lawn, separate the vegetation and add the turf remnants to the compost pile, and sow seed without the wait.
Before laying the seed, add two to four inches of soil amendments. A mixture of topsoil, organic matter and washed sand will do wonders: Incorporate the mix into the existing soil before raking smooth. Add starter fertilizer at the recommended label rate.
Overseeding the lawn
If the lawn is beginning to decline but still looks okay, you can overseed to bring it back to full vigor. Overseeding probably is the most misunderstood aspect of lawn repair. You can’t just spread seed on an unprepared lawn and expect it to germinate. It needs good soil contact to grow. One of the most effective ways to create that is to use a core aerator, designed primarily to open compacted soil but effective, too, in exposing the soil surface for seeding. The thinner and weedier the lawn, the more you aerate. After aeration, top-dress the lawn with organic matter, such as Leafgro. The raked layer should be between a quarter- and a half-inch thick. That translates into between four and eight cubic yards per 5,000 square feet.
Follow grass-seeding rates on the label. While you don’t want to put down too little, too much inhibits healthy seedling growth.
Patching the lawn
The third option is to patch areas that are thin or overrun with weeds, which is basically a complete renovation in a small area. Fashion the areas into well-defined squares or rectangles. Lawns can be renovated through a combination of patching and overseeding.
Rolling will help with seed-to-soil contact. The seed should be misted once or twice a day (not heavily watered) until germination, especially in a dry fall. Keep people and pets off newly seeded lawns until they are established. A light, thinly spaced mulch of straw, not hay, will help retain moisture and reduce bird feeding. Some pros worry about weed seeds in straw and recommend products that combine an inert mulch with starter fertilizer.
Be patient. It takes two to three weeks for tall fescue to germinate, longer for bluegrass. Mow at three inches once the seedlings reach four inches. Fit a new mower blade before doing this and don’t use herbicides until spring.
Don’t allow autumn leaves to pile up and mat on seedling lawns. A leaf blower is less likely to disturb soil than a leaf rake.
County extension agents recommend soil tests before lawn renovation so you can add the right amounts of fertilizer, organic matter and lime as part of the process. However, if you want to renovate your lawn now, it’s too late to wait for soil testing. Take soil samples before you start your lawn renovation, and once the results and recommendations are back this fall, make adjustments as needed. You can lay fall fertilizer until early December, and lime at any time.