If your lawn is abused or overrun by weeds, now is the time to fix it

For some, the lawn is still about projecting the trophy landscape. For most of us, it's the default green feature around the home. And for a third group, it's an environmentally harmful holdover from the last century that needs to go.

Whatever your view of the lawn, it's not vanishing anytime soon. It is still America's predominant landscape element, and alternatives such as wildflower meadows are far harder to achieve than most realize.

The lawn surely should be admired for one reason alone. What other garden plant do you cut repeatedly to within an inch of its life, walk all over and still expect to look great?

But as we know, over time, the lawn doesn't look so great. It needs periodic overhauling, and now is the time of year to fix it.

Late August to mid-October offers the prime period for tackling thin and weedy lawns, repairs that progress from simple patching of small areas to overseeding to complete lawn renovation. You can lay sod for an instant effect, but the cost per square foot is much higher than for seed, and the laborious site preparation is still needed.

The earlier you do this, the better. Seed will germinate more quickly when soils are warm; the seedlings will be further along before fall leaf drop, when leaves must be removed; and you will have time to go back and reseed areas that didn't take.

Before getting into the nuts and bolts of seeding, though, it's worth understanding why lawns decline and fail.

Weeds are not a cause of lawn failure; they are a result of it. A lawn that is kept thick and healthy will exclude weeds, though a weeding regimen is still required.

One of the main problems for lawns is that the grass is cut too short, causing it to burn out and weeds to move in. The mower blade height should be at least 2½ inches and preferably 3 inches or more. If you are in the market for a new mower, check that it meets these needs.

Another cause of thinning is the absence of a sound fertilizing regime. Organic feeds are available in addition to the traditional synthetic products.

“A lot of people don't fertilize at all, and if you don't, you're going to have weeds that are more competitive,” said Geoffrey Rinehart, a lecturer in turf-grass management at the University of Maryland's Institute of Applied Agriculture.

But too much fertilizer, or feeding during the summer or in periods of drought, can be as detrimental as no feeding.

A third common problem is poor drainage, which is often associated with compacted and hardpan soils. Mild ponding can be corrected with sufficient soil amendment and aerification, but persistently wet areas will not support turf; create beds for trees and shrubs that will endure wet soil instead.

For all these reasons, lawns degrade and need ongoing annual maintenance and, after years of neglect, a complete redo.

Rinehart uses a few criteria in deciding whether a lawn needs renovation: whether at least 25% of the lawn consists of weeds, whether the ground is “bumpy and lumpy,” and whether the existing grass is of old, coarse-textured varieties.

I don't want to minimize the amount of effort involved in renovation, including the need for soil amendments, such as screened compost, leaf mold and builder's sand, or the array of equipment required, including rakes, a spreader, a lawn roller and a wheelbarrow. For all the effort, though, there is also a great sense of satisfaction in turning a weed patch into an attractive lawn, particularly at a time when the novel coronavirus has kept us closer to home and in search of constructive projects. If you are thinking of selling your home in the next year or two, you'd be well-advised to fix the lawn now.

Before seeding, you have to deal with the weeds. Because you have to rough up (and then smooth) the soil before seeding, you may be able to remove weeds physically. In small areas, this can be done with a metal rake. A dethatching rake is well-suited to this task. On larger areas, this can be tackled with rented equipment, typically a rototiller.

Where weeds are entrenched, you may have to use a nonselective herbicide, which will also kill what remains of your lawn. You will need to wait at least a week after spraying before laying grass seed; see the product label. On tenacious bermudagrass or wiregrass, you may need two applications, delaying seeding for about a month.

The makeover gives you an opportunity to fix dips in the lawn and spread a layer of compost or other organic matter that will improve the soil vitality. After laying the seed, you should firm it with a roller or, in small areas, by tamping with the back of a shovel or hoe. A light blanket of straw (not hay) will help discourage bird feeding and retain moisture. Some experts believe the application of a starter fertilizer is important to get the grass seedlings quickly established. A soil test will establish whether your lawn has sufficient phosphorus, potassium and the correct pH (over 5.5) to forgo fertilizing or liming.

If you don't want to tackle a full renovation, spreading seed over an existing lawn — overseeding — is a good way to thicken a declining lawn and also introduce new, better varieties of seed.

However, spreading seed without adequate soil preparation is a waste of effort; seeds need good contact with soil to germinate and grow. In smaller lawns, this can be done by raking out the thatch and incorporating compost or other soil amendments into the soil surface. On larger areas, rented equipment in the form of a power rake and a machine called a slit seeder will work. Some people overseed after a thorough session with a core aerator, which extracts plugs of soil that can be crumbled after drying. The aerator's chief function is to relieve soil compaction.

Steep slopes will need anchoring until the grass gets established to prevent soil erosion. This can be done with jute cloth or other erosion-control matting, pinned to the area after soil preparation and seeding. The grass blades will grow through the loose weave, and matting made of organic materials will rot away in time. Some slopes are too steep for safe lawn mowing and should be planted with something other than turf grass.

Established lawns need an occasional soaking when dry to encourage deep root growth. But newly seeded lawns will require a light watering twice a day. Reduce the frequency of watering as the lawn gets established. If watering is impractical, it is better not to irrigate at all and let rainfall and dew dictate the timing of germination and growth.

The new grass should be cut when the seedlings grow a few inches. This is also a good way to keep leaf litter off the lawn. But do them a favor: Replace or sharpen the mower blade first, so the tender seedlings are cut cleanly with minimal trauma or uprooting.

Next year, the lawn will still be thin and need extra help against weeds. Pre-emergent herbicides are available for crabgrass, Japanese stiltgrass and other spring-germinating plants. A variety of post-emergent herbicides work against weeds in active growth. Organic herbicides are available, but they may not be as effective, especially if weed pressure is high.