A new lawn can be planted with greatest confidence if the seedbed has been cultivated, mixing in plenty of fertilizer (and lime, too, if a soil test shows acidity.) It is possible to scorch old vegetation chemically, scratch the surface (as with a powered thinning machine) and then seed. But seed stands the best chance of settling to a good site for sprouting and rooting among loose soil chunks.
If you want to plant a lawn successfully, don’t rework the soil more than necessary to get it level, for repeated tillage pulverizes soil as well as aggregates and destroys structure. A dusty soilbed melts upon first watering to an impervious surface which seals off the rootzone from air and causes future water to run off rather than soak into the lawn.
Use a lawn spreader to sow seed uniformly. About 3 pounds of a Kentucky bluegrass-fine fescue blend is all that is needed for a thousand square feet – or only half this much of tiny-seeded varieties such as Highland and other colonial bengrasses. Even if you are in a moist “bentgrass country” a little bluegrass and fine fescue is suggested along with the bentgrass; but mow low and water and fertilize to favor the bent.
The new perennial rye-grasses are not only attractive but sprout quickly; they are good in seed blends for slopes that must be grassed-over in a hurry. If possible, mulch the new seeding. Any loose material that conserves moisture and protects the soil will suffice. Clean straw is an old favorite, though seldom obtainable by city folk. Garden centers usually carry woven nettings or mulch mats; or you can even use plastic if you are willing to lift it any time temperature approaches 100 degrees (as it will on a sunny day).
Around home you might find dried lawn clippings or the power company can perhaps provide chipped twigs. Stringy sphagnum peatmoss can be used, also. If the soilbed is kept moist by light sprinklings and weather is warm, the seeding should show a fuzz of green in two or three weeks.
Natural mulches need not be removed, but, of course, a plastic covering is another matter. Roots of new grass grow about as much as the tops, so when the grass is an inch or two tall watering can become less frequent. AS soon as the grass leaves turn a bit floppy, 2 to 3 inches tall, it is time for mowing. From then on mow each time the lawn exceeds its customary height (usually about 3/4-inch for bentgrass, 1.5-2 inches for bluegrasses and fescues) by 50 percent.
After a few mowings, the lawn will be well enough established to endure weed treatments, if needed, including spring crabgrass preventers such as Azak, Betasan, Tupersan and so on.