The best time to seed a lawn, either to repair an old one or start a new one, is late summer. A few years ago it was almost the only good time. Bluegrass lawn seed planted in the spring took two, three and even four weeks to germinate, the new grass did not have time to become established before hot weather and crabgrass and other weeds got ahead of it.

New grasses and special weed control chemicals make the difference. A crabgrass preventer, siduron, can be applied after sowing the seed and it will prevent crabgrass from getting started without inhibiting lawngrass seed from sprouting. Other chemicals , such as 2,4-D, can be used later on to eliminate broadleaf weeds without harm to the grass.

The new grasses are turf-type perennial ryegrasses, such as Citation, Darby, Game, Manhattan, NK-200, Pennfine and Yorktown. These are fast'starting beauties capable of providing a green cover in only days, providing moisture and warmth are adequate.

It is important to prepare a good seed bed before sowing the seed. Neither seed nor sod will thrive on a rockhard base into which it cannot send roots. It is best to cultivate the soil, mixing in fertilize (5-10-5) and lime if needed.

After sowing the seed, the seed bed should be kept moist until the seed germinate. Sprinkle the seed bed just enough to moisten the surface until the seed germinate. After germination, when roots of the new grass start to penetrate the soil, water less often but for a longer period of time in order to get the water down where the roots are.

If you want to bluegeass lawn, use a mixture of bluegrass and perennial rye, about one-fourth ryegrass by weight, three-fourths bluegrass.

The perennial ryegrasses are excellent for quick starting, lawn patching and general utility. Alone they do not make so strong a sod as does bluegrass and may not endure climate extremes as well.

When seeded in combination with bluegrass, they provide a quick ground cover and help provide a more favorable environment for growth of the bluegrass.

Before seeding, it is a good idea, if possible, to figure out why the old lawn went bad and see whether the cause can be eliminated. Was it neglect, was there too much shade, was it because of poor drainage?

The new lawy may go the same way as the old one unless you find a solution to the problem.

There is a lot to be said for using sod, particularly if the task of seeding the lawn is distasteful.

Although the cost of installing sod is much greater than seeding, it is relatively foolproof, if done by professionals. A regular seeded lawn, however, may have to be reseeded several times before it successfully takes root, with costs mounting each time.

Turf lawsn can be installed almost any time during the growing season while seeded lawsn are best put in at late summer or early spring. Once established, sodded turf does not need any more special care and fertilizing than a seeded lawn.

A common misconception is that sodding a lawn need not be as painstaking as sowing of seed need be. Actually, the soilbed should be equally well prepared for either kind of planting.