Overseeding Your No Mow Lawn

Lawns sometimes experience damage due to fungal diseases, dogs, burrowing animals such as moles, human activity, and drought. Over-seeding at the right time of year can restore the structure and appearance of the lawn. This article is a guide to over-seeding your No Mow Lawn.

The cool season grasses in No Mow do best when seeded either in late summer (August 20 to September 30) or early spring (March 15 to May 15). These grasses germinate best when soil temperatures are cool, between 50º and 80º Farenheit (8º – 22º Celsius). Seeding when soil temperatures are too warm usually results in poor germination and spotty lawn establishment.

Preparing the Site for Overseeding

Damaged and dead areas of the lawn should first be prepared for overseeding by raking and removing any residual dead grass and thatch, using either a stiff-tined garden rake or a specially designed de-thatching rake. This will expose the soil so a proper seedbed can be created for the new seeding. The soil should be scratch lightly with a rake to break up any crusted areas. If the soil is compacted, the layers of compaction should be dug up or tilled up to loosen them and encourage good air and water flow down to the roots.

If the soil in the area to be re-seeded is poor, one inch of fresh, loose loamy or sandy loam topsoil can be applied over the top. This will provide a good seedbed for germination. When working on heavy soils, at least one inch of loosed loamy or sandy loam topsoil should be applied over the existing soil after tilling to create an optimal seedbed. The hard, compacted soils must still be tilled to break up zones of compaction before applying topsoil.

Seeding Procedures

Once the seedbed has been prepared, the areas can be re-seeded, either by scattering by hand or with a hand-push lawn seeder. The seed should then be raked lightly into the soil and rolled to create good seed-to-soil contact. On small patches the newly seeded areas can be firmed by stepping on them to push the seed down into the soil.

Larger areas can be over-seeded using a “slit-seeder” which drills new seed directly into the soil. Dead grass and thatch should still be removed with a mechanical de-thatching machine prior to over-seeding with the slit-seeder. This will prevent dead thatch from fouling the seeder and leaving blank spots. De-thatching machines and slit seeders can be rented at hardware stores and equipment rental facilities.

Determining How Much Seed to Use

The amount of seed required for over-seeding a lawn depends upon the percentage of the area that has no grass growing on it, and how the seed will be applied. If there are only small open patches that can be easily hand-seeded, the total area can be estimated in square feet and the appropriate amount of seed calculated. The recommended seeding rate for a new No Mow Lawn is 5 pounds per 1000 square feet, or one pound per 200 square feet. It is wise to obtain a little more than the estimated quantity, just in case the seed is applied at too high a rate or new open areas are discovered during the over-seeding process.

On larger areas, it is not feasible to spot-seed small areas. In such cases the over-seeding rate can vary from 50% of the original rate (2.5 pounds per 1000 square feet) up to the original seeding rate of 5 pounds per 1000 square feet if most of the lawn requires re-seeding. Even if half or more of the lawn is in good conditions, when seed is applied using a spreader or slit-seeder the seed is applied across the entire area evenly. Some seed will be applied in areas where the lawn is growing well, adjacent to open areas that require over-seeding. It is virtually impossible to control where the seed is placed when using a mechanical seeder for over-seeding, so a higher rate is generally recommended to ensure full coverage and good establishment.


Following re-seeding, the area should be watered daily for 15 – 20 minutes in the early morning to help stimulate germination (unless it has rained recently). Once the little green grass shoots appear, watering can be cut back to once every three days. When the grass reach one inch high, watering will only be required about once a week. If rain is plentiful, watering should not be necessary after the new shoots reach one inch in height.

To ensure proper watering, install a rain gauge with a short post for installing at soil level and monitor how much water your new lawn receives. One inch of water per week is adequate in normal spring weather with temperatures between 55º and 80º Farenheit.

When seeded in spring, the grasses in your new lawn will not have sufficiently deep roots to survive the summer without irrigation, unless you receive regular, timely rain. Plan to water your new lawn about once a week in the absence of any significant rainfall in the first year. Long, deep waterings are better than frequent shallow waterings. Deep watering promotes downward root growth into the lower soil, making your lawn more drought-tolerant.

Watering should be done in the early morning, between 3a.m. and 7a.m. Watering during the day is inefficient and can actually “burn” the grass by creating “water lenses” on the leaves that concentrate the sun’s rays, similar to a magnifying glass. Watering at night creates high humidity conditions at the ground level, which encourages the growth of harmful disease-causing fungi. Night watering should never be attempted during periods of high temperature and high relative humidity, as this creates optimal growth conditions for fungi that can attack your grass.

Long Term Maintenance

De-thatching your No Mow lawn every two to three years also helps reduce fungal diseases by improving air flow between the leaves and reducing the moisture-holding capacity of the turf near the ground level. In lieu of de-thatching, mow your lawn to a height of one to two inches in late fall (mid to late November) to reduce thatch buildup and stimulate denser grass growth in the ensuing spring. Never mow your No Mow Lawn closer than 3.5 inches during the growing season, as this can severely damage it. Close-mowing should only be done in late fall after the grass has entered its winter dormant phase.

With attention to these seeding procedures and post-planting maintenance, re-seeded areas of your lawn should fill in within two to three months.

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