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Renovating an Existing Lawn to Achieve Sustainability


Introducing Lower Maintenance Grasses into an Existing Lawn

Introducing lower maintenance turf varieties into an existing lawn is usually done through some type of overseeding practice. Selecting grass varieties adaptable to lower input levels is the first important step in making the transition to a lawn adaptable to lower inputs.

Lawn grasses more tolerant of lower moisture and fertility levels include the common type varieties of Kentucky bluegrass and the fine-leaved fescues (e.g., creeping red fescue, chewings fescue, and hard fescue). Some examples of common type bluegrass varieties include Kenblue, Park, South Dakota Certified, Argyle, and Newport. It should be noted that many of the newer bluegrass varieties available may also do acceptably well once adapted to lower input levels. Examples include: Rugby, Parade, Touchdown, Ram-I, Vanessa, Nugget, Sydsport, Monopoly, Harmony, and Kimona. Also, see the section on Cool Season Grass Selection for a Sustainable Lawn.In addition, many fine-leaved fescue varieties are adaptable to lower water and fertilization levels. Because there are many more seeds per pound of bluegrass than fine-leaved fescues, slightly higher seeding rates are required when using blends and mixtures that include fine-leaved fescues.Determining When Renovation Is Needed

In addition to introducing different types of grass into a lawn, renovation may also be considered when lawn quality has become unacceptable. Such as:

1. Approximately 40 to 50 percent of the lawn is dead or has very sparse growth. This may be due to a variety of factors such as low soil fertility, drought and heat, insect damage, poor mowing practices, disease, moderate soil compaction, or increasing shade and competition from growing trees.2. The lawn is soft and spongy when walking across it and responds poorly to regular watering and fertilizer applications. This condition usually indicates excessive thatch (greater than 3/4 inch). Thatch is a layer of partially decomposed grass stems, roots, and rhizomes (not leaves) at the soil surface but below the green vegetation.

3. Broad-leaved weeds (such as dandelion, plantain, and knotweed), or grassy weeds (such as crabgrass) cover about 40 to 50 percent of the lawn area and there is insufficient existing turf cover to fill in the bare areas once the weeds are removed.


These are just three of many possible situations where lawn renovation might be considered. However, it is very important to determine the reasons for the lawn declining before renovating the area. Make any changes in cultural practices or site conditions (where possible) before resigning oneself to renovating the lawn. Many times making modifications in basic lawn care practices or improving site conditions can bring a lawn back to good health and vigor such that renovation is not necessary.

The preferred time for lawn overseeding/renovation is from mid-August to early-September. The second best time is usually early spring just as the lawn is beginning to turn green and grow. The basic steps for introducing different species and varieties into a lawn are outlined below.

Basic Steps for Lawn Renovation and Introducing Different Grasses into an Existing Lawn

 

Step

Options

Comments

1. Soil test

 

Contact local county extension offices for information.

Soil Test    
     

2. Weed control

Broadleaf herbicides

Use if weeds are primarily non-grasses.

     
Weed Control

Non-selective herbicide (e.g., glyphosate)

Kills most green vegetation; requires 5 - 14 days.

     

3. Soil moisture

If needed (especially in the fall)

Soak soil to a depth of 6 - 8 inches; then allow the surface to dry until steps 4 and beyond can be done (may require 1-2 days).

     

4. Mowing

Mowing

 

Mow existing lawn very short, even to the point of scalping it, to allow good sunlight levels to reach the soil and encourage faster establishment of the new seedlings. If one is only intending to remove excess thatch, then the grass does not have to be cut as short as when planning to overseed.

     

5. Thatch removal

Thatch Removal

Vigorous hand raking

Not practical for extreme thatch problem or large areas.

     
Vertical Mowing

Vertical mowing

Can be rented or hired; can also be used to prepare seedbed.

     
Sod Cutter

Sod cutter

Recommended for extreme thatch problem; sod should be removed; can be rented or hired.

     

6. Soil preparation

Vigorous hand raking

For small patches with little vegetation remaining.

     
Aerification

Aerification

Three to five passes with commercial aerifier; especially recommended if soil is compacted.

     
Vertical Mowing

Vertical mowing

Tines should nick soil surface to a depth of 1/8 to 1/2 inch. Two to three passes are necessary. Vertical mowers are available with a seeder attached. See slit seeding in step 8.

     

7. Fertilize

Nitrogen (N), Phosphorus (P), Potassium (K)

Apply additional P and K as determined by a soil test. Avoid N as it will over stimulate the existing grass thereby crowding out the new seedlings.

     
Post-seeding fertilization

Post-seeding fertilization

Fertilize with 1/2 pound of actual N per 1000 ft2 from a slow release N source after the first mowing. (For information on slow release N, see sections on Selecting Lawn Fertilizers & Understanding Their Labels and Fertilizing Practices.

     

8. Seeding

 

Divide seed lot in half to quarters and seed in two or four directions.

     
 

Hand seeding

For patches or small areas (less than 8 feet across); mix 1 part seed with 4 parts of a natural organic fertilizer like Milorganite. This is termed "bulking-up" the seed and makes small amounts of seed easier to distribute uniformly.

     
 

Rotary spreader

This is an acceptable method when the seed is bulked-up with Milorganite as described in hand seeding. Seed in two directions.

Drop Spreader

Drop spreader

This method is often used when seed is used alone or bulked-up with Milorganite as described in hand seeding. Seed in two directions or overlap 1/2 of previous swath.

 

Slit seeding

Equipment can be rented but requires skill to operate correctly; generally best be done by a professional; go over site in two directions using half the seeding rate in each direction.

     

9. Irrigate

Irrigate

 

Lightly to provide good seed to soil contact; then, water lightly and often enough to keep the soil surface just damp. Do not allow soil to become too dry or too wet. Continue to keep the area moist until all varieties have germinated. Remember, Kentucky bluegrass can take 3 to 4 weeks to germinate.

     

10. Mowing

 

Initially maintain the shorter height of cut on the existing lawn to insure that enough sunlight will continue to reach the new seedlings. As the new seedlings develop and attain the same height as the existing grasses, the overall height of cut can be raised to the desired level. Continue these shorter heights of cut for about 1 month or until the slowest germinating seeds are up and growing.

For more information on renovating lawns, see Lawn Establishment and Renovation.

 

 
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