Lawn Care/New Grass/Establishment/Seeding
Drop spreaders are the ideal tool for applying
grass seeds. Rotary spreaders do not provide
uniform patterns because seeds are too light and inconsistent to spread accurately.
However, there are no spreader calibration guides for turfgrass seed. Calibrate
for grass seed by running the spreader over a known distance in a garage. Sweep
up and weigh the seeds and determine the rate of application. Or more easily,
divide the seed lot in half. Set the spreader at a low setting and spread half
the seed over the entire area in one direction (this might take a number of
passes over the area). Then spread the other half of the seed at right angles
to the first direction. Reserve a small amount of seed for repairs.
After seeding, a light raking will help to mix seeds with soil. Do not attempt to bury seed. A light rolling is invaluable at this time to insure good seed-soil contact. Seed-soil contact is critical because seeds do not hold water but rely on soil to provide moisture for germination. The better the seed-soil contact, the quicker the germination and establishment.
Hydro-seeding is a recent advancement for turfgrass establishment. Seed, paper or wood mulch, and sometimes starter fertilizer are mixed in water and then sprayed over the area. Hydro-seeding is excellent for areas that are inaccessible like steep banks or highway embankments. Hydro-seeding provides a mulch, reducing evaporation and increasing germination and establishment. Hydro-seeding can be costly, but might be worthwhile because of convenience and excellent germination.
Establishment of turfgrass areas is most commonly accomplished with seed, although sod can be used. Sod offers the advantage of an "instant lawn" whereas seed takes much longer to produce a green turf. Establishment with seed is much less expensive and is surprisingly less complicated than with sod. But in no way is establishing a lawn with seed an easy task that should be taken lightly. Following proper establishment procedures can produce a healthy turf that one can be proud of for many years to come.
Please select among the following topics to learn more specifics about seeding.
A good turf area starts with the selection of the correct turfgrasses for a given set of conditions. Determining proper species and cultivars for a given situation is the first step. Once species and cultivars have been chosen, the next decision is what seed to buy. Regardless of the use, quality seed is always the best buy. Quality depends on purity and viability. Purity is the percentage by weight of pure seed of an identified species or cultivar in a lot of seed. Viability is the percentage by weight of seed that is alive and will germinate under laboratory conditions. Pure live seed (PLS) is the product of purity and viability. If a seed lot is 80% pure and germination is 90%, PLS is 72%. Comparing the cost of PLS between seed lots determines the best buy. In the above example, Lot B is the best buy. Quality seed is usually more expensive by the bag, but is normally less expensive when calculated by pounds PLS. In addition to purity and viability, other factors that determine the quality of a seed lot are % crop, % weed, noxious weed, and % inert.
Crop indicates the percentage by weight of seeds that are grown as a cash crop. This includes many of the coarse hay or pasture grasses. Examples of crop may include orchardgrass, timothy, redtop, clover, and bentgrass. The crop percentage for high quality turfgrass seed should be as close as possible to 0.00% and avoid seed lots with anything over 0.5% crop. A label indicating 0.1% crop is approximately 1-1/2 oz. in 100 pounds. A seeding of 50 pounds of Kentucky bluegrass per acre with 0.1% crop on the label is like spreading 60,000 timothy seeds or 235,000 bentgrass seeds. Though the % crop may be very low, the number of seeds and eventual number of weeds may be very high.
Weed indicates the percent by weight of weed seeds. A weed is any seed that has not been included in pure seed or crop. As a general guideline, anything over 0.3% should be avoided. A seeding of 50 pounds of Kentucky bluegrass per acre with 0.05% weeds on the label is like spreading 18,000 knotweed seeds, 140,000 chickweed seeds, or 37,000 Poa annua seeds.
Noxious weed is the number of seeds per pound or per ounce of weeds that are considered legally undesirable. Most of the noxious weeds listed are usually not problems in turf but are more problematic in agricultural crops. Even so, avoid seed lots with noxious weeds present.
Inert indicates the percent by weight of material in a seed lot that will not grow. This can include corn cobs, chaff, sand, or soil. The lower the % inert, generally the better the quality of seed and seed lots with more than 8% inert should be avoided.
Date tested is when the lot was tested for viability and purity. Because germination decreases over time, it is best to buy seed that was tested in the last nine months.
Seed certification is a program in which seed production fields are tested to insure genetic purity of the seed. Certified seed carries a blue tag and is the classification that professionals should buy. Blue labels do not guarantee the highest quality seed, but it does guarantee the cultivar listed on the label is true to type. This is especially important when buying bentgrasses for golf course use.
The best way to buy high quality, pure seed is to purchase from a reputable dealer. Chose a seed dealer that has been in business for a number of years and has a good reputation among fellow turf professionals.
Drop seeders are the ideal tool for applying grass seeds. Rotary seeders do not provide uniform patterns because seeds are too light and inconsistent to spread accurately. There are no spreader settings for turfgrass seeding. Calibrate for grass seed by running the spreader over a known distance in a garage. Sweep up and weigh the seeds and determine the rate of application. Or more easily, divide the seed lot in half. Set the spreader at a low setting and spread half the seed over the entire area in one direction (this might take a number of passes over the area). Then spread the other half of the seed at right angles to the first direction. Reserve a small amount of seed for repairs.
After seeding, a light raking will help to mix seeds with soil. Do not attempt to bury seed. A light rolling is invaluable at this time to insure good seed-soil contact. Seed-soil contact is critical because seeds do not hold water but rely on soil to provide moisture for germination. The better the seed-soil contact, the quicker the germination and establishment.
Hydro-seeding is a recent advancement for turfgrass establishment. Seed, paper or wood mulch, and sometimes starter fertilizer are mixed in water and then sprayed over the area. Hydro-seeding is excellent for areas that are inaccessible like steep banks or highway embankments. Hydro-seeding provides a mulch, reducing evaporation and increasing germination and establishment. Hydro-seeding can be costly, but might be worthwhile because of convenience and excellent germination.
General seeding rates are presented in Table 1
Table 1. Seeding rates for cool season turf grasses. | |
| Species | lbs seed/1000 ft2 |
| 100% Kentucky bluegrass | 1.5-2.0 |
| 80% Kentucky bluegrass+20% perennial ryegrass | 3.0-4.0 |
| 100% perennial ryegrass | 4.0-5.0 |
| 100% tall fescue | 6.0-8.0 |
| 100% creeping bentgrass | 0.5-1.0 |
| Kentucky bluegrass+fine fescue and/or perennial rye | 2.5-3.0 |
The amount of grass seed to apply depends on the species of grass, use of the area, and time of year. On areas such as sports fields where they are often put into use before seedlings mature, the upper end of the seeding rate range should be used. The upper end of the seeding rate range should be used when seeding during less than optimum times of the year like winter and spring. Low maintenance areas where aesthetics are not as important as cover, lower seeding rates could be used. Do not attempt to get a thicker stand by excessively increasing seeding rates. Competition among seedlings leads to a weakened stand susceptible to damage from insects, disease, traffic, and weather.
The best time to seed a lawn is in the late summer to early fall. Adequate soil moisture, warm soil, and limited weed pressure allow for excellent seedling growth. Between August 15 and September 15 is optimum seeding time in the northern states, from September 1 to September 30 is optimum in the southern states. It is critical to seed as early as possible within these windows. Even when seeding within these windows, waiting one week later to seed may mean the stand will take two to four additional weeks to mature. Establishment in the spring is possible but not as effective as fall seeding.
A soil test should be taken from the site. The test will determine fertilizer recommendations for the area. Correct any deficiencies in nutrients or pH by following the recommendations on the soil test report. Use a rototiller or other cultivation equipment to work the soil to a depth of 4-6 inches, incorporating the fertilizer or other soil amendments. Do not till wet soil because clodding will result; in addition, overtilling will destroy soil structure and is not desirable. The soil should be allowed to settle after tilling. Heavy rains and/or irrigation will hasten settling. Allowing time for the soil to settle now will prevent undulations and difficult mowing in the future. Just prior to seeding, rake the area to the finish grade.
After the area is at finish grade, apply a "starter fertilizer" to enhance seed germination and development. Starter fertilizer is high in phosphorus which is listed as the second number in the analysis on the fertilizer bag. For instance, a 16-22-8 fertilizer contains 22% P2O5. Apply the fertilizer according to the label at 1.5 lb. P2O5/1000 ft2. Refer to Table 1 for the proper amount of starter fertilizer to apply.
Mulching the area will prevent erosion and conserve water. Therefore, mulching is most important when it is impossible to adequately irrigate newly seeded areas. One bale of clean (weed-free) straw per thousand square feet will give a light covering that will not have to be removed after germination. Most homeowners will apply too much mulch which will shade seedlings and have to be raked off later. Apply the mulch very lightly so you can still see approximately 50% of the soil through the mulch layer.
Seedlings are very susceptible to desiccation, and the seedbed should not be allowed to dry. A newly seeded lawn will need to be irrigated two to four times daily depending on the weather. Enough water should be applied to moisten the top one to two inches of the soil profile, but avoid over-watering and saturating the area. Once the seedlings are two inches high, gradually reduce the frequency of irrigation and water more deeply. After the turf has been mowed two or three times, deep and infrequent irrigation is most effective.
Mowing a new lawn will encourage the turf to fill in quickly. Mowing should begin when the first few seedlings are tall enough to mow. You may only mow 10% of the plants in the first mowing, 20-30% of the plants in the second mowing, and so on. Most wait too long to mow a newly seeded lawn, so mow early and often. Initially mow Kentucky bluegrass, perennial rye, and fine fescue at 1.5 inches and tall fescue at 2.0 inches. After the first three to four mowings, you can adjust your mower to the permanent mowing height which is 2.5 - 3.5 inches for Kentucky bluegrass, perennial rye, and fine fescue and 3.0 - 4.0 inches for tall fescue. As always, never remove more than 1/3 of the grass blade at any one mowing.
New seedlings have poorly developed root systems and thus they cannot effectively absorb nutrients from the soil. Therefore, it is important to fertilize frequently after seeding to encourage establishment. Apply 0.75 to 1.0 lb N/1000 ft2 four to six weeks after germination and again eight to ten weeks after germination. Assuming seeding in mid-August, these applications would be mid to late September and again mid to late October.
There is little weed pressure in the fall so weed control may not be needed. Broadleaf weeds may become a problem in the fall, but these can be easily controlled with a broadleaf herbicide application in October or November, after the third or fourth mowing. Annual grasses such as crabgrass can be easily controlled with preemergence herbicides applied in the spring. In seedings made very late in fall where the lawn is not fully established by winter, avoid applying a preemergence herbicide in early spring because it may damage late-developing seedlings. In this case, consider using a postemergence crabgrass herbicide later in summer to control crabgrass. Always apply according to label instructions.
The best time to seed a lawn is in the late summer/early fall (mid-August to mid-September). Seeding in spring is very difficult and often unsuccessful. However, there are circumstances that warrant a spring seeding:
To make your spring seeding most successful, you must:
If a spring seeding is necessary, consider doing it before the frost comes out of the ground. This is defined as "dormant seeding" because the seed will lie dormant until the soil temperatures warm in April or May. Depending on your location, dormant seeding can be done as early as Thanksgiving and as late as March. The benefit of dormant seeding is that as the soil heaves and cracks during the winter, crevices are created for the seeds which create ideal germination conditions. Additionally, dormant seeding is easier to schedule than spring seeding, because spring rains make it difficult to seed.
Weed Control Guidelines
Seeding into an Existing Lawn
Depending on your lawn, you can use one of three methods to prepare the soil:
The success of a seeding project depends largely on the post-seeding care. Seedlings are very susceptible to desiccation and the seed bed should not be allowed to dry. Newly seeded areas should be irrigated two to four times daily depending on weather conditions. Apply enough water to moisten the top 1/2 inch or so of the profile, but avoid overwatering, saturating the area, and possibly washing away seeds. As seedlings develop and roots grow deeper, gradually decrease frequency but increase duration of irrigation.
A common mistake when establishing an area is waiting too long before mowing. Mow when seedlings are old enough to mow and do not remove more than one-third of the grass blade at one time. Individual seedlings develop differently and only a few seedlings may have grown enough to be cut during the first mowing but it is still important to mow at this time.
Seedlings can be very susceptible to fertilizer burn. Avoid applying soluble fertilizer to a newly seeded are for at least six weeks. An application of 0.5 lbs. N/1000 sq. ft. at this time will quicken establishment.
Most weeds in a new seeding can be controlled with regular mowing. Seedlings are also susceptible to damage from many herbicides applied either before or soon after seeding. Avoid applying preemergence annual grass herbicides for 3 to 4 months before seeding. One exception to this is siduron which is a selective preemergence herbicide that can be used during seeding. Avoid applying preemergence annual grass herbicides until after the third or fourth mowing of a newly established area. Postemergence annual grass herbicides can also damage seedlings when applied before or after seeding. Postemergence broadleaf herbicides will also damage seedlings before or after seeding. Be sure to check all pesticide labels before use, especially on newly established areas.
Mulching prevents erosion and conserves water. One bale of weed-free straw per thousand square feet will give a light covering without smothering the seedlings. A light layer of mulch will not have to be removed after germination.
