By R. Mugaas and B. Pedersen, University of Minnesota Cooperative Extension
When establishing a new lawn, a common question asked is, "Should I seed or sod?" Both have advantages and disadvantages. There are three important decisions when considering establishment methods: 1) turfgrass selection, 2) site preparation, and 3) care of the new lawn. These considerations will be discussed for each establishment method.
The pros and cons
The most important difference between seeding and sodding is the time necessary for developing a mature or durable turf. Sodding is essentially transplanting a mature turf that has been cared for by a professional. Seeding involves the same process used in the establishment of sod and can be accomplished by a professional or the homeowner. The number of variables involved in seeding make it difficult and many times unsuccessful for the homeowner. The following outline lists some of the advantages and disadvantages of each establishment method.
More grass types and varieties to choose from
Less expensive than sodding
Stronger root system development initially
Initial establishment is longer
For best results, time of seeding is limited mainly to late summer and early fall
Moisture is critical for the young seedlings
Rapid establishment and relatively weed-free in the beginning
Good for slopes or areas prone to erosion
Can be laid any time during the growing season
Less selection or control over kinds of grasses, especially shade tolerance
In Minnesota*, Kentucky bluegrass, fine fescue, and some of the perennial ryegrass cultivars are recommended. Grasses that are sold in the state, but not recommended, will be discussed later. Before a seed mix is chosen, evaluate the location: Is there shade, excessive use or wear, etc.? Is the lawn desired to be a showcase and green throughout the season (high maintenance), or is a healthy turf desired with a minimum of fuss (low maintenance)? These are important questions to consider when choosing grasses.
For shady locations, look for seed mixtures specifying shade tolerance. These will contain fine fescues along with some common and shade-tolerant Kentucky bluegrasses.
For sunny areas that receive a lot of wear, mixtures of 50% improved Kentucky bluegrasses and 50% perennial ryegrasses are best.
For low maintenance turf, mixtures of Kentucky bluegrasses and fine fescues will offer a durable lawn.
The availability of specific varieties will vary from year to year; however, within a particular kind of grass (e.g., fine fescue or improved Kentucky bluegrass), most varieties will perform equally well.
Your local seed distributor, garden center, or county extension educator can help you evaluate the best varieties for your lawn. Some varieties may be special ordered as seed, but at a higher cost.
Grasses to avoid
Zoysia: Well adapted to the southern U.S., but not in the north. Establishes slowly and is green only between the last spring frost to the first frost of fall.
Annual Ryegrass (Italian Rye): Usually found in cheap seed mixtures. Useful as a temporary green cover or nursecrop, but will not come back the following year. Different from perennial ryegrass.
Bentgrass:Major use is in golf course turf under low mowing heights (1/8" to ½"). At lawn mowing height (2–3"), bentgrasses tend to be very puffy, not uniform, poorly colored, and disease prone.
Tall fescue: Older varieties have not performed well in Minnesota due to their coarse texture and limited hardiness. Newer varieties, however, are being developed and may be recommended in the future.
When sodding a lawn, the consumer is limited in the varieties available. Most of the sod grown in Minnesota is a mixture of Kentucky bluegrass.
Occasionally, some perennial ryegrass or fine fescue is available in the mixture. A retailer or installer should know what varieties are in their sod; if not, they can get this information from the sod grower.
Soil preparation: Seed and sod
Whether seeding or sodding an area, preparation of the soil is critical, yet often neglected in establishment. Good site preparation will simplify maintenance for years to come and ensure healthier turf. Soil preparation should be the same for seeding or sodding. Before you begin, take a soil test to find out the characteristics of the soil you are working with. Consult the nearest county extension office for sampling materials and procedures.
The best type of soil for growing turf is a sandy loam. This soil is mostly sand with some silt and clay. Other soils may need amendments and more care, but will support a good lawn. Amending heavy clay soil with organic matter such as peat (2–3 cubic yards) will open up a soil, allowing better air and water movement. The addition of "black dirt" should be evaluated since it often consists of mainly silt and clay soils, and compacts easily. If a large amount of fill is needed, such as to raise up an area, good quality topsoil can be used as long it is less than 20% clay and free of residual herbicides. Any topsoil or soil ingredient should be incorporated into the native soil carefully.
Once amendments have been tilled in, fine grade the area with the addition of phosphorus and potassium fertilizer, as prescribed by the soil test. Additional nitrogen can be added after the lawn is mowed the first time. A roller or cultipacker (a segmented roller that also breaks up soil lumps) can be used to firm the soil slightly. The site is now ready for seed or sod.
The best time to seed in the north is late summer (mid-August to mid-September) due to favorable conditions for germination and growth. In addition, fewer weed seeds are germinating that might compete with the grass seedlings. Lastly, there is ample time for the plants to be well established before winter.
Seeding can be done in the spring; however, weeds and high summer temperatures often reduce the chance of success. Most annual weeds that compete with new grass seedlings germinate in spring. A selective herbicide (such as) Siduron, may be used on newly seeded lawns, reducing these weed problems to some extent. In addition, the short growth period in spring allows little time to develop a root system to survive the summer heat stresses.
Seed should be spread in two steps, each at a half rate, in perpendicular directions across the site. This technique ensures the most uniform coverage. Follow up with a light raking allowing about 10–15% of the seed to show. Use a roller or cultipacker over the area to ensure good seed-soil contact.
Watering the new site is very important. For the best germination, be sure that there is moist soil to a depth of 4–6 inches. After seeding, water only as needed. Some drying during the day will not harm the seeds, and may actually enhance germination. Cease watering when free water (puddles) begin to appear. When the seed has germinated, begin regular watering while the seedlings are very small. Gradually taper off the watering as the plants grow larger and the temperature (in fall) cools off. Ordinarily, 6–12 weeks are needed for establishment. It takes nearly a full season for the new lawn to be a mature and durable turf able to withstand considerable traffic.
Purchase sod as fresh as possible. Ideally, it should have been cut no more than 24 hours prior to delivery. The sod should be laid as soon as possible, or within one day after delivery. If the sod needs to be stored for a time, it should be kept in a cool, shaded area to avoid drying out of exposed rolls.
Lay the sod on slightly moistened soil, staggering the joints much like brick laying. When laying sod on a slope, lay the rolls across the slope and stake each piece to hold it in place. Fill any cracks with soil to prevent edges from drying. Use a roller about one third full of water to smooth the site and ensure the roots of the sod have good contact with the soil.
Keep the sod moist but not saturated until it is firmly rooted in the soil (a few days), then gradually reduce watering. In two to three months it can be treated as an established lawn.
Aerification may help to prevent layering caused by peat or soil that came with the sod. Aerify after establishment in spring or fall, to at least a depth that goes through the sod and penetrates the existing soil layer.
Once the lawn is established, it will provide its many benefits such as cooling effects, erosion, runoff control, and allergen reductions.
For more information about sustainable lawn care see the Sustainable Urban Landscape Information Series website at www.sustland.umn.edu.
*Note: Not all variety or timing recommendations are applicable nationwide. Your local Cooperative Extension has information specific to your area.
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