“Fall” Into Your Lawn: Establishing Cool-season Turfgrasses

After selecting the best plant material for your location and preparing your soil, it is now time to plant your seed or sod.  This podcast takes you through the steps in fall turf establishment and post-planting management.

Related Links

• Fall Lawn Care
• Establishing Lawns
• Establishing Cool-season Turfgrasses Handout

After making your selection of plant material and preparing your soil, it is time to plant your seed or sod. This podcast takes you through the steps in fall turf establishment and post-planting management.

Fall is the IDEAL time to plant cool-season turfgrasses.

Cool-season turfgrass establishment potential is optimized from September through mid-October across most of Virginia, especially for seed installations. Take advantage of this window of opportunity to plant cool-season grasses such as bluegrass, fescue, and ryegrass. Sod establishments are also ideal during this time, but sod is much more flexible in timing, as it can be done almost any time the soil is not frozen.

Seed establishments.

Certified seed. No matter what type of seed you select, make sure you purchase certified (blue-tag) seed. Blue-tag seed guarantees that what is on the tag is in the bag. Pay attention to several items on the seed tag as well. For instance:

• What is the germination test date? It should be within one year of the current date.
• What about the percentages of other crop and weed seed? These should either be zero or very low.
• What are the % germination and % purity values? These should be very high, typically 95% or greater for germination and 85% or greater for purity.

Seeding rates. Each grass species has a recommended seeding rate that considers just how many plants can survive within a given area. These rates deliver an appropriate number of seed per sq inch that maximizes establishment potential without too much competition by the plants themselves for space, light, nutrients, water, etc. In units of pounds/1000 sq ft, the seeding rates are as follows:

Follow the recommendations on the bag for appropriate seeding rates for mixtures because the level will vary depending on the percentage compositions of the species in the mix. And note that for fall seeding under optimal conditions (i.e. warm soils, plenty of moisture) that the lower recommended seeding rates listed work just fine.

Seed application. There are many ways to seed, from using a drop or rotary spreader, a commercial seeder, hydroseeding, or even by hand. The key is to ensure uniform distribution over a given area. Most often, it is best to seed in at least 2 directions, applying the seed at ½ the recommended rate in one direction. This is especially important when using a drop spreader for new lawn establishments because no matter how careful you are in pushing the spreader, you will have skips. One advantage to drop spreaders is there are few concerns with wind during seeding, something that can be a major problem with a rotary spreader. However, rotary spreaders provide the quickest means of covering large areas with large-seeded grasses like tall fescue and perennial ryegrass. Hand-held rotary spreaders available at most lawn and garden centers are ideal for applying small-seeded grasses such as Kentucky bluegrass.

Hydroseeding is a planting method offered by many lawn care professionals in the establishment of lawns at new construction sites. A slurry of seed, fertilizer, and mulch are sprayed onto a tilled soil with surprising accuracy. Finally, there are several versions of power-driven and slit seeders that can be used to directly plant seed into the soil. This delivery method ensures soil to seed contact, but a concern is to keep the planting depth in the ¼ to ½ inch range so that the seed are not buried.

Ensuring soil to seed contact.

After seeding on new construction sites, lightly rake or drag the seed into the soil surface or turf canopy to ensure soil to seed contact. Again, since turfgrass seeds are so small, it is advantageous if they remain at or just beneath the soil surface as long as you can provide supplemental irrigation. For situations where irrigation is not available, it is advantageous to use a slit seeder so that the soil’s moisture holding potential can be put to use.

Mulching seedings.

In order to improve soil moisture retention for newly emerged grass seedlings, it is preferable to use a mulch for seed establishments. Clean wheat straw at 1 bale/1000 sq ft is a very effective mulch that can simply be chopped and returned to the canopy during the first couple of mowing events. Avoid obviously weed-infested straw sources that will greatly increase weed pressure in your new lawn. There are also commercially available pelletized mulches and seed germination mats that conserve moisture and have no weed pressure concerns. These are particularly useful products for spot renovations.

Sod establishments.
Pick the longest, straightest point on your property (say the edge of a sidewalk or driveway) and initiate sod installation from here. Stagger the seams of the sod as new strips are applied and butt the seams together without overly stretching the sod—this will reduce desiccation. After installation, roll the sod to ensure soil to sod contact and promote rooting. And as soon as the sod is installed, initiate watering as soon as possible.

Watering—the final key to establishment success.
Regardless of the planting method, if you have done everything correctly to this point you can still lose your new establishment if you do not manage water appropriately. For fall seedings where no supplemental irrigation is available, try to time seeding events based on pending weather patterns that are likely to supply moisture. Understand that it is better not to irrigate at all IF there can be no commitment to regular irrigation once the seed germination process is initiated. If you can make the commitment to irrigation, then your philosophy for establishment should be “light and frequent”—keep the seed or sod moist, but not saturated. As establishment progresses, change your irrigation strategy to “deep and infrequent” in order to promote the deepest root system possible.

Mowing, Fertility, and Weed Control Options for New Plantings.
I think the best rule of thumb on how soon to mow a newly emerged grass is to cut it when it needs to be cut! Keep the 1/3^rd rule in play (that is, never remove more than 1/3^rd of the leaf blade at any mowing event). Don’t mow the turf when there is potential for rutting or footprinting the soil; if the turf needs to be mowed and the soil is too wet to get the mower on, then this is a sign that it is time to reduce irrigation amounts and frequency. It is important to have a sharp mower blade when clipping these new seedling as they are more susceptible to stress now than at any other time in their life (plus it will keep you from pulling the stems out of the ground!). Mow often during the latter stages of establishment to encourage lateral growth and improve lawn density.

After establishment is complete, initiate fall N applications that deliver no more than 1 lb of N/1000 sq ft every 4-6 weeks from Sept. through November. If other nutrients and/or lime were applied according to soil test results, then no additional chemicals should required for the rest of the fall.

Weed control is not a major concern for sod installations (as long as quality sod is used) but it can be a serious problem in new seed establishments. Obviously, most preemergent herbicides used to control winter annual weeds can NOT be used during seed establishment. Dr. Shawn Askew, extension Turfgrass Weed Specialist at Virginia Tech, has developed a podcast that specifically addresses the concerns of weed control during fall establishment.

Summary.
Fall truly is THE time for planting cool-season turfgrasses, so take advantage of the change in seasons to establish or freshen up your lawn after another difficult summer. For further information on how to maintain a great looking, environmentally friendly lawn, be sure to consult your local Virginia Cooperative Extension office.