Renovation is the process of killing the existing turf on an area and reseeding it with new grass without grading, tilling, and other processes that usually go into the grass establishment process. See (How do I prepare a good seed bed before planting grass seed?) in this series.

So, when is renovation possible and when do you need to go through the more difficult and expensive process of completely reestablishing a turf area? Renovation will be the best approach when the existing grass on the site is not suitable, but appropriate grades exist on the site and there are no low spots where water builds up. This is a common situation around older homes where the grade is fine, but you are just not happy with the existing turf. A common problem is that the area may have been established many years ago with older cultivars that are highly susceptible to diseases like the fungal disease ‘leaf spot’. This is particularly true of Kentucky bluegrass. There are now many newer cultivars of Kentucky bluegrass that provide good resistance to leaf spot and other fungal diseases and do not need to be treated with fungicides to keep them in good condition.

Another situation in which renovation becomes necessary is when the area has become infested with perennial grassy weeds for which there is no selective control. These weed species include grasses like quackgrass, and bromegrass that are nearly impossible to control selectively with herbicides and must be killed with a non-selective herbicide that kills all plants on the area, including the desirable lawn grasses. Both quackgrass, and bromegrass have underground rhizomes that make them particularly hard to control and must be treated with an herbicide that that will translocate through the plant tissue and move through the plant to kill rhizomes. The best herbicide for this purpose is Roundup (glyphosate). This herbicide is non-selective, meaning that it kills most plant species, including any desirable turf on the area. It is systemic, which means that it will translocate through the plant and kill underground rhizomes to prevent weeds from coming back with the new seed. It also has the advantage that it is deactivated when it comes in contact with soil and there is no residual that can damage newly planted seed. This makes it the best available herbicide for lawn renovation. Notice that while it is deactivated right after application, the label says to wait up to 10 days before reseeding. This is not over the concern about damage to the new seedlings, but to give the herbicide enough time to translocate down to rhizomes. If the rhizome is severed from the plant during the seeding process before the chemical translocates, the weed will likely come back during the establishment process. The 10-day delay is generally enough time to allow complete translocation. Some weed species, like quackgrass, have a very extensive rhizome system. One application of glyphosate may not be enough. In that case, start early and allow enough time for any rhizomes that were not killed by the first application to grow new plants above ground. A second application should be enough to complete the process and prevent regrowth of the quackgrass.

Note that glyphosate is the generic or common name for this herbicide. Roundup is only one of the commercial names that it is sold under. If you have any doubts, check with your herbicide dealer to make sure that you are getting the right material.

Once all the plants in the existing canopy have been killed, it will be time to reseed. Seed-soil contact is critical to establishment success. If the seed is simply spread over the dead canopy, little of it will become established. There are several ways to assure seed-soil contact. On small areas, a garden rake can be used to scratch up the surface. This will be difficult, but it can be done. A better approach is to use mechanical equipment designed for the purpose of slicing seed down into the turf canopy. This type of equipment will have a vertical mowing blade that slices down into the dead canopy and a seed box that precisely measures out the seed and applies it into the slits left by the vertical mower. These units are available at many rental centers. They are in great demand during the best seeding season and you may want to reserve one ahead of time if you know that you are going to do some renovation.

You can also use a vertical mower that designed for thatch removal that does not have a seeder attachment. Cut the dead grass short. Then set the vertical mower deep enough to cut slits in the soil. Spread your seed at the desired rate and then go over it again at right angles to your first pass. You may feel like you are damaging the seed, but most of it will survive and this is a very successful method of renovation. For very large areas, there are tractor mounted drill seeders that can slice the seed into the dead canopy and deposit it in the underlying soil. You will have to use a professional landscape company to have access to one of these.

For renovation, it is wise to use about 20% more seed than the recommended rates for seeding on a prepared seed bed. The mortality rate of seedlings will be a little higher for renovated areas than for areas where a new seed bed has been prepared.

Once the seed has been sliced into the underlying soil, apply a starter fertilizer. See (What is a starter fertilizer?) in this series. The area should then be kept moist until seedlings have fully emerged. One of the advantages of renovation is that the dead canopy will serve as mulch to preserve moisture, which is useful in areas where irrigation is difficult.

For more information, see https://www.extension.iastate.edu/turfgrass/turfgrass-renovation.

 

Nick Christians, University Professor of Horticulture, Emeritus, Iowa State University

books: http://www.amazon.com/Nick-Edward-Christians/e/B001H6SB7A/ref=ntt_dp_epwbk_0

turf blog: http://www.iaturf.blogspot.com/

Fundamentals of Turfgrass Mgt. 5^th ed http://www.wiley.com/WileyCDA/WileyTitle/productCd-1119204631.html

Web site: https://www.hort.iastate.edu/directory/nick-christians/

• Share on:
• WhatsApp
• Deel
• Tweet
• Pin it
• Messenger
• Email

---