August 9, 2011
University of Arkansas, Division of Agriculture
Turfgrass Science Program (http://turf.uark.edu) – Turf Tips
Seeding, sprigging, sodding, plugging – what is best for re-establishing bentgrass?
As we get closer to the end of another long, hot summer, many golf course superintendents are looking at their greens and wondering what their options are to re-establish turf in areas that have been thinned during the season. Although seeding seems like the easiest approach, new seedings will often fail more than they succeed. Here are some options to consider to hopefully make your renovation a success.
This is probably the safest option, but will usually only work in small areas. Since the turf you are transplanting to the green from your nursery or practice green is already mature, has a mature root system, and has been maintained under putting green conditions, it will usually take wear and traffic similar to the existing turf. Although a standard cup-cutter will work, the round shape will leave gaps in the area and create an uneven surface. Pluggers that are either square or hexagonal (see picture at right) will create a finished surface much quicker. Top-dressing these areas a little more will help smooth the surface quickly.
Although this was a common method of propagating bentgrass a century ago, it is rarely done today and would not be a recommended strategy for re-establishing thin greens. A vegetative option that is similar to sprigging and you might consider would be to use aerification plugs to re-establish weak turf. After core-aerification, cores are harvested (see photo at right) and spread into weak areas and top-dressed heavily with sand. The small plugs of bentgrass will contain crowns and stolon nodes and those can serve as new growing points for re-establishment. These areas should be rolled aggressively to smooth the surface and top-dressed frequently during grow-in to encourage growth. Although the surface may not be immediately playable, these plugs are generally pretty durable and can take much more traffic than bentgrass seedlings.
Sodding can be a very effective option for getting greens quickly back into playing shape. When using sod, it is important to harvest the thin or dead sod from the green at the same depth that the new sod has been harvested for transplanting. Although some courses have a large enough nursery to harvest sod and re-establish areas of turf, there are also some sod growers that are maintaining bentgrass sod for such applications (see photo at right). If you are purchasing sod from a grower, it is very important that the sod is being grown on a soil or sand that matches the existing rootzone in the greens or potential layering problems can occur. Again, if the area to be renovated can be harvested close to or maybe slightly deeper than the bentgrass sod to be planted, the surface will tie together with the surrounding grass much easier. Aggressive top-dressing and rolling should be maintained during grow-in to smooth the seams and to tie the new sod with the remainder of the green. One downside of using sod from a local grower is that you may not be able to use the same cultivar that you are currently growing on your course and it could have different management requirements than the existing cultivar.
Seeding is one of the more cost-effective means of renovation, but is probably the toughest to do with success. There are several reasons that seeding renovations will often struggle. First, the existing canopy of grass and thatch is not like fresh sand and germination and rooting can be difficult into the existing turf. Second, seedlings require much more water than other propagation methods, so you will likely over-water the remainder of the green in an attempt to germinate and establish the seedlings. Finally, seedlings are very susceptible to traffic injury, so seeded areas will need to be treated a little more gently to avoid causing damage to the new plants.
For best success with seeding, the canopy needs to be opened up prior to seeding. This can be done with core-aerification, aggressive verticutting, or spiking (see photo at right). After opening the canopy, seed should be applied at a higher rate (2-4 lb / 1000 ft2) than you would normally use for a new seeding, since germination and seedling survival will probably be lower. After seeding, the entire area should be topdressed with 0.125-0.25” of fresh sand and then irrigated as necessary to maintain a moist surface. If the area is going to be mowed regularly, you might consider removing the baskets for the first 7-10 days to prevent seed from being picked up by the mower. We would also recommend a higher mowing height for a period of time to allow the new seedlings to tiller and get established. It is also beneficialto minimize other forms of traffic and cultivation in those areas until the seedlings are well-established.
We hope that you do not have many areas on your greens that need to be re-established this fall, but these are some options you might consider. Let us know if you have any other specific questions about this topic.
Mike Richardson and Doug Karcher