Grass and Forb Mixtures
for Low Maintenance Settings

* Contact:
       * Leslie Weston
       * Department of
         Horticulture

Overview of the Project

           Weeds consistently appear in less maintained landscape and turf settings, particularly in stressed turf or unattended landscape beds. To manage vegetation with reduced inputs, we recommend a better understanding of the reasons why weeds often persist in these settings. Factors involved in successful weed establishment include ability to germinate or repropagate vegetatively, availability of resources and space, disturbance of the soil or seedbed, neighboring types of vegetation, presence or absence of pests and herbivores and current environmental conditions. A greater understanding of the landscape plant or turfgrass plant’s interactions with their environment, including the rhizosphere environment, and impact of stress on plant growth should assist us in developing better strategies to manage weeds with reduced inputs. For less managed landscapes and roadsides, the most critical time for effective weed management is before planting or seeding. Effective planting and design, especially selection of appropriate plant materials and turfgrasses, will assist in prevention of weed infestation in the landscape.

           Herbicides are still a predominant means for managing weeds in commercial and roadside settings. However in the home landscape and also in many public areas, greater emphasis has now been placed on development of alternative means for weed management, for many reasons. The cost of vegetation management along N.Y. State’s roads and highways results in expenditures of millions of dollars per years for herbicides, mowers, labor, and hand-pulling or trimming. With declining resources, the management of certain invasive weedy species with low inputs can be very challenging, and often requires hand labor. Hand removal of noxious weeds such as giant hogweed has been proven to be dangerous as the plant releases toxic exudates from its cut foliage, which can result in serious skin injuries or burns. Although hand removal and mowing of weeds is not always feasible, the concern about herbicide safety and persistence has led some countries to ban the use of all herbicides in public areas, despite increased weed pressures in landscape and roadside settings. However, with the increasing spread of invasive and noxious species across New York’s landscape, greater attention to the development of effective management alternatives is clearly needed. As discussed, the selection of well-adapted turf and landscape plant materials that can successfully withstand and suppress weed invasion, while requiring limited inputs for establishment and maintenance can result in effective long-term weed management. In addition, since certain noxious perennials such as Japanese knotweed are particularly difficult to control using any means of weed management in roadside and landscape settings, more information related to weed biology and cultural practices including trimming, mowing, application of herbicide concentrates plus additional effective cultural practices to limit vegetative spread are needed. It will be important to consider the utilization of competitive or weed suppressive landscape plantings to further prevent the spread of noxious invasives by severely limiting their ability to invade or establish.

           This site is focused upon the studies we have performed with a variety of turfgrasses and mixtures of native and non-native plant materials for direct-seeding in the landscape or in various roadside settings. Our ultimate objective was to evaluate the success of direct-seeded grasses and forbs in minimal maintenance settings, which included research plots and roadside locations. Established turf and groundcover mixtures received no supplemental irrigation once established and only a monthly mowing. Once established, we evaluated the ability of these species, cultivars and mixtures to establish densely, suppress weeds and provide an attractive, easily maintained stand in two main locations across New York State. Initial research was performed in Ithaca and Riverhead, NY over several years, and studies were expanded in both locations to evaluate not only cool-season grasses, but warm-season grasses and forb mixtures. Cool-season grasses were seeded in September, and generally were well-established by late spring in both locations. Warm-season mixtures were established in late spring only in both locations. Not surprisingly, weed pressures in field and roadside stands were generally very intense, but increased when grasses and forbs were established in the spring versus the fall planting.

           We present here a description of the turfgrasses and forb mixtures that proved to be both aesthetically appealing and more or less successful in establishment and weed suppression in low maintenance settings. Species and cultivars are presented individually when evaluated individually, and are presented as a grouping when various species were evaluated together in a mixture. We have attempted to describe all species which were components of the mixtures evaluated. It is clear that after 5 months or more of evaluation this spring and summer that some species are proving to be much more successful in terms of overwintering ability, establishment and weed suppression than others. For example, some turfgrasses germinated rapidly and formed dense stands, while others did not. Some selections are completely weed-free, one year after establishment, while others are completely weed infested. Here we present a description of each species biology and growth habitat, as well as its performance over time. These studies will be conducted for several seasons to evaluate long-term performance, when maintained using reduced inputs in the landscape, including mowing on a limited basis.

           In addition to this site, we have linked you to our weed fact sheets presented in weed-of-the-month publications as well as our groundcover website describing successful performing herbaceous ornamental groundcovers, which were established only by transplanting groundcover seedlings into a densely planted bed. Many of these groundcovers have proven beautiful, resistant to pests and disease, stress tolerant and weed suppressive! It will become rapidly apparent that many newer and very attractive plant materials are now available for incorporation into the urban and rural landscape.