Most riparian areas will have a slope to the landscape, since this is the area where the land gradates to the water. In some locations the slope may be quite gradual, while in others it may be very steep. To limit erosion on slopes prior to the establishment of the riparian vegetation, the best approach with lawn areas is to kill the turf, but leave it in place and plant through the dead grass residue. The leaf residue and the dead roots will continue to hold the soil in place for a period of time while the new riparian plants are installed and become established. Mulch can be applied directly over the killed vegetation if desired.

Using a non-selective herbicide

Perhaps the easiest and most effective way to kill large areas of lawn grass is to use a non-selective herbicide containing the active ingredient glyphosate (commonly known as Roundup). Glyphosate can be applied to lawns anytime there is active turfgrass growth and it will be effective at killing most grass species and common lawn weeds. Glyphosate is relatively safe to use and does not persist or bioaccumulate in the environment, but it must have sufficient time to dry on the foliage prior to a rain or irrigation event. Once glyphosate is absorbed through the leaves of the plants it is translocated into the roots and rhizomes of grass and weeds, killing the plants completely. Before using an herbicide in close proximity to a waterway, be sure to check that it is legal to make herbicide applications to your property. If you do not wish to use herbicide, or herbicide use is not allowed on your property, there are other options that can be used to kill lawn.

Using newspaper or cardboard layering

This method can be effective, but will take time to kill the grass and lawn weeds. It is also not that practical on sites with very steep slopes. Start this process by mowing the lawn as short as possible. The turf should then be covered with 8 to 10 layers of newspaper or cardboard. Choose a calm day to do this so the newspaper is less likely to blow away and utilize small rocks to hold the paper in place. The paper layers should then be covered with 4” to 6” of organic mulch. The organic mulch can be wood chips, bark chips, or partially composted chopped leaves. Water the mulch thoroughly to settle it and add weight to the layer. Over the course of 2 to 3 months, the vegetation will be killed off due to lack of light and air circulation. In general this method has to be employed during the growing season to be effective. Even when done correctly, it is likely that some tough, durable plants will survive the process and need to be mechanically removed. Planting of new riparian species should be possible directly through the paper and mulch layer once the old lawn has died off.

Using vinegar sprays

If you would like to use a spray, but do not wish to use a synthetic herbicide, you may be able to use vinegar to kill your lawn. The approach is usually best applied to smaller areas of turf primarily due to the cost of vinegar. The active ingredient in vinegar is acetic acid and you will want to use vinegar that has the highest available acetic acid concentration. This is usually white or pickled vinegar, which will contain 5% or slightly higher acetic acid. To get the best results with vinegar sprays, choose a period where the forecast calls for a few consecutive days of warm temperatures and sun. Mix full strength vinegar with some dish soap (1 gal of vinegar plus 1 oz. of dish soap) to increase the efficacy of the vinegar to kill plants. Apply the vinegar on a calm day to avoid drift of the spray. It will take at least two days to begin to see the plants dying. It is likely that the vinegar spray will have to be repeated one or more times to produce acceptable results.

Using solarization

Soil solarization is a nonchemical method for killing lawn and weeds using high temperatures produced by capturing radiant energy from the sun. The method involves heating the soil by covering it with a clear plastic tarp for 4 to 6 weeks during a hot period of the year when the soil will receive the most direct sunlight. When properly done, the top 6 inches of the soil will heat up to as high as 140°F, depending on the location. The top 12 to 18 inches of soil will usually get sufficiently warm to kill turf and many weed roots and rhizomes. Solarization can only be used to kill turf that receives full sun exposure. Shaded or partially shaded lawn areas will not be killed sufficiently by solarization. Optimum conditions for control (good soil moisture, tightfitting plastic, and high solar radiation) are needed to kill tougher plants, especially those with deep roots or rhizomes. Results from solarization can be inconsistent, even under favorable conditions. The area being treated also looks unsightly for a couple of months. When attempting solarization, first mow the grass very short, and then water it heavily to saturate the soil and cover with clear plastic sheeting. Be sure to seal down the edges of the plastic so that the moisture and heat are trapped beneath the plastic.

Using mechanical removal

The quickest method of removing a lawn is to dig it out. This is a very labor intensive process, but it can be made easier using a sod cutter. This machine removes the grass and a thin layer of soil in strips. Sod strips cut from the lawn can be turned over and left in place or composted in another location. Alternatively, there are hand tools designed to cut thin layers of lawn sod from the soil. If lawn is going to be mechanically removed, riparian plants should be installed and mulched in immediately to avoid erosion which could occur to the bare soil during a significant rain event. While sod removal is a fairly complete process, it is possible that grass and weed rhizomes or roots could remain in the soil and regenerate some plants in the future. One other drawback to sod removal is that a significant amount of organic matter and topsoil can be lost with the removed sod. Frequently, coastal soils are sandy and have only a thin layer of topsoil with limited organic matter, so minimizing their loss is important.

If you choose to mechanically remove turf, there is an opportunity to add organic matter or compost to the soil if it is deficient in this area. A 3” layer of compost or peat moss can be spread over the area where the lawn has been removed and cultivated into the bare soil with a rototiller. Before deciding to add compost to the riparian planting area, be sure that the soil is very deficient in organic matter and nutrients based on a soil test. Generally adding organic matter to soils is beneficial, but it will add cost to the project, require extra labor, can potential bring in new weed seeds or propagules and have a minimal impact on the long term success of the riparian planting if properly adapted plants are selected for the site.

For areas that are not in lawn, but are instead covered with a mix of woody shrubs, small trees, vines and herbaceous perennial plants, the first step is to determine if there are any plants in the area that are native and would be desirable to save and incorporate into the new riparian planting and landscape. There are many resources available that can help you identify plants on your property.

Helpful websites for plant identification: 

• UConn Plant Database
• Go Botany Advanced ID Tools
• CT DEEP Plants Page

There's also an app for that! Search "plant identifier" in your app store or consider these popular apps: 

• PictureThis - Plant Identifier
• PlantNet
• Seek by iNaturalist

Mechanical removal of plants

One way to prepare an area containing mixed woody and herbaceous vegetation for riparian planting is to physically dig up and remove the plant material, including the underground roots and rhizomes. This can be done by hand, or using machinery. This method quickly removes the unwanted vegetation and the area is then ready for riparian plant establishment. Mechanical removal can be very labor intensive and expensive. In addition, remnant roots and rhizomes that can get left behind may regenerate plants and because the soil is disturbed during plant removal, replanting must occur immediately to avoid erosion on sloped areas.

Using non-selective systemic herbicides

Systemic herbicides are absorbed into the plant foliage and stems and are then translocated into the roots and underground portions of the plant where they accumulate and kill the plant tissue. Systemic herbicides sprayed at the end of the summer are often most effective because this is the time of the year when plants transfers nutrients, carbohydrates and the herbicide from the foliage to the roots in preparation for winter dormancy. The two most effective and commonly used systemic herbicides for controlling mixed perennial vegetation are glyphosate and triclopyr. With both of these herbicides it is recommended that a surfactant be used which will enhance the efficacy of the herbicide by improving coverage of the herbicide as well as its absorption. Some formulations of these herbicides will already have the surfactant included with the herbicide.

• Glyphosate (Roundup®) will control broadleaf plants as well as grasses and sedges, but it may take more than two weeks for plants to die. To control woody plants and tough herbaceous perennials most effectively with glyphosate containing herbicide formulations, it is important to make applications at the end of the summer (usually mid-August through early September). Woody plants, in particular, may appear relatively unaffected by the herbicide at this time of year, but leaves will fail to emerge from buds the following spring or will be stunted and distorted. Glyphosate is rapidly deactivated and biodegraded when it contacts the soil and it presents a low environmental risk.
• Triclopyr (Brush-B-Gone, Weed Killer) will control most broadleaf plants, but will not be effective against grasses and sedges. In comparison to glyphosate, triclopyr is faster acting and plants will usually show damage with 24 hours and will die within a few to several days. This herbicide is best applied to plants when they are in active growth, so earlier in the growing season (May through July) is the best time for application. In general, triclopyr will be more effective at killing woody plants than glyphosate. Formulations containing triclopyr are especially useful on freshly cut stumps to prevent resprouting. Triclopyr is also a relatively safe herbicide, but carries slightly more environmental and human risk than glyphosate.

There are different ways that systemic herbicides can be used to kill existing vegetation in an area designated for a riparian planting. Foliar sprays of an herbicide using a backpack or hand held sprayer can be very effective. Foliar sprays use a relatively diluted application of herbicide. Foliar sprays are ideally suited to areas where control is needed for herbaceous perennial plants and low growing dense brush. Spray should be applied to the leaves and stems to the drip point. It may be necessary to repeat an application to achieve complete control.

Using a Foliar wipe is another technique where somewhat more concentrated herbicide solution is painted, wiped, or swabbed on the plant foliage. Paint brushes, special wick applicators, or plastic gloves inside
cloth gloves can be used to apply the herbicide to plant material in a very focused and directed fashion. Foliar wiping can be very useful to kill plants surrounding desirable plants that are to be retained. With foliar wiping there is little risk to non-target plants resulting from spray drift.

Cut stump applications of concentrated herbicide can be painted, sprayed or sponged onto cut off stumps and stems to prevent resprouting. This method is very useful for larger stem diameter plant material such as large vines, shrubs and small trees where aerial foliar sprays would produce too much spray drift and damage to non-target plants. It is often recommended to mix the herbicide with fuel oil or kerosene to make it more effective. Efficacy will be best when cut stump applications are made at the end of the summer. Repeat applications may be necessary.

Whatever process you choose, be sure to follow manufacturers safety instructions for application and storage. Eye protection and gloves are recommended.