Why should we restore riparian zones?
Riparian plantings are vegetation corridors directly adjacent to the water’s edge separating the water from upland areas. These are critical interfaces between land and water, and restoring them with native plantings can play a significant role in protecting water quality and aquatic habitats. Riparian corridors provide many useful functions, including filtration of stormwater runoff. Increases in impervious surfaces, such as roads, parking lots, and roofs, can cause greater storm runoff carrying pollutants, sediments and nutrients into our waterways. Riparian corridors slow water runoff (both surface flow and subsurface flow), minimize erosion, trap and filter pollutants and nutrients, and provide important wildlife habitat. Planting vegetation along waterways can also help mitigate increasing surface water temperatures by providing shade, thereby improving habitat for fish and other aquatic organisms that require cooler environments. When done properly, riparian corridors also provide privacy, increase property value, and beautify the landscape.
Interested in looking at impervious surfaces in your community? Check out the Riparian map and the Built Environment Layers in the CT ECO Advanced Viewer!
Have an area to restore? See the steps below to get started!
There are two common situations that are likely to exist for property owners when preparing a coastal area for installation of a riparian buffer planting. Often a riparian planting will be replacing an area of mowed turf grass. In other cases, riparian plantings will be replacing mixed woody and herbaceous perennial plants, most likely comprised of some native species and invasive exotic species. These two types of vegetation will need to be handled differently to successfully prepare an area for establishment of a riparian planting
Preparation of an area of lawn grass
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.
Preparation of an area of mixed vegetation: woody and herbaceous plants
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:
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.
A wide variety of invasive herbaceous and woody invasive plants have become established in many areas. It is likely that at least some of the vegetation that will need to be controlled in preparation for installation of a riparian planting will be one or more species of invasive plant. Below is a listing of some of the most commonly found invasive species and approaches that can be used to successfully control and remove them prior to installing a riparian planting. This is not a complete list, see the Connecticut Invasive Plant Working Group or the UConn Integrated Pest management Invasive Species page for more information.
Tree of Heaven
Tree of Heaven (Ailanthus altissima) is a Chinese tree that can grow to 80’ tall, with smooth gray bark, coarse branching, and large compound leaves from 1’ to 4’ long. There are male and female plants, with the females producing flat, twisted, winged fruits at the end of the summer. Fruits look like “leafy” clusters and may turn salmon-pink as they ripen.
- Control: Young seedlings can be pulled by hand, but older plants are best handled with herbicide treatments. If trees are small enough to allow for foliar sprays then use either glyphosate or triclopyr to spray over the tops of the plants. Larger trees should be cut down and the stumps treated with a combination of triclopyr and oil to kill the stump and roots. Glyphosate treatments of Ailanthus stumps will be less effective than triclopyr. Stump treatments will be most effective if the trees are felled during the growing season and if the triclopyr herbicide is applied immediately after the tree is cut. Follow-up herbicide sprays of root suckers may be required.
Asiatic Sand Sedge or Japanese Sedge (Carex kobomugi) is a grass-like perennial sedge from northeastern Asia that is found along coastal beaches and dunes. While it has not yet been found in Connecticut or on Long Island, it is in neighboring states and definitely a plant to watch out for. It produces coarse stout stems and forms colonies that are connected by cord-like rhizomes. Terminal brown flowers may be present in April-June and are held on triangular stems. Leaves are yellowish-green with fine serrations (teeth) along the tips.
- Control: Small numbers of plants can be dug out without too much effort, but care must be taken to be sure that all connecting rhizomes are also excavated at removal time. Rhizome tips are sharp, so leather gloves should be worn for this work. Glyphosate sprays are another good method of killing this species. Often two applications will be required: the first in mid-summer and the second in early fall. Follow-up the next growing season may be required.
Oriental Bittersweet
Oriental Bittersweet (Celastrus orbiculatus) is a deciduous, perennial vine that is native to many parts of Asia and climbs by twining around objects. Leaves are somewhat rounded and alternate along the stem. There are male and female plants and fruits are produced in clusters from the leaf axils of female plants in the fall. Fruits are rounded, about the size of a pea, with the yellow capsule splitting to reveal orange arils inside.
- Control: Smaller vines can be pulled by hand. It is important to remove the roots as well since bittersweet can resprout from the tops of roots that remain in the soil. Large infestations are usually best controlled with herbicide sprays and both glyphosate and triclopyr are effective. In areas where bittersweet is intermingled with desirable grasses, triclopyr should be used since it will not harm the grasses when used at appropriate concentrations. Large vines that have reached tree canopies should be cut and the stump should be treated with concentrated herbicide. The vine should be pulled from the canopy as much as possible if the tree is to be retained in the landscape.
Black Swallow-wort (Cynanchum louiseae) is an herbaceous, perennial, twining vine that has opposite oval leaves with pointed tips. Small, dark purple, five-petaled, star-shaped flowers are borne in clusters in June and July. Soon after flowering, slender tapering green pods form that eventually turn tan.
- Control: Foliar sprays with either glyphosate or triclopyr are the most effective methods to control black swallow-wort. Wait until plants have begun flowering before making an herbicide application. Because black swallow-wort grows in dense, layered thickets it is likely that a second herbicide spray application will be needed later in the summer or early fall if there is regrowth from lower layers of the vine. An alternative herbicide approach is to cut and remove the vines and immediately treat the cut stumps with concentrated herbicide. Glyphosate is more effective for cut stump treatment than triclopyr. Pulling and manual removal of this species is rarely an effective or practical approach.
Japanese Honeysuckle (Lonicera japonica) is a perennial vine that can climb by twining around structures or grow as a groundcover, scrambling over anything it encounters. Its oval or slightly lobed leaves are tardily deciduous in Connecticut and New York, but can remain semi-evergreen or totally evergreen in warmer coastal locations. Leaves are opposite each other along slender stems. Tubular, fragrant flowers change from white to yellow with age and are highly visible from May through July.
- Control: Plants can be dug out of the soil, but it can be very difficult to completely remove all roots and underground rhizome pieces. Follow-up checks for sprouting will be necessary. Foliar sprays of either glyphosate or triclopyr are effective at killing both the above and below ground portions of Japanese honeysuckle. Late summer and fall are good times to apply herbicide since it will be readily translocated to the underground plant parts at this time of year. Since Japanese honeysuckle is so slow to lose its leaves at the end of the growing season, herbicide sprays can be made later in the fall than for many other woody plants. At this time of year, non-target plants are likely already dormant and leafless and will be relatively unaffected by the sprays.
Black Locust (Robinia pseudoacacia) is a fast growing tree that typically reaches 40’ to 60’ tall. Young trees have smooth gray bark that gives way to deeply furrowed bark with flattened ridges. Leaves are compound, with many small, oval leaflets and are held in an alternate arrangement along the stem. Pairs of thorns can be found where leaves join the stem. Pendulous clusters of fragrant, white flowers with a yellow blotch in the upper petal are produced in late May to early June. Fruits are 2” to 4” long smooth, flattened pods.
- Control: Black locust very readily suckers from roots, so digging out trees often leaves roots behind that resprout colonies. The most effective method of eliminating black locust is to cut the trees down and immediately treat the cut stump with fairly strong glyphosate or triclopyr solution. Stumps treated with herbicides that appear to be dead may still produce new root shoots a few years later. Follow-up herbicide treatment of new root suckers may be needed.
Rugosa Rose, Beach Rose, Japanese Rose (Rosa rugosa) is deciduous, suckering shrub that is typically 4’ to 6’ tall with an equal or greater spread. Stems are stout and covered with straight, sharp spines of varying lengths. Compound leaves are alternate, and have 5 to 9 leaflets that are dark green on the upper surface, fairly thick and show embossed veins. Flowers are 2.5” to 3.5” across, produced from June through August, are fragrant and may be white, pink or rose and either single or double. Fruits are flattened, round hips that ripen to a shiny orange/red at the end of summer.
- Control: Small numbers of young plants can be dug out by hand or with machinery. Since they sucker readily and produce rhizomes, it is important that no underground plant parts are left behind or they may regenerate. Glyphosate foliar sprays are effective if applied after the plants are done flowering. Triclopyr foliar sprays are also effective and can be applied earlier, either before or during flowering. An alternative herbicide method is to cut off the shrubs and immediately apply concentrated glyphosate to the stumps.
Choosing Plants
Use Native Plants
A plant is considered “native” by the Native Plant Trust if it is “indigenous and naturally occurring in the area without human introduction.” We suggest using native plants when restoring riparian zones. While native plants are not always as showy as horticultural varieties, they provide many practical and ecological benefits that make them ideal for these areas. Native plants have occurred in an area for thousands of years and therefore are well adapted to soil and moisture conditions. They can also reduce management costs, as they rarely need chemicals or fertilizers, protect soils through erosion control, and can help minimize the spread of invasive plants. Additionally, native plants provide essential food (through pollen, berries, and seeds) and shelter for a variety of wildlife and can act as host plants for many butterfly and moth caterpillars.
The Riparian Plant list below includes a number of native species that are appropriate for riparian restoration.
What are your goals?
Are you looking to reduce erosion, increase pollinator habitat, or shade your waterbody? These goals will influence the plants you may want to consider in your restoration project. MAYBE MORE INFO ON THIS?
Consider the Different Riparian Zones
Certain plants may be more appropriate for different sections of a riparian area. Riparian buffers are generally split into three different "zones":
- Streamside / Toe and Bank Zone
- Location: Directly adjacent to the normal water line and on the lower stream bank.
- Conditions: Saturated, highly prone to flowing water, flooding, and erosion.
- Best Plants: Wetland-tolerant sedges, rushes, grasses, and flexible-stemmed shrubs like silky dogwood or specific shrub willows that bend rather than break in high water. Plants in this area should be able to tolerate frequent flooding and wet soil conditions.
- Middle / Overbank Buffer Zone
- Location: Moving landward from the immediate bank onto the lower floodplain.
- Conditions: Occasionally flooded (every few years) with moist to damp soils.
- Best Plants: Moisture-loving medium-to-large shrubs and trees (such as alder, red-osier dogwood, river birch, and sycamore) that absorb excess nutrients and slow down surface runoff.
- Outer / Transitional Upland Zone
- The furthest landward area bordering residential lawns, fields, or commercial land.
- Conditions: Drier, stable soils that experience only minor runoff during heavy storms.
- Best Plants: This area can include native trees, shrubs, deep-rooted grasses, and herbaceous wildflowers that can help filter pollutants and provide food and habitat for wildlife.
Salt Tolerance
Some regions, such as those near the coast, require plants that are adapted to grow under salty soil conditions. Be sure to check the salt tolerance of the plants before planting them in these regions and check out the Coastal Riparian sections below and under the "Assessment" tab. Also take a look at the salt tolerance of the native plant species in the Riparian Plant list.
A properly planted tree, shrub or herbaceous perennial will have a high survival rate, grow and establish quickly, perform as expected and be tolerant of adverse conditions. Proper planting techniques must be used in conjunction with proper site preparation activities and proper plants selection for the site and location. Failures in any one of these three aspects of establishing a riparian corridor can lead to unsatisfactory results, damage to the environment and an unattractive waterfront landscape
Remember, call before you dig
In Connecticut, call toll free: 1-800-922-4455 or dial 811. Call 2 full working days in advance to locate buried utility pipes and cables. Visit the CT Call Before You Dig page for more information.
Planting Techniques
Container vs. Balled & Burlapped Plants
Trees, shrubs and vines can be purchased in a number of forms, but the two most common forms available are balled and burlapped (B&B) or container-grown plants. B&B plants are those that have been grown in mineral soil in a field setting and they are either hand dug or tree spade dug in the early spring. Growing areas for B&B plants generally have good agricultural soils, so the rootball on these plants will have a mineral soil that is different than the sandy loam soil that exists in some locations.
B&B plants will have biodegradable burlap covering the rootball that is held in place with pins (nails) or is tied. Tree spade dug trees (generally larger tree sizes) will often have their rootball covered with burlap that is framed with a wire basket. The wire basket is necessary to keep the rootballs from falling apart due to their large size and weight. B&B or tree spade dug plants have lost up to 75% of their root system when they were dug (i.e., 75% of the roots remain in the field where the plant was grown), It is important to be aware of this fact when utilizing B&B plants. Do not expect to see significant new top growth on B&B plants during the first growing season. During the establishment year the plant will be putting its resources into restoring its root system and not into top growth.
Container-grown shrubs will most often come in 2 to 5 gallon pots and trees will be in 7 to 25 gallon pots. Container-grown plants are typically grown in a very well-drained organic medium comprised of composted bark, peat moss and sand. During production, container-grown plants are watered nearly every day and are supplied with a constant source of nutrients through controlled release fertilizer prills. The plants grow very rapidly and lushly and are subject to drying out if not watered regularly. Another issue with container-grown plants is that they can easily become pot bound and develop circling roots if grown too long in a particular pot size. Circling roots can lead to girdling roots as the plant grows older in the landscape. Treatments to correct circling roots (see section on “Plant Preparation”) should be employed prior to planting. In general, for sandy coastal soils, it is recommended to use plants in a larger pot sizes when possible. As long as the plants are not pot bound, and proper aftercare is provided, plants with larger root balls should be better able to establish in the sandy soil conditions found along the coast.
Planting Time
balled and burlapped (B&B) and container stock can be planted in the spring, summer or early fall. B&B material is dug in early spring and then healed in to hold it for the season. Once supplies of plants are sold out, new plants cannot be dug until late summer or the following early spring. Container plants are generally available throughout the growing season, but best selection can be found in the spring. Spring is the best time to plant trees, shrubs and vines, but early fall is another good time to plant for many species. Summer planting can also be successful, but special attention will have to be given to regular irrigation. Spring gives plants more time, essentially the whole growing season, to get their roots established. Fall planting is successful for many species because the tops of the plants are going dormant and need less water and nutrients, but the roots continue to grow well into the fall since soil temperature remain warmer than the air temperature.
Planting Hole
A planting hole for a tree or a shrub should be dug two times as wide as the root ball. The hole should only be dug as deep as the root ball depth, so when planted, the top of the root ball is at the same level as the surrounding soil, or slightly higher. In the past, planting recommendations used to suggest digging the hole deeper than the root ball depth and then back filling the bottom of the hole with loosened soil. The problem with this recommendation is that the loosened soil settles and the whole plant sinks into the planting hole, and ends up being planted too deep. Now, the recommendation is for the bottom of the root ball to sit on firm, undisturbed soil so that settling is less likely to occur.
Plant Preparation
When using B&B plant material, try to remove the burlap, twining and/or pins as much as possible. Even though burlap is biodegradable, before it decomposes it can slow root establishment, create air pockets and wick water out of the soil and into the air. If the burlap can’t be completely removed without causing the root ball to break apart, roll back as much of the burlap as possible and cut it off so any remaining burlap will be buried. Buried burlap will not function as a moisture wick to dry out the root ball area. For trees with wire baskets on the root ball, cut away as much of the basket as possible without causing the root ball to fall apart. Although it doesn’t seem as though leaving the wire basket in place would have detrimental effects on plant establishment and growth, research has proven otherwise.
When using container-grown plants for your planting, carefully remove the pot and inspect the root system. In some instances it may be necessary to cut the pot from the root ball. Recently potted plants may not be well-rooted into the entire ball, so care must be taken to not break apart the root ball. In contrast, plants may be root bound or pot bound with lots of roots circling around the bottom part of the root ball. Circling roots need to be corrected prior to planting so there is no longer a potential for development of girdling roots. Girdling roots result from circling surface roots that press against the plant trunk as they grow in diameter, eventually girdling part of the trunk. One method to correct circling roots is to separate and straighten the circling roots with your hands as the plant is being planted.
Alternatively, shallow vertical cuts can be made on four sides of the root ball to cut through the circling roots. The bottom of the root ball must also have criss-cross cuts made into it to sever circling roots. The distal parts of cut roots will die and the remaining root stubs will re-grow roots out into the soil in a non-circling formation.
Backfilling the Hole
In most cases, it is best to backfill the planting hole with the native soil that came out of the hole. In sandy soils, adding 30% organic matter can be helpful for moisture retention, nutrient retention and improving soil texture, but it isn’t necessary. Adding too much organic amendment to the backfill soil should be avoided. Overdoing it with amendment can create unnatural moisture gradients where the organic amended soil and root ball is either wetter or drier than the surrounding soil. Remove roots and rocks from the backfill soil and homogenize the topsoil layer with the lower subsoil layers and any amendment being added.
When the hole has been half backfilled with soil, water it thoroughly to work the soil around the root ball and to minimize air spaces. Finish backfilling, create a 2”to 3” high watering berm around the plant, and water thoroughly. A soil berm will contain the water so it is forced to percolate into the root ball area.
Aftercare
Watering
Newly planted plants will need to be watered regularly during their first year to insure successful establishment. Consistent watering is probably the single most important aspect of plant aftercare. Typically, trees or shrubs will need two to seven gallons of water weekly, but this depends on natural precipitation received, temperatures and wind. Slow application of water is preferred to allow for deep penetration of the irrigation.
Mulching
The best mulch to use is non-dyed, softwood barkbased mulches (pine, spruce, fir, hemlock, or cedar). Mulch allows for better water infiltration, holds soil moisture, moderates root zone temperature, suppresses weeds and helps prevent mower and string trimmer damage. A 3” deep layer of mulch is usually ideal and mulch reapplication should not be at a frequency which allows the depth to increase. Beds or areas of shrubs and herbaceous perennials should have mulch applied throughout the planting. Trees should have a 3’ to 6’ diameter circle of mulch around them, but the mulch depth should thin to nothing as one approaches the trunk. Mulch “volcanoes” around trees are unacceptable and will lead to trunk diseases. In general, the use of porous weed barrier fabric or plastic under mulch is not recommended.
Fertilization
Fertilization during the first growing season is recommended, but do not expect to see dramatic growth stimulation from the fertilization application. During the first year, especially for B&B plants, plants are becoming root established and significant top growth in response to fertilizer is often not seen. The fertilizer is still benefitting the plant even if it isn’t clearly visible as shoot growth. Ideally, fertilizer should be applied based on recommendations stemming from soil test results. Special care must be exercised in riparian areas to avoid nutrient runoff and leaching that can easily pollute the nearby Long Island Sound. A surface applied granular 10-10- 10 (N-P-K) fertilizer is often the most economical choice for riparian plantings. Apply in late April or early May at a rate of 1 to 2 pounds of actual N per 1000 sq. ft. of area. Once established, properly selected riparian species may not require annual fertilization to remain healthy and attractive.
Pruning
Prune out any dead or damaged shoots or branches at planting time. In the past, the recommendation was to remove 25% to 40% of the plant canopy to compensate for root loss during digging, but this practice is no longer promoted. With expanded use of container-grown plants there is not root loss as there is with B&B plants. Also, research has shown that it is better to preserve the canopy so maximum photosynthesis can be realized, which helps build back the root system quickly
Staking
Young trees will do better without staking. Free movement of a tree canopy in the wind causes the trunk to thicken in response to the motion and develop proper trunk taper and flare at the base. Staked trees have “skinny” trunks and are less strong. Only stake trees that are unstable or bend over in winds or after rainfall. Coastal locations often receive relatively strong winds, so staking may be required. Staking materials should use padded ties so the bark isn’t damaged and should allow for some trunk movement. Tree stakes should generally only be left in place for one year.
Planting Techniques for Herbaceous Perennials
Herbaceous perennials are perennial plants whose tops go dormant and die down each fall. They do not develop permanent, above ground woody stems. This group of plants includes flowering perennials, foliage perennials, grasses, sedges and non-woody groundcovers. Herbaceous perennials are commonly sold in quart, 1 gallon and 2 gallon sizes, so digging their planting holes is easier than for large tree and shrub rootballs. If herbaceous perennials are being installed in beds or large groupings, it can be useful to cultivate in a 2” layer of organic matter (compost) over the planting area prior to planting. The organic matter will improve water and nutrient retention in sandy coastal soils.
All herbaceous perennials can be planted in the spring and many can be successfully planted in the fall (late August through early October) as well. Warm season grasses (those that grow optimally in the heat of the summer) should not be fall planted. For fall planting, it is probably better to use larger sized plants since the rootball is larger with a more extensive crown and root system. Larger plants are less likely to heave out of the ground in the freeze-thaw cycles of the winter than smaller plants. The same recommendations made for trees and shrubs regarding planting depth and circling root remediation also apply to herbaceous perennials. Excavating a large hole diameter for herbaceous perennials is not as important as it is for trees and shrubs. Furthermore, digging very wide holes is typically not practical in most herbaceous perennial installations due to the close spacing of plants and the large numbers of plants that are used.
For areas with perennials, a mulch layer between 1” to 2” deep is recommended. Watering during establishment is critical and a weekly 1” application of water should be provided except when substantial natural precipitation is received. Herbaceous perennials will benefit from a surface application of a complete granular fertilizer, such as 10-10-10 (N-P-K) at a rate of 1 pound of actual N per 1000 sq. ft. during their establishment period.
Tools and Other Helpful Information
Riparian Plant List
Not sure which plants should go in a riparian zone? See our list of recommended native plants to get started! These plants have been selected based on the benefits they provide to our local ecosystems, such as for valuable wildlife habitat, nectar sources for pollinators, and more.
Coastal Specific Riparian Restoration
If you are looking to plant along the coast, see the links below to get more comprehensive information on coastal riparian restoration.