Native plant installation in fall colors. Photo: Ronda Burnett
Native Landscape Installation Best Management Practices
A resource for professionals
Jump to Site Assessment and Planning, Site Preparation, Planting Time, After Installation.
This document describes basic native garden installation techniques common among native landscape professionals. Proper installation increases the success of landscaping projects. As the green industry shifts towards more ecologically and environmentally focused practices, it is important to incorporate such knowledge into the native landscape industry. Grow Native! will update this document over time to stay current with the latest trends among native landscape professionals. Homeowners doing their own native landscaping may find this information useful as well.
Site Assessment and Planning
While the urge to march out to the project site and start digging may be strong, there are a few things to keep in mind and actions to take before breaking ground. The following steps will help your landscaping project proceed smoothly and succeed in the long-term.
Client perceptions and expectations
Clients should understand that native plantings are not inherently messy or wild. Also, they go beyond small patches of wildflowers and can be designed to meet the aesthetics of any conceptual layout plan. Communicating not only the vision of a design, but also the requirements necessary for establishing and maintaining a healthy native planting is key to a planting’s success, as well as a client’s long-term satisfaction with the project. Consider offering an installation and maintenance “snapshot meeting” before beginning the project and walk the client through the process it takes to achieve an established, mature native planting, which can take one to three or more years. Some native plant landscaping businesses furnish their clients with a “client expectations” document to sign.
Once the client understands the process of native plantings, be sure to check governing homeowner association covenants, conditions, and restrictions and/or local ordinances to see if there are any landscaping guidelines that must be followed or if a permit will need to be procured for the project.
Record all site components that will inform your design. These include the location of access points, easements, utilities, and structures. Make note of physical site conditions including existing vegetation, soils, topography, hydrology, aspect, and views to and from the site. Also consider potential nuisances such as surrounding noise levels, odors, and dust from nearby fields or unpaved roads.
The site analysis phase of a design project is when opportunities and constraints are identified. A comprehensive analysis will consider the context of the site. Observe the culture of the neighborhood and make note of neighboring land uses. This will allow you to capitalize on appealing views from the site looking out and may inform your design choices if there is an opportunity to tie into a local theme, community event, or continue an established rhythm along the street, if desired. Other opportunities the site analysis might uncover are ways to improve site circulation or where a focal point can be created. Design constraints may be those that affect plant health such as winter salting practices, herbivory from deer and rabbits, and artificial lighting from overhead street lights and parking lot lights.
Design of native plant landscaping plans are guided by the information gathered during the site inventory and analysis phase of the project. Additional considerations include an understanding of how the client wants the site to perform (ecosystem services), how the site will be used (programming), and how the client wants people to feel while at the site (phenomenology). By adhering to design principles and elements of art, the designer will select and arrange plants, hardscaping, and site furnishings in a way that will achieve the client’s goals.
DESIGN PROCESS & CONSTRUCTION PLANS
Pre-design is composed of the above steps of checking into local regulations, conducting client interviews, and site inventory and analysis. Next comes the conceptual design phase, which starts with consideration of design themes and bubble diagrams and ends with a master plan for the property. Construction documents are developed so that the design can be successfully implemented on the site. A layout plan shows both existing and proposed site conditions. It provides a good overview of the scope of the project. Additionally, layout plans provide dimensions so new elements can be located on the site. A grading plan is necessary if the design calls for any topography modification of the site and or if any hydrological concerns need to be addressed. A planting plan specifies the plant species to be planted along with their location on the site and provides guidance on planting techniques. Irrigation plans are provided when permanent irrigation systems need to be installed, but this is rare for native plant landscaping projects. And finally, a maintenance plan or site stewardship plan provides guidance on the long-term management of the site including how to prepare beds and/or specific plants for dormant seasons and growing seasons as well as how to identify and manage common weeds, pests, and plant diseases.
This document conveys the overall design intent for the garden space: size of the bed, placement of the plants, intended human flow through and usage of the garden space, and long-term spread of specific plants, to mention a few considerations. Familiarizing yourself with the site plan, including the location of downspouts, heavily traveled paths and walkways, areas of water mitigation, and possible hardscape construction will help keep the design intent intact and the expectations of installation clear.
Erosion and sediment management
Before digging, all materials needed to prevent soil erosion and/or manage sediment need to be sourced, gathered, and transported to the project site. It is possible that some of these materials will need to be installed prior to or during the demolition phase. These may include wattles, erosion control blankets, and silt fences.
Soil tests provided by most University Extension offices as well as environmental laboratories will provide a profile of existing soil characteristics such as pH, levels of nutrients (Nitrogen, Phosphorus, Potassium) and micronutrients (Boron, Magnesium, Copper), soil texture, and cation exchange capacity (CEC). CEC influences the soil’s ability to hold onto essential nutrients and provides a buffer against soil acidification. Soils with a higher clay fraction tend to have a higher CEC. Organic matter has a very high CEC. A soil test is generally performed before a site plan is developed to help inform whether amendments are needed. Most native plants are best planted within their native soils (i.e., without amendments or soil replacements), however, some rainscaping systems and specialized plantings may require amendments to facilitate groundwater infiltration or to meet the specific subsurface stormwater storage capacity specified in the construction plan.
It is possible to learn to identify soil textures by taking samples for study and using a soil texture triangle to determine a soil’s characteristics. This information is indispensable when identifying an appropriately designed plant community for a site.
Note: In many residential and commercial locations, native soils have been removed and replaced with construction-grade or virtually “dead” topsoil. It is possible that a topdressing of compost and/or multiple applications of a liquid tea compost may be necessary to jumpstart building up healthy, microbial and mycorrhizal growth in the soil.
Land use history
Often overlooked in the planning stage, knowing the land use history of a site can help mitigate heavy weed pressures and decrease maintenance requirements. For example, if the site of a proposed native meadow is a fallow field formerly used for pasturing horses, it is likely that the seed bank (seeds dormant in the soil) will have a higher concentration of tall fescue, ragweed, or other undesirable plants, and preparing the site for a native planting may require more time, to treat germinating weeds from the seedbank. Understanding the land use history can increase the likelihood of a successful native garden perpetuating over time.
Removal plan for existing vegetation
Developing a removal plan for existing vegetation is extremely important in the installation process for native plantings. Depending on the site and type of native planting to be established, a sod cutter can be used to remove existing turf, or cardboard can be applied to kill vegetation. Some invasive or aggressive species may require multiple applications of herbicide over the course of a year, or repeated cutback to successfully remove them from a site. In some instances, sites can be converted to a temporary cover crop for a year or two to ensure complete removal of unwanted species before installing native plants. In lieu of herbicides, solarization is an option that may take up to 3 to 6 months, or longer, in order to kill off existing vegetation, depending on the time of year. If large trees need to be removed, equipment or subcontractors will be involved. Executing removals on a schedule helps to minimize hidden costs associated with last-minute removals and can be more easily folded into the bidding process. See more information on methods of removing existing vegetation in the Site Preparation section below.
Native plants are adjusted to a project site’s climate, including levels of precipitation. Thus, they generally do not need a consistent watering regime. Landscapes with existing irrigation schedules can sometimes discourage native species and encourage weed/exotic species that thrive in consistently moist, disturbed soil. Once a new planting has established its root systems, allow natural precipitation to water the landscape. In instances of drought, an existing irrigation system can be used until the rains resume. Temporary water irrigation systems to water plants for the first 30 to 45 days after installation until there is sufficient root growth.
Procured plant evaluation
All plants to be installed should be evaluated prior to planting. Ideal tree specimens should have a strong central leader (if appropriate to the species), a firm root ball, no girdling roots or buried root flares, no pest activity, and healthy, undamaged bark. Damaged or crossing branches should be removed. Container-grown trees and shrubs should be inspected for pest activity, root bounded-ness, girdling roots, healthy bark, and branching structure. Herbaceous forbs, grasses, ferns, and sedges should also be inspected for healthy root systems, disease, and pests. (However, finding native insects feeding on their specific host plants—like monarch caterpillars feeding on milkweed leaves, even before the milkweeds are planted—is an added bonus!)
Evaluation Tips Specific to Native Trees
- Leaves are a good indicator of the health of the tree/shrub. In general, curled, spotted, pimpled, or discolored leaves are symptoms of stress, disease, or an insect infestation. Be forewarned that species such as Cornus spp. (dogwoods) and Aesculus spp. (buckeyes) tend to suffer more frequently from stress and disease, especially in the warmer months. Early leaf fall in these species does not mean the trees are dying; this is simply a drought-survival adaptation.
- Many native species are host plants for moths, butterflies, wasps, flies, and midges. Nibbled foliage can be a sign that the native plants are providing a valuable food/nesting source to wildlife.
Specific Issues with Type of Tree/Shrub Sizes:
- Ball and Burlap (BB) – Typically large specimens measured by caliper or ball size, e.g. 1.5” or 36”.
- Balls should be tightly held together with little to no weeds growing out of the burlap.
- Wraps should be snug, but not chokingly tied around the base of the tree, just above the root flare.
- If possible, check to see if the root flare is visible or if it has been buried. Too much soil too high above the root flare can cause girdling roots and other issues.
- If there is a plastic protector high up the trunk, ask for the vendor to remove it so that the trunk can be inspected for gauges, rubbing, or other signs of potential trouble.
- Container – Typically, medium to small specimens measured by container size, e.g., 3, 15, or 25 gallon.
- Containers should not be root bound. Girdling roots on the surface of the container plant is an indication that the plant is most likely rootbound and there will be more girdling roots underground.
- The ideal container is weed-free, although in practice this is a hard rule to follow. A few weeds are acceptable, but stay clear of containers that are overflowing with weeds. It is generally possible (and recommended) to remove the top inch of soil from a containerized plant in order to remove weed seeds.
- Root balls should be loose enough to allow you to stick your finger into the dirt, but not so loose as to fall apart when removed from the container.
- If possible, pull the tree/shrub carefully out of the container and look at the roots for signs of insect activity and new growth.
Evaluation Tips Specific to Native Forbs, Grasses, Sedges, and Ferns
- Always check the roots to make certain the plant is healthy. Depending on the time of year, it may not be possible to judge the health of a plant by the aboveground portion. Roots should be well formed and numerous, but not root bound.
- Some growers inoculate their growing medium with mycorrhizae or use specialized, fast draining growing medium. Developing a good relationship with growers will help you understand how the plants you install have been treated during the growing process. This knowledge may help reduce transplant shock and other possible stressors.
- Be mindful of how dry or wet the container medium is during installation. Sometimes it may be necessary to soak the plants before putting them in the ground. Never plant an ultra-dry plant without soaking it first; not doing so could lead to plant death.
Specific Issues with Forb, Grass, Sedge, and Fern Sizes
- Container stock – Typically, small-to-medium specimens are specified by container size, e.g., gallon-sized pots are six inches and quart-sized containers are four inches.
- Check roots for health and adequate growth. Some growers will “up-pot” too soon, resulting in very small, weak roots and too much soil.
- Plugs – Typically small specimens measured by size, usually 2” wide by 5” deep
- This size of specimen is generally used on larger landscape projects, when laying in ground planes, or when immediate gratification is not a client’s preference. If choosing to install plugs make sure the client expects smaller starter plants.
- Some landscape plugs do not have individual containers. They come in a tray and are “naked.” These plugs can dry out very quickly if not adequately watered or if they lay out in the open for long periods of time.
Timing installation work for when conditions are promising for planting success is often overlooked. An ideal planting day is one that is cloudy with little or no air movement and 50% relative humidity. Avoid planting immediately after a rain event or in excessive wind, as planting in wet soil will ruin soil structure and wind can desiccate root systems. Laying out plugs, especially those that are not in containers, should be done in a manner that limits exposure time to the elements as much as possible. Plants that have been laid out on sunny, windy days can dry out very quickly while they await installation.
Calling the appropriate utility locator service, such as Dig Rite at 811 in Missouri, must always be done and often within specific time frames in advance of initial demolition or installation work. The average cable line is anywhere from 1 to 3 feet in the ground and can easily be cut through by mistake. Utility locates are best made prior to estimates as issues with utilities can add a large burden to the cost of labor.
Safe equipment operation + PPE
Safe operation of equipment and proper use of personal protective equipment (PPE) is essential at any jobsite. When in doubt, wear gloves, eye protection, and ear protection. Consult your company’s safety manual for guidance as to what PPE is required when operating equipment. Before starting up machinery, consult the operator’s manual and ensure all individuals have received proper training. When operating machinery, be mindful of your surroundings, including other people, cars, plants, utilities, etc. In Missouri, call DigRite at 811 to locate utilities prior to using earth-moving equipment. If subcontracting work involving machinery, verify that subcontractors are insured for liability. Care should be taken when operating heavy equipment near tree roots as this can damage existing mature plants. If needed, create a “plywood highway” for equipment to drive on to protect turf, pavement, or other surfaces. Have a plan in place in case of emergencies.
After site assessment and planning activities have been completed, planting sites can be prepared. There are a number of factors regarding site preparation, including existing vegetation and invasive plants, to consider during this stage of a project. Note: tilling under unwanted vegetation and/or tilling to prepare a site for new plants is not recommended. Not only does tilling not always kill existing vegetation, it can stimulate germination of weed seeds and destroy soil structure.
Existing boundaries of a planting bed may need to be enlarged or otherwise modified to accommodate the new planting. At this time, when sod is removed to create a new bed line, soil amendments or top dressings, if needed, can be added. Also, edging the bed can prevent turf from spreading into the native planting.
Whether manually removing sod or using a machine to do the work, the depth of removal will be determined by the type of existing sod (turf grass). Since turf grass root system depths vary by species, it is best to base your removal depth by measuring the depth of the root system. Simply dig up a small test portion of turf grass, measure the root depth, and then set the overall depth accordingly. If the depth of the roots measure three inches or so, strip the sod at a depth of three inches. It is best to remove the least amount of soil as possible. Note: for seeded landscapes, it is not necessary to strip sod. After existing vegetation has been killed, seed can be planted with a no-till drill or broadcast, as long as the seed can make contact with bare soil. A heavy roller applied across the site following seeding can help make seed to soil contact.
Cardboard can be used to kill existing vegetation. Grow Native! recommends single face corrugated cardboard, which is not coated, and supplied in rolls. First, cut weeds/vegetation in the area as low as possible. Then, cover with cardboard. Pin the cardboard in place and cover it with compost or mulch. Leave in place for a minimum of three months.
Scalping is an approach that generally involves using a string trimmer or other equipment to cut off the surface layer of plant material at least ten days after it has been treated with herbicide. Scalping works well on sites where erosion is an issue. Note: for seeded landscapes, it is not necessary to scalp. After existing vegetation has been killed, seed can be planted with a no-till drill or broadcast, as long as the seed can make contact with bare soil. A heavy roller applied across the site following seeding can help make seed-to-soil contact.
Existing vegetation and weed seeds in the soil can be killed through the process of solarization, whereby a tarp or other plastic sheets are pinned to the ground, effectively trapping heat from the sun. This heat will kill the vegetation underneath the plastic. Tarps or plastic sheets should be left in place for at least three months during the growing season, but may require a longer solarization period depending on the time of the year.
Anyone who intends to use herbicides in their professional work or on property he/she doesn’t own must have a commercial applicator license. Find out about state requirements (in Missouri) here. Always follow herbicide label instructions carefully. Wear appropriate personal protective equipment (PPE), be mindful of herbicide use and weather conditions, and understand which herbicide to use for specific plants/purposes. Consult this handy table (“Common Invasive Plants in Grasslands and Recommended Treatments”) from the Missouri Prairie Foundation on which herbicides to use to treat specific invasive plants in grasslands, and at what time of year. You may also wish to consult this Missouri Prairie Foundation guide to establishing and maintaining seeded prairie plantings and this recorded webinar by MPF Director of Prairie Management Jerod Huebner on establishing prairie plantings, which include information on using herbicides. Use the least toxic herbicide to complete the job. Note: Some herbicides are labeled “restricted use” and their use is regulated by an applicator license. Extensive information on invasive plant identification and herbicide and other treatment methods is available here.
Given the wide range of available chemicals, it is understandable that some clients may be confused about the purpose of specific ones. You may want to explain to clients that herbicides, when used correctly, are intended to kill plants, and only plants, and explain the differences between herbicides, insecticides, and other pesticides.
Existing, unwanted vegetation on your project site can be killed using herbicides. This technique is especially useful when treating large areas of non-native vegetation, as is often the case when preparing to seed a landscape with a mix of native plants. Herbicides are also useful for treating invasive plants that can invade native gardens/plantings and threaten native biodiversity.
While all chemicals should be used judiciously, herbicides, when used correctly, are an important tool in killing monocultures of turf or other non-native vegetation so that biologically diverse plantings can be established. These plantings will support monarch butterflies, native bees and other insects, and many other wildlife species that depend on native plant diversity and structure. Even after understanding the differences between them, some clients may not want chemicals of any kind to be used on their property. In that scenario, an alternative method of killing existing, unwanted vegetation is to smother it (see solarization), but this can take a minimum of three months and is only recommended for smaller areas.
In contrast to non-native ornamentals/exotics, most native plants do not require additional amendments in order to become established and thrive. Natives such as little bluestem will flop in highly organic soils. Consider planting without adding amendments. Note: Many native plant professionals recommend inoculating native plants with appropriate mycorrhizae fungi. This is an emerging and evolving technique and there are numerous mycorrhizal products on the market. Grow Native! recommends researching mycorrhizal fungi products carefully before purchasing and using them. Some native plant professionals use liquid “tea” compost, which is a concentrated, highly nutritious liquid compost used when watering in new plantings.
Depending on the client, it may be desirable to put some temporary signs in place to explain that “native landscaping is in progress.” This practice can help clients/neighbors/community members understand that disruption or establishment time is intentional.
Preparing a site for seeding and broadcasting seed is covered in the Native Gardening Overview. This topic is covered in detail in the Missouri Prairie Foundation guide to establishing and maintaining seeded prairie plantings and this recorded webinar by MPF Director of Prairie Management Jerod Huebner on establishing prairie plantings. See also month-by-month seeded landscape stewardship in the Native Landscape Care Calendar.
Planting Time: Getting Your Hands Dirty
When planting a tree, the hole should be dug twice as wide as the container size or root ball. The depth should be approximately the same size as the container or root ball, making sure that the crown of the plant or root flare of the tree sits even with or up to an inch above soil level. When planting a seedling, the plant should be placed where the first roots on the stem are even with the soil line.
Scoring the roots
It is advisable to score the roots of plants to encourage immediate, lateral root growth. For pot-bound plants, this will also create openings for new roots to emerge.
All plants should be placed in their holes and backfilled so that they do not become dislodged by watering or other planting procedures. Crowns and root flares should sit approximately 1 inch above soil level. It is important to make sure the roots have plenty of soil firmly surrounding them so that the plant does not sink upon watering in or the soil settling. This also will help decrease the possibility of frost heave or air pockets that could prove detrimental to plant health in the winter. It is important to remove metal cages from ball and burlapped trees and shrubs! Failure to do so will result in decreased vitality and possible death of the plant.
If choosing to use mulch, consider applying a thin layer of leaf compost for perennial plantings or hardwood mulch/bark chips for tree plantings. Note that larger mulch pieces allow for better flow of water and air to the soil. Very fine wood mulch can create a crust and promote fungal growth, which may not be helpful to your plants. While the benefits of mulch include moist, cool roots, suppressed weeds, and a “tidy appearance,” most native plantings do not require mulching. For an alternative approach, use a green (living) “mulch,” such as a sedge groundcover or underplanting. Not only will this suppress weeds, but it will also provide wildlife and invertebrate habitat. Avoid rock, dyed mulches, shredded tires, or other inorganic materials as mulch. An exception to this guidance is the use of rock mulch for certain types of native gardens such as a glade garden, where it might be appropriate. (Note: check for sustainable sourcing of mulch products.) If mulching a rain garden or other area prone to flooding, use living green “mulch,” an erosion blanket, or hardwood mulch. Water will move the small, light particles of leaf compost and smaller aggregates, increasing the likelihood of clogging up outlets and drains.
Cleanup starts with proper planning to prevent or minimize mess. For instance, creating a plywood highway for wheelbarrow transport can save existing turf. Plywood can also be used to protect surfaces like concrete from getting dirty. Tarps are also a good tool. Using these simple tools can save a lot of end time cleaning up. As with all work sites, cleaning up the installation area is essential to presenting the final product to a client. Clean up and put away any equipment, wash off mud and debris from hardscapes, rake through turf, and make sure all trash has been removed to an offsite location.
Establishing a new planting requires consistent waterings. If rain is not plentiful and depending on the time of year, a deep watering two to three times a week will suffice. To determine the correct watering depth, use a soil knife or your finger to dig at least 4” below the surface. If the soil is moist, you have adequately watered. This is especially important in the winter. While everything may look “dead,” most root systems continue growing until the ground freezes solid. Throughout the winter the ground may freeze and thaw multiple times, and during these thaw cycles roots continue taking up moisture. If a week goes by without adequate moisture (less than 1 inch) or if there are several windy days in a row, trees and shrubs can become desiccated and/or stressed causing potential future issues or even premature death. If adequate precipitation (less than 1 inch) has not occurred for a week, soak the soil around each newly planted shrub and tree pausing over the roots for at least 10 to 20 seconds. Standard household hose pressure is ideal. This small contribution of moisture will yield a tenfold reward when the tree buds open in spring. Note: some native plant professionals water new plantings for 30 to 45 days after installation until sufficient root growth has occurred, and recommend that clients water through the first few years of a planting during periods of extreme drought.
Client Walk Through
After installation, offer the client a walk-through of the planting to ensure their expectations were met, to inform them about specific plants, and to offer additional services like watering, maintenance, evaluations, education, etc. Some Grow Native! professional members find that investing time in good client relations sustains working relationships and increases the success of the landscape over time.
Evaluation + Documentation
Document steps taken during the installation process as well as the final product. Any adjustments to the planting plan should be noted and tucked in a file for future reference. Depending on the maintenance/warranty contract, evaluate the planting at least once a month over the course of the first year, and then quarterly in year two. If the maintenance contract allows, repeat visits will allow for design intent and plant health evaluation. Be on the lookout for plant decline, human disturbance, soil moisture inappropriate to the site, and any changes to the surrounding environment that might impact the success of the installation.
Investment in quality installation practices will help you develop and implement sustainable maintenance practices for the planting. You may wish to consult the Grow Native! Native Landscape Care Calendar for more information.
The development of these Grow Native! Native Landscape Installation Best Management Practices was supported via funding from the Missouri Department of Conservation in FY2021.