Native plant installation in fall colors. Photo: Ronda Burnett
Native Landscape Installation Best Management Practices
A resource for professionals
This document provides basic native garden installation concepts and techniques that are shared among native landscape professionals. Proper installation increases the success of the landscaping project and increases the sustainability of maintenance. As the green industry shifts towards more ecologically and environmentally focused practices, it is important to constantly expand the knowledge base in the native landscape industry. The Grow Native! program aims to update this document over time with new information as it is learned and shared 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 proposed area and start digging may be strong, there are a few things to keep in mind and actions to take before sliding your shovel into the ground. Considering these steps will help your landscaping project succeed long-term and keep you sane in the meantime.
Client perceptions and expectations
Native plantings are not maintenance-free, but they needn’t be messy or wild either. It is important that clients understand that a native planting goes beyond just a patch of pretty wildflowers. Communicating not only the vision of a design, but also the requirements necessary for establishing (and maintaining) a healthy, sustainable 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 a mature native planting.
General site assessment
While your design phase will go into the details of a site assessment, make sure that research is done properly on the front end so that installation is not stalled due to permit, homeowners’ associations, or local ordinance issues. Considerations need to be made in reference to plant placements next to sidewalks, doors, and other property features, or if neat edges or buffer strips are desired. In addition to common environmental considerations, others that may affect plant health include overhead street and parking lot lights, winter salting practices, and herbivory, especially where deer or rabbit pressure is high.
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 for erosion and/or sediment management need to be sourced, gathered, and transported to the installation 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 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 (N, P, K) and micronutrients (B, Mg, Cu), 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 or not 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.
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 appropriate 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 an overall removal plan of existing vegetation in advance is extremely important in the installation process for native plantings. Some invasive or aggressive species may require multiple applications of herbicide, or repeated cutback to successfully remove them from a site. If a more organic approach is desired, solarization 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.
Plants native to a specific region differ from many traditionally ornamental non-natives in that they are adjusted to a region’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. Some clients and/or Grow Native! professionals use 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 and butterflies, in addition to 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., 15 gallon or 25 gallon).
- Containers should not be root bound. Girdling roots on the surface of the container plant is a good indication that 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 those 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 will install have been treated during the growing process. This knowledge may aid in deterring transplant shock and other possible stressors.
- Be mindful of how dry or wet the container medium is when installing. 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 – Typically small-to-medium specimens measured by container size [e.g., gallon (6”) or quart (4”)].
- Check roots for health and adequate growth. Some growers will “up-pot” too soon, resulting in very small, weak roots and too much soil.
- Plug – 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 your installation when conditions are ripe for planting success is an often overlooked part of the process. 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, as planting in wet soil will ruin soil structure. Excessive wind will dessicate root systems. Watering is typically the key ingredient to initial plantings. Laying out plugs, especially those that are naked, or containerless, should be done in a manner that allows the plug to be exposed for only minimum amounts of time. 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, in Missouri, Dig Rite at 811, must always be done and often within specific time frames in advance of the initial demolition or installation. The average cable line is anywhere from 1” to 3” 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 to any jobsite. When in doubt always 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 a site assessment and planning 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 undesirable vegetation to prepare a site is not recommended. Tilling does not always kill existing vegetation, it stimulates weed seeds to germinate, and it destroys 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.
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. For example, if the depth of blue fescue roots measure approximately 3” then strip the sod at a depth of 3”. 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 there is bare soil for seed to make contact with.
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 e months.
This approach generally involves using a string trimmer or other equipment to cut off the surface layer of plant material that 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 there is bare soil for seed to make contact with.
Existing vegetation and weed seeds in soil can be killed through the process of solarization, whereby a tarp or other plastic sheets are pinned to the ground, and trapped heat from the sun kills the vegetation underneath. Plastic should be in place for at least 3 months during the growing season, but may require a longer solarization period depending on the time of the year.
Existing vegetation can be killed using herbicides, especially to treat large areas of non-native vegetation to prepare for native seeded landscapes. 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. Some clients may not want chemicals of any kind to be used on their property. It is important to respect a clients’ wishes, and for smaller areas, it may be possible to smother existing vegetation to prepare for native plantings (see solarization), but it can take a minimum of three months to do so.
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.
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. Before using herbicides, 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 which specific plant/purpose. Consult this handy table from the Missouri Prairie Foundation on which herbicides to use to treat specific invasive plants, and when. 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.
In contrast to traditional ornamentals/exotics, most native plants do not require additional amendments in order to establish 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 projects carefully before purchasing and using. 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.
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.
Planting Time: Getting Your Hands Dirty
A hole twice as wide as the container size or root ball is the best-sized hole to dig for planting a tree. 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 an inch above soil level. When planting a seedling, the plant should be placed at the same height as the soil line or half an inch lower.
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. Do not forget to remove metal cages from BB trees/shrubs! Forgetting to do so will result in decreased vitality and possible death.
If choosing to use mulch, consider applying a thin layer of leaf compost in a perennial setting or hardwood mulch/bark chips for tree plantings. If you use bark or wood mulch, larger mulch pieces allow water and air to flow to soil. Very fine wood mulch can create a crust and also 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 underplanting. Not only will this suppress weeds, it will also provide wildlife and invertebrate habitat. Avoid rock, dyed mulches, shredded tires, or other inorganic materials as a mulch. However, using rock as a mulch for certain types of natives gardens, for example, a glade garden, 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 client expectations are met, to inform the client 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 installation practices will help you develop and implement sustainable maintenance practices of the planting. You may wish to consult the Grow Native! Native Landscape Care Calendar for more information.