Changes

*'''Low Zone''': Lowest area of the feature, along the bottom of the planted area and is the area that gets fully inundated with water during rain events or heavy runoff leveles enter. Plants that should be chosen here prefer moist soils and should be rated a "3" when referencing our STEP tables above.

*'''Low Zone''': Lowest area of the feature, along the bottom of the planted area and is the area that gets fully inundated with water during rain events or heavy runoff leveles enter. Plants that should be chosen here prefer moist soils and should be rated a "3" when referencing our STEP tables above.

*'''Middle Zone''': Middle zone of feature, which can still possess higher soil moisture levels, but that doesn't persist as long as the levels seen in the Low Zone. Plants that should be selected for this area prefer alternating wet and drier periods and should be rated a "2" when referencing our STEP tables above.

*'''Middle Zone''': Middle zone of feature, which can still possess higher soil moisture levels, but that doesn't persist as long as the levels seen in the Low Zone. Plants that should be selected for this area prefer alternating wet and drier periods and should be rated a "2" when referencing our STEP tables above.

*'''High Zone''': High area of the feature in question and as a result its soil moisture levels are very low and it is the driest section of the planted area. Plants selected should have good drought tolerance and should be rated a "1" when referencing our STEP tables above..

*'''High Zone''': High area of the feature in question and as a result its soil moisture levels are very low and it is the driest section of the planted area. Plants selected should have good drought tolerance and should be rated a "1" when referencing our STEP tables above.

==Plant Characteristics==

==Plant Characteristics==

===Drought tolerance===  

===Drought tolerance===  

These categories represent broad generalisations regarding drought tolerance.

These categories represent broad generalizations regarding drought tolerance.

===Salt tolerance===  

===Salt tolerance===  

The low, medium and high categories indicate the tolerance of plant species to [[salt]] exposure and/or uptake. Plant species with low salt tolerance should not be used in any LID practice receiving runoff from salted roads and parking lots. Species with medium salt tolerance can be utilised in LID practices that will be receiving road runoff but should not be in the line of salt spray or be receiving the bulk of the runoff. Species with high salt tolerance should be planted in LID practices that receive road or parking lot runoff that routinely contains road salt.  Few plants are truly halophytic or “salt-loving”.  In most cases, elevated salt levels are temporary and precipitation quickly dilutes and removes salt from the soil profile. The plant lists below include recommended species for LID practices likely to receive road or parking lot runoff.

The low, medium and high categories indicate the tolerance of plant species to [[salt]] exposure and/or uptake. Plant species with low salt tolerance should not be used in any LID practice receiving runoff from salted roads and parking lots. Species with medium salt tolerance can be utilized in LID practices that will be receiving road runoff but should not be in the line of salt spray or be receiving the bulk of the runoff. Species with high salt tolerance should be planted in LID practices that receive road or parking lot runoff that routinely contains road salt.  Few plants are truly halophytic or “salt-loving”.  In most cases, elevated salt levels are temporary and precipitation quickly dilutes and removes salt from the soil profile. The plant lists below include recommended species for LID practices likely to receive road or parking lot runoff.

===Compaction and pollution tolerance ===

===Compaction and pollution tolerance ===

Development nearly always causes compaction of on-site soil, and bioretention facilities  in road-right-of-ways should be pollution tolerant.

Development nearly always causes compaction of on-site soil, and bioretention facilities  in road-right-of-ways should be pollution tolerant.

|}

|}

[[File: Altonraingarden2_kb.jpg|thumb|Rain garden on residential lot in Alton, ON.]]

There are two basic categories:

#Exposure to roadway or parking lot runoff. Runoff is contaminated with deicers and vehicle pollutants. These can take on several forms, including parking lot islands, traffic islands, roundabouts, or cul-de-sacs and are often used as [[snow]] storage location

Whatever the choice of style, it is essential that the surrounding context is taken into account.  While a planting design can have a natural appearance, the landscape should never appear haphazard or messy. The aesthetic goal is to achieve a visual sense of fit and scale with the site.  The design should be intentional, appropriate and pleasing to the eye and consider the following:

Selection of plant species suited to tolerate the varied conditions common to green infrastructure is essential for the success of a planting plan. A plant’s ability to tolerate flood conditions is further correlated to its age, adaptation to the site, and condition. A well-established plant has greater reserves to withstand flood events. While it is recommended to leave the LID practice offline until plants become established (one to several years), in most instances this may not feasible. Measures incorporated into the LID practice such as erosion and sediment controls and pre-treatment cells can moderate flows enhancing survival potential. In all cases, soil surfaces must be stabilized prior to allowing flow to enter the LID facility.

*Maintain visual interest throughout the seasons

Selecting plant material that will be appropriate for a particular site should take into consideration the local context or setting. Some species, especially rare or potentially aggressive species, are not always conducive to the type of site or objective of the project, especially in areas near or next to natural communities. For example, a [[green roof]] that is isolated from all natural areas may be ideal for regionally rare species that are specially adapted to conditions of high exposure and shallow soils. Among the questions that should be asked are:

*Use of selective species palate

*Is this LID site located within, adjacent or close to a natural area? Or, is this LID site location isolated (i.e. beyond 120 m of natural feature) from the natural environment?

*Use of one or two species or elements to create an accent

*What is the composition of the nearby natural area?

*Consistency in plant placement and spacing; incorporating mass groupings, repeating plant groupings, materials and/or design elements

*Avoid sparsely spaced greenery; the planting beds should be fully vegetated once mature

*Consider habitat attributes of plant material

*Enhanced LID function related to pollutant uptake, temperature mitigation, filtration, and [[evapotranspiration]]

To help you select appropriate plants for your site, we've developed tables for [[Graminoids: List|graminoids]], [[Perennials: List|perennials]], [[Shrubs: List|shrubs]], [[Vines: List|climbing plants]], [[Trees: List|trees]] and [[turf]] focusing on their suitability for implementing LID practices and their aesthetic appeal.

==Native, introduced and rare plants==

The goal of planting design for LID practices is to achieve a sustainable vegetation community that is tailored to the ecological qualities of the site and the aesthetic considerations of the landowner. Plant selection for LID practices is predicated on the principle of ‘right plant for the right place'. Many LID practices are carried out within a highly urbanized context that poses unnatural stresses on plant growth and survival. This guide provides general recommendations to direct species selection. Landscape professionals should use this information to generate specific [[Plant lists#Plant Selection|Plant Selection]] lists that are tailored to the conditions prevalent on site while addressing surrounding urban and natural land uses.  

==Basic principles==

===Native and introduced species===

The basic principles of landscape design that should be considered in the creation of any planting plan, no matter how small, are described below. For projects that don't require a landscape architect, LID proponents may have to engage in small-scale landscape design. Not all of the following principles need to be applied in each case, but a basic understanding of each provides guidance. The manner in which these principles are applied creates a particular aesthetic.  

Native plants have co-evolved with the local ecosystems and natural processes. They are genetically better adapted to local climate, soils, insects and diseases of the area, and may require less maintenance to ensure health and survival. Working with native plants helps protect local native biodiversity, allows the LID feature to function ecologically while creating a more diverse, naturally-beautiful, landscape.

Where conditions for growing native plants are inhospitable, diversifying the planting palate with introduced species may have a more successful result. In addition to native species, many introduced plants are grown in nurseries and garden centers and are readily available to landowners.  

===Unity and Simplicity===

Some introduced species escape from gardens and other managed landscapes and begin to reproduce in the wild. Invasive plants are typically non-native plants that out-compete native species. These species lack natural predators, grow aggressively and reproduce rapidly and can be problematic in the natural environment. Invasive species have not been included on the recommended plant list for LID practices and should not be planted in any situation.

Unity and simplicity in planting design is essential to create an appealing aesthetic. This can be achieved through repetition and consistency. The landscape associated with an LID practice needs to convey that all parts of the planting design fit together to make a whole. The repetition of groups of plants or the character of elements (ie. height, size, texture, and colour) throughout the landscape design can assist on creating a sense of unity in the landscape.

Whilst repetition is a key element used to achieve unity, it is important not to overuse this technique as the result can become monotonous. A landscape design that employs a variety of species in groupings that are repeated throughout a site assists in achieving unity and interest. In contrast, a design that uses just two or three species repeated throughout the entire LID practice may be monotonous.

*In all applications of LID, designing with native plant species is the preferred and strongly recommended option.

*In areas containing, adjacent to, or within a linkage to an existing natural heritage feature, native plants should be used exclusively. In areas regulated by a conservation authority, native plants will be required for approval.

*In settings that have restricted or harsh conditions for plant growth (e.g. limited root volume, unusual patterns of drought and/or inundation, exposure to salt, sun, wind, shade and pollutants) introduced species can be used to substitute/augment native species selection. Introduced species shall be chosen to be functionally and aesthetically appropriate for the location.

*Introduced invasive species should not be planted as these can compromise the function of an LID practice, the ecology of nearby natural areas and can lead to higher maintenance costs. Non-native invasive species have not been included in the LID plant list.

*When sourcing native plant material, especially from commercial nurseries and garden centres, always refer to the scientific (botanical) name for the desired plants. Confusion over cultivated varieties of plants can be avoided by asking questions of the staff to ensure that only the correct native varieties are sourced. Species that are often mislabeled and other common concerns are noted elsewhere on this page.

There is often one visually dominating item or component in a landscape design. Every other component in the design should then be subordinate to this single, dominating focal point. Properly selecting and setting this one focal point in a view should evoke a feeling of satisfaction and pleasure. <ref name=LO52>Landscape Design Manual, Landscape Ontario (2014) Page 52</ref>

Some of the native plants in the LID plant list are ‘rare’ and/or ‘uncommon’ within the Province of Ontario. STEP does not support the incorporation of rare native species in planting plans and designs unless locally sourced material can be obtained and there is little to no threat of escape into naturally occurring populations. Genes from plants adapted to other areas can inadvertently introduce harmful traits that weaken the ability of the native population to thrive. Rare species are not always appropriate for LID practices depending on the project objectives or the characteristics of the site, especially in situations where rare species may be planted near natural communities. In these situations, the opportunity for genetic contamination of native populations is higher and the planting of rare species is unadvised.

*Some native species are rare because they require specific habitat conditions in order to grow which may not exist or be able to be restored easily. The benefits to landscaping with native, common plant material is that plantings may be better adapted to a wider range of conditions, and may tolerate more disturbance. A higher success rate and lower maintenance requirement may be achieved.  

===Variety and Rhythm===

The method and collection of native plants is an important consideration when sourcing rare plant material. Ecologically responsible methods of seed collection and propagation ensure that wild populations are not over harvested and that they have the ability to keep adapting over time. Seeds should not be collected or existing plants relocated from the wild for use in LID practices. When sourcing material from growers and nurseries, the plant material origin should be confirmed as well as its method of collection and propagation.

The subtle varying of contrast in line, form, texture or colour can attract attention to a design without inhibiting the overall unified appearance of the design, particularly if there is a smooth, gradual and progressive change in the design element. If applied sparingly, the result can be an increased attraction to the overall composition. <ref name=LO51>Landscape Design Manual, Landscape Ontario (2014) Page 51</ref>Moreover, the creation of sequence may be achieved by using gradation (e.g. the progressive changing of sizes of components or intensity of textures) or by using fixed repetition (i.e. the repeating of an element on a constant spacing) or by using alteration (i.e. the alternating of contrasting or graded colours and textures). When done successfully, the designer creates a sense of movement or flow through a design. <ref name=LO52/>

'''Recommendation:''' In areas containing, adjacent  to, or within a linkage to an existing natural heritage feature, common native plants should be used exclusively. In areas regulated by a watershed authority 

rare species are not suitable for planting unless the local source/provenance is documented and approved. Rare species should only be used sparingly when there are no suitable common species available and reasons for selection should be provided. Where rare species are included in a design, it should be ensured that the plants are procured from locally adapted seed sources. Biologists, botanists and ecologists can help guide the sourcing and selection of plant material. Furthermore, nurseries that specialize in native plants and associated rare species should be contacted to source material.

===Grouping/massing===

==Natural processes==

Planting different species as single individuals can create a disjointed and un-natural aesthetic in a landscape design. Plants should be placed into groupings of varied numbers (e.g. groups of 3, 5 or 7) to create a mass, which can create a much greater visual appeal. One way to create a grouping is by beginning with a larger specimen, and then adding smaller species with complementary textures, colours and shapes. To create a seasonal grouping, evergreen species, and species with dormant season distinctiveness (ie. form, height, colour) should be included.  [[File: Kenollie Rain Garden.jpg|thumb|Rain garden at Kenollie Public School in Mississauga, ON.]]

A plant community is not a static entity; rather it is always growing and changing in response to natural processes and disturbance events. When utilizing a plant community as an analogue for design, it is essential to understand the role of agents that affect the composition of the plant community over time. Designers and managers may need to mimic or compensate for the natural processes in a management plan. Consideration should be given for the impact of natural processes and disturbances to the long term vision of the proposed LID landscape design. Natural ecosystems develop and are maintained through natural changes such as the onset of shading, and disturbance events such as:

*Seasonal storm events / flooding outside the design norms

 

*Prolonged drought

*Microclimate change and progression - sun / shade / moisture

Balance must generally equalize the overall impact of each of the different design elements so that a visually harmonious composition results. <ref name = LO52/> Balance in a landscape design can be either symmetrical or asymmetrical. A symmetrical design is one that exactly duplicates itself along an axis. The informal nature of many LID practices tends to promote the application of the asymmetrical balance approach. This is achieved through the irregular placement of plant groupings along an imaginary axis so that the resulting mass is balanced.

*Plant competition, successional growth, invasive behaviour

 

*Weeds entering from other sources

*Herbivory

Scale and proportion simply refer to the size of the elements, objects and spaces of the landscape in relation to one another, to the LID site and to its surroundings. While there are no rules dictating how this principle is to be achieved, it is important to consider scale and proportion when designing. The relationship in size between components must b relative, or the result can be a lack of harmony in the design.<ref name=LO53>Landscape Design Manual, Landscape Ontario (2014) Page 53</ref>  For example, the placement of a large tree in a stormwater planter would be out of scale for this site condition, while the planting of an individual ornamental flower species may appear insignificant in a bioretention cell. Some plant materials may require management (thinning, pruning) in order to maintain the scale and proportion of the intended design over time.

*Pests and diseases

 

Colour animates a landscape design. It is affected by light at different times of the day and changes throughout the seasons. Flowers, fruit, leaves or bark of vegetation contribute to colour variation; in response, the designer should understand the details of the life cycle of the plants to be utilized and include plants that flower at different times of year. Colour theory dictates that warm colours (red, orange, yellow) take prominence in the view, while cool colours (green, blue, violet) recede. Colour also has an emotional impact:

*Maturation and decline of plants

Colour can be used in developing unity, repetition and balance in a landscape design, and to direct the eye to a focal point, if desired.

 

The designer should be aware of the texture of the planting materials specified. An appealing aesthetic can be achieved by contrasting fine textured vegetation, such as grasses, sedges, with coarser texture species. However, in exploring design solutions it is important to understand the distance from which the LID practices will be viewed, and to mass vegetation textures accordingly when applying this element to the design. Using both coniferous and deciduous vegetation helps create visual appeal throughout the seasons.  [[File: Rain garden with a decorative trench drain cover_Portland_OR_April 2013_Photo credit_EmilyBlueGreen.jpg|thumb|Rain garden with a decorative trench drain cover in Portland, OR. Photo credit: EmilyBlueGreen.]]

 

Straight lines represent clean, more formal organizing elements in a design, and they imply a sense of direction and movement. Curved, organic lines promote a more ‘natural’ aesthetic. In either case, clean and contrived shapes have a greater visual interest than weak shapes or indistinct edges.

 

Form describes natural shape of an individual plant. The variety of forms include weeping, globular, spreading or columnar. The form of plants should be considered both individually and as they relate in the composition of the design.

 

Features incorporated into planting designs, such as benches, stones, paths, and works of art, can make LID spaces more aesthetic, enjoyable and multi-functional.

 

 

A qualified landscape architect should prepare documents in coordination with engineering design, including tender documents that encompass site development, soil preparation and earthworks. Plans are prepared on a site-specific basis, incorporating planting layout, species composition and spacing. In addition, landscape plans should include construction details and pertinent notes specifying site supervision, monitoring and maintenance.

 

Early initiatives and successes are more likely to be public, commercial or industrial applications as there is a higher requirement for landscape professionals to be involved and usually a greater opportunity to control and monitor initiatives. Contracts for LID practices may need to be structured slightly differently than a standard construction contract in order to address the long term function of the LID practice, including provision for an extended warranty period.

 

*Vegetation must meet Canadian Standards for Nursery Stock, 9th Ed<ref>https://cnla.ca/uploads/pdf/Canadian-Nursery-Stock-Standard-9th-ed-web.pdf</ref>.

*Seed planting is not recommended for low impact development.

*Plants should be container grown, balled and burlapped or wire basket.

 

|-  

|Coniferous Shrubs / Broadleaf Evergreens

*40 cm height and spread for dwarf type

*60 -80 cm height or spread for medium form type

*25 cm root ball for spreading form type

*80 - 100 cm height for columnar form type

|Perennials and grasses||#1 or 1 gal. container stock

 

Plants should be kept in their containers until they are to be installed, which should take place as soon as possible upon completion of the [[grading]] and installation of drainage structures. In addition to the planting plan, plant installation details for herbaceous plants, shrubs and trees should be followed per municipal and landscape industry standards, specifications, and guidelines. Avoid staking unless necessary (ie. vandalism or high wind exposure). If staked, then the ties should be a biodegradable web or burlap and removed after the first growing season. If any plant substitutions are required, then the contractor or contract administrator should defer to the designer or municipal agency to make the substitution.

==External resources==

==External resources==