Gardening with Native Shrubs: A Toronto Master Gardeners Guide

Shrubs in the garden landscape

Although shrubs may be somewhat “overshadowed” by their taller and more charismatic tree cousins, their size and multi-branching habit make them the unsung heroes of the garden, valuable for both their variety and versatility.

In a larger garden, shrubs can be used to divide a large space into smaller functional areas, grouped to frame a viewpoint or obscure a less desirable feature. Used along a garden boundary, they provide shelter and privacy and block the noise of traffic. And in any size garden, a shrub with an elegant shape can be a focal point, perhaps as a feature in a new front garden, underplanted with spring ephemerals and hardy native groundcovers. Since they tend to grow at eye level, we can easily appreciate their beauty year round: the delicate blossoms of early spring, colourful berries in summer, brilliant autumn foliage and bare branches dusted with snow in winter.

But we need to go beyond thinking of how shrubs can be useful to us as garden plants and think about how they benefit the creatures that we share our space with.

Native plants in the garden

There are many reasons why gardeners are increasingly drawn to using native plants. For some, it creates a “sense of place”, a connection to the wilder world beyond the boundaries of our gardens or cities. There is also a growing understanding that nature needs help, due to habitat loss from increasing urbanization and agricultural practices. Exotic plants and invasive species are also a contributor to habitat loss, pushing out our native plants with a resulting in a dramatic decline in pollinators, other beneficial insects and the insect-eating birds that depend on them.

When we use native plants, we create places for wildlife to find food and shelter in a welcoming space. If you are trying to decide between a non-native shrub with attractive blossoms and a native shrub that has those same beautiful blossoms for pollinators but will also feed and shelter insects and provide berries for birds, why not choose the native one that can offer all these services?

Native plants are adapted to our native soils and have coevolved with our local insect, bird and mammal populations over thousands of years. Studies have shown that native plants support a greater number and diversity of insects that depend on those plants for food and shelter than non-natives. This is because our plant-eating insects can overcome the chemical defenses found in the leaves of native plants, allowing them to be consumed. However, an estimated 90% of plant-eating insects are specialists, restricted to a narrow range of plants. Some of these relationships become so specialized that a particular species of moth or butterfly can only consume the leaves of one larval host plant, e.g., the monarch butterfly’s exclusive relationship with milkweed.

There may also be a correlation between the availability of insects and the fluctuations in bird populations. Nearly all terrestrial birds in N.A., an estimated 96%, depend on an abundance and variety of insects for migration and breeding and they prefer the protein and fat-laden larvae of butterflies and moths to feed their young.

As useful as they are to us, shrubs are the critical mid-layer for attracting wildlife to the garden, creating habitat between the upper layer of the tree canopy and the ground layer of perennials. Native shrubs provide most of the essentials for sustaining wildlife in the garden: food, shelter and a safe place to breed and raise young – a living landscape.

Native shrubs as a food source

Native shrubs can become part your garden’s ‘food hub’ offering the following services:

  • Pollen and nectar spring to fall for pollinators
  • Host plants for feeding insects, especially the larvae of butterflies and moths
  • Habitat and food for (insect-eating) beneficial and predatory insects
  • Insects and berries for songbirds, including migratory and overwintering birds

Pollinator plants: When we think of pollinator plants, we usually associate them with the bright summer flowers of the perennial border or wilder meadow spaces. However, trees and shrubs can be an important food source for early emerging bumble bees and solitary bees.  For example, a serviceberry (Amelanchier spp.) may bloom for only a few weeks in early spring, but fills the critical gap in providing pollen and nectar before other plants are available. And although the individual blossoms are small, the sheer mass of blossoms on a shrub can create an ‘all you can eat and take-away’ spread for pollinators. Other early blooming shrubs for pollinators include cherries, willows and dogwoods. At the other end of the growing season is the native witch hazel (Hamamelis virginiana), blooming long into fall and early winter, our last native shrub to flower.

Host plants for feeding insects:  As mentioned above, native insects have developed specialized relationships with our native plants and need them for food. The leaves of native shrubs are particularly important as a food source for caterpillars, the larval stage of butterflies and moths. Most adult butterflies and moths feed on nectar but their caterpillars have a totally different diet, namely the leaves of their larval host plants.

Habitat and food for beneficial insects: By providing shelter and food for caterpillars, you are also supporting a food web of other insects, such as solitary wasps and spiders, that feed on the caterpillars or use them to feed their young. These insects and spiders are an important food source for songbirds.

Insects and berries for songbirds: As adults, songbirds can feed on the many insects and spiders found around native plants. But for raising their young, birds depend on caterpillars, a high-protein tasty meal easily stuffed into a baby bird’s open mouth. Ninety-six per cent of North American terrestrial bird species rear their young on spiders and insects, with caterpillars being a favourite food. If the caterpillars are not available, birds may not breed successfully.

As the seasons change from summer into fall, birds are supplementing their diet with berries, a necessary food source that fuels them for overwintering or for migration. The berries of native shrubs contain the right ratio of fat to sugar, unlike berries of non-native shrubs. Berries left on the branches are also an important food source for birds later in winter, when little else is available.

Native shrubs for shelter and nesting sites

Birds can be quite specific about where they eat and raise their young. Some birds prefer the upper canopy of trees, while others, like chickadees and cedar wax-wings, prefer to forage in the understory trees and shrubs. Planting a variety of large and small native shrubs will fill in the mid-layers of the garden, providing nesting places and food for a variety of songbirds as well as shelter from weather and predators. If you have the space, include some evergreens which provide a denser habitat than open, deciduous shrubs and the possibility of cones or seeds for food.

Butterflies and moths don’t make nests but they need a place to lay their eggs, a larval host plant. They also look for a protected place to rest within the foliage of a shrub or by hanging upside down from a twig or leaf.

Getting started with native plants

Making the transition to growing native plants may seem like a daunting process, but you can do it step by step by changing a small area at a time.

Site assessment: The growing conditions in your garden can tell you a lot about which native shrubs might thrive or languish. Look at the sun and shade patterns, the shadows from surrounding buildings or a neighbour’s tree. Determine your soil type and whether it holds moisture or drains quickly.

Native plants will do best in your garden if you try to match their native habitat.  If a plant grows naturally in the forest understory, it would be a good candidate for a shady woodland garden, bolstered with plenty of compost and leaf litter to retain moisture. Or if a shrub grows naturally at the edge of a field, it may like a sunnier and drier location in your garden.

Making a plan: By drawing up a garden plan, you may get some ideas about where to incorporate more native plants. Here are some possibilities:

  • Replace a shrub that is underperforming or is on a list of invasive plants with a native shrub.
  • Lose some lawn and replace it with a mixed planting of shrubs and perennials.
  • Move beyond the traditional non-native evergreens traditionally used in foundation planting
  • Consider an informal mixed hedgerow along a property boundary. It will give a succession of bloom and become a refuge for insects, birds and mammals.
  • Fill in the gaps. Do you need a feature shrub or one that is low-growing? Are there times in your garden when nothing is blooming? Perhaps you could add an early blooming shrub for pollinators or a shrub to provide berries for birds later in summer.

Choosing the plants

  • Smaller plants may be a good choice. They are cheaper and can adapt more readily to their new surroundings, quickly putting on new growth. For tips on planting, see Planting a tree for life: A Toronto Master Gardeners Guide.
  • Buying from local, reputable native plant nurseries ensures that the plants are grown locally: they will be more resilient and adapted to local conditions. (See links below for native plant nurseries.)
  • Generally, native species are more desirable than cultivated native varieties – the “nativars”. Please be aware that nativars are often bred for an “improved” characteristic which may make them less useful to pollinators and insects, e.g., the red-leaved cultivar of the native ninebark, that is of less food value to wildlife than the species. Nativars are also propagated vegetatively and lack the genetic diversity of species grown from seed.

Garden practice for maintaining a living landscape

  • Try to have native plants from each garden layer: the variety of trees, shrubs and perennials is in direct correlation to the abundance and diversity of beneficial insects and birds. Look for keystone plants for each layer, those plants of most benefit to wildlife in your area.
  • Plant densely, especially in the perennial layer. Plants like to grow in communities, rather than as isolated individuals in a sea of bark mulch that inhibits the plants’ ability to fill in and thrive. Native groundcovers are particularly useful for suppressing weeds and providing a natural “green mulch” under taller perennials and shrubs.
  • Have a source of water for birds and insects. This can be as simple as a shallow dish with some pebbles on the bottom for perching. Keep the dish clean and replenish it with fresh water often.
  • Remove any invasive plants. For more information about invasive plants and their alternatives, see the Ontario Invasive Plant Council booklet, Grow Me Instead, and the Toronto Master Gardeners Invasive Species Initiative fact sheets.
  • Avoid pesticides which can move up through the food chain. Use organic methods, such as soap spray or horticultural oil, only as a last resort. Remember that there may already be beneficial predatory insects, such as parasitic wasps, sawflies, beetles and spiders in your garden, looking for a handy meal.
  • Leaf litter can be your gardening ally. It provides shelter for some overwintering bees as well as the pupae of many moths and butterflies that drop to the ground from their larval host plants and need a “soft landing” to complete their life cycle. It is also home to countless other minute organisms, some of which will act as decomposers, returning the nutrients in the leaves to the soil through the cycle of decay. Birds will forage through it looking for food. Leaf litter acts as a mulch protecting the soil from erosion and compaction while helping to retain moisture. Best of all, it is free and replenished yearly.
  • Take care of your garden soil by digging as little as possible and never when the soil is wet. Avoid walking on your garden beds which also compacts the soil. Feed from the top down with compost, healthy plant debris and leaf mould laid on the soil surface as mulch, not dug in.
  • Don’t be too tidy. Brush piles, tree cavities and fallen logs are all habitats for birds and insects. Hollow or pithy stems of elderberries or sumacs can also be nesting sites for bees to overwinter.
  • Become part of a larger native plant community in your neighbourhood through a local gardening society or by becoming a member of Carolinian Canada, North American Native Plant Society or Homegrown National Park.

Using native shrubs in the garden

 The plants listed below are just some of the many that you might discover to ‘fill in the gaps’ in your garden. All are native to Ontario and hardy in the GTA. More detailed descriptions of these shrubs and their uses to wildlife can be found in the resources listed below.  Keystone plants can be found on this chart.

Shrubs for dry, sunny areas

 

Shrubs tolerant of shade

 

Shrubs for wet areas

 

Structural shrubs that can be used as feature plants

  • Serviceberry (Amelanchier)
  • Alternate-leaved dogwood (Cornus alternifolia)
  • Witch hazel (Hamamelis virginiana)

Low-growing/groundcover shrubs

  • New Jersey tea (Ceanothus americanus)
  • Northern bush honeysuckle (Diervilla lonicera)
  • Common juniper (Juniperus communis)
  • Creeping juniper (Juniperus horizontalis)
  • Shrubby cinquefoil (Potentilla fruticosa syn. Dasiphora fruticosa)
  • Fragrant sumac (Rhus aromatica)
  • Meadowsweet (Spiraea alba)
  • Maple-leaved viburnum (Viburnum acerifolium)

Early spring pollinator shrubs

  • Serviceberry (Amelanchier)
  • Dogwood (Cornus)
  • American hazelnut (Corylus americana)
  • Spice bush (Lindera bezoin)
  • Chokecherry (Prunus virginiana)
  • Fragrant sumac (Rhus aromatica)
  • Willows (Salix)
  • Bladdernut (Staphylea trifolia)

Shrubs with berries for birds

  • Serviceberry (Amelanchier)
  • Black chokeberry (Aronia melanocarpa)
  • Alternate-leaved dogwood (Cornus alternifolia)
  • Gray dogwood (Cornus racemosa)
  • Winterberry (Ilex verticillata)
  • Spice bush (Lindera bezoin)
  • Chokecherry (Prunus virginiana)
  • Wild blackcurrant (Ribes americanum) Note: alternate host to white pine blister rust
  • Common elderberry (Sambucus canadensis)
  • Nannyberry (Viburnum lentago)
  • Wild raisin or witherod (Viburnum cassinoides)

Shrubs for fall colour

  • Serviceberry (Amelanchier)
  • Chokeberry (Aronia melanocarpa)
  • Witch hazel (Hamamelis virginiana)
  • Spicebush (Lindera bezoin)
  • Fragrant sumac (Rhus aromatica)
  • Maple-leaved viburnum (Viburnum acerifolium)
  • Nannyberry (Viburnum lentago)

Shrubs for winter interest

  • New Jersey tea (Ceanothus americanus)
  • Red-osier dogwood (Cornus sericea)
  • Beaked hazelnut (Corylus cornuta)
  • Winterberry (Ilex verticillata)
  • Meadowsweet (Spiraea alba)
  • Eastern snowberry (Symphoricarpus albus)

 

Resources and references

 Darke, Rick and Doug Tallamy. The living landscape; designing for beauty and biodiversity in the home garden. Timber Press, Portland OR, 2014.

Eierman, Kim. The pollinator victory garden. Quarry Books, Beverly, MA, 2020.

Johnson, Lorraine and Sheila Colla. A garden for the rusty-patched bumblebee; creating habitat for native pollinators, Ontario and Great Lakes edition. Douglas & McIntyre, Madeira Park BC, 2022.

Soper, James and Margaret Heimburger. Shrubs of Ontario, ROM, Toronto, ON, 1994.

Tallamy, D. Bringing nature home; how you can sustain wildlife with native plants. Timber Press, Portland OR, 2009.

Canadian Wildlife Federation. Native Plant Encyclopedia.

Gardening for birds

In Our Nature native plant nursery for useful native plant lists and resources.

Lubell, Jessica. Landscape Use for Northeast United States Native Shrubs.

Network of Nature database.

The North American Native Plant Society database.

Ontario Native Plants for plant lists and online catalogue.

Ontario trees and shrubs

Upper Thames River Conservation Authority Recommended trees and shrubs.

 

Where to buy native plants

Canadian Wildlife Federation. Native plant suppliers list, Ontario.

Credit Valley Conservation. Guide to native plant nurseries.

Leaf for native shrubs to order.

 

Date published: April 2023

Prepared by the Toronto Master Gardeners, these Gardening Guides provide introductory information on a variety of gardening topics.  Toronto Master Gardeners are part of a large, international volunteer community committed to providing the public with horticultural information, education and inspiration.  Our goal is to help Toronto residents use safe, effective, proven and sustainable horticultural practices to create gardens, landscapes and communities that are both vibrant and healthy.

Statement on Invasive Plants: When choosing plants, avoid invasive plants, which can spread quickly and dominate gardens.  Invasive plants are sold by nurseries, big box stores or even at community plant sales.  Invasives may already be present in your garden.  They can invade gardens by spreading from under a neighbour’s fence or may be transported by wildlife.  For beautiful, sustainable options to invasive plants, see the Ontario Invasive Plant Council’s “Grow Me Instead – Beautiful Non-Invasive Plants for your Garden” at https://www.ontarioinvasiveplants.ca/resources/grow-me-instead/ before purchasing or accepting “gifts” of plants.

Statement on Home Remedies: The Toronto Master Gardeners do not recommend home remedies, as these have not been proven effective through scientific investigation, and may even damage other living organisms in the soil or plants in your garden.  There are other garden friendly options you can use.

If you have further gardening questions, reach us at our gardening advice line 416 397 1345 or by posting your question here in the Ask a Master Gardener section.  To book Toronto Master Gardener volunteers for talks, demonstrations, advice clinics, or other services, please contact us at 416 397 1345  or bookamg@torontomastergardeners.ca