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. Invasive species are also a major contributor to habitat loss, pushing out our native plants and resulting in a dramatic decline in pollinators and songbirds.
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 these same beautiful blossoms for pollinators but will also feed and shelter insects and provide berries for birds, why not choose the 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. Our plant-eating insects can overcome the chemical defences found in the leaves of native plants, allowing them to be consumed. 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 relationship to milkweed.
As useful as they are to us, shrubs are the critical mid-layer for attracting wildlife to the garden, creating habitat between the arching tree canopies and the smaller ground hugging 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.
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 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 viburnums. 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.
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 among 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.
- Choose plants from a local native plant nursery for plants adapted to our growing conditions and grown without pesticides, especially neonicotinoids.
- Native species are best, but cultivars of those species can also be used as long as they retain the characteristics useful to insects and birds.
Good garden practice for sustaining wildlife
- 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 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. The links are below.
- 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 which 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. Wood chips can also be a good garden mulch for plantings with shrubs and trees.
- 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.
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. There are many great books and websites with comprehensive lists of native shrubs for various growing conditions and as a food source for birds or insects. More detailed descriptions of these shrubs can be found on the websites listed below.
Structural shrubs that can be used as feature plants
- Serviceberry (Amelanchier)
- Alternate-leaved dogwood (Cornus alternifolia)
- Witch hazel (Hamamelis virginiana)
Early spring pollinator shrubs
- Serviceberry (Amelanchier)
- Spice bush (Lindera bezoin)
- Willows (Salix)
Shrubs with berries for birds
- Chokecherry (Prunus virginiana)
- Common elderberry (Sambucus canadensis)
- Nannyberry (Viburnum lentago)
Shrubs for fall colour
- Maple-leaved viburnum (Viburnum acerifolium)
- Chokeberry (Aronia melanocarpa)
- Witch hazel (Hamamelis virginiana)
Shrubs for wet areas
- Buttonbush (Cephalanthus occidentalis)
- Gray dogwood (Cornus racemosa)
- Meadowsweet (Spiraea alba)
Shrubs for winter interest
- Red-osier dogwood (Cornus sericea)
- Winterberry (Ilex verticillata)
- Maple-leaved viburnum (Viburnum acerifolium)
- Fragrant sumac (Rhus aromatica)
- Bush honeysuckle (Diervilla lonicera)
Other useful shrubs that support butterflies, moths and birds
- Beaked hazel (Corylus cornuta)
- Ninebark (Physocarpus opulifolius)
- Purple-flowering raspberry (Rubus odoratus)
- Canadian yew (Taxus canadensis)
- Common juniper (Juniperus communis var. depressa)
- Creeping juniper (Juniperus horizontalis)
Resources and references
Ontario Invasive Plant Council. Grow Me Instead; beautiful non-invasive plants for your garden. 2020. https://www.ontarioinvasiveplants.ca/wp-content/uploads/2020/04/Southern-Grow-Me-Instead-1.pdf
Toronto Master Gardeners. Invasive Species Initiative fact sheets. 2021 https://www.torontomastergardeners.ca/invasive-species-awareness-initiative/
Canadian Wildlife Federation. Native plant encyclopedia: https://cwf-fcf.org/en/resources/encyclopedias/native-plant-encyclopedia/
Credit Valley Conservation. Native Plant Lists (for purchase or free downloads): https://store.cvc.ca/product-category/gardening/
Ontario trees and shrubs: http://ontariotrees.com/main/speciestype.php?type=SH
Gardening for birds: https://birdgardens.ca/
Where to buy native plants
Canadian Wildlife Federation. Native plant suppliers list, Ontario: https://cwf-fcf.org/en/explore/gardening-for-wildlife/plants/buy/native-plant-suppliers/native-plant-suppliers/on/
Credit Valley Conservation. Guide to native plant nurseries: https://cvc.ca/wp-content/uploads/2021/02/com_lo_native_plant_nursery_guide_cs1_20210125-print.pdf
For information about native shrub characteristics and growing conditions:
Leopold, Donald J. Native plants of the northeast: a guide for gardening and conservation. Timber Press, Portland, OR, 2005.
Soper, James and Margaret Heimburger. Shrubs of Ontario, ROM, Toronto, ON, 1994.
Native plants and biodiversity
Tallamy, D. Bringing nature home; how you can sustain wildlife with native plants. Timber Press, Portland OR, 2009.
Tallamy, D. and Rick Darke. 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.
Date published: March 2022
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 email@example.com