Claudette Sims & Janet Mackey – Halton Master Gardeners
Begin a discussion about native plants with gardeners present, and its likely to become a very active discussion.
“What is a native plant? How is it defined? “…”Why should I plant native species in my garden?”… “If I plant a native species, can I still keep my favourite plants?” Isn’t it messy?
It is a very complex subject that has been shared more recently in mainstream media, bringing it to the minds of all homeowners, from beginning to experienced gardeners. This is an exciting trend as it offers homeowners and gardeners the ability to build a landscape legacy for future generations. The status quo of landscaping solely to ‘decorate your home’ for your own benefit now seems rather empty because of course we share our space with creatures of all kinds. How can we create landscapes only for ‘us’?
On the Master Gardeners of Ontario Facebook page, Moderators and Admins volunteer their time to support gardeners by assisting with plant, disease or pest identification; gardening maintenance/strategies; informing gardeners about invasive plants (identified by the Ontario Invasive Plant Council, along with the Grow Me Instead booklets highlighting alternative plants). Routinely the inclusion/substitution of suitable native plants for home landscapes is encouraged and promoted in advice.
How to define native plants?
In a recent presentation, Lorraine Johnson, author of ‘100 Easy-to-Grow Native Plants‘, proposed an updated definition of native plants. Previously, a native plant was often defined as those that ‘existed prior to European settlement’. Lorraine has shifted to get away from the colonial language focus. The new definition aligns with the idea of function or “plants with a purpose”.
”Native plants are a species that has evolved in association with all the features of a place and developed specific and important functional relationships and interactions that contribute to the specificity and identity of that place.”Lorraine Johnson
Why Native Plants?
Native plants matter because they’ve evolved with native insects. The monarch being an easy-to-understand example. Without milkweed, there are NO monarchs. So when we plant species from other geographic regions, we don’t sustain the local insect population. Why is this important? Well, the insect population is currently collapsing. Why is that important? The bird population is collapsing.
The Problem with ‘The Elevator Music’ of the Plant World
We’ve all seen it, and there’s some part of us that may desire the look that is achieved by planting those highly popular landscape plants promoted by nurseries, home decor websites and growers. Often, directly promoted as ‘pest free’ and or ‘low maintenance’. The reason they are ‘pest-free’ or ‘low maintenance’ is they offer almost no value to local ecosystems and add nothing to biodiversity. They do not support any insects which means they do not support birds. The flowers, sap, and leaves of trees and shrubs do not appeal to insects that have evolved in North America (Insect diversity decreases in gardens with non-native plants Burghardt,Tallamy 2015). Sometimes the timing of blooms/fruit doesn’t co-inside with the emergence of native insect species or bird migration. In other cases, some of our native plants have been hybridized to create leaves of unusual colours, showy blossoms but offer little to no value to insects or birds. Take for example hydrangeas. The horticulture trade has developed many cultivars that actually don’t have flowers! The ‘blossoms’ are made up of sterile bracts which have no nectar or pollen. – Lacecaps is one variety of hydrangea that does have some value for pollinators. Read more HERE.
Some plants have altered leaf colour. These too do not appeal to many pollinators (Read more HERE). While there are concerns from many about the use of native cultivars or ‘nativars’, some positives can be found. Mt. Cuba Centre in Delaware are completing studies on the value of nativars to lepidoptera (butterflies & moths) and results are encouraging.
Why all the concern about caterpillars? Birds rely on insects to feed their young, which are like little baby food sausage that’s easy to poke into their mouths. Chickadees need from 4,000 to 7,000 caterpillars to raise just one clutch of young. Finally, the caterpillars need to be within about 50 feet of the nest, otherwise they use too much energy finding them. Really the best choice a homeowner can make is to choose to plant a tree or shrub that are ‘keystone’ species which will support biodiversity.
Watch Doug Tallamy, Etimologist, author: Bringing Nature Home (2009); Nature’s Best Hope (2020), excellent video for more detailed information about ‘keystone species’.
Plants from other regions are sometimes ‘well-behaved’…remaining within their boundaries and not leaping into nearby natural areas and may even offer some nectar value. Plants brought home from the nursery that originated in Asia, Europe or Africa do not have natural predators (i.e., caterpillars, browsing by animals etc.) “Over the centuries, travellers – including specialist botanists and plantsmen – have brought back new and attractive species to their home. While some have remained in botanical gardens or cultivated with tender loving care by gardeners, others have adapted rapidly to their new environments – often with problematic results.” (Decoded Science.org: Problems of Non-native Invasive Plant Species). The question to be considered is: Which plant from another region is going to become the next Knotweed, Hogweed, Phragmites, or Vinca. If you’re concerned, why not consider planting a few new native plants each year. This does not mean you need to let a part of your garden ‘go wild’, if that’s not your style. Research the location, appropriate cultural conditions and plants that you have an interest in growing. Mt. Cuba Centre offers some beautiful, traditional landscapes and our own Royal Botanical Gardens in Hamilton/Burlington have created some stunning new native plant gardens as well as integrating native plants into more traditional garden areas (i.e., the Rose Garden). Nativars often offer native plants that are a more suitable size for smaller gardens. Once you begin to see the life that native plants bring to your garden, you just may find that the appeal of exotic species is lost.
More Good Information about Native Plants
Missouri Botanical Garden – well-organized, good reference, reliable information, lacks specific information on plants location (i.e., will identify plants as originating in Eastern North America)
USDA Plant Atlas – Good information with maps indicating range but does not include Canadian provinces and maps re native range
In Our Nature espouses-plants that have a positive ecological impact. e.g. support birds/insects. Check the Group Files on the page for plant lists.
Ecozones/Districts This reference contains detailed and accurate information about native plants based on Ecozones/districts in Ontario.
Ecolandscaping.org/ Ecological landscape alliance – information about using native plants in the landscape