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Meet Zigzag Goldenrod, a native plant that helps native butterflies and insects thrive, unlike fast-spreading goutweed, which takes over surrounding wild spaces and reduces the diversity of beneficial plants for pollinating insects.
More and more, people in urban, suburban, and rural areas are tired of spending precious weekend hours mowing lawns, and are actively converting parts, or all, of their lawns to gardens. Not only does this shift give back time (and save gas!), it provides habitat and food for a whole ecosystem of wildlife: from butterflies and native bees, to birds and mammals. However, some new gardeners don’t realize that many plants you can buy in garden centres, nurseries, and online are actually invasive. These plants actually don’t help native insects and other animals the way native plants do, and can wreak havoc on surrounding forests and ravines.
One common invasive ground cover plant found in many gardens is goutweed. Goutweed is a herbaceous, perennial groundcover plant in the parsley (Apiaceae) family. It is known by a variety of names, such as Bishop’s weed, ground elder, Herb-Gerard, and snow-on-the-mountain. It can have both a variegated (white-edged) and non-variegated (solid green) form, with the variegated form often reverting to the solid green, more aggressive type. In fact, Goutweed is labelled as one of the worst garden weeds in perennial gardens and has many characteristics that make it extremely difficult to control.
Why Goutweed Gets the Thumbs Down
Goutweed is a very popular ground cover choice in gardens as it is adaptable to a range of conditions and requires little maintenance. However, it spreads rapidly through its underground rhizomes and can escape into nearby natural areas, where it has a range of negative impacts including:
- 👎🏼Displacing native understory plants
- 👎🏼Reducing plant species biodiversity
- 👎🏼Inhibiting native tree and shrub germination
- 👎🏼Altering decomposition and nutrient cycling
How it got here:
- Goutweed is native to Eurasia and was brought to North America as an ornamental groundcover by early European settlers in the mid-1800s. It is found in gardens throughout North America and still widely available in nurseries and garden centres.
Why it’s such a good invader:
- It is able to form dense mats of vegetation quickly, spreading by underground rhizomes and seeds.
- It can tolerate a wide variety of soil and light conditions, which makes it highly adaptable to many different habitats. Once established, it can dominate the forest understory, crowding out native plants.
- It starts to develop in early spring before many native species, giving it a competitive advantage.
- The non-variegated (green) type of goutweed spreads more aggressively than the variegated type, and is the type most frequently found escaped in ravines, however the non-variegated type frequently reverts back to the variegated type.
How to remove it:
Once established, goutweed can be challenging to control as it can re-root from any leftover rhizomes fragments. Small patches can be carefully removed through persistent hand-pulling or digging, making sure not to miss any rhizome fragments. In the early spring once all the plants have fully leafed out (April – May), cut the plants back and cover the area with a black tarp or landscape fabric for at least a season. This can effectively eliminate goutweed in small areas. The Goutweed Best Management Practices in Ontario guide is available on the Ontario Invasive Plant Council (OIPC) website to download.
Why Zigzag Goldenrod Gets the Thumbs Up
Zigzag goldenrod (Solidago flexicaulis) is a native, non-invasive ground cover alternative to goutweed:
- 👍🏼Its name refers to the way the stem tends to zigzag between the leaves in an interesting pattern, with oval-shaped alternate leaves that are softly hairy and coarsely toothed.
- 👍🏼It has attractive yellow flowers found in clusters at the top of the plant that bloom in late summer and early fall (Aug – Oct), offering some attractive fall colours to your garden.
- 👍🏼The nectar and pollen of the flowers attract many kinds of bees, wasps, flies, and butterflies. It is also a larval host plant for many species of moth.
Where to plant it:
Ground cover for shaded woodland gardens. It tolerates a range of light conditions including part shade, and is adaptable to a variety of growing conditions.
Where to buy it:
The North American Native Plant Society (NANPS) offers a list of commercial growers.
Why Native Plants?
Not all flowers are created equal. Native plants provide habitat and food for a whole ecosystem of wildlife, from butterflies and native bees, to birds and mammals. Non-native plants, which may look the same to the untrained eye, take up space and resources but create a wildlife desert. Some non-native species are also invasive, which means that their introduction or spread negatively impacts native biodiversity, as well as the economy and society, including human health.
The horticultural and nursery trades are one of the primary pathways for invasive species introductions. While many horticultural plants are harmless garden additions, some can escape cultivation into natural areas and negatively impact biological diversity. Several invasive groundcovers like goutweed are still widely available for sale in garden centres and nurseries. You can take a proactive approach by not buying invasive plants and choosing non-invasive alternatives instead.
The Grow Me Instead (GMI) Guide
To help gardeners make informed decisions about the plants they are buying for their gardens, the Ontario Invasive Plant Council (OIPC) developed the Grow Me Instead (GMI) guide. The GMI guide is a practical and easy to use guide that informs gardeners about the invasive tendencies of common garden plants and suggests appropriate non-invasive alternatives. It provides tips for ecologically sound gardening and choosing plant species that will benefit local populations of insects and other wildlife. The Ontario Grow Me Instead guide is available on the Ontario Invasive Plant Council (OIPC) website to download.
Want more? This is the second in our series showcasing native plants to choose for your landscaping, rather than invasive species. Read about Wild Geranium, which is a good groundcover alternative to invasive Periwinkle.
