Navigating between native and non-native plants
For many of us, gardening is an enjoyable hobby that brings peace and relaxation – a welcome distraction from the outside world. Few things provide the instant satisfaction of planting a tree or weeding and mulching a garden bed. But even the simple act of weeding or choosing the right tree for your garden can be a challenge when trying to navigate the landscape’s nuances of native, non-native and invasive plants.
Decisions about which plants are appropriate, desirable, or environmentally beneficial can be difficult. A variety of factors complicate our choices. For example, Worcester has been subject to Asian longhorn beetle eradication and quarantine efforts administered by the USDA since 2011. It is still not recommended to plant some native tree species that host beetle larvae to prevent the potential spread of this invasive insect beyond the quarantine area .
Many plants, such as burning bush (Euonymus alatus), once considered a great introduction to gardens from other parts of the world, are now invasive and prohibited for sale or distribution in the Commonwealth. Meanwhile, plants such as English ivy (Hedera helix) and hardy kiwi (Actinidia arguta) pose potential threats to areas that are sparsely managed and monitored as invasive species. Although it is not banned now, it may be in the future.
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According to the Massachusetts Invasive Plant Advisory Group (MIPAG), invasive plant species are “non-native species that have spread into native or minimally managed plant systems in Massachusetts. These plants cause economic or ecological harm by developing self-sustaining populations and becoming dominant and/or destructive to those systems.
MIPAG is a collaborative group of members representing research institutions, nonprofit organizations, the commercial green industry, and state and federal agencies. They meet regularly to review data and make recommendations to the Massachusetts Department of Agricultural Resources (MDAR) about whether plants should be added to the state’s list of prohibited plants. The MIPAG website also provides lists of plants that have been reviewed but do not currently meet the strict criteria for acceptance onto the Plants to Avoid list.
Few plants truly rise to the level of “invasion” as defined above, escaping cultivation and threatening biodiversity in natural areas. According to the Native Plant Trust’s 2015 State of the Plants report, more than 3,500 different plant species have been documented throughout New England.
Nearly 30% of these plants were introduced from other parts of the world, and fewer than 200 of those introduced plants are considered invasive, posing a threat to natural areas. This is the true sign of an invasive species: a plant that affects natural areas or poses an economic threat, perhaps to agriculture or another industry. For those plants that pose an environmental or economic threat, state and federal agencies regulate their sale and distribution.
Experienced gardeners know well that some plants, whether native or invasive, grow beyond the boundaries we set for them in our gardens. Japanese Spurge (Pachysandra Terminalis), a dense evergreen ground cover, comes to mind. Although it is an effective ground cover, many gardeners regret planting it after realizing how quickly it spreads.
We characterize these plants, describing their behavior as “aggressive,” or calling them “garden thugs.” Although we may regret growing them, and may censure them for their success, plants are not sentient beings. They don’t “act”. They simply grow in response to their environment, and some plants are more successful than others in adapting to a new environment when brought from other parts of the world.
We often add our own sense of morality to the equation when deciding what is “best” or “right” to farm. Instead, let’s do the best we can with what we know. Before considering adding a new plant to your garden, check your state’s list of invasive plants, or another reliable source. To make sure you’re not introducing an invasive plant into your garden, consider planting something native to the area. Native plants are locally adapted, support native birds and other wildlife, and can be great ornamental plants for your garden.
Central Gardening Mass New England Botanical Garden on Tower Hill CEO Grace Elton and Horticulture Director Mark Richardson. Located on 171 acres in Boylston. The New England Botanic Garden creates experiences with plants that inspire people and improve the world. Learn more through www.nebg.org. The column is published on the third Sunday of the month.