Climate Crisis: Gardeners, Zones, Nurseries, and Choices

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Did you hear the news? The U.S. Department of Agriculture (USDA) hardiness maps were recently revised, placing Granby on the cusp of zones 6a and 6b, a couple notches warmer than we were.

Most gardeners have felt: “I love that plant; I wish I could grow it here.” As we continue to heat up our planet, we can plant things that previously flourished to our south. But should we?

Some plants we might want to add to our gardens may already be invasive further south, or they may become invasive once they move here.

It is often said that nature is resilient. Invasive plants tend to be more resilient than natives: they are by nature more adaptable, more able to flourish in a wide range of soil, water and light conditions. A hotter world puts more pressure on native plants and makes things easier for invasives.

Researchers up the road at UMass Amherst have been studying the impact of a hotter world on invasives in a series of reports: RISCC – Regional Invasive Species and Climate Change. In 2021, they documented how commercial nurseries accelerate the spread of invasives. “Invaders for Sale” found that, nationwide, 61 percent of 1285 invasive plants are available through nurseries and online vendors. “People might assume invasive species are moving because of birds or the wind dispersing seeds,” said Evelyn M. Beaury, lead author, “But commercial nurseries that sell hundreds of different invasives are actually the primary pathway of invasive plant introduction.”

A follow-up report, available at, highlights 24 plants that may be attractive to us but are new invasive threats; it also suggests alternative native plants.

One attractive invader is Chocolate Vine (Akebia quinata), originally from Japan and Korea. Its tolerance of shade allows it to completely blanket forest floors, choking out native life. It’s considered invasive in states south of us —Pennsylvania, New Jersey, Delaware, and Rhode Island, according to While its presence has been noted in selected areas of our state and Massachusetts, it’s not considered invasive here yet.

Another is the unfortunately named Butterfly Bush (Buddleja davidii), a native of China. Butterflies do, photogenically, harvest nectar from the plant, but their larvae (caterpillars) cannot survive on it, which systematically cuts their numbers. Its abundant dust-like seeds fly with the wind, escaping from gardens and gaining purchase at forest edges and disturbed habitats. It’s considered invasive in several states south of us, not yet here

Other crowd-pleasers in the UMASS report, not officially considered invasive in our state,but could be —as they continue to be sold and propagated —include Wintercreeper (Euonymus fortunei), English Ivy (Hedera helix), Crape Myrtle (Lagerstroemia indica), Callery Pear (Pyrus calleryana), and two Wisterias (Wisteria floribunda and sinensis).

Our state’s invasive plant shield is flawed, fragile and flimsy.

Eighty of the 97 plants on the state invasive plant list are “prohibited from importation, movement, sale, purchase, transplanting, cultivation and distribution under CT Gen. Stat. §22a-381d.” What’s not prohibited? Invasives that are totally out of control, like Mugwort, Winged Euonymus, Japanese Barberry and Norway Maple, for example.

Seven of the 97 are “not currently known to be naturalized in Connecticut but would likely become invasive if they are found to persist in the state without cultivation.” Most are prohibited by statute. If the UMASS researchers are right, many more “soon” invaders should be added to the list.

Invasive plants are a huge problem already. There are all kinds of things we can do to keep it from getting worse.

Here is what we can do:

• Granby’s Conservation Commission has asked the Planning and Zoning Commission to require that developers plant from the list of 2,500-3,000 natives and plant no invasives.

• Get familiar with the Conn. invasive plant list at

• Before buying plants, check sites like • and

• Ask nurseries why they sell plants that are invasive here or in nearby states.

• Plant native! Ask nurseries to stock more native plants. Grow your own.

• Support Granby’s Wildflower Meadow –

Join Invasive Action – Second Saturdays of the month. Granby volunteers contributed 376 hours in 2023 to fighting invasive plants in visible public places in town.

• Visit for resources and pictures, for answers to questions, and to sign up to take action.