May is the number one month for gardening, and that means decisions! What to add, what to subtract, what to divide—and how to cope with the relentless multiplication of invasive plants.
For gardeners focused not just on beauteous displays but also the health of ever-diminishing habitats for bugs, bees, birds, critters and the rest of us, here is a short run-down of May tasks, discretionary and obligatory. The plants mentioned here have been explored in detail in previous NOT WANTED columns, available at GranbyInvasivePlants.weebly.com
Musts—don’t make things worse
First, do no harm. Don’t buy infamous invasives like Japanese barberry (Berberis thunbergii), winged euonymus/burning bush (Euonymus alata), Bradford pear (Pyrus calleryana), and butterfly bush (Buddleya davidii), for example. These are commonly available despite being on the list of about 100 officially-designated invasive plants. (For that list, search for CIPWG, Connecticut’s invasive plant info hub). Commercial nurseries are “the primary pathway of invasive plant introduction,” according to UMass Amherst researchers at the Regional Invasive Species and Climate Change (RISCC) project.
Choose wisely. Some attractive plants can newly survive in our region as we continue to heat up the planet. But plants that are well-behaved in a nearby region can become invasive in ours. RISCC identifies chocolate vine (Akebia quinata), wintercreeper (Euonymus fortunei), English ivy (Hedera helix) and crape myrtle (Lagerstroemia indica), among others, are attractive but potentially invasive,
Shoulds—make progress where possible
Get ‘em when they’re young. Multi-flora rose (Rosa multiflora), Japanese barberry, winged euonymus and Japanese bittersweet (Celastrus orbiculatus) are downright vulnerable as seedlings, and in the spring their roots have a looser grip on the soil. They are infinitely harder to remove and often well-armed with prickers when just a couple years older.
Get ‘em when they’re few. Japanese knotweed (Reynoutria japonica), mugwort (Artemesia vulgaris) and garlic mustard (Alliaria petiolata), may have redeeming culinary or medicinal qualities, but once they get started they rapidly take over, depriving benevolent plants of light and nutrients, and rapidly becoming dense monocultures. Learn to identify them and dig out the pioneers to avoid thousand-times greater labor in the future.
Mays—rebalance with native plants
It’s not hard. Over 2,500 plants are native to Connecticut, and nurseries are getting better at stocking and marketing natives. A great resource available on the CIPWG site is the Connecticut Native Plant and Sustainable Landscaping Guide, with plant lists for every setting. Another is a list of where to find native trees, shrubs and plants, updated March 2025, at ipm.cahnr.uconn.edu/connecticut-native-availability
It’s important. Planting twice as many natives as non-natives helps birds harvest the thousands of caterpillars and insects they need to raise each family, for example. It’s not necessary to rip out non-native favorites (as long as they’re not invasive); instead, rebalance by adding natives. Prioritize adding the most useful, “keystone,” native plants with the National Wildlife Foundation’s Plant Finder, nativeplantfinder.nwf.org/Plants
Now sit back and enjoy what your garden does for you and for every other living thing.