by Tim Kennelty
Taghkanic resident, Tim Kennelty is a Master Gardener and Master Naturalist volunteer through Cornell Cooperative Extension, and is the co-host of Cornell’s weekly Master Gardener podcast, Nature Calls: Conversations from the Hudson Valley.
Column #5 – Ironweed and Barberry
Good Plant/Bad Plant is a monthly feature of the TGazette, focusing upon two plants in each edition, one that is ecologically valuable, and one that is invasive or a noxious weed.
Could somebody tell me how it’s already August? But let’s not get blue, because there are so many beautiful native plants that begin to bloom now. Unfortunately, the exotic invasives don’t take this month off either. This month’s good plant may be one that you’ve never heard of or haven’t grown, but trust me if you have some room in your garden at the back of the border and you like bold plants, you’re going to love it. And the bad plant is one you probably do know, because until recently it was being sold in garden centers and has been a regular feature in many people’s landscapes. My advice, however, is don’t ever plant it and if you already have it, you may just want to think about deleting it from your garden..
Okay, the big reveal…the good plant is Ironweed and the bad plant this month is Japanese Barberry.
As always, let’s start with the good guy. Ironweed is in the Asteraceae or daisy family. There are quite a few different species of Ironweed that are great candidates for your garden, especially if you’re interested in supporting pollinators. So you may find Vernonia fasciculata (Common Ironweed), Vernonia gigantea (Giant Ironweed), and one that we see most in our area, Vernonia noveboracensis (New York Ironweed). The biggest difference among these is the size. New York Ironweed can grow to a whopping 8 feet tall in a single season with a profusion of small, brilliant purple blossoms in the late summer garden. Gigantea can get even bigger.
The species, Vernonia is named for the British botanist, William Vernon who collected plants in the New World in the 1600s. The plant most likely gets its common name, from its constitution – it’s a very tough plant. Carole Ottesen in the Native Plant Primer recommends root divisions be made with an ax or a chainsaw. I moved some large plants last Fall and it was quite a chore. I used a pickax.
So, you probably know by now that I really like bold plants and that’s why Ironweed is one of my favorites. With its impressive height and beautiful purple flowers appearing on the tops of the stems, Ironweed is a great plant for the back of the border, and it’s a useful plant to add some structure to your perennial bed. I’ve even seen it used as an alley – or almost a maze in a beautiful display I visited a few years ago.
And WOW is it ever a pollinator plant. When it blooms in late summer to early fall it is covered in both large and smaller butterflies and native bees. And the small seeds that develop in the fall are readily eaten by a variety of birds.
This is a clump-forming plant that is not picky about soils (I’ve seen volunteers growing in gravel driveways) and it can take both wet and dry conditions, provided it is planted in a sunny location. And if you are reluctant to spend a lot of money on perennials, know that this is a plant that reliably returns year after year and is relatively deer resistant. And if you like free plants (and who doesn’t), Ironweed is a prolific self-seeder. Just move the seedlings when small to a new location. Otherwise, getting all the root mass may be a challenge. I’ve started whole new areas of ironweed in my perennial garden with just a few wayward seedlings relocated in late spring. One more great thing about this plant is that you can reduce its height by cutting off the tops in late spring to early summer. This plant can take it and will even branch out more and may produce more flowers. That way you can have multiple ironweed plants at varying heights to add even more interest to your garden. So, if you’re a purple lover and want a really tough, bold pollinator plant, head to the “V’s in the perennial section of your nursery and pick up an ironweed for your garden. Or better yet, get some free seeds from a friend and spread them in late fall. The bees, butterflies and birds will thank you.
And now for the bad plant, Japanese Barberry. If you’ve been gardening for a while or inherited an established garden, you probably know this plant and maybe even like it for its toughness. Japanese Barberry or Berberis thunbergii is thought to have first been introduced to the United States in 1875 when seeds were sent from Russia to the Arnold Arboretum in Boston. The following year it was planted in the New York Botanical Garden. It was subsequently promoted and planted as a substitute for Berberis vulgaris. That plant, common barberry, was brought to the New World by settlers in the 1600s but was almost completely eradicated when it was found to be responsible for failing wheat crops. So, we substituted one invasive plant for another.
Japanese barberry is a deciduous shrub that can grow from 3 to 8 feet tall. It has small alternate oval leaves in shades of green to bluish to burgundy, with simple spines along its stems. It has pale yellow blossoms in spring and small bright red fruits that occur from July to October. The plant is drought resistant and can grow in a variety of soils in sun and shade. It spreads rapidly through seed dispersal from birds and can spread vegetatively through root creeping and tip rooting.
So, like many invasive shrubs because of its rapid spread and lack of natural controls like deer, it can push out native vegetation and form monocultures. However, this is not the only problem with Japanese Barberry. It has also been linked to deer ticks and Lyme Disease. In areas with large populations of Japanese Barberry there can be a 90% increase in Lyme and related disease-carrying ticks. This is most likely because the plant is an excellent habitat for white-footed mice, the larval deer tick’s host, providing cover and high humidity. Japanese Barberry has also been linked to invasive earthworms and increased soil erosion.
As for its management, smaller shrubs can be pulled in Spring and Fall when the soil is moist. For larger infestations, you may want to consider herbicides. If you have the plant as an ornamental specimen in your garden, I recommend removing it and please don’t compost it if it is fruiting as you may cause further spread. Japanese Barberry is prohibited from sale in New York State. I include links to identification and management below. All and all, a plant that you really don’t want in your garden and an invasive that you want to manage to reduce or eliminate if possible in your landscape.
That’s it for another edition of Good Plant/Bad Plant. And remember, as a gardener you can make a difference. If you want to support wildlife, plant natives.
Links for #5 of Good Plant/Bad Plant: