About Drought

What makes a plant, or a whole landscape, “drought tolerant”? Why do some plants need water regularly while others are fine without it for weeks or longer? Drought tolerance depends primarily on two factors:

The first is where a plant evolved. Adaptation to particular environments happened over millennia, and most plants will thrive only in conditions very similar to those where they evolved. That is why, when considering a plant for our gardens, we always want to know whether it is native to our region. Plants that evolved in tropical rainforests will never be drought tolerant. On the other hand, plants that evolved in America’s open meadows are well-adapted to life under baking sun with occasional torrential thunderstorms. Those plants can withstand weeks of heat and drought still looking great, and then stand up to the floods that so often follow.

American meadow plants can tolerate weeks of drought and heat without irrigation

The second big factor in drought tolerance is root depth. Plants that evolved in wet climates usually have shallow roots. Plants that evolved in hard-packed prairie have strong, deep roots that force their way down through poor soil to reach and hold any available water. They can withstand long periods of drought. They also can absorb flood water because their roots break up the soil, allowing water to penetrate rather than run off.

Comparative root depth of plants – note lawn grass on the far left.
Graphic used with the permission of artist

As the chart above indicates, many plants that evolved in America’s prairies like Goldenrod, Coneflower, Prairie Dropseed, Switch Grass, and Wild Indigo have very deep roots, reaching down 4 to 8 feet! As a result, they make great garden plants because they are both beautiful and very drought tolerant.

In contrast, lawn grass is not at all drought tolerant. Despite its name, Kentucky Bluegrass is not from Kentucky. It is native to mild climates in Europe and Asia. Lawn grown from typical seed mixes has very shallow roots, about 2 inches deep. Shallow roots do not retain water, so lawn needs frequent irrigation, and in heavy rain, excess water runs off rather than being absorbed and held in the soil.

An unirrigated lawn after 8 weeks of heat and drought
Heavy rainfall rushes off of lawn, dislodging pavers and overwhelming storm drains

But Americans love lawns. Perhaps perfect lawns and tightly-manicured shrubs became a status symbol in America because of our historic connection with England, where 19th Century aristocrats demonstrated their wealth by employing countless servants to hand-cut lawn and trim elaborate hedges.

Landscape fashion among English aristocracy in the 1800’s — Cliveden House, England
Landscape fashion in suburban New York, 2022

Maybe it’s time for a change of fashion? Here is a photo of that same 19th Century landscape this summer:

Cliveden House, England, August 2022 
Photo: Lawrence Siskind

Most of Europe is suffering from heat and drought this summer, and watering restrictions are now in place. Because lawn requires so much water and retains so little, lawn irrigation is usually the first target of water regulation. In the US, lawn watering (not agriculture!) uses an average of 8 billion gallons of water daily – that’s 32 gallons for every man, woman, and child in our country, every day! (Tallamy, Nature’s Best Hope) Clearly, our love for lawns is not sustainable. 

Restrictions on residential landscape watering have been a reality in California and many of our Southwestern states for years now. So, it makes sense that landscape fashion there has rejected big expanses of lawn, and turned instead to drought tolerant native plants.

Front yard in Berkeley, California
Native plant landscape in Tucson, Arizona
Lawn used only as an edger in a Mexican garden

Prolonged periods of drought and low reservoirs are becoming common in the Northeast as well. Watering restrictions were imposed this summer in much of the Hudson River valley. So, it’s time to think about changing landscape fashion here, too. We can reduce our demand for water by replacing at least some of our lawn area with native trees and drought-tolerant shrubs.

Trees, shrubs, and flowering plants replaced lawn here
Trees, shrubs, and flowering plants replaced lawn here

By planting drought-tolerant native perennials, we can replace even small areas of lawn with color and flowers for pollinators.

A pollinator garden reduces lawn area and is a beautiful addition to this backyard
A raised flower bed full of life is so much more interesting – and drought tolerant – than lawn
 The drought-tolerant staircase garden at the Nature Center would be a stunning entry garden for any residence

Modern American landscapes need to be resilient as well as beautiful. As we rethink landscape fashion, we recognize that there is as much beauty in a vibrant drought-resistant garden as there is in a bare expanse of thirsty lawn. 

For information on drought-tolerant perennials, download the plant list we used for the Nature Center’s pollinator garden here.

THIS BLOG IS AUTHORED WEEKLY BY CATHY LUDDEN, CONSERVATIONIST AND NATIVE PLANT EDUCATOR; AND BOARD MEMBER, GREENBURGH NATURE CENTER. FOLLOW CATHY ON INSTAGRAM FOR MORE PHOTOS AND GARDENING TIPS @CATHYLUDDEN.

Who Was Joe Pye?

Joe Pye Weed is a classic American perennial, and a garden favorite for generations. It is tall, beautiful, long-blooming, and easy to grow. It is a butterfly magnet. Whenever we are asked about the best plants for pollinators, Joe Pye Weed is at the top of the list.

Monarch butterfly on Joe Pye Weed
Painted Lady butterfly on Joe Pye Weed

Native to wet meadows in the Eastern half of the US, Joe Pye Weed nurtures butterflies, bees, and is the host plant for more than three dozen species of moth and butterfly caterpillars. It is a great alternative to non-native “Butterfly bush” (Buddleia spp.), not only because it attracts as many or more butterflies, but because it also allows them to reproduce. Caterpillars native to the US cannot eat the leaves of “Butterfly bush,” so Joe Pye Weed is the right choice if you want more butterflies.

There are five species of Joe Pye Weed, which is the common name of all five plants in the genus Eutrochium (formerly part of the genus Eupatorium), and all are North American natives. The main difference among them for gardeners is height. Hollow Joe Pye (Eupatorium fistulosum) is the tallest at around 10 feet. Spotted Joe Pye (Eupatorium maculatum) is usually about 6 feet tall, and Coastal Joe Pye (Eupatorium dubium) is the shortest at about 4 feet, with a cultivar marketed as ‘Baby Joe’ growing only 3 feet tall. They all bloom from late summer through fall, and they all have big flower clusters in shades of pink to lavender. Hardy in Zones 3 to 9 and deer resistant, Joe Pye looks great at the back of a formal flower bed or along a rustic fence.

Joe Pye in an informal garden

The flowers of Joe Pye Weed go through a fascinating progression. The initial buds are almost silver. From there, they develop into clusters, 4 to 8 inches across, composed of tubular pink blossoms. Each tube then emits a single forked pistil, the female reproductive part. The male pollen-bearing stamens remain hidden inside the tubular structure. The huge array of pistils over the top of the flower mass ultimately creates a fuzzy appearance.

Flower buds in early August
The pistils emerge, indicating available nectar
Large clusters of tubular flowers top each stem
As more flowers open, the cluster begins to look fuzzy

Joe Pye Weed does best in wet sunny areas, so it is perfect for a rain garden, or a low spot too soggy for lawn. Though it is not particularly drought tolerant, Joe Pye manages well in our Meadow at the Nature Center without irrigation.

Joe Pye in a rain garden with White Turtlehead and Swamp Milkweed
Joe Pye Weed in the Meadow at the Nature Center

So, who was Joe Pye and why was this wonderful plant named for him? There was a story, repeated in various forms over the past 100 years or so, that Joe Pye was “an Indian medicine man” who saved an entire colony of English settlers in the 1600’s from typhus fever using a tea made from the plant. As with many such stories, the details often changed in the telling, and the only cited source was “legend has it.” Recently, however, curiosity prompted the first scholarly research on the question, and in 2017, Richard B. Pearce and James S. Pringle published their findings in The Great Lakes Botanist journal. They concluded that the plant was likely named for Joseph Shauquethqueat, a highly-respected Mohican sachem or paramount chief, also known to white neighbors as Joe Pye, who lived in the Mohican community in Stockbridge, Massachusetts in the late 1700’s to early 1800’s. Although there is no evidence that he was an herbalist or ever used or recommended the plant medicinally, many members of the First Nations did know of the medicinal properties of the plant. Pearce and Pringle speculate that since Joseph Shauquethqueat was also a selectman in Stockbridge, well-known and respected by his white neighbors, “it would not have taken many observations of his collecting the plants now called Joe-Pye-weed for medicinal use, or suggestions from him that they use those plants for the treatment of fevers…before someone, when referring to those plants, associated them with the man they knew as Joe Pye.”

Joseph Shauquethqueat was a remarkable man. Remembering him with a plant as remarkable as Joe Pye Weed is a worthy honor, indeed.

THIS BLOG IS AUTHORED WEEKLY BY CATHY LUDDEN, CONSERVATIONIST AND NATIVE PLANT EDUCATOR; AND BOARD MEMBER, GREENBURGH NATURE CENTER. FOLLOW CATHY ON INSTAGRAM FOR MORE PHOTOS AND GARDENING TIPS @CATHYLUDDEN.

Worth a Mint

What makes a garden plant special? Beautiful flowers? Reliability? Long season of bloom? Easy care? Attractive to butterflies? Maybe even useful for humans? Mountain Mint checks all the boxes! This perennial garden plant is so valuable it’s a wonder we don’t see it everywhere.

The only problem with Mountain Mint is its name! The scientific name, Pycnanthemum, is a mouthful, and the common name “Mountain Mint” is just wrong. The plant does not come from the mountains, and it’s not a true mint. It’s actually a plant native to America’s meadows, from New England to the Midwest and from Florida to Texas. And unlike spearmint and peppermint, it is not in the mint genus, Mentha. (Though it does have a decidedly minty flavor, and can be a pretty good alternative.)

We have three species of Mountain Mint at the Nature Center: Pycnanthemum virginiana (“Virginia Mountain Mint”), Pycnanthemum tenufolium (“Narrow-leaved Mountain Mint”) and Pycnanthemum muticum (“Broad-leaved Mountain Mint”). All three grow in our Meadow in full sun, average soil, and without special care or irrigation.

Virginia Mountain Mint
Narrow-leaved Mountain Mint
Broad-leaved Mountain Mint

Our favorite is Broad-leaved Mountain Mint. The plant grows about 3 feet tall with shiny, dark green, and very minty leaves. In early summer, it produces a pair of fuzzy gray-green “bracts,” leaf-like structures that frame a cluster of flower buds at the very top of the plant. The flowers themselves are tiny little polka-dotted tubes that open sequentially over two to three months. The very long sequence of blooms keeps pollinators coming back all summer for fresh nectar.

Tiny flowers keep opening for months

Mountain Mint is incredibly valuable for pollinator gardens. It is loaded with nectar attractive to bees, butterflies, and a wide variety of other pollinating insects. It is very entertaining to count how many different species visit the flowers.

Honey bees love Mountain Mint
Red-banded Hairstreak butterfly
Clubbed Midas Fly is a native pollinator
Native bumblebees do, too!
Golden Digger Wasp sharing flowers with bees
Grey Hairstreak butterfly on Mountain Mint

Apart from its value to pollinators, Mountain Mint is a wonderful garden perennial. It is tough! Deer, rabbits, and woodchucks avoid it. Like most meadow plants, it is drought-tolerant and does best in full sun, though the Broad-leaved species may want more moisture than Narrow-leaved Mountain Mint. Both are hardy in Zones 3 through 9 and both do well in our Meadow without irrigation. The long season of bloom means Mountain Mint looks good well into the fall, and the seed heads add interest if left standing all winter.

September in the Meadow

Mountain Mint has been used by humans for a wide variety of purposes. Indigenous people in the Eastern US made a tea from the leaves to treat headache, stomach problems, and respiratory congestion. Dried leaves of Broad-leaved Mountain Mint are said to make an effective insect repellant when rubbed on skin or clothing. Carrying fresh sprigs in a pocket or under a hat-band helps keep gnats and mosquitos away from gardeners’ faces. The leaves of Broad-leaved Mountain Mint contain pulegone, a substance said to cause liver damage if ingested in significant quantity. But reliable sources assure us that the leaves may be used safely in teas and infusions, and we have some satisfactory experience with that…

A handful of chopped leaves from Broad-leaved Mountain Mint boiled for a few minutes with equal parts sugar and water, then allowed to steep until cool, makes a lovely scented infusion for use flavoring lemonade, iced tea, or even a specialty cocktail! Strain the liquid to remove the leaves and add the syrup to your preferred beverage. Mix a bit of the syrup with gin, lime juice, and elderflower liqueur, and you have a Mountain Mint Martini!

Cheers!
THIS BLOG IS AUTHORED WEEKLY BY CATHY LUDDEN, CONSERVATIONIST AND NATIVE PLANT EDUCATOR; AND BOARD MEMBER, GREENBURGH NATURE CENTER. FOLLOW CATHY ON INSTAGRAM FOR MORE PHOTOS AND GARDENING TIPS @CATHYLUDDEN.

Summer Buzzin’

Have you ever heard a plant hum?

On a sunny summer day, you can actually hear Shrubby St. John’s Wort humming. It’s not the plant itself, of course, but the sound of extremely happy bumblebees buzzing as they collect pollen from countless bright yellow pom-pom flowers.

“St. John’s wort” is the common name for a family of almost 500 plant species worldwide. The name refers to its time of bloom – around St. John’s Day on the Christian calendar, or June 24. “Wort” is the old English word for “plant,” especially plants known for their medicinal value. Perhaps you’ve heard St. John’s wort recommended as an herbal remedy for mild depression? That particular St. John’s wort is Hypericum perforatum, a weedy perennial native to Europe and now considered invasive in parts of North America.

 Shrubby St. John’s Wort in front of the Manor House

The “humming” plant we love is Hypericum prolificum, or Shrubby St. John’s Wort. It is a beautiful shrub, native to the US from New York west to Minnesota and south to Louisiana and Georgia. It does indeed start blooming at the end of June, and continues to dazzle for weeks into the summer. The scientific name “prolificum” refers to the enormous number of flowers the shrub produces. The shrub itself forms a rounded mound 3 to 4 feet tall and wide with small blue-green leaves.

Shrubby St. John’s Wort loaded with flowers

If you go shopping for Shrubby St. John’s Wort, you will likely see Hypericum frondosum, a very similar shrub with a cultivar called “Sunburst” that has slightly larger flowers. Its original native range is further south, in Tennessee and Kentucky, but it does perfectly well in southern New York gardens and throughout Zones 5 to 8. Another species, Hypericum kalmianum, is native to the Great Lakes region and hardy to Zone 4. While botanists can tell these three shrubs apart, most gardeners consider them virtually interchangeable. And all of them have year-round value as landscape plants.

Shrubby St. John’s Wort is essentially carefree, and makes an attractive foundation plant or hedge in full sun. It doesn’t need pruning, but you can shape it to suit your site. The leaves produce a substance that is mildly toxic to deer, so deer avoid it. In autumn, the shrub holds onto its leaves until late in the season, and it has great fall color. And in winter, interesting seed capsules remain on branches that have attractive grey-brown bark.

 Fall color is a mix of red, yellow, and orange

There is no nectar in the flowers of St. John’s Wort, so it’s not a stopping place for butterflies. However, caterpillars of several moth and butterfly species, including the lovely gray hairstreak butterfly, do use the leaves as a host plant. Pollen is the big attraction. The flowers have a huge number of stamens, all loaded with pollen, so bees of every size and description come to the party.

How many bumbles can you find on just 3 flowers? (Hint: there are 5!)

We never get tired of watching the action, and we can observe up close because the bees won’t spare a second even to notice nearby humans. They are fixated on pollen collection, as you can see in this slow-motion video:

Pollen collection

And what about that summer buzzin’? Turn your sound up and, technology permitting, you may hear the sound of a plant humming!

Summer buzzin’
THIS BLOG IS AUTHORED WEEKLY BY CATHY LUDDEN, CONSERVATIONIST AND NATIVE PLANT EDUCATOR; AND BOARD MEMBER, GREENBURGH NATURE CENTER. FOLLOW CATHY ON INSTAGRAM FOR MORE PHOTOS AND GARDENING TIPS @CATHYLUDDEN.

How Sweet It Is!

Itea virginica is one of our most beautiful and versatile native shrubs. Its romantic common name, “Virginia Sweetspire,” is a good one, because this shrub is a sweet addition to the landscape year-round.

Itea virginica or “Virginia Sweetspire” shrub 

Itea (pronounced eye-tee-uh) grows in a loose mounding form, reaching 4-5 feet tall and wide in a few years, with gently arching branches. In mid-June, after most trees and shrubs have finished blooming, Itea is just starting its summer show. Spikes of white flowers 4 to 6 inches long cover the shrub, arching away from the deep-green leaves on long stems. 

Itea starts blooming in mid-June
The flowers open gradually

The star-shaped flowers begin opening from the stem to the tip, and last several weeks. And they are sweet! The elegant fragrance is not over-powering, but definitely carries in sultry June air. The flowers are loaded with nectar and butterflies flock to them. When the flowers fade, birds will feast on the seeds that remain all winter.

Itea’s fragrant flowers justify the name “Sweetspire”

Itea is native to swampy meadows and wet woodlands from New Jersey to Florida, and west as far as southern Illinois, but it does very well in more northern gardens. It can thrive in full sun or part shade, and is surprisingly drought tolerant given its swampy origins. It is winter hardy in Zones 5-9, and is not attractive to deer or rabbits. 

Throughout the summer, the foliage remains fresh and glossy, so Itea looks great in full sun as a hedge or foundation plant. But because of its shade tolerance, it can even replace pachysandra, vinca, or ivy under trees.

Itea is part of our full-sun foundation planting at the Nature Center’s Manor House
Itea in part shade under a Redbud tree at the Nature Center

And have we mentioned fall color? Itea is known for its gorgeous fall foliage, turning various shades of red, orange, and purple while holding onto its leaves until snowfall. Cultivars called “Henry’s Garnet” and “Merlot” are specifically marketed for their brilliance in the fall landscape. Fall color is best in full sun, but it’s still impressive in part shade. We frequently recommend Itea as a native alternative to invasive burning bush.

The same Itea planting in mid-November
All the fall colors

So, Itea is carefree, a hedge or foundation plant, an under-tree plant, has showy and fragrant flowers, offers nectar for butterflies and seeds for birds, grows in sun or shade, and has fabulous fall color – we think that’s pretty sweet!

THIS BLOG IS AUTHORED WEEKLY BY CATHY LUDDEN, CONSERVATIONIST AND NATIVE PLANT EDUCATOR; AND BOARD MEMBER, GREENBURGH NATURE CENTER. FOLLOW CATHY ON INSTAGRAM FOR MORE PHOTOS AND GARDENING TIPS @CATHYLUDDEN.