Feed That Hungry Caterpillar!

This week in Around the Grounds, we recommend two great plants for attracting beautiful butterflies to your garden.

Ah, butterflies…the “winged blossoms” of the garden! Let’s talk about a couple of our favorite plants for butterflies.

If you want more butterflies in your garden (and don’t we all?), you have to feed their caterpillars. True, adult butterflies will visit just about any flower with nectar. So yes, if you have a butterfly bush (Buddleia spp.), or other non-native flowers, you may attract adult butterflies. But you won’t be making more butterflies unless you provide what their caterpillars need.

 Not one species of native caterpillar can survive on “butterfly bush” (Buddleia spp), a non-native plant that is also invasive in many areas

Even very hungry caterpillars won’t eat just anything. They are “specialist” insects, and can only eat certain “host” plants. If butterflies can’t find that host plant, and happen to lay their eggs on whatever is around, the caterpillars will die. So, pollinator and butterfly gardens should include host plants.

In recent posts, we’ve talked about planting Milkweed for Monarchs, and Switch Grass for Skippers. Both are essential hosts for their particular butterfly friends. Here are two more important host plants:

Zizia flowering in May

Zizia (Zizia aurea), sometimes called “Golden Alexander,” is the native host plant for Black Swallowtail butterflies. Maybe you’ve seen Swallowtail caterpillars on parsley, dill, or carrot plants? Although those plants are not native to the US, they are in the same plant family (Apiaceae) as Zizia, and genetically so closely related that Black Swallowtail caterpillars accept them as hosts, and do indeed eat them. 

Black Swallowtail caterpillar on parsley
Black Swallowtail adult on Zizia

Zizia is a lovely garden plant. It likes full sun, as do most pollinator-friendly plants, and is easy to grow. It blooms in early summer and often reblooms later in the season. Its flowers are loaded with nectar, so it attracts plenty of pollinators in addition to Black Swallowtails. It prefers moist conditions, but will do fine in average garden soil.  Zizia works well near the front of the border where it typically stays under 3 feet tall.

Zizia in the garden

Another excellent host plant is Antennaria neglecta, which has the curious common name “Field Pussytoes.” Maybe the fuzzy white flowers do vaguely resemble a cat’s paw? Antennaria should be used much more than it is. It’s a great ground cover along sunny walkways or at the edge of pavement. It holds up to summer heat, and actually prefers shallow gritty soil, so it’s happy where paving has left gravel in adjacent areas. It does not do well in rich or moist soil.

Antennaria blooming in a driveway bed

Antennaria is the host plant for the beautiful American Painted Lady butterfly. We found this exhausted Painted Lady laying her eggs on Antennaria, and it looked like she was very grateful to finally have found her host plant. It shouldn’t be so hard to find!

American Painted Lady laying her eggs on Pussytoes
American Painted Lady eggs and baby caterpillars
Developing Painted Lady caterpillar

Antennaria is semi-evergreen and survives even where snow plows bury it. In the spring, new leaves come up through the old foliage, and then it starts blooming in April.

Antennaria emerging in spring

Antennaria, or Field Pussytoes, is an underused plant in our landscapes. It is a great garden plant that should be found everywhere — because we really do need to feed those hungry caterpillars!


Let’s “Switch Grass”

On this week of Around the Grounds we learn about Switch Grass, a native plant that can replace invasive ornamental grasses.

Do you have this ornamental grass in your yard? If so, it may be time to switch grass!

Miscanthus sinensis, or Chinese silver grass, is a too-popular ornamental grass so problematic that New York State has regulated it as an invasive species. Switch Grass (Panicum virgatum), on the other hand, is a native ornamental grass that is a perfect substitute. Maybe it’s time to switch?

Ornamental grasses have become increasingly popular as modern tastes have shifted to more naturalistic garden designs. Grasses bring year-round interest, movement, structure, and seasonal changes of palette that enhance every garden. Unfortunately, at least this one non-native grass has created an ecological problem.

Invasive Miscanthus sinensis offered for sale on line
Miscanthus sinensis “zebra grass”

Sold under the names Chinese silver grass, zebra grass, maiden grass, and porcupine grass, Miscanthus also has many cultivars, including “Morning Light,” “Flamingo,” “Ghana,” “Adagio,” and over 100 others. Despite being identified as invasive by New York and other states, it is still being sold, and is still spreading itself everywhere. It is invading natural areas because it has no biological controls on this continent.

Switch Grass is just as attractive as Miscanthus, just as easy to grow, and just as diverse. An original denizen of America’s prairies and meadows, it has deep roots and is both drought tolerant and deer resistant. It is increasingly available in a huge variety of sizes, shapes, and colors. And Switch Grass is the host plant for very cute native butterflies called, “skippers.”

Skipper butterflies lay their eggs on Switch Grass
Photo: Pixabay
Switch Grass is a beautiful native plant 

Switch Grass is gorgeous through all four seasons, and its versatility is on full display at the Greenburgh Nature Center. The cultivar “Heavy Metal” is steel blue in summer and grows up to 5 feet tall. It is equally impressive in winter when it provides texture, movement, and contrast to evergreen shrubs.

Panicum virgatum ‘Heavy Metal’ frames our patio in summer
The golden tones of ‘Heavy Metal’ contrast with Inkberry and Red Twig Dogwood in winter

Another Switch Grass cultivar, ‘Shenandoah,’ is 3 to 4 feet tall and has a graceful vase shape that complements both shrubs and perennials. Because it hosts skipper butterflies, it is a great addition to pollinator gardens. Like all Switch Grasses, it enjoys full sun and tolerates poor soil. No supplemental water, no fertilizer, no worries.

 Panicum virgatum ‘Shenandoah’ in the Pollinator Garden at the Nature Center

When we planted the Gerrie Shapiro Memorial Pollinator Garden at the Nature Center last June, we started with tall Switch Grasses as the center “spine” of the garden. Along with ‘Heavy Metal,’ we planted ‘Northwind,’ a Switch Grass cultivar that stays tall, narrow, and straight all season long. These two native grasses support tall flowers that would otherwise flop over when in full bloom. Switch Grass evolved supporting tall wildflower companions in American meadows and prairies, so it’s perfect for that job.

Tall Switch Grasses define the structure of the new garden
A month later, ‘Northwind’ Switch Grass supports tall flowers

One of our favorite smaller Switch Grasses is ‘Ruby Ribbons.’ At only 3 feet tall, it’s a good choice for smaller gardens. It has multi-colored leaves in shades of red and purple all summer long, and just gets prettier in the fall. Even smaller is ‘Cape Breeze.’ At less than 2 feet, it makes a great edger along the garden path.

Panicum virgatum ‘Ruby Ribbons’
‘Ruby Ribbons’ in October

And if you want to see what Switch Grass looks like in its natural habitat (almost) come visit our Meadow! After spring mowing, Switch Grasses start showing new growth. By late June, they fill out the Meadow terrain. And in the fall, clouds of tiny seeds hover above the Switch Grass stalks, feeding flocks of birds then and all winter long.

 Switch Grass in the Meadow in the fall

So, are you ready to switch grass?


Marvelous Milkweed – Not Just for Monarchs!

This week on Around the Grounds, we learn about the wonders of Milkweed and why it should be a staple in every home garden.

Last week in Around the Grounds we joined the happy buzz about pollinator gardens springing up everywhere. We know that bees need native flowers for nectar and pollen. Butterflies also need nectar, and they need the host plants their caterpillars eat. So, a good pollinator garden supplies all three resources – nectar, pollen, and host plants. Planting a big variety of native plants is the best way to do that.

However, there are a few special plants that do all three jobs. Top among them is Milkweed (Asclepias spp.). Milkweed, of course, is the only host plant for Monarch butterflies.

A Monarch caterpillar

If you go looking for monarch caterpillars on Milkweed, you may discover an entire, complex ecosystem. A research study in Ohio documented 457 different insect species on just one stand of Milkweed! That’s a lot of biodiversity supported by this amazing plant.

In addition to monarchs, Milkweed is the host plant for 11 other species of Lepidoptera (the insect family for moths and butterflies). One of them is the Milkweed tussock moth. Many a gardener has been shocked to discover a mass of little wriggling black caterpillars rapidly devouring their prized Milkweed plants. But before you panic, consider the careful balance nature has designed.

The Milkweed tussock moth arrives later in the season, after most of the Monarch caterpillars already have eaten their fill and turned into butterflies, so there is plenty of Milkweed for everybody. As these little black caterpillars mature, they wander away from the pack and grow from creepy to… sort of cute? But don’t touch them without gloves. Those funny hairs can sting like nettles.

Milkweed tussock moths are important night-pollinators, and their main predator is bats. Astonishingly, they have developed a defensive sonar-type beep that warns bats away from them.

Milkweed tussock moth caterpillar
Photo: M.J. Raupp

Another common sight on Milkweed is a large population of Milkweed aphids. You could hose them off, or squish them with your fingers. Or, you could just watch as ladybugs show up to feed on them. Ladybugs are very effective insect-eaters. One ladybug can eat up to 50 aphids a day. Lacewings, tiny parasitic wasps, and several other beneficial insects also are likely to join the aphid hunt, so the aphid situation seems to take care of itself in our garden.

Ladybugs feeding on Aphids

We’ve found walking sticks, praying mantids, ants, bees, flies, wasps, spiders, and specialized Milkweed bugs and beetles, all living their best lives on Milkweed.

You never know what you’ll find on the underside of Milkweed leaves
A spider sets up shop to see what wanders in
Milkweed bugs eat the seeds in late summer and fall 
Photo: Travis Brady

Oh! Did we mention butterflies? Milkweed is loaded with nectar and draws ALL the butterflies – not just Monarchs. 

Spicebush swallowtails in mating dance on Milkweed

While the best Milkweed for supporting all of this life is probably Common Milkweed (Asclepias syriaca), that species is rather big, coarse, and an aggressive spreader for smaller gardens. Sadly, it’s the loss of Common Milkweed from roadsides, farmyards, and wild places all the way from Mexico to Canada that has caused the tragic decline of monarch populations.

But gardeners are making a difference, and with beautiful Milkweed species for smaller gardens, it’s really easy to do. Swamp Milkweed (Asclepias incarnata) grows 3 – 4 feet tall and blooms for months. Its lavender-pink flowers blend in with lots of other sun-loving perennials. It is perfect for pollinator gardens, meadows, and mixed borders. And it also comes in white!

Swamp Milkweed (Asclepias incarnata) is a butterfly magnet
Asclepias incarnata ‘Ice Ballet”

Every garden can find a place for Butterfly Weed (Asclepias tuberosa). This lovely Milkweed is a perfect front-the-border plant. It grows about 2 feet tall and is fairly compact. It stays where you plant it and is reliably hardy. The straight species is a sunny orange, and there is a bright yellow cultivar called ‘Hello Yellow.’ Butterfly Weed does best in full sun and well-drained soil. It rarely needs supplemental water, and never needs fertilizer.

Butterfly weed (Asclepias tuberosa) at the Nature Center 

Whether or not you are planning a pollinator garden, if you love nature, be sure to add marvelous Milkweed to your spring planting list.


What’s the Buzz?

This week on around the grounds, we learn about the ecological advantages of pollinator pathways. Additionally, get some useful home gardening tips that help our pollinator pals! 

Have you heard all the “buzz” about pollinator gardens? It seems that community groups everywhere are planning, planting, or maintaining pollinator gardens. Schools, parks, churches, and homeowners are adding pollinator-friendly native plants to landscapes all around us. Are you involved?

Pollinator Pathway garden sign

The original “Pollinator Pathway” idea was to create linked gardens through urban and suburban areas so that pollinators could travel, finding what they need to survive along the way.

The concept has grown wildly and Pollinator Pathway organizations are popping up everywhere, including locally in Irvington, Hastings-on-Hudson, Dobbs Ferry, Bedford, Elmsford, and many others.

Physically connecting pollinator gardens into an actual pathway is less important than having lots of them everywhere. From big meadows to front lawn patches to container gardens on balconies, every blooming native plant helps pollinators.

August Brosnahan and friends started a pollinator garden along the Old Croton Aqueduct
Friends of Dobbs Ferry Waterfront Park planted native plants for pollinators
Photo: Don Vitagliano

Driving this movement is recent documentation of a stunning decline in insect populations, especially pollinators. Since many of our food crops depend on insect pollination, this is a huge wake-up call for all of us. Insecticides, agricultural techniques, and loss of habitat all contribute to crashing insect populations. And since most birds depend upon insects to feed their young, bird populations also are declining rapidly.

The New York Times reports on the “Insect Apocalypse”

Unlike many other global problems, we can actually do something about this crisis — right in our own yards. Pollinator gardens are a powerful force for good. And the bonus? They are gorgeous! Every time we convert a patch of lawn, or bare dirt, or a weed-infested spot to a pollinator garden, we not only provide survival essentials for birds, bees, and butterflies, we brighten our neighborhoods with color and life.

The pollinator garden at Dobbs Ferry Waterfront Park
Photo: Nancy Delmerico
This pollinator garden replaced a lawn in Hastings
Photo: Myriam Beck

So, what makes a garden a pollinator garden? Short answer: native flowering plants. The two main classes of pollinators we are trying to save are butterflies and bees, especially native bees. Bees need flower nectar and pollen. Butterflies need nectar and host plants for their caterpillars to eat. Pollinator gardens should provide all 3 essentials: nectar, pollen, and host plants.

Native bumblebees need pollen from native plants
Photo: Travis Brady

The reason we keep emphasizing native plants is because most of these insects are specialists — they depend upon one or two specific species of plants for survival. For example, there are over 20 species of native bees that can only eat the pollen of Goldenrod! And just as Monarch caterpillars can only eat the leaves of Milkweed, other butterflies’ caterpillars are also completely dependent upon specific plant species – their “host”plants.

Swallowtail butterfly caterpillar on its host plant, Zizia
Adult Black Swallowtail on Zizia at the Nature Center

Pollinator gardens do best in sunny spots. Butterflies and bees prefer sunshine and are more active in sunny areas. Any place that lawn grass grows is a good spot for a pollinator garden.

The best plants for pollinator gardens are native meadow or prairie plants. Adapted to harsh environments, they don’t need rich soil and never need fertilizer. Most of these plants are drought-tolerant, so they don’t need irrigation once they are established, and many are deer-resistant. And we recommend perennials rather than annuals, so the plants come back every year. It is easier, and definitely cheaper in the long run, to plant a perennial pollinator garden than it is to buy, plant, water, and fertilize annual bedding plants every year.

Pollinator Garden at the Nature Center

Spring is almost here! If you are thinking about planting or expanding a pollinator garden, there are loads of great resources to get you started. The Pollinator Pathway website linked above has how-to’s and plant lists. Watch for local native plant sales. The Native Plant Center will hold its annual plant sale this year at Westchester Community College on April 30. And the Garden Club of Irvington will have native plants for sale at the Greenburgh Nature Center on May 7, plus lots of knowledgeable help on hand.

And watch this space! Over the next several months, this blog will highlight many of our favorite pollinator plants. Come see them in action at the Greenburgh Nature Center all season long!

Come visit our Pollinator Garden!

The All-American Shamrock

This week on our Around the Grounds blog, we discuss the origin of the shamrock to celebrate Saint Patricks day.

Legend tells us that St. Patrick used a shamrock, with its three leaves on a single stem, to teach ancient Celtic peoples about the Christian trinity. There is no agreement among historians, theologians, or botanists, however, as to which specific plant is the legendary Irish shamrock.

Some believe St. Patrick’s shamrock was one of several species of clover (Trifolium spp.) native to Europe and Britain. Others claim that the true Irish shamrock is in the family Oxalis, perhaps due to a report from a 16th Century Englishman who wrote that the Irish ate “shamrocks,” and plants in the Oxalis family were known to be edible. Adding to the confusion, the Irish word “seamróg” means “little clover.”  

Today, in honor of St. Patrick’s Day, several Oxalis species are sold as shamrocks both here and in Europe, which just annoys those who insist the traditional shamrock is a clover. In 1988, someone conducted a public opinion poll in Ireland asking which plant is the true shamrock, and the results split among several plants, including two varieties of clover and at least one Oxalis, with no real majority view.

In any case, St. Patrick’s Day seems an appropriate time to nominate an American native plant as the New World shamrock. Yellow Wood Sorrel (Oxalis stricta) is sometimes called “sourgrass,” “pickle plant,” or adding to the general confusion, “lemon clover.” As a candidate for St. Patrick’s Day shamrock, Yellow Wood Sorrel certainly looks the part. 

Yellow Wood Sorrel in bloom
Photo: Ansel Oomen,

Yellow Wood Sorrel is useful, maybe even pretty if you look closely, and it is found absolutely everywhere. Yes, it is a weed! You’ve probably pulled it out of your lawn, your garden, your containers, your driveway or sidewalk — maybe without knowing or caring what it is.

Like many other weeds, Yellow Wood Sorrel grows in a wide variety of habitats – sun or shade, dry or wet, and rich or poor soil. Each of its 3 leaves has a fold down the middle. At dusk, the leaves close up and stay that way until warmed again by the sun.

The little yellow flowers have 5 petals and bloom from spring through late fall. The plant produces lots of seeds in capsules that stand upright above the foliage. When the seeds are ripe, the capsule explodes, throwing seeds up to 3 feet away! 

Oxalis stricta leaves fold up at night like little pleated skirts
Photo: Courtesy of 

Yellow Wood Sorrel is edible, though in very large quantities it may be mildly toxic. You really should try clipping some tender leaves, or the little yellow flowers, and sprinkling them like micro-greens on top of salads, fish, or chicken. The taste is like lemon, sour and a bit bitter, but refreshing. Tender stems and leaves may be steeped in hot water (a handful of leaves per pint of water) to make a lemonade-type drink high in Vitamin C.

Bees, butterflies, and ants make use of the flowers of Yellow Wood Sorrel, and its long season of bloom means the flowers are available throughout the nectaring season. Perhaps we should be grateful that this weed provides some wildlife benefit by stubbornly popping up in even the most manicured suburban landscapes.

Yellow Wood Sorrel is a small weedy plant that grows everywhere
Photo: T. Webster, USDA,

So, the next time you find yourself pulling Yellow Wood Sorrel from all the places it doesn’t belong, think of it as shamrock and then save a few leaves for your lunch. Sláinte!