My Favorite Tree

Ten years ago, I planted a Willow Oak. At the time, I didn’t really know enough about it to make the minimum 100-year commitment expected with oak trees. I had never actually seen a Willow Oak in person, only photos. In retrospect, planting that tree was a bit like deciding to get married before a first date. The tree looked good in photos, but we had never met.

According to its “on-line profile,” Willow Oak (Quercus phellos) is native to stream banks and wet meadows in the eastern US from the southern tip of New York to Florida, and inland to southern Illinois, Oklahoma, and Texas. So, where I live, north of New York City, Willow Oak technically is not native. And it’s definitely not common. But I had heard that Willow Oaks are very popular as far north as Pennsylvania and southern New Jersey, and I figured with ranges pressing northward due to global warming, it should work. The hardiness rating of Zones 6 to 9 included my area, so I decided to commit.

At first sight, you might not even guess that this glorious tree is an oak, but it is a member of the red oak family. Typical oak leaves are divided into lobes with pointed or rounded tips, but Willow Oak leaves are long, narrow, and undivided – somewhat like willow leaves.

An array of various oak leaves with Willow Oak at the bottom
Willow Oak leaves in fall

The long slender leaves of Willow Oak are part of its charm. They cast a dappled shade in summer and dance lightly in the wind. In the fall, the unusual leaves of Willow Oak make me the envy of my neighborhood. While leaf blowers roar and leaf bags pile up everywhere, I can completely ignore the Willow Oak leaves falling on my lawn and driveway. They just seem to disappear!

Willow Oak leaves are no problem on lawn

Willow Oaks are surprisingly fast growing. For the first several years, their energy is dedicated to developing a shallow, fibrous root structure; but after that, they can add 2 feet per year in height. Ultimately, they will reach 60 to 80 feet or more with a majestic spread of 30 to 60 feet. They are easier to transplant than typical oak species with tap roots, so if you’re in a hurry, you can start with a larger tree. Knowing that much, I chose a young tree, already about 15 feet tall with a trunk diameter of 2.5 to 3 inches, rather than a smaller sapling. Ten years later, my tree is well over 30 feet tall with a trunk diameter of 15 inches.

Willow Oak planted in 2012
The same tree in 2022

The shallow root structure of Willow Oak makes sense for a tree that evolved in low-lying flood zones and along streams, but it also makes sense for a specimen tree planted in irrigated lawn. Willow Oak is ideal for suburban lawns and parks, and makes an excellent street tree if enough room is provided for its roots to expand laterally. Unlike oak species with deep tap roots, Willow Oak will buckle pavement if planted too close to sidewalks or driveways, but with enough space, it is a great tree for front yards.

Although it needs ample water when young, once established, Willow Oak is fairly drought tolerant. Full sun is essential, and Willow Oak prefers acidic soil. It is a favorite shade tree in the South, where it is valued for its storm-resistance. It withstands flooding and heavy clay soil, as well as urban pollution, heat, and strong wind. Given the right place, a Willow Oak can survive well over 100 years.

Willow Oak in Autumn

Like all native oak trees, Willow Oak has exceptional wildlife value. The leaves host hundreds of species of butterflies and moths, as well as many other beneficial insects, including fireflies. A mature oak provides habitat and food for all of our native song birds and many small mammals. My Willow Oak is still a baby, so it doesn’t produce acorns yet. It takes 15 to 20 years for the tree to start producing acorns, and the acorns take two years to ripen before they fall. The acorns are small, about a half-inch long, and they are a favorite food of blue jays, squirrels, and chipmunks. 

I look forward to a long and happy life together with my favorite tree, and it makes me happy to think it will supply beauty, shade, food, and shelter to other living things long after I’m gone.

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.
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A Better Hedge

Are you frustrated with deer destroying your arborvitae? Are you sick of seeing your curbside hedge poisoned by road salt? Are you fertilizing your boxwood or yew hedge to make it grow even though you end up trimming off the new growth every year? Are you embarrassed to learn your barberry, privet, burning bush, or forsythia hedge is invasive and spreading into natural areas provoking disapproval from the neighbors?

Does your hedge look like this?

Well, friends, we’ve got good news for you! How about a hedge that is deer tolerant, salt tolerant, drought and flood tolerant, doesn’t need pruning, and even makes its own fertilizer? This wonderful shrub grows in sand, clay, or rocky soil and survives mostly on sunshine. It’s beautiful, fragrant, supports wildlife, and provides you with a long-lived privacy screen.

Northern Bayberry (Myrica or Morella pensylvanica) is a fantastic plant that is inexplicably under-used in suburban landscapes. It is native to the Atlantic coast from Newfoundland to North Carolina and as far inland as Ohio. Its natural habitats include seaside dunes, pine barrens, dry forests, rocky slopes, and even bog and swamp edges, which explains its versatility in gardens. It is hardy in zones 3 to 7, and semi-evergreen in the warmer part of that range.

Bayberry naturally takes the form of a dense rounded shrub, 5 to 10 feet tall and wide, with glossy fragrant leaves and gray-green scented berries. It can be used as a specimen or foundation plant, but it is particularly attractive massed as a privacy screen or informal hedge. It does not thin out at the bottom with age or become leggy. The shrub expands very slowly by extending suckers out from its base, but does not try to take over. Once it reaches its full height, it will retain its shape and survive for many years. We suspect the Bayberry hedge along the Meadow path at the Nature Center has been there for close to 50 years.

 A very old Bayberry hedge lines the Meadow path at the Nature Center

As the name suggests, Bayberry produces interesting berries that cling close to the stems over the summer. The shrub is naturally dioecious, meaning male and female plants are necessary for berry production. But modern horticulturists have managed to combine at least some male and female flowers on single plants for guaranteed berries. Planting both male and female plants, as you would in a hedge, assures maximum berry production.

Bayberry’s spring flowers are inconspicuous
By mid-October, a few waxy berries still cling to the stems

The berries are a magnet for birds, including chickadees, mockingbirds, blue jays, cedar waxwings, cardinals, robins, catbirds, and the beautiful yellow-rumped warbler. Even after Bayberry drops its leaves in the winter, the dense branches form a thicket that shelters birds from predators. At least two species of caterpillars also rely on Northern Bayberry as a larval host, including the red-banded hairstreak butterfly and the Columbia silk moth.

Red-banded hairstreak butterfly

Northern Bayberry belongs to that interesting group of plants that utilize specialized bacteria to fix nitrogen in the soil. It is amazing to see Bayberry growing lush and green in nothing but sand because it is essentially manufacturing its own nutrients from air and sunlight. In your garden, the nitrogen provided by Bayberry can enrich the soil for other plants as well.

Northern Bayberry growing in the salt air and sandy soil of Nantucket, MA

Northern Bayberry does best in full sun. It is relatively slow-growing, so pruning is not necessary, but it can be pruned for a more formal effect.

A young Northern Bayberry hedge at the New York Botanical Garden
Photo: Carolyn Summers
The same hedge in early winter 5 years later pruned into a more formal shape
Photo: Carolyn Summers

American colonists recognized the value of Northern Bayberry for making scented candles. The berries were boiled until the waxy outer coating floated to the top. After cooling and re-melting, the wax could be poured into molds or used for dipping tapers. The wax burns clean with a lovely herbal scent, and is still used for that purpose. The aromatic leaves have been used for their fragrance and various medicinal purposes as well. It is the aromatic quality of Bayberry leaves that makes the shrub so unattractive to deer.

Northern Bayberry catches the afternoon light in October

Though American settlers appreciated Northern Bayberry and planted it in their gardens as early as the 1700’s, the introduction of exotic ornamental plants in recent times seems to have diminished its popularity. That should change. If you are frustrated with the failings of over-used hedge plants, consider Northern Bayberry. It really is a better hedge.

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.
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5 Stars – Totally Recommend

Sometimes you discover a product that performs so well, you just have to tell all your friends to try it. If you’re a gardener, the same thing can happen with a plant!

We are obsessed with Prairie Dropseed (Sporobolus heterolepsis), a little native grass that is carefree, beautiful, and versatile. We’ve planted it in multiple places at the Nature Center, and we’ve admired it in other public and private gardens. We definitely give it 5 stars!

Prairie Dropseed edges the path in front of our Greenhouse

Prairie Dropseed is an ornamental grass with fine-textured leaves that reach out from its center in graceful arches. The grass is small enough, and elegant enough, to form a well-behaved edge along a sidewalk or path. It reaches only 18-24 inches in height before blooming in mid-summer. The tiny flowers are on delicate stems that stretch 18 to 24 inches above the leaves and then branch into dancing seed clusters. Most surprising for a grass, the blooming stalks are fragrant! The scent is hard to define, and is variously described as being like popcorn, or green coffee beans, cilantro, or anise. The scent fades as the seeds ripen in fall.

Prairie Dropseed is native to American prairies and dry meadows and is found in at least 26 states from the Canadian border to Georgia and west as far as New Mexico, but it is most common in the Central Plains states. It is categorized as a “warm season bunch grass,” which means it starts turning green as the weather warms (late spring), and it forms “bunches,” tidy clumps that stay where you plant them. It does not spread itself by runners and, despite its name, does not easily spread by seed. The “dropseed” in the common name apparently refers to the fact that ripe seeds do fall to the ground where they may be eaten by birds and small mammals, but they do not seem to germinate easily. In our own experience, and based on reports from other gardeners, the plant does not self-sow in gardens, so you won’t see it popping up in other spots. 

Prairie Dropseed is happy in Zones 3 to 9. As a true prairie plant, it prefers dry, even rocky, soil in full or part sun. It never needs fertilizer, and is rarely bothered by deer or rabbits. Its roots are great for stabilizing slopes, and the plant needs so little care it is ideal for roadsides. It is relatively salt tolerant as well. And it is a great substitute for non-native “fountain grasses” (Pennisetum spp.) that are now recognized as invasive in the Northeastern US and other parts of the country.

The easiest way to establish Prairie Dropseed is from nursery-grown container plants or plugs. It may take a couple of seasons for the roots to form a dense clump, but once they have, Prairie Dropseed becomes very drought tolerant and care free.

A new planting of Prairie Dropseed and native perennials
The same planting two years later

We keep planting Prairie Dropseed in new places, and it does not disappoint. We planted it in the Pollinator Garden at the Nature Center, using it as an edger and a filler among flowering perennials. It makes a lovely unifying matrix, tying a flowerbed together visually, and covering the soil to eliminate the need for mulch. We’ve planted it in front of shrubs, in sunny flowerbeds, and at the edges of our Meadow. It is a winner in each site.

In late summer, the flowering stalks of Prairie Dropseed are fragrant
Prairie Dropseed catches the light and ties the garden together

Prairie Dropseed turns gold in October, and continues to add structure to perennial beds even in winter. The seeds are eaten by migrating birds and persist long enough to supply food for winter birds as well. The plant is a host to several native leaf hopper insects, and small animals may take cover under the grass year around.

November in front of the Manor House
Birdseed!

Prairie Dropseed is deciduous, which means that its leaves die off in winter, but they hold their shape even after being buried in snow. By late winter, the plants look rather quirky – somewhat like Cousin It of the Addams Family. In spring, when green shoots are starting to show, a quick haircut tidies things up.

Winter structure
Spring haircut in late March

A few weeks later, Prairie Dropseed leafs out again with fresh spring color, bringing the garden back to life. Totally a 5-star plant!

Spring greening
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.

Autumn Hy-lights

Everybody loves hydrangeas. But especially at this time of year, it’s the Oakleaf Hydrangea that really steals the show. Just when other hydrangeas start dropping their leaves, Oakleaf Hydrangea (Hydrangea quercifolia) lights up the landscape with colors ranging from hot pink to deep burgundy. The shrub holds its leaves until very late in the fall, and the colors keep changing for weeks — so the show lasts well past Thanksgiving!

Oakleaf Hydrangea in mid-November
 Most hydrangeas fade away in autumn
Oakleaf Hydrangeas blaze (no photo filters!)

Oakleaf Hydrangea is a flowering shrub native to woodlands in the Southeastern US, from Georgia and Tennessee to Florida. It does very well in more northern gardens and is an excellent year-round landscape shrub in Zones 5 to 9, and even in Zone 4 with some protection. It prefers moist soil, but is surprisingly drought tolerant once established, especially with some afternoon shade. The fall color is best with more sun, so a morning sun/afternoon shade situation is ideal. Oakleaf Hydrangea is fast growing and can occupy a space 10-12 feet high and wide in just a few seasons. It is easily pruned for size, but should be pruned just after flowering to avoid cutting off the flower buds that form later in the season.

The scientific name “quercifolia” means “oak-shaped leaves.” The shrub is not related to oaks, but the leaves do resemble very large oak leaves. Interestingly, the leaves of the shrub grow significantly larger in shade than in sun. Deer resistance is questionable. Deer have not bothered the shrubs at the Nature Center, but neighbors report deer browsing, especially on younger plants.

Fall color may be the “hy-light,” but Oakleaf Hydrangea has advantages over non-native hydrangeas in other seasons as well. In spring, Oakleaf Hydrangea leafs out earlier than Asian mop-head hydrangeas (Hydrangea macrophylla) and seems to be less vulnerable to late spring ice storms. While mop-head hydrangeas suffer significant winter die-back, leaving lots of twiggy stems into late spring, Oakleaf Hydrangea fills in attractively and reliably by the end of May.

Side-by-side comparison in late May of Oakleaf Hydrangea on the left and mop-head hydrangea on the right

Oakleaf Hydrangea blooms in June with large cone-shaped clusters of white flowers. The 4-petaled outer flowers are sterile, and their only purpose is to attract pollinators to the tiny fertile flowers hiding underneath. A huge variety of bees and other tiny insects feed on the pollen produced by the smaller flowers.

 Large cone-shaped clusters of white flowers in mid-June
The outer 4-petaled flowers attract pollinators
The tiny inner flowers supply the pollen

While many gardeners love the big blue and pink flowers of mop-head hydrangeas, those flowers come at a price: they have been manipulated by growers to dramatically increase the number of colorful sterile blossoms, while eliminating entirely the tiny fertile flowers that feed pollinators. Have a closer look at mop-head hydrangeas and you will notice the complete absence of butterflies and bees. There is nothing for pollinators there.

After the fertile inner flowers of the Oakleaf Hydrangea have been pollinated, seeds form inside the flower clusters. At the same time, the sterile outer flowers begin to turn pink. It’s an enchanting sort of garden magic.

The outer flowers turn pink in July sheltering the seeds produced by pollinated inner flowers
By late October, the flowers have turned craft-paper brown and the seeds are available for songbirds

In November, Oakleaf Hydrangea lights up the late-season landscape as no other hydrangea can. When the leaves finally finish their show, they reluctantly fall, revealing cinnamon-brown bark on stems and twigs. As the shrub ages, the bark peels attractively, adding layers of warm brown color for winter interest, and forming a great shelter for winter birds.

Oakleaf Hydrangea really is a “hy-light” of the landscape all year long.

Late season landscape composition with Winterberry and Hemlock
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.

Boo!

Ghosts, skeletons, and zombies! It’s Halloween, and our neighborhood is overrun by scary creatures playing trick-or-treat. 

But look carefully. The most terrifying monsters in our neighborhood are the ones strangling our trees! Invasive vines are real-life ‘serial killers’ — stealing food, water, and light from trees, and leaving ghosts, skeletons, and zombies behind.

Ghosts
Skeletons
Zombies

You’ve seen these vines doing their evil deeds. Our roadsides are infested with them. Our woods are being devoured by them. They cause trees to fall onto roads and buildings, costing taxpayers, utilities, highway departments, parks, and private property owners billions of dollars in property damage, clean-up, and removal. Even worse, in forests, meadows, and wetlands, these vines are replacing the native plants essential to maintaining biodiversity –the insects, birds, and animals in our ecosystem.

Three of the most destructive vines in our region are Oriental Bittersweet, Porcelain Berry, and the ever-popular English Ivy.

Oriental Bittersweet (Celastrus orbiculatus)
Porcelain Berry (Ampelopsis glanduosa)
English, Irish, or Persian Ivy (Hedera spp.)

All of these vines belong on other continents. They are invasive here because they have no natural controls in North America and, therefore, are able to aggressively out-compete our native plants. 

So, how did they get here?

Gardeners! All of these killer vines were imported and planted here intentionally because gardeners found them attractive. European colonists introduced English Ivy as early as 1727. Oriental Bittersweet was introduced as a garden plant in the 1860’s, and Porcelain Berry was brought to the US from East Asia as an ornamental ground cover in the 1870’s. These plants had no commercial use or food value for humans or animals — they were planted solely for decoration. To be fair, gardeners back then had no idea what horror they were unleashing on the Eastern US. But we can learn from their mistakes.

Oriental Bittersweet is invasive from Maine to North Carolina and west to Wisconsin and Missouri. It is fast-growing and easily overwhelms native vegetation, both on the ground and in the tree canopy. Its enormous vines, up to 4 inches in diameter, can strangle, and even uproot, mature trees and shrubs. 

Oriental Bittersweet vine choking a tree 

Porcelain Berry is invasive from New England to Virginia and west to Wisconsin and Iowa. It is extremely aggressive on roadsides and other disturbed areas, as well as along forest edges. It runs along power lines, and often brings them down in storms. Porcelain Berry kills by completely enclosing shrubs and trees, stealing all available light, until the smothered plant dies.

A young spruce tree struggles under a mound of Porcelain Berry
It’s too late to save these trees and shrubs from Porcelain Berry

Ivy is a serious problem for us at the Nature Center, and we have warned about its dangers in earlier posts. See Evil Ivy Over Everything here. Where Ivy has escaped gardens in the US, it has destroyed vast areas of woodlands, reducing vibrant and diverse local ecologies to monocultures with no value at all for birds, insects, or forest animals. In suburban landscapes, Ivy causes enormous damage to trees, fences, and wood siding.

 Ivy, the Boston Strangler

So, what have we learned from these gardening mistakes? According to the National Park Service, of the 1200 invasive plant species currently documented in natural areas, almost two-thirds were intentionally imported and planted as ornamental plants. Until recently, all three of these killer vines were still being sold and planted in gardens. In 2015, Oriental Bittersweet and Porcelain Berry finally were recognized as threats to the environment, and legally prohibited for sale and distribution in New York and a number of other states. English Ivy, however, has somehow been given a pass, and is still legally sold in every state except Oregon. Unfortunately, hundreds of other ornamental plant species, already known to be invasive, are still being sold and planted by gardeners all over the US. Legal regulation of invasive plants lags way behind the science.

So, what can we do to help? First, remove and destroy these three killer vines wherever you can, and be sure that the vines and berries go into the trash – not into brush piles or compost where they can easily spread further. 

Next, before buying or planting any ornamental plant, do a quick investigation. It’s easy! Enter the name of the plant you’re considering into Google, or another search engine, along with the word “native” to quickly find out where the species originated. Plants native to your region are safe and beneficial to the ecology.

If the plant you are considering is not native to your region, do the search again, adding the word “invasive” along with the plant name. Websites devoted to preventing the spread of invasive plants will come up in your search and warn you if a plant is a known threat to our environment. Here is a sample search for the common landscape plant, Burning Bush.

Collectively, home gardeners have a huge impact on the environment. The most obvious example of their power – for good and for ill – is the horror of almost 1000 invasive ornamental species damaging our ecosystem. Our gardening forebearers made some terrible mistakes and unleashed these scary monsters on us. We can do better.

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.