Pollinators Archives - Nature Center at Greenburgh

November 15, 2023January 7, 2025 Cathy Ludden Around the Grounds, Invasives, Native Plants, Pollinators

Privacy Without “O-fence”

Suburban yards are places for families and friends to relax, perhaps enjoy a barbecue, and watch children and pets play safely. Privacy is important.

No wonder, then, that suburban homeowners often decide to plant a “privacy screen.” Hedges of trees or shrubs, planted as living “green fences,” are as common in suburbia as the lawns they typically surround.

But too often, these hedges are made with invasive plants that spread themselves into natural areas causing ecological harm. Top offenders include privet, Japanese barberry, forsythia, bamboo, and burning bush. All of these plants are recognized as invasive species and should be avoided.

Forsythia is not a good choice for a privacy screen

Burning Bush — Burning bush may look good for a minute

Japanese barberry, now banned in several states, spreads by seed into vacant lots, woods, and roadsides and actually increases the population of ticks carrying Lyme disease!

The good news is that the need for privacy does not require bringing any of these offensive plants onto your property. There are so many better choices!

In the Eastern US, the most popular privacy screen by far is Arborvitae (Thuja occidentalis), also known as Northern White-cedar. Favored by builders and landscape maintenance companies, a row of inexpensive and readily available Arborvitae is often planted along the property line as soon as a new house is built.

Though Arborvitae is a much better choice than any of the invasive plants mentioned above, it is not the only — or best — option. In areas populated by deer, Arborvitae is extremely vulnerable.

Here are some alternatives – beautiful evergreen trees and shrubs, native to the Northeast, that make ideal privacy screens. And because they are native, they also offer value to native birds and pollinators!

American Holly (Ilex opaca) makes a dense, evergreen privacy screen and has the bonus of tiny flowers for pollinators in the spring and beautiful berries that add winter interest to the landscape.

American Holly may be pruned into a hedge

Rhododendron is another good choice for privacy. When European settlers first explored the Eastern US, they struggled through massive stands of Rhododendron maximum that formed impenetrable evergreen thickets. Why not use that same feature now as an effective screen? Our native songbirds love to hide in a thicket!

Inkberry (Ilex glauca), another native evergreen, grows quickly and has shiny, dark green leaves that form a dense screen. More winter-hardy than boxwood and growing taller, Inkberry is a great hedge plant.

Red Twig Dogwood and Switch Grass — Inkberry in a mixed border with Red Twig Dogwood and Switch
Grass

The very best privacy screen, though, is not a row of one species of plant, but a forest! The Northeastern US was once predominantly forest, and many of the plants in those forests are still the best plants to grow here. In suburban yards, we can mimic the beauty, seclusion, and peaceful quiet of a diverse forest simply by planting more stuff! And a bigger variety of
that stuff is inspired by our native forests!

Maybe it’s time to reconsider our approach to the “privacy screen.”

Hedges can be great, but they can also be visually boring and ecologically sterile. There is no law requiring homeowners to mark their property boundaries with a row of identical plants. Just because your property line forms a rectangle doesn’t mean your landscape has to be one. A diverse mix of plants – native trees, shrubs, grasses, and perennials – planted in masses makes a landscape interesting, lush, ecologically valuable, and very private.

Contrasting approaches – the mixed border of deciduous and evergreen trees on the right offers more interest, and more privacy, than the hedge on the left

white pine, arborvitae, spruce, juniper, and Rhododendron — A mix of White Pine, Arborvitae, Spruce, Juniper, and
Rhododendron completely screens a house from the road

If you already have a hedge or a fence along the property line, consider planting inside it using a mix of native trees and shrubs that change with the seasons. Start with the corners.

Trained landscape designers tend to avoid square corners and straight lines in their designed plantings. You can do the same thing. Map out curved beds that soften the corners and bring more plants further into your yard. Plant taller shrubs at the back, and choose flowering shrubs and perennials to plant in the foreground where you can enjoy them.

Fences along two neighboring properties meet to form a hard corner that is softened, and completely screened, by a curved planting of mixed trees, shrubs, and perennials

So, consider creating a privacy screen that looks more like a forest than a fence. By planting more plants, and a bigger variety of plants in more of your yard, you will have more privacy, more seasonal interest, less lawn to tend, and more habitat for birds, butterflies, and fireflies.

How’s that for a win-win-win-win?!

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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October 20, 2022January 7, 2025 Cathy Ludden Around the Grounds, Native Plants

Seasons in the Meadow

Meadows change. All landscapes change, of course, even the most formal manicured gardens. But native plant meadows are wilder, less predictable. Nature has a freer hand where plants are allowed and expected to reproduce naturally, and where humans impose less control over conditions. In each season since the initial planting of our native Meadow (see last week’s blog post here), we have been surprised, sometimes frustrated, and always fascinated by the changes we see. Our challenge is to accept as many of nature’s changes as we can, while preserving the value of the Meadow for nature itself.

In the Northeastern US, which was once almost entirely forest, naturally-occurring meadows are typically “successional.” They occur when a storm or fire opens a spot in the forest and more sunlight allows grasses and wildflowers to emerge. Eventually, woody shrubs and tree seedlings settle in, grow taller, cast shade, and the forest returns. Unfortunately, in modern times, any newly opened ground is immediately colonized by invasive species, plants from other parts of the world that out-compete native plants because they have no natural insect or animal controls here.

So, maintaining a designed meadow in the Northeastern US requires effort to prevent invasive plants or forest from claiming the space. The incredible value of a native meadow as habitat for insects, birds, reptiles, and mammals makes that effort totally worthwhile.

Guy Pardee of Suburban Natives, LLC mowing the Meadow in early April

We begin each year in the Meadow by mowing to prevent tree seedlings from developing, and to allow sun and water to reach new growth. The timing of mowing is important. We need to wait for over-wintering insects, including native bees and caterpillars, to emerge from their hiding places in leaves and hollow stems, usually in late March or early April. The Meadow is cut to the ground, leaving plant debris in place to add nutrition to the soil and to protect emerging growth from late frosts.

**Seedlings of White Pine, sumac, and birch appear every spring, trying to re-forest our Meadow**

**Plant debris is left on the ground after mowing**

Spring mowing also allows us to check the Butterfly Arbor and the trees in the Oak Circle for any winter damage. And it’s a good time to look for and remove invasive species before they can hide among the native plants.

A few weeks after mowing, when the first spring flowers emerge, we see that the Meadow has changed again. Each year there are surprises, and occasional disappointments, as plants appear and disappear. We are delighted when native plants volunteer in places they were never planted – a true indication of a healthy landscape! And, sometimes, we notice that flowers we love have disappeared as they reach the end of their life expectancies, or lose ground to stronger plants.

**Whorled loosestrife, Wild Sarsaparilla, and Appalachian Sedge are native plants that volunteered at the Meadow edge**

**Prairie Smoke, a spring bloomer, sadly disappeared from the Meadow after a few years**
Photo: Travis Brady

By June, the Meadow is in full bloom. Coreopsis, Penstemon, Baptisia, and many other flowers greet visitors — including butterflies, bees, and countless other pollinators!

Throughout the summer, the Meadow continues to change – not just seasonal changes, but changes in plant populations. Years after the original seeding, plants have appeared and bloomed for the first time as slow-growing seeds finally matured. And the number and location of plants in the Meadow changes every year.

**An uncommon plant, *Castilleja coccinea,* was included in the original seed mix planted in 2014, but only appeared and bloomed for the first time in June 2021**

**Joe Pye Weed was not a big presence in the early years of the Meadow, but after one rainy summer, it became prolific**

Throughout the growing season, some weeding is necessary to keep invasive plants out of the Meadow. Even some native plants are too aggressive to leave uncontrolled, or they would soon dominate. We make careful edits, avoiding use of herbicide, and quickly fill in weeded areas with container-grown native plants.

**Canada goldenrod is a beautiful native plant, but can out-compete everything else, so we cut it back before it goes to seed**

Autumn is the most dramatic season in the Meadow. Late-blooming flowers and grasses change the scene daily with a profusion of color. Seed pods from faded flowers attract songbirds in large numbers, and bees scramble to stock up for winter.

**Milkweed seed pod**
Photo: Travis Brady

**Late October view of the Butterfly Arbor**

Meadow plants are left standing all winter to provide seeds for birds, cover for animals, and winter hiding places for insects. There is a lesson here for all of us as home gardeners: a little mess, a little bit of wild in the landscape, can be as beautiful as it is beneficial for living things.

As the light changes with the seasons, the Meadow changes, too. It really is a different place each time we visit!

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

June 9, 2022January 7, 2025 Cathy Ludden Around the Grounds, Invasives, Pollinators

The Trouble With Double

One beautiful spring morning, we stood under our Kwanzan cherry tree and noticed that something was missing: pollinators! Not one bee or butterfly was visiting the tree, even though it was loaded with flowers. Not far away, a blooming crabapple tree was literally humming with pollinators! What accounted for the difference?

We realized that the cherry tree has “double blossoms.” Its flowers have been modified by humans to replace all of its pollen-bearing stamens with flower petals. The flowers are beautiful – but only to people. There is no pollen or nectar for bees or butterflies. The flowers of the crabapple, on the other hand, were loaded with pollen and nectar. And the pollinators were all there for breakfast!

**The stamens are missing completely in these sterile double blossoms**

**The stamens in these flowers are ready for pollinators**

Flowers are the reproductive organs of plants. Pollen contains the genetic material that must be transferred from the (male) stamens to the (female) pistil for pollination (fertilization) to occur. In most flowers, the petals form an outer ring and the stamens are just inside, forming a second ring around the pistil. The flower’s colorful petals, its fragrance, and the sweet juice called nectar all are designed to attract pollinators. As pollinators sip the nectar located at the base of stamens, and collect pollen to feed their offspring, they “accidentally” transfer pollen from flower to flower and deposit it on the pistil where pollination happens. Successful pollination results in seeds, which then grow to produce more plants.

But sometimes nature makes little mistakes. Sometimes a plant will develop extra flower petals where the stamens should be. This is not a good thing for the flower, because with fewer stamens there is less pollen, which reduces the chances of pollination and, therefore, reproduction. In nature, plants that continue to develop too many petals instead of stamens eventually would fail to reproduce.

For hundreds of years, however, horticulturists have been fascinated by this “mistake” of nature. Humans enjoy flowers, and we tend to think bigger and fuller flowers are better. So, when horticulturists discover a flower that has extra petals where stamens should be, they can select that plant for special treatment. They can propagate the plants with extra petals and, eventually, even develop plants with so many extra petals they have no stamens (or pollen) at all! Without stamens, of course, those plants are sterile. They cannot develop fruit or seeds or reproduce themselves.

Roses are a good example. Natural roses have 5 petals surrounding a circle of many stamens carrying pollen.

**A simple rose with 5 petals, stamens with pollen, and pistil in the center**

Roses frequently make the “mistake” of trading stamens for extra petals.

**Note the under-developed petals in the ring of stamens**

Over centuries, horticulturists have selected these “mistakes” for intentional manipulation to create roses that are more interesting to people.

**In fully double roses, extra petals replace virtually all of the flower’s stamens and pollen is scarce or non-existant**

Today we have thousands of flowering trees, shrubs, perennials, and annuals that are popular specifically because they have double blossoms. But this comes with a cost to pollinators. Butterflies need nectar. Bees need nectar and pollen to feed their offspring. Butterfly and bee populations are declining under pressure from loss of habitat, pesticide, and limited food sources. We can help with our garden choices.

**Double peony with no stamens, pollen, or nectar**

**Double trillium with no stamens or available pollen**

**Double sunflower – native, but not useful for pollinators**

**Single peony with stamens and pollinator**

We humans love our double blossoms, but if you’re making a choice, think about providing a big variety of native single-blossom flowers for our pollinator friends!