Category Archives: native new england plants

Groundcovers for Moist Shade

I’ve heard a lot of questions lately about substitutes for the ‘old standby’ shady groundcover plants Japanese Pachysandra (Pachysandra terminalis) and Periwinkle (Vinca minor). Both of these imports have been used for generations for the shady blanket effect under trees, but for nature-friendly gardeners who want to increase biodiversity in their yards, these plants offer very little value to birds, beneficial insects and soil health. Not to mention, but they can also become invasive in moist woods where they spread out of control – read about my ongoing battle with Japanese Pachysandra.

Here are some suggestions for native groundcover plants for New England to replace the invasives:

Running Foamflower (Tiarella cordifolia) – this is my all-time favorite native New England groundcover. In early May, it’s covered with a sea of soft white gasp-inducing blooms:

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The rest of the year, its foliage forms a nice weed-suppressing mat – as long as it’s grown in moist, rich woodland-type soil. An area under deciduous trees where leaves and duff are allowed to build up in the soil is ideal.

Wild Ginger (Asarum canadense) is an essential component of New England native plant gardens as green “filler” to weave in and around larger plants – forming a living mulch that keeps the soil cool and prevents weed formation. Its dull-red flowers form in early spring – at ground-level to cater to ground-dwelling pollinating insects.

Shown below at the right of the photo, the heart-shaped leaves of wild ginger mingle beautifully with ferns and other woodland plants – remaining green and lush after the spring ephemerals are long gone:

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Another native plant that will quickly cover a moist shady area is Mayapple (Podophyllum peltatum), shown here growing under oak trees at Garden in the Woods in Framingham MA:

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Mayapple will dominate surrounding plants, so give it an area all its own where it won’t dwarf its neighbors.

Bunchberry or Creeping Dogwood (Cornus canadensis) is a native woodland plant with late-spring flowers that look like small dogwood blossoms:

bunchberry IMG_7493Bunchberry is late to fully form its foliage in the springtime, so it’s not as effective at suppressing weeds at Pachysandra, but if grown in a cool, damp soil, it will happily spreads into large patches that can be occasionally mowed to keep other weeds at bay.

Last but not least, did you know there is a Pachysandra native to the eastern US? Allegheny Spurge (Pachysandra procumbens) grows wild in rich woods from West Virginia and Kentucky south to Louisiana and Florida, but it is quite hardy in most of New England (to zone 4). It’s semi-evergreen (unlike its evergreen Asian cousin Japanese Pachysandra) with spring flowers that smell like cinnamon:

pachysandra procumbens IMG_9972In my experience, Allegheny Spurge needs consistent moisture in its first few years, but becomes quite drought-tolerant once established. It’s most happy with some summer shade in New England, and spreads nicely from clumps rather than the aggressive underground runners of the Asian variety which invade moist woods here in Massachusetts.

Native wildlife gardening purists might disagree with using a southern native in the northeast where it’s not traditionally indigenous, but as average temperatures continue to rise in the coming decades, we may find that growing southern species here in New England will support their co-adapted pollinators and other specialized insects as they migrate north in an effort to survive. As we struggle to maintain biodiversity in an era of mass species extinctions, these kinds of assisted migrations may become essential…

The Year I Shall Win the Pachysandra War

Anybody who has heard me talk about gardening knows that I have an uneasy relationship with Japanese pachysandra (Pachysandra terminalis) which is easily the Number 1 planted shade groundcover in New England gardens. Oh sure, it spreads quickly to form a solid green mat in the shade under trees, and its evergreen foliage stays green all winter. You can find this plant at every garden club plant sale and divisions of it have been passed from gardener to gardener for at least a generation. There is probably not a single neighborhood in Massachusetts that doesn’t have an acre or two of of what horticulture guru William Cullina calls “the vinyl siding of landscaping” (an expression that makes me giggle every time)…

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 But this plant has a darker side, through no fault of its own other than the fact that it’s a foreign import into a landscape where it has no natural controls. Unfortunately, when Japanese pachysandra is planted near moist woodlands in New England, it can quickly spread into the woods through its underground roots, choking out anything else that happens to be growing there and threatening unique and fragile woodland plant communities. There are few (if any) native herbivores (insects or other leaf eaters) that can digest the foliage of this alien plant, or co-evolved pests that control its growth in any way. And once Japanese pachysandra is established in an area to its liking, good luck removing it. Ever!

In the photo above, this lush border of pachysandra needs to be rigorously “pushed back” with a sharp spade twice a year, to keep it from becoming an entire backyard of pachysandra….

When we moved onto our small farm six years ago, we were delighted to find a beautiful stream flowing through it, and even more thrilled to discover unique native plants such as trilliums, jack-in-the-pulpit, Christmas and sensitive ferns, and winterberry holly growing in the rich, moist soil along its banks. I did find some Japanese pachysandra also growing along with Japanese barberry (another invasive planted by a previous well-meaning gardener), but I targetted those for removal in hopes of expanding the populations of the native plants. I spent a few hot summer days standing in the cool water of the stream pulling the roots out by hand (it was not a very large area), and thought my work was done.

Fast forward a year or two, when I noticed that not only was the pachysandra still holding on along the streamside, but that it had literally jumped the garden gate, and had spread at least 10′ into the woods:

pachysandra streamside

I began beating back the pachysandra again – trying carefully not to damage tree roots and the now-tattered jack-in-the-pulpits. I do not use the weed killer Roundup (or its cousin Rodeo) because of its negative impacts on amphibians, not to mention the fact that this heavily-used neuro-toxic herbicide is being increasingly linked with fetal cell death in humans, along with other alarming impacts to people and wildlife. So armed with only a small garden fork and my hands, I have opted for hand-to-hand pachysandra combat. This spring, I declared 2011 “The Year I Shall Remove the Pachysandra Regime”, and each day I’ve resolved to pull out pachysandra roots for 15 minutes until the pachysandra is completely GONE. Wish me luck! I hope to report back in a few years on the newly restored native plant populations that should be making a comeback!

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Jack-in-the-Pulpit (Arisaema triphyllum) is one of the cool New England bog plants that I’m trying to save from a thickening mat of Japanese pachysandra in our “wet woods” (Photo of jack-in-the-pulpit copyright Trudy Walther) 

A note about hand-weeding: Pulling weeds by hand might seem like a lot of work, but its slow and steady pace is great for teaching you about the makeup of your soil and how certain plants impact their surroundings. I’ve noticed that where my pachysandra roots form a tangled mass of stolons (runners), they seem to suck up all the soil moisture from an otherwise boggy area, and the resulting soil becomes dry and lifeless. In my pachysandra monoculture, I find no other plants, no tiny decomposing insects or butterfly caterpillars looking for leaves they can eat, no salamanders or frogs, nothing at all except the thick white pachysandra roots. It’s clear to me that the pachysandra has, in a few short years, impoverished my rich woodland soil, and nearby plants (and their associated wildlife) are all suffering from these rapid changes to their environment.

If you’re also battling pachysandra, please share your control stories from the trenches!

 

Virginia Rose

Have you always loved roses, but hate the spraying, fertilizing, watering and pruning they require to keep them from looking a mess? Please meet the lovely Virginia rose (Rosa virginiana). Unlike its highly-bred, cultivated cousins (hybrid tea roses and modern cultivars of climbing roses) this native eastern rose is hardy to the coldest parts of New England, grows happily in almost any soil, needs little to to no irrigation except for rainwater, and blooms its head off through June with pink flowers with the most heavenly fragrance. Not to mention, their beautiful red fruits (hips) persist right through the winter, feeding birds and providing winter interest when the landscape is otherwise white and brown. What’s not to love?

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Most Virginia roses bloom in light or medium pink, although there are white-flowering cultivars available too (I’ve not had good experience with the white-flowering form, however). Their flowers might not have the fluffy allure of the larger double-formed hybrids, but their single-flowering form makes them much more attractive to butterflies and other pollinators, who don’t have to fight their way through many layers of petals to access the sweet nectar and pollen at the center of the flower. And did I mention its fragrance?

When it’s happy, which is in any decent soil with good drainage and plenty of sunshine, Virginia rose will spread fairly rapidly within just a few years, so if you have a large area you’d like to fill in quickly with a wildlife-friendly native plant, Virginia makes a great choice.

In bloom, a pink tapestry of Virginia rose mingles beautifully with foxglove, cranesbill and other late spring bloomers and will form a low, thorny hedge that offers excellent year-round predator protection for the birds visiting your gardens. This sunny hillside of our farm was planted with a single container of Virginia rose in 2006, and by June 2009 it had happily spread to form a sizeable thicket:

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As you might imagine, its spreading habit (through underground roots that snake in every direction) makes Virginia rose unsuitable for small gardens, where its roots will eventually take over surrounding plants and form dense canes that shade them out. A better-behaved but just as pretty wild rose is Virginia’s closest cousin, Carolina or pasture rose (R. carolina) which spreads by slowly enlarging clumps rather than spreading roots.

In the thicket above, an annual mowing stops Virginia rose runners from spreading into the adjacent lawn, but you can also contain its advancing roots with a hard root pruning every few years with a sharp shovel. A driveway also makes a good boundary, as long as you don’t use large amounts of salt to de-ice your driveway.

Note: Please let it be known that I would dearly love for the above Virginia rose thicket to spread and cover the entire hill, but hubby has drawn a literal line in the sand (with rocks!) where his lawn cannot be further encroached! I am hoping he won’t notice the line has moved a few times

So planting Virginia rose in beds with other perennials is not a good idea, but in a new planting of a large area, you can interplant with self-seeding annuals, biennials or short-lived perennials to fill the bed for the first few years while the rose spreads….I initially planted the above bed with common sage, purple coneflower, cranesbill, foxglove, cosmos and cleome, and after 4 years, mostly only the foxglove remains in the area, probably because its seedlings are more shade-tolerant than the others. The others I have simply moved to other areas of the garden or given away to friends.

If you’ve grown roses before, you’ll appreciate that Virginia’s foliage is very resistant to most of the common diseases that disfigure roses. Like all roses (wild or cultivated), Japanese beetles love to eat its foliage, but if your plant is healthy and vigorous, it should shrug off any damage. These roses bloom in June in central Massachusetts, and Japanese beetles don’t tend to arrive in large numbers in our area til early July, so by the time the beetles start chewing, you should have other beautiful blooming plants to distract you from a few holes in their leaves.

 Virginia rose canes top out at about 4′, so you should never need to prune them for height, especially because you’d be cutting off one of the plant’s best features, its plump red hips that you barely notice until the first winter snows suddenly bring them to life:

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The hips must be pretty sour to taste, because the birds don’t seem to touch them at all during the winter. They disappear around the beginning of spring here, so winter’s deep freezes must sweeten them up a bit, or else late winter birds are too hungry to be picky. I often see their thorny stems used as a temporary hideout by foraging winter birds, who get spooked by hungry hawks hovering around my bird gardens and feeders. The white background makes tiny birds much more visible to larger predators (my dogs will confirm this because they constantly mistake them for chipmunks!) but even a cat is unlike to risk those nasty thorns and go in after them…

If your garden conditions are boggy or wet, the best native roses for garden use are swamp rose (R. palustris) and New England rose (R. nitida), although these bloom a little later than the field roses in summer.

If you look, you may still find native roses growing wild in natural areas. More often than not, though, roses that you see in the wild are the invasive multiflora rose (R. multiflora), which is often assumed to be native but is an introduced rose from Asia that has been steadily overtaking old fields in New England for decades:

19-x Multiflora rose closeup cropped reduced Although birds do eat their berries, multiflora rose has a highly negative impact on its surroundings, forming enormous thickets that crowd out the native plants that underpin balanced and healthy ecosystems. Chances are, if you see a large, fragrant sprawling wild rose with white flowers and arching stems, it’s multiflora rose. Removing these from your property can be a great contribution to protecting local biodiversity…you can either replant with one of our native New England roses, or use the “wait, weed and watch” approach, which means simply rooting out any remaining multiflora canes that pop up over time, and allowing any native plants that are still hanging on to make a comeback.

If you try the wait, weed and watch approach, be prepared for a funny thing to happen. You’ll begin to notice an increasing variety of birds, butterflies and other interesting wildlife that visit your naturalized area, many more so than your more cultivated garden areas, and eventually you will realize that your wildlife garden, with all the life it attracts, is your most beautiful and favorite garden of them all…

** BY THE WAY ** Apologies to my email blog subscribers who received a half-written article on Wednesday by email – I hit the “Publish” button instead of the “Save” button and the article went out as is  {deep embarrassment}. The complete article is available here: Gimme Shelter…for the Birds

Resurrecting the American Chestnut Tree

american chestnutOnce upon a time, when most of the eastern US was covered with a thick canopy of trees, the dominant tree species was the American Chestnut (Castanea dentata). Loaded with sweet and nutritious nuts, chestnut was an important “mast” tree, feeding and sheltering many forms of wildlife. In the early 20th century, a fungal blight imported on Chinese chestnut trees tore its way through our native chestnuts, virtually obliterating the species from our landscape in just a few decades. Since then, oak and hickory have replaced chestnut as the dominant tree species in many areas of the northeast, but there is hope for the return of the American chestnut to our landscapes. Healthy American chestnuts are occasionally found still growing in various parts of the country, unaffected by the deadly blight, proof that with enough genetic diversity in a species, often a few individuals can withstand whatever nature throws at them.

This is where science, technology, horticulture and medicine have all come together to resurrect the magnificent American chestnut species. Through a lengthy process of controlled pollination, genes from the blight-resistant Chinese chestnut are crossed and back-crossed into the American chestnut gene pool, which over the span of many generations develops a greater resistance to the blight. Those offspring that show the most resistance are then cross-pollinated with pollen from blight-free American specimums. The healthiest of all are inoculated with the blight, and nuts from these chestnuts are being planted in various areas across the country for further selection for regional adapability.

How can you help this project? If you own woodlands, or just like to walk in the woods, you can contribute to the American chestnut restoration program by looking for mature, surviving American chestnuts to add to the pool of blight-resistant genetic material. If you see what you believe may be a healthy American chestnut, contact The American Tree Foundation for details of how to collect and send a leaf and twig sample for analysis. The resulting nuts will then be planted in chestnut orchards to continue the breeding and selection program. To date, over 500 “mother trees” have been found along the eastern seaboard, and regional groups are hoping to find more.

To identify an American chestnut , look closely at the leaves. They are unmistakeably long and toothed (see below), but look a lot like the foliage of other trees such as American beechchestnut oak, as well as Chinese, Japanese and European chestnut. One feature that sets them apart is that American chestnut leaves are not hairy, whereas other similar tree species have hairy leaves.

chestnut foliage

Even if you can’t find mature blight-free American chestnuts on your travels, you may well spot the living remains of blight-affected chestnut trees that collapsed many decades ago. Chestnuts affected with blight can take a long time to die, and living stems will continue to sprout from old root systems, growing to about 10-15′ high before being attacked by the blight. If you find a stem with living leaves alongside dead stems rising from the same root base (see above), you have found an old American chestnut dying from blight. You might even be lucky enough to find the remains of the long-fallen trunks. The lightweight but hard wood of chestnuts was highly prized by settlers for its rot-resistance, and fence posts, telephone poles, coffins, furniture and even pianos were some of the products that fueled a thriving chestnut logging industry over the centuries.

The good news for wildlife gardeners is that in time, we will be able to buy seedlings of American chestnuts to restore this majestic tree back into our landscapes. As Sudden Oak Death (another imported pathogen) threatens our native oaks, the re-introduction of the American chestnut could eventually fill gaps left by other declining trees, pre-empting the incursion of invasive species and insuring the health of our forests and woodlands into the future.

Photo credits:

Historical photo of American chestnut tree, W. Virginia, 1924, courtesy of the Forest History Society, Durham, N.C. 

Photo of blight-infected American chestnut at Broadmeadow Brook Audubon Sanctuary in Worcester, MA. by Ellen Sousa.

 

Where are the Monarchs?

 

DCF 1.0Where oh where have the Monarch butterflies gone? I heard this question many times this past summer. Mostly, it seems the weather was to blame, at least in New England. Butterflies need sun and warmth in order to fly, and they need to fly to locate Milkweed plants to lay their eggs. Their wings are like little solar chargers, soaking up the sun to fuel their flight. This year’s cold and rainy weather in New England provided few opportunities for female Monarchs to fly to areas containing Milkweed plants (Asclepias species), which is the only plant that Monarch butterfly caterpillars can use as a food source.

The good news is that this could be just a regional blip. According to Journey North, a project that documents Monarch numbers during their fall and spring migration, in the past week, Monarchs have been seen crossing into northern Mexico in numbers that have not been seen in years. Hopefully this means that although Monarchs were scarce in New England this year, the weather simply kept them away.

But the weather isn’t the only problem affecting Monarch populations. Illegal logging in the forested regions of central Mexico, where Monarchs make their winter home, has reduced the winter habitat available to those butterflies who survive the long flight south. And according to research at the University of Georgia, since 1976 the female-to-male ratio of Monarch butterflies shows a major decline east of the Rockies. Because females can lay up to 400 eggs over the course of their lifetime, any reduction in their numbers is troubling for population stability.

Researchers are not sure why female populations are declining, but as gardeners we can all help Monarch populations by planting Milkweeds in our yards and gardens to provide food for Monarch caterpillars. If you think they’re weedy looking, think again. There are several types of Milkweed that will grow in New England, and whatever your conditions, there’s a beautiful variety suitable for your garden.

Well-drained, sunny spot? Just perfect for the neon-orange Butterfly Weed (Asclepias tuberosa), shown below with our Farm Director “Speck”:

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If your soil contains some moisture, Swamp Milkweed (Asclepias incarnata) is a good choice. It’s tolerant of drier soils, too. Besides being the sole food source for Monarch caterpillars, Milkweed flowers contain huge amounts of sweet nectar that all butterflies (not just Monarchs) love. Below, a Great Spangled Fritillary butterfly sips nectar from Swamp Milkweed flowers:

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If you have a larger property with areas that you can let “go wild”, Common Milkweed (Asclepias syriaca) has gorgeous ball-shaped pink flowers with an intoxicating honey scent. Common Milkweed grows naturally in waste places and old fields in New England, so who knows, if you have an area that you can leave unmowed, it may just pop up on its own…

Although not native to New England, Scarlet Milkweed or Bloodflower (A. curassavica)is a worthwhile annual to include in flower beds and patio pots. Its flowers bloom in a striking red, orange and yellow:

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The first year we planted Scarlet Milkweed in a container on our patio, almost immediately a Monarch butterfly found it and laid her eggs. To our delight, two of them hatched, and one climbed onto a nearby trellis to start its transformation into a butterfly:

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Below is the chrysalis that eventually morphed into a brand new adult Monarch butterfly:

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How do they do it?

Scientists and naturalists have always been fascinated by the complex life cycle of the Monarch butterfly, but new research published in Science magazine is showing just how these tiny creatures are able to navigate their way 2000 miles to the same small region of Mexican forest each fall to spend the winter. It turns out that Monarchs have a type of GPS navigation system and circadian clock built right into their antennae, which allows them to use the sun to guide their travel as well as to correctly adjust their direction based on the time of day. Amazing!

Remember, no  Milkweed, no Monarchs. Let’s help these unique winged wonders survive for future generations to enjoy by growing Milkweeds anywhere we can!