Pruning Hydrangeas: A Step-By-Step Guide For Old And New Wood

To prune or not to prune? This is one of the quintessential gardening questions. Recently, I asked a top landscaper in Virginia to weigh in on the issue. “When is the best time to prune hydrangeas without cutting off next year’s flowers?” I asked. 

“Never,” she replied with a laugh. “But your best shot is after they’ve bloomed.”

It turns out that knowing how and when to prune hydrangeas involves first, identifying what kind of shrubs you own. And it all starts with determining whether they flower on old or new wood. Continue reading

Top Red, White and Blue Flowers For The Summer Garden

For many Americans, Fourth of July is synonymous with fireworks. But for gardeners, the pyrotechnics start early. That’s because by mid June, spring pastels are already giving way to dazzling color as red, white and blue flowers begin lighting up the summer garden. Continue reading

True Blue Flowers: Why Real Ones Are So Hard To Find

For centuries, people around the globe have searched for a true blue flower. Elusive and rare, it is seldom found in nature. Or, to put it another way, it is rarely perceived in nature. It all has to do with what each of us sees as true blue.

To find out why this is so, I signed up for an on-line lecture given by Brandon George, a grad student in public garden stewardship at Cornell Botanic Gardens. His research not only produced a great list of blue flowers, but also shed some (hint) light on the issue.

WHAT CONSTITUTES BLUE

So why is blue so rare in the plant world? For starters, I’ll ask you to refer to the color wheel below.

Blue is a primary color. On the visible color spectrum, it is located between green and violet. But that’s where things get murky. Take a look at the wheel. Some blues tend towards green, while others tend towards violet. Do all of these pigments deserve the name blue?

Indeed, how does one determine what constitutes a true blue? This has turned out to be a problem for horticulturalists and growers the globe over.  To address the issue, the Royal Horticultural Society (RHS) has created a chart by which users can match precise colors to flowers, fruits and other plants. It contains 920 colors.

Still, though it helps differentiate among different shades of blue, the color chart doesn’t explain why a true, pure blue remains so elusive. And here’s the kicker. While blue is a prominent color on earth, it is rarely produced in nature. In fact, of all the 280,000 known species of flowering plants, only 10 percent are blue.

HOW PLANTS PRODUCE BLUE

It turns out that plants aren’t born blue. Instead, much like artists, they must mix naturally-occurring pigments to achieve their blue hue. The most common of these pigments are called anthocyanins. Anthocyanins are responsible for many colors, from orange and red to violet and blue. And they can vary according to soil pH, which indirectly impacts flower color.

Hydrangea macrophylla ‘Nikko Blue’

What we perceive as blue, then, is actually the result of reflected light from these anthocyanins. And just the tiniest tweak of metal ions in the soil can result in the same plant producing entirely different blues. (Think blue hydrangeas, which are produced by adding acid to the soil.) Finding a true blue flower is pretty hard indeed.

WHEN PURPLE LOOKS BLUE

Even then, some of us may still see purple as blue.  Deutan Color Blindness (do-tan) is an anomaly of the ‘M’ cone (Medium Wavelength Light) in which spectral sensitivity is shifted toward longer wavelengths. If you have it, you may experience confusion between colors such as purple and blue. Take a look at the photo below. Do you see purple and blue or just blue?

Photo credit/enchroma.com

TRUE BLUE PRETENDERS

Nowadays, blue flowers are highly prized. As a result, growers are introducing more and more plants that are labelled as blue. But beware – many are not truly blue! To differentiate among cultivars, horticulturalists now use the term ‘true blue’ to indicate a more true blue pigment.

Take, for instance, the hardy geranium ‘Rozanne’, a popular choice for the perennial garden. Some growers list it as violet, others lists it as blue. How do you perceive it? To my eye, it tends towards purple. While my colleague sees it as blue.

Hardy geranium ‘Rozanne’/Photo: anniesannuals.com

Have you ever wondered why the same blue plant can look entirely different across catalogs? Just because a plant has blue in its name doesn’t necessarily mean it’s blue. Some growers manipulate photos to make plants appear more blue. While others use tricks of light. If you can’t see the plant in person, George recommends consulting user uploads rather than seller photos to get a better perspective on a plant’s true color.

TRUE BLUE FLOWERS

There is one plant family that typically produces the truest blue flowers in nature. Boraginaceae, also known as the forget-me-not family, includes more than 27,000 species. The plants of this family are frequently hairy and include such garden ornamentals as Virginia bluebell (Mertensia virginica), Lungwort (Pulmonaria), Forget-Me-Not (Myosotis) and Heliotrope (Heliotropium).  Horticulturalists agree that these are indisputable blues, although changes in pH can induce color changes as the petals age.

Virginia bluebells

Other indisputable blue flowers include Grape hyacinth (Muscari), Siberian squill (Scilla siberica) and Blue Drumstick (Allium caeruleum), in addition to pH-sensitive Hydrangea macrophylla, which in acidic soil (a pH below 6) will turn blue. 

Blue Drumstick, Allium caeruleum

And don’t overlook the sky blue flowers of Brunnera macrophylla, Delphinium grandiflorum, and Plumbago cerastostigma, which are all great additions to the spring/summer border.

TRUE BLUE ANNUALS

Perennials not your thing? There are also some great almost-true blue annuals. Evolvulus ‘Blue My Mind’, is a dwarf morning glory with fuzzy, silvery-green foliage. It looks great in containers or windowboxes, where it will happily trail over the edge.

Other great true blue annuals include Plumbago auriculata (a very light blue), Love-In-A-Mist, and Gentian sage (Salvia patens), a tender perennial that has the deepest blue flowers you’ll find.

Gentian sage, Salvia patens

DESIGNING WITH BLUE

When working with blue, remember it is considered a cool color, so it will recede into the landscape. Consider bringing it forward to enjoy it and plant cultivars in mass for a stronger effect.

But a word of caution. Placing a lot of different ‘blues’ together will often cause some to look bluer than others (see below). To prevent this from happening, separate them out and plant them instead next to contrasting colors (such as orange or yellow), which will give the illusion of a brighter blue.

Blue or purple? Delphiniums growing in Dalat, Vietnam

 

How To Identify Poison Ivy

Even bad boys can have a good side; and so it goes with an unwanted inhabitant of many a garden, poison ivy.  The native plant sure knows how to take over a room. For humans, its ornamental qualities are less than desirable. That being said, poison ivy does have its uses. See below.

WHAT IT IS

According to the Centers for Disease Control and Prevention (CDC), poison ivy is one of the most common poisonous plant species found throughout the continental United States. A native of North America, it grows mostly in the eastern and midwestern states where it tends to inhabit forests, fields, and shorelines. More worrisomely, it’s also come to love urban/suburban environments such as road sides and parks. This in turn has led to it taking up residence in many of our backyards. 

Poison ivy is a member of the sumac family, Anacardiaceae, which comprises over 860 known species. Along with poison sumac and poison oak, it is part of the genus toxicodendron, whose toxic properties produce contact dermatitis in affected individuals. 

A TOXIC RELATIONSHIP

So what makes toxicodendron so toxic? The culprit is urushiol, an oily resin with allergenic properties. Urushiol is found in every part of toxicodendron, including dead or dormant plants. When poison ivy, poison oak or poison sumac are bumped, damaged or even burned, they release urushiol as a means of protection.

In fact, research shows that only a small amount of exposure can cause an allergic rash. And by small amount, that means just 1 nanogram or one billionth of a gram. There is even evidence that urushiol can remain on a surface for up to five years. The take-away? I’d say avoid these plants altogether.

On a good note, apparently about 10 to 15 percent of the human population is immune to poison ivy and its cousins, and therefore will never experience the rash. And poison ivy is less common outside the U.S., although it can still be found here and there around the globe. 

HOW TO IDENTIFY POISON IVY

A common adage says ‘Leaves of three, let it be’, while another counsels ‘Leaves of three, run and flee’. I prefer the latter, having suffered from major breakouts throughout my lifetime in the garden. That being said, poison ivy is a chameleon when it comes to appearance. it can be downright hard to identify. Compare the photo below to the two above. You’ll see what I mean.

The truth is poison ivy has so many variations it can baffle even the most seasoned horticulturalist. Take for instance its make-up. It can be a creeping groundcover, or a woody vine (referred to as a liane) which, once it scales a tree, can put on 20 feet of growth in just one season. And full sun can cause it to take on a shrub form.

And while most of us know to look out for a plant with three leaves, from that point on, things can get murky. Poison ivy has a compound leaf, which means that what presents as a single leaf is actually three. Additionally, its leaves can be shiny or dull, and their size and shape can vary greatly. Some leaves are toothed, while others are deeply lobed. And in some rare instances, poison ivy can have five leaves instead of three. 

Poison ivy taking on fall color

Look for bright green leaves during the growing season and bright red ones in the fall.

HERE’S THE RUB

The good news is that, according to the U.S. Food & Drug Administration (FDA), poison ivy rashes are not contagious and therefore cannot be spread from person to person. However, it is possible to pick up the rash from toxins stuck to clothing, tools or other items including pets (see below.) And contrary to common thought, the rash occurs only where the oil has touched the skin. So rubbing or scratching won’t spread it. What may seem like a spreading rash is actually the toxin’s effects appearing gradually over time.

Photo credit/medicinenet.com

Always wash your skin and clothes after coming into contact with poison ivy. This is essential to removing all traces of urushiol. And use cold water, not hot. Hot water thins the oil and helps it dissipate more quickly.

CAN ANIMALS GET POISON IVY?

According to the Pet Poison Helpline, the answer is rarely. Usually, their long protective coats prevent the plant oils from ever reaching their skin. However, animals can carry the toxin on top of their fur, so don’t let your pet rub against you if you think he or she’s been in contact. Try bathing yours with a colloidal oatmeal shampoo while wearing gloves to eliminate the urushiol.

My cat, Squeaky

IT’S GOOD FOR SOMETHING

Before you decide to remove that patch on your slope, you might want to think again. Like kudzu, poison ivy is great at erosion control, especially on coastlines where it acts as a stabilizer for sandy soil. (It’s a big player along the Eastern coastline.) Moreover, it provides valuable food for many species of wildlife, who eat its fruit, stems and leaves.  And it also functions as a protective shelter for small mammals.

Small animals like rabbits like to feed on poison ivy

WHAT TO DO ABOUT IT

As with most unwanted plants, the best way to eliminate them is to get to know their seedlings and start early. As poison ivy matures, however, it may require years of patient digging to totally eliminate its root structure.  You can apply an herbicide like glyphosate to the plant’s roots, leaves or vines. However, be sure to wear eye protection and gloves when chopping down vines. And never use a chain saw, which can spread the toxins by air.

 

 

How To Build The Perfect Monarch Butterfly Garden

monarch on pink flowers

Daniel Potter freely admits he’s not an expert on monarchs. But as Professor of Entomology at the University of Kentucky, he and his grad students sure love to run experiments. Recently, they completed a two-year study on the likes and dislikes of the popular orange and black butterfly. Now for the first time ever, there’s a roadmap for building the perfect monarch garden.

WHY WE CARE

If you’re reading this post, you’re probably already a monarch fan. The butterflies’ annual migration from Mexico to Canada is one of the most spectacular events worldwide. All told, the tiny insects fly upwards of 2000 miles roundtrip each spring, stopping four times to breed and lay their eggs. They are the only butterfly species to make such a long, two-way migration.

monarch migration

Over the past 25 years, however, there’s been a sharp decline in monarch populations. Part of this is due to a loss of habitat at the butterflies’ overwintering site in Mexico. Activities such as logging, agriculture and urbanization have all taken their toll on the central highland forests that play host to the insects six months out of every year.

But by far the most significant factor driving the decline is the dwindling supply of a plant called milkweed. The native wildflower is the only plant that monarch caterpillars will eat. And without it, the butterflies cannot complete their life cycle, sustain their migration and ultimately, perpetuate their species.

monarch feeding on milkweed

MONARCH BUTTERFLY GARDENS NEED MILKWEED 

According to the North American Monarch Conservation Plan, we need 1.8 billion milkweed stems to replace those that have been lost to agriculture and urbanization. And to sustain the annual migration, these contributions need to come from all land sectors. This includes farms, roadsides, schools, zoos and rights of way. And it also includes suburban and urban gardens located along the butterflies’ migratory corridor.

Luckily, an initiative called the Monarch Waystation Program is starting to make a crucial difference. Established in 2005, it engages citizens in conservation by providing instruction and materials on how to build and maintain a monarch habitat. The guidelines are simple: Plant two or more milkweed varieties for the caterpillars to feed on, some nectar sources for the adults, and you become part of a national registry. To date, over 6000 Monarch Waystations in 46 states have become part of the effort. 

WHAT MONARCHS LIKE

As it happened, the Waystation Program Registry provided the perfect jumping off point for Potter’s research into monarch butterfly gardens. A quick Google Earth search by his team revealed hundreds of habitats scattered along the butterflies’ northward route. What’s more, they represented every kind of landscape.

As Potter put it, ‘Some were non-structured, others ‘wild’, and still others were surrounded by hardscape or located in open rural areas.’ Below are some aerial shots of a few of them. (Photo courtesy Dr. Daniel Potter.)

What Potter and his team wondered was this – with all of this diversity, could there be certain habitats that were more appealing to the butterflies than others? To find the answer, the group decided to survey 22 citizen-planted Waystations. Below are some key outcomes from their investigation. 

1. MONARCHS LIKE STRUCTURE

Like most species, monarchs use visual cues to zero in on what they’re looking for. And in the butterflies’ case, these ‘search images’ are made up exclusively of milkweed. But as the Registry revealed, not all Waystations are the same. Did monarchs favor certain monarch butterfly gardens over others?

Monarchs from ‘search images’ for milkweed

To find out, the researchers counted larvae and caterpillars for a year in their target Waystations to see if the type of habitat made any measurable difference.

monarch caterpillar on milkweed leaf

Monarch caterpillar on milkweed leaf

And they discovered that yes, the butterflies exhibited a strong preference. A structured garden, with milkweed surrounded by mulch, attracted three to five times more monarchs.

The takeaway? If you want more monarchs, make it easy for them to find the milkweed to lay their eggs on. Plant it apart from other plants. Even better, surround it with a mulch circle. But make sure to provide other nectar producing plants nearby for the returning adult butterflies to feed on.

2. MONARCHS PREFER A NORTH-SOUTH ACCESS

Interestingly, the researchers found that gardens with unimpeded north-south access recruited more monarchs. This makes sense since it coincides with the butterflies’ migratory route.

monarch migration map

Monarchs prefer gardens with a north-south access

3. THE TALLER THE BETTER

While all milkweed species are suitable for food, not all are equally favored by monarchs. To find out why, the group compared 8 varieties of milkweed all grown in Kentucky and native to the area. They evaluated them as to their suitability for egg-laying as well as their usability as food for monarch caterpillars. And there was a clear preference.

Where they had a choice, monarchs preferred the taller varieties, Swamp, Common and Showy over the smaller varieties like Butterfly weed

The takeaway? If you want to attract more egg-laying monarchs to your monarch butterfly garden, plant the tall, broadleaf milkweed varieties.

4. MILKWEED CULTIVARS ARE EQUALLY TASTY

But what about all of the new milkweed cultivars, you say? As it has grown in popularity (mainly due to monarchs), milkweed is now available in many cultivated varieties boasting unusual colors and sizes.

Asclepias Gay Butterflies Mix/White Flower Farm

Not to worry. Potter and his students discovered that monarchs find these cultivars just as attractive as the straight species. But again, go with the bigger varieties if you want more monarchs.

5. DON’T BECOME AN ECOLOGICAL TRAP

Finally, there’s the case of tropical milkweed, a non-native plant that has exploded in popularity over the past decade. Both gardeners and monarchs love it. But buyer beware. Tropical milkweed is not ‘bad’, per se, but when planted in warm areas of the U.S. it encourages monarchs to stick around longer. It even enables them to winter-breed.

tropical milkweed

Tropical milkweed, Asclepias curassavica

Research shows, however, that monarchs breeding on tropical milkweed throughout the winter (rather than returning to Mexico) have higher levels of protozoan infection compared to monarchs in the normal migratory cycles. It turns out that migration is key to outrunning these pathogens.

The takeaway? Stick to the tried and true native milkweed species and help the insects keep to their schedule.

To learn more about Daniel Potter and his research into monarchs and other insects, click here for the Dr. Daniel A. Potter Laboratory.

This article was updated January 2022.

Why Carnations Are The Official Mother’s Day Flower

For those of you who think Mother’s Day was created by Hallmark, the real story is much more poignant. It all sprang from a daughter’s love for her mother, the trials of war and a gift of 500 white carnations.

IT ALL BEGAN IN WEST VIRGINIA

It all began in 1905 when Anna Jarvis lost her mother. She and her mother had been very close during Anna’s lifetime. Consumed by grief, Anna made a solemn vow. She pledged to establish a national day to honor her mother and all mothers for the positive contributions they made to society.

Anna’s mother, Ann Reeves Jarvis, had raised her family in the mid 1800’s and had suffered great hardship. Of the 12 children she gave birth to, only four survived. The others died from diseases common at the time, including measles, typhoid and diphtheria. 

MOTHERS HELPING MOTHERS 

But despite having suffered so much loss, Anna’s mother was stout-hearted. In the 1850s, she began organizing coalitions of mothers from across West Virginia to combat childhood illness. The women raised money for medicines, inspected food and milk and provided nursing care for those who were sick. 

The coalitions became known as the Mothers Day Work Clubs.

Ann Reeves Jarvis

And when the Civil War broke out in 1861, the mothers acted as volunteer nurses, caring for soldiers of both the Confederate and Union armies.

Mother’s Day Work Club members took care of all soldiers

Even after the war, the clubs continued to be a unifying force. In 1868, Jarvis organized a Mothers’ Friendship Day, which brought together mothers of former foes and encouraged reconciliation among area families.

ANNA JARVIS AND 500 WHITE CARNATIONS

Shortly after Ann’s death, her daughter Anna organized a memorial at her mother’s church in Grafton, West Virginia. During the service, she passed out 500 white carnations (her mother’s favorite flower) to all the mothers in attendance. With this unofficial inauguration, Anna began writing letters to national, state and local politicians to gain their support for a Mother’s Day movement. 

And unbelievably, in just a little over a decade later, 46 states and many foreign countries, including Canada and Mexico, were holding Mother’s Day celebrations. Then in 1912, Anna began campaigning for international recognition of the day.

Finally in 1914, President Woodrow Wilson made things official. He signed Proclamation 1268, which created a national Mother’s Day as A public expression of love and reverence for the mothers of our country.

Letter signed by President Woodrow Wilson establishing Mother’s Day

The second Sunday in May became the official day of celebration. And the wearing of a white carnation, Ann Jarvis’ favorite flower, became a tradition.

THE CONTROVERSY OVER MOTHER’S DAY CARDS

Anna Jarvis’ originally intended for Mother’s Day to be a personal celebration between mothers and their families (this is why Mother’s takes the singular possessive and not the plural). She imagined it as a time when millions would visit their mothers and write personal, hand written notes expressing their love and affection.

Vintage Mother’s Day card

With the official recognition of the holiday, however, florists, card companies and other merchants began jumping on the bandwagon. Jarvis became more and more enraged as she watched Mother’s Day drift further and further away from her original idea. And nothing upset her more than the growth in popularity of the printed Mother’s Day card. She wrote,

A printed card means nothing except that you are too lazy to write to the woman who has done more for you than anyone in the world. 

By 1920, Jarvis had become so upset over the commercialization of Mother’s Day that she launched a campaign to abolish the holiday. Declaring Mother’s Day a failure, she organized boycotts and threatened lawsuits to stop others from profiting off of the day.

In 1923, she even filed suit against the Governor of New York over a Mother’s Day celebration. When the court rejected her plea, she formed a protest and was arrested for disturbing the peace. She devoted the remainder of her life to fighting against the very day she had established.

Jarvis died, childless, in 1948 at the age of 84. She is buried next to her mother in Philadelphia.

THE ROLE OF CARNATIONS

Yet a century later, Jarvis’ legacy lives on in our annual Mother’s Day celebration. And there’s no doubt that carnations have become the official Mother’s Day flower. In her day the carnations were white, but since then pink and red colors have also become popular.

In fact, today it is generally believed that pink carnations represent gratitude while red ones signify admiration. And white carnations are now reserved for honoring a mother who is no longer living.

Red carnations signify admiration

Despite Jarvis’ later efforts, every U.S. president since 1914 has issued an official Presidential Mother’s Day Proclamation recognizing and honoring America’s mothers. And today, the custom is celebrated all over the world (albeit on different days.)

On a personal note, I like receiving printed cards and flowers on Mother’s Day, but have to agree with Jarvis that nothing beats a hand-written note from your child. I’m lucky enough to receive such letters each and every year.

Wishing all of you a very happy Mother’s Day!

 

Why Lily of the Valley Is The Official May Day Flower

Years ago, I was living in Paris when there was a knock at the door followed by the sound of running footsteps. Opening the door, I discovered a basket of tiny white flowers on my doorstep. Little did I know, I had just received a gift of lilies of the valley, a flower exchanged each year in France on the first of May.

A ROYAL HISTORY

In France, lily of the valley (or muguet in French) has been given as a gift for centuries. Legend has it that the custom started on May 1, 1561 when King Charles IX received a sprig of the tiny flower as a token of good luck.

The King liked the idea so much that he decided to start a tradition. From that day forward on the first of May, he presented a bouquet of lilies of the valley to each of the ladies of his court. And thus began in France the Fête du Muguet, otherwise known as May Day. 

Portrait of King Charles IX

MAY’S MOST CELEBRATED FLOWER

Over the centuries, lily of the valley has become one of May’s most celebrated flowers. And for good reason. Depending on climate, it typically blooms in mid April and retains its blossoms for most of May. The species itself is small, averaging only 6″.  Each plant is composed of a pair of upright, sword-like leaves enfolding a single stalk of sweetly scented, white or pink bell-shaped flowers. 

Still, for what it lacks in size, lily of the valley rapidly makes up for in numbers. When given ample shade, it will form low, thick masses of bright evergreen color, making it the perfect complement to other shade-loving perennials.  

THE STORY OF LILY OF THE VALLEY AND THE NIGHTINGALE

According to legend, the very first lily of the valley was in love with a nightingale. Every night, the nightingale would come to her garden to sing. Even so, the lily of the valley was shy and hid herself from the bird. So after a while, he grew lonely and flew away.

Alone in the garden, the lily of the valley waited in vain for the nightingale to return. Eventually, she grew so sad that she stopped flowering. She started blooming again only after the nightingale reappeared (in May) and her happiness was restored.

A SYMBOL OF ROMANCE

In the early 20th century in France, men often gave bouquets of lilies of the valley as tokens of affection. They presented their gifts, in accordance with tradition, on the first of May. In their absence, they sent romantic postcards featuring pictures of the flower accompanied by wishes of good luck. French people still practice the card-sending ritual today.

A vintage Fête du Muguet card

A NATIONAL HOLIDAY IN FRANCE

In modern-day France, the first of May coincides with National Labor Day. As a result, the Fête du Muguet is a public holiday. In the days leading up to the event, lilies of the valley are sold from roadside stands that pop up all over the country. And while it’s normally forbidden to sell flowers on public streets, the ban is lifted on May 1 in honor of this long-standing tradition.

Photo credit/Shutterstock.com

HOW TO GROW LILY OF THE VALLEY

Easy-to-grow lilies of the valley are indigenous to temperate climates. Spreading by tiny rhizomes underground, they naturalize easily and can quickly become invasive in the garden. Unless you’re up for continually digging them out to control them, it’s best to plant the flowers in their native woodland or in a contained area in the yard.

And like most shade-loving plants, lilies of the valley prefer moist, well-drained loamy soil. Never plant them in full sun. If you do, their bright green leaves will lose their color and turn ugly shades of brown. 

DON’T EAT THEM

Finally, you may be surprised to learn that all parts of the lily of the valley are toxic if eaten. So when handling the flowers, it’s best to wear gloves to prevent any residue from being transmitted to food. Symptoms of lily of the valley poisoning include stomachache and blurred vision.

 

 

Six Secrets From Bunny Mellon’s Garden

Bunny Mellon never formally studied landscaping; yet she grew to be one of the most celebrated gardeners in America. Her list of accomplishments is staggering, ranging from installations on family properties in Virginia, Nantucket and Antigua, to private residences in Paris, to the White House Rose Garden. There is much to be learned from her trial-and-error approach to horticulture. And now, a new book entitled Garden Secrets of Bunny Mellon offers a glimpse into how she developed her aesthetic while providing readers with practicable tips on design. Continue reading