Managing Hydrangeas: To Prune Or Not To Prune And Other Existential Questions

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

“Never,” she said 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, knowing what kind of hydrangeas you have growing in your garden. Different varieties require different pruning methods. Prune at the wrong time and you risk trimming off next year’s blooms. It all starts with knowing whether your hydrangeas flower on old or new wood.

HYDRANGEAS THAT BLOOM ON OLD WOOD

Nikko Blue hydrangeas bloom on old wood

Old wood is quite simply, last year’s wood. Hydrangeas that bloom on old wood set their buds on stalks that have been on the plant since last summer. These type of hydrangeas set their flower buds for the following year sometime in August, September or October.

Hydrangeas that bloom on old wood include the Mophead, Big Leaf and Lacecap types (Hydrangea macrophylla) as well as Oakleaf hydrangeas (Hydrangea quercifolia). These are the varieties that, until recently, were most commonly found in gardens.

Oakleaf hydrangea is recognizable by its foliage that resembles oak leaves

Knowing when and what to prune is key to protecting next year’s blooms on these magnificent plants. Remember that for hydrangeas blooming on old wood, the more old wood you take, the less the floral display will be next summer. These shrubs generally need little pruning, but if you must, your hydrangeas will thank you if you follow these simple steps:

  1. Immediately after flowering and no later than July, remove flowering stems back to a pair of healthy buds.
  2. Prune out weak or winter-damaged stems in later winter or early spring by cutting out no more than 1/3 of the oldest stalks, taking them down to ground level.
  3. Repeat the process every summer to rejuvenate the shrub and control its shape.

HYDRANGEAS THAT BLOOM ON NEW WOOD

Limelight hydrangeas bloom on new wood

Hydrangeas that bloom on new wood set their flowering buds on the current season’s growth. Because their flowers come from new growth from the base of the plant, they can be pruned almost any time of year, except summer. Most gardeners recommend pruning these types of hydrangeas in the late winter or very early spring when you can best see the branch structure.

Hydrangea arborescens ‘Annabelle’

Considered the crème de la crème of all the varieties that bloom on new wood, hydrangea arborescens ‘Annabelle’ is what is called a ‘smooth’ hydrangea. Smooth hydrangeas are known for their giant white blooms and are native to the southeastern United States.

Distinctive white blooms of Hydrangea ‘Annabelle’

What makes ‘Annabelle’ so special is that it produces enormous, pure white blooms from June to fall on a compact shrub that grows just 3 to 5 feet tall and wide. At first glance, it can be hard to tell Annabelles apart from other white-blooming hydrangeas, but a number of gardeners go by this golden rule: Annabelle hydrangea flowers open lime green in early summer, change to bright white mid-summer and then switch back to light green in late summer before turning tan in the fall.

(Another smooth hydrangea cultivar ‘Incrediball’ features spectacular 12″ blooms and has been bred to have sturdier stems that ‘Annabelle.’)

‘Incrediball’ features 12″ flower clusters and blooms on new wood

To control for shape and increase blooms, some gardeners cut their Annabelle hydrangeas all the way back to the ground (within 6″) in late winter or early spring. Some say this encourages the shrubs to produce the largest flowers and sturdiest stems. Still others say it weakens the plants over time, causing them to need to be staked. I recommend taking the middle road and cutting Annabelle hydrangeas back to between 1 and 3 feet above the soil.

Panicle hydrangeas

Panicle hydrangeas bloom on new wood

Panicle hydrangeas (Hydrangea paniculata) also bloom on new wood. Like Annabelles, they can be pruned in later winter or early spring, either by cutting them to the ground or to just a few feet above the soil depending on the size plant you want to maintain. The best known of the panicle hydrangeas include PeeGee hydrangea and Limelight.

When they were first introduced from Holland in the early 2000’s, Limelight hydrangeas took the garden world by storm. Featuring enormous, football shaped clusters of flowers, the shrubs performed great in full sun (although for best color, they need some shade). Limelight hydrangeas keep their beautiful celadon color all summer long and slowly age to pink, turning shades of dusty red and burgundy in the fall.

Limelight hydrangeas bloom on new wood

BEST OF BOTH WORLDS  

There’s a new kind of hydrangea in town called Endless Summer and it’s rocking the hydrangea world. Introduced in 2004 by Bailey Nurseries, Endless Summer hydrangeas bloom on both previous season’s growth AND current season’s growth. This gives them the ability to flower repeatedly all summer. The company’s tag line is, appropriately,

Experience life in full-bloom.

Endless Summer mophead variety

As of 2018, there are three different varieties currently available. Blushing Bride produces pure white mophead flowers that mature to soft pink, Twist-n-Shout is the first re-blooming lacecap variety and BloomStruck has vivid purple or rose-pink mophead blooms that hold their color all summer. Summer Crush (available in 2019) will feature raspberry red or neon purple blooms.

Its easy to imagine the possibilities of plants that bloom on both old and new wood – their blooms naturally last most of the summer. The company says Endless Summer hydrangeas bloom 10 to 12 weeks longer than average hydrangea macrophylla plants.

Additionally, Endless Summer has formulated a product that changes the color of your blooms for you (until now we’ve had to change the pH of our soil). Color Me Pink adds garden lime to the soil to raise the pH level to produce pink flowers and Color Me Blue adds sulfur to encourage blue blooms to develop.

SOME COMMONLY ASKED QUESTIONS ABOUT HYDRANGEAS

Why are my hydrangea flowers turning brown in the summer?

The main reason that mophead flowers turn brown is too much sun; specifically hot mid-day to afternoon sun. To prevent this problem, site your shrubs in areas where they receive direct sun either in the early morning or late afternoon. Same goes for the lacecap varieties, which tend to have a much shorter flowering span than the mopheads. Attention to watering during dry spells also helps prolong blooms.

What do I do if my hydrangeas have grown too big and floppy?

Most gardeners advise waiting until the shrubs have been in the ground for 5 years before beginning a pruning program. If you’ve got the type that blooms on new wood, prune your shrubs in late winter or early spring for shape, taking them down to between 1 and 3 feet from the ground. If you’ve got the kind that blooms on old wood, follow the method above, removing 1/3 of the oldest living stalks each summer after the shrubs have flowered.

When I cut blossoms will it hurt the other blooms?

After August, cut only short stems to avoid affecting next year’s blooms

For hydrangeas that bloom on old wood, deadheading (or cutting flowers for indoor arrangements) can be performed on long or short stems in June through July without affecting next year’s flower buds. After August, it’s best to harvest only short stems.

Can I prune some of the branches and not affect others?

Yes. You are only cutting off the flower buds on the stalks that you prune.

Does watering keep the blooms going? Why do my hydrangeas look so dry in July?

As with all plants, watering during dry spells is key. Keep the soil moist around your hydrangea shrubs to keep the flowers going all summer.

I did all the right things and my hydrangeas didn’t bloom this year. What happened?

Weather can negatively affect blooms, too

Finally, you can follow all the rules and prune your new or old wood shrubs correctly, but weather can also have its negative effects, particularly frost. In colder regions, flowering can be adversely affected by either early fall or late spring frosts, making it confusing as to whether you pruned off the blooms yourself or left it to Mother Nature.

 

10 Great Plants For A Care-Free Spring Garden

A spring garden brings renewed hope in all things growing

There’s nothing quite like the look of spring flowers. Bursting to life on the heels of winter, the delicate forms are so fresh as to almost seem edible. That, compounded by the returning sun and its impact on color, and spring gardens bring hope this time of year, renewing our faith in life and everything growing. Continue reading

US Botanic Garden Presents The Latest Poinsettia Varieties

One of many beautiful poinsettias at the US Botanic Garden

I’ve been to the US Botanic Garden (USBG) many times and have always enjoyed the beautiful displays that change with the seasons. But in December, I bypass the holiday dazzle of the evergreen-draped lobby, work my way through the steamy medicinal plant and orchid gardens and head straight to the restrooms. There, behind the glass atrium in a quiet passage all its own is the USBG’s best-kept secret: a one-of-a-kind poinsettia display. Continue reading

Top Holiday Plants And How To Keep Them Blooming

Soon, many of us will be receiving gifts of holiday plants with no clue what to do with them. Sure, the seasonal blooms look great in their decorative wrappings, but too often, just one week later they’re already showing signs of distress. Why toss these beauties in the trash when there’s still so much floral potential? Here’s how to keep your holiday plants looking their best and blooming well past the holiday season. Continue reading

Daylilies Giving You Trouble? Here’s How To Divide Them

Hemerocallis fulva, commonly known as Tiger Daylily

We parents know that when our children aren’t getting along it usually helps to divide them. The same goes for many perennials that stop behaving as mature specimens in the garden. Daylilies are one common plant that benefits from a good shaking up from time to time when things start to get out of control.

Warning signs

You may have noticed that your daylilies aren’t blooming as prolifically as they used to. Or that they’re crowding out or overshadowing other plants in the garden. Recently I lifted up an overgrown clump of ‘Happy Returns’ (pictured below) to find a few forgotten Heuchera ‘Obsidian’ barely surviving.

If this sounds familiar, now is the time to start dividing!

Tips for dividing

It’s pretty hard to kill daylilies (I’ve left clumps out, unplanted, for an entire winter and they still flowered come summer.) However, to play by the rules, most experts advise dividing them right after they flower, or in late summer or early fall.

Depending on your soil type, daylilies can be a bear to dig out. I prefer using a long, narrow shovel with a platform step for my foot. This seems to be the right length for getting under the daylily while providing me with a little extra leverage.

Step 1

Start by inserting the shovel into the soil about 6 inches away from the roots. Dig around in a circle, gently prying up the plants as you go. Once the plants are loosened, slide the shovel horizontally underneath the clump and cut it from the ground.

TIP:  Most times I dig the whole clump up and immediately begin dividing. However, you can save a little time by leaving a small sized clump in the ground.

Step 2

Once you’ve removed the clump, you have two choices. You can simply cut it into smaller groups, leaving the soil on. Just dig new holes and replant. (Don’t worry if you cut through a few of the roots. The plants will do fine.)

Or, you can remove the dirt from around the roots and pry the plants apart. I prefer this latter way because it gives me an opportunity to tease out the roots and replant my divisions in fresh soil.

If the clump is a large one (which it probably is if you’re dividing it), then 4 to 5 fans (green sections) is a good number. This will ensure you get blooms the next year.

But, there’s no reason you can’t break the clump down to single fans if you’re looking to fill a big area. You may have to wait a year to see new flowers, though.

Step 3

Not really a step, but very important: No matter how many divisions you choose, always leave a fan attached to the roots. Without it, the daylily won’t grow.

Step 4

Finally, replant your divisions 12′ to 18′ apart (remember, daylilies grow fast), adding compost or LeafGro to the soil. Build a small mound under your transplant and fan the daylily roots out into the soil. Cut the foliage back to around 4 to 6 inches, water generously and look forward to next summer’s abundant new blooms!

 

Life On the Edge: The High Altitude Plants of the Grand Canyon

Point Imperial, Grand Canyon North Rim

Anyone who’s been to the Grand Canyon North Rim can tell you that hiking can be hard on the lungs given the altitude of just under 8,300 feet. And that’s just for starters, beautiful Point Imperial, the highest of the North Rim overlooks, tops out at almost 9,000. My daughter recently observed while gingerly approaching the edge, that she felt as though she were slogging through a pool of molasses. This prompted me to wonder; how do plants grow under such challenging conditions? I set out to find the answer.

How they do it

The first thing I discovered was that plants that are able to live at high altitude are not like their lowland cousins. In order to survive, they have made some structural adaptations. These include irreversible, highly evolved physical responses to high-altitude environments not seen in low altitude plants. This mix of strategies, while particular to each species, often benefits the surrounding plant and animal communities as well.

Following are just a few.

The creamy flowers of cliffrose, blooming at 8,800 feet

Taking a breather

As chests heaving, we make our way to Point Imperial, I pause to reflect on the many plants that border the trail. How are these species thriving at altitudes of 8,000 feet plus? For one, air pressure is much thinner at higher elevations, making it difficult for my veins to pump oxygen throughout my body.

It turns out that at high altitude, the reduced pressure makes it harder for plants to pump water from soil to stem as well. But unlike humans, high altitude plants have come up with a solution. Rather than struggle to draw water and nutrients through inefficient transport systems, they have evolved smaller sized pathways. These vascular pathways allow them to channel fluids more quickly through a tighter area.

Firecracker penstemon, a desert native, growing at 8,800 feet

Partly due to these reduced hydraulic systems, trees and plants at high elevations tend to be smaller (to conserve energy) and to grow more slowly. They also are more likely to be spaced further apart. Western juniper, for instance, prefers to make its home on dry, rocky sites where there is less competition from larger species. And in exposed areas, it often assumes a stunted form, growing low to the ground.

Western juniper is sometimes described as looking like ‘polka-dots on the hillside’ for this reason.

Juniper growing on the slopes of the Grand Canyon

Taking it slow

Slower growth has the added benefit of longevity. Some of the oldest trees in existence grow at high altitude. This includes the bristlecone pine, which is said to be the oldest known living tree, with some believed to be over 4,000 years old.

An old bristlecone pine

Putting down roots

But I’m particularly impressed by the resilience of the Utah juniper, which can survive even the harshest of conditions. It can grow a 40 foot-long tap root that extends straight down through rocks and crevices, while its lateral roots can travel as far as 100 feet away. This strategy ensures that parts of the tree survive even if the tree itself is knocked down. In extreme cases, Utah juniper can even concentrate nutrients in just a few branches, keeping the main tree alive while the rest of the body shuts down.

Crooked remains of a Utah juniper – is it just conserving energy?

Drilling down

There’s no mistaking this shaggy, twisted shrub that grows high on dry rocky slopes in the Western United States. A member of the rose family, cliffrose has fragrant, creamy blooms that appear from spring to fall and provide important forage food for deer, cattle and sheep, especially during the winter. Its highly absorbent bark enables the plant to retain moisture as do its evergreen leaves.

Gnarled branches of cliffrose

But here’s the coolest thing about cliffrose; its mature seed has a long-tailed hair that attaches to the end of it. When the wind disperses the seeds, the hairs act like tiny parachutes and once the seed lands on the ground, the hair acts like a drill, rotating with the wind to drive the seed into the rocky soil.

A silver lining

Finally, who can resist the allure of gray and silver foliage? These plants employ an altogether different coping strategy. Gray and silver-leaved plants have tiny white hairs covering the leaf surface. The hairs reflect solar radiation, cooling the plant tissues and trapping moisture, which slows evaporation. This is especially important given the low moisture levels of the higher elevations.

Silver-leaved Winterfat, a species of flowering plant in the amaranth family

Gray-green Big Sagebrush growing on Point Imperial

One has only to look at the sun reflecting off their brilliant leaves to see these plants’ strategy at work.

These are just a few of the many fascinating plants that populate the upper reaches of the Grand Canyon. For more information on plant and tree life, as well as great hikes to see them, click here for the National Park Service’s Official Site. We stayed at the Grand Canyon Lodge, a spectacular property run by the Park Service, located on the lip of the North Rim.

 

Bridging the Gap: DC To Build First Elevated Park On 11th Street Bridge

Washington, DC’s 11th Street Bridge Park/Photo: OMA + OLIN Anacostia Crossing

There’s a new movement afoot that aims to turn old infrastructure into public parks, breathing new life into spaces that have long since been neglected or forgotten. Of these, the transformation of an old rail line into a 1.5 mile landscaped park on Manhattan’s West Side (the High Line) is perhaps the most well known. Now comes Washington, DC’s own variation on the theme: the 11th Street Bridge Park, the city’s first elevated park that will soon be floating above the Anacostia River. Continue reading

All’s Fair At Macy’s 44th Annual Spring Flower Show

Revolving carousel at Macy’s Spring Flower Show

New York City’s Macy’s Day Parade is an American fall tradition with its festive floats, high school marching bands and trademark balloons. But until this weekend, I had never heard of another spectacular show sponsored each spring by the 100-year-old department store. That is, the Macy’s Flower Show; a show so big that it transforms an entire floor of the giant Herald Square building into a veritable garden extravaganza. Continue reading

Seasonal Eating: The Best ‘Warming’ Foods to Try This Winter

cover garlic

The downside of winter is that it can be a tough time to find fresh produce. But, if you look beyond the imported berries and other out-of-season foods in the grocery, you can still find many great options available. Eating foods that are in season is not only good for the body; it puts a person in sync with his environment. Small wonder that nature has already prepared for cold weather by producing some of the best ‘warming’ foods around. Continue reading

Nature’s Flu Remedy: Antiviral, Anti-inflammatory Lemon

lemon cover

With the flu season approaching, most of us are looking for ways to boost immunity and increase our chances of staying well. For some, this means getting the flu shot, for others it means restocking their arsenal of home remedies, for many it means a combination of both. Among the natural remedies, there seem to be no end to what’s available. But, sometimes it doesn’t take more than opening your refrigerator door to uncover one of the best flu fighters of all: the humble lemon. Continue reading