Last week we looked at coral bells and covered some of the dark leaved options that are grown in this garden and easy to find on the market. This week we are going to look at some spectacular options for sunny sites.
Coral bells were traditionally thought of as shade lovers. Heuchera villosa, however, is a species that is native to southeastern U.S. It is an adaptable species that thrives in full sun to part shade, grows happily in soils ranging from slightly wet to slightly dry and is unfazed by high humidity. Understandably, it is a popular plant for southern gardens.
Hybridizers have latched on to this species and it is now part of the parentage of many successful hybrids. The French hybridizer, Thierry Delabroye has taken the world of coral bells by storm by flooding the market with a number of mouthwatering cultivars that are designed to make you either hungry or thirsty. Delabroye’s offerings include cultivars such as ‘Carmel’, ‘Brownies’, ‘Mocha’, ‘Pistache’, ‘Tiramisu’, ‘Pinot Gris’, and ‘Beaujolais’. We have used a number of these cultivars in container displays. This year we are growing ‘Brownies’ in the Trial Bed Garden in the Home Gardening Center.
The reputation of Heuchera ‘Brownies’ as an attractive and adaptable coral bell is attested to by the fact that it is flourishing in the challenging environment of New York’s High Line park. Its foliage emerges brown and then transforms into a greenish brown with a rich purple-red underside. Like the majority of Heuchera villosa hybrids it features large foliage and has a fuzzy texture. It grows over a foot tall and forms a generous two foot clump.
When I started gardening, I thought of coral bells (Heuchera) as a pleasant choice for the front of a shade border or a nice accent in a tapestry of low growing woodland inhabitants.
I now have a much deeper appreciation for this versatile plant. While some of it has to do with an increased knowledge in horticulture, and a better understanding of the dynamics of design and what constitutes a garden-worthy plant, part of my growing admiration comes from the vast strides that have been made by hybridizers over the past decade.
In our Trial Bed Garden in the Home Gardening Center we have a bed that is devoted to coral bells. It has been there several years so I have been able to watch and see not only how the Huechera have performed during the growing season but also how they have held up over several winters.
On one end of the bed we have planted a coral bell named ‘Black Out.’ One objective of Heuchera hybridizing programs has been a search for the coral bell with the darkest foliage. The results has been a number of newer cultivars that range from chocolate brown to deep burgundy brown, with the ultimate goal of producing a Huechera with true-black foliage.
Heuchera ‘Black Out’ is one of the blackest coral bells on the market. It has glossy deep burgundy foliage that transitions into black with burgundy overtones on its undersides. ‘Black Out’s maple-shaped foliage is medium sized and has a compact shape (without being too small) that makes it ideal for container plantings. All of the plants survived this past winter, although a few of them died back a little and are not as vigorous this year. In general, however, their performance has been good.
Another winner in our Trial Bed Garden is Heuchera ‘Frosted Violet Dream’. This coral bell has deep burgundy foliage that is mottled with silver. The maple-shaped foliage shimmers in a garden setting. It is another medium sized coral bell that is a vigorous grower with a spectacular performance record in this garden. In early to mid summer this coral bell is covered with an attractive haze of dainty pink flowers.
One of the casualties in our garden this year was a cultivar called ‘Sugar Plum’. While it performed beautifully last season, it struggled over the winter and we ended up replacing it this year. We were growing this cultivar in full sun whereas it would normally be happier in part shade. I am not sure if that contributed to its demise; poor drainage is a more likely explanation.
I would love to hear back with your experiences. What are your favorite black coral bells on the market and how do they perform in your gardens? Next time we will look at some coral bells that are ideal for tough, sunny locations: the Heuchera villosa hybrids.
Daylilies start appearing in the garden in June, but the heyday for these flowers is in July. Starting from the beginning of July until the third or fourth week our Daylily Walk is awash with color. This is happening right now at the Garden!
Daylilies are generally grown for their large, trumpet shaped blossoms that jump out at you in a mixed planting, shouting ‘look at me’. And you should; they come in a vast array of shapes, colors and sizes and there are over 52,000 cultivars to choose from–many of them garden worthy companions.
When you are navigating catalogs and descriptions to find a daylily that suits your gardening style there is a basic terminology that is helpful to know. The throat is the interior of the flower, the eye zone lies just above it forming a band of color on the petals, and a halo is a faint band of color.
Some daylilies are bi-colored, some are doubles and some have a graceful recurved (curling backwards) shapes. While size, color and form are generally the attributes that gardeners assess when buying a daylily, fragrance is another factor to consider.
Snapdragons (Antirrhinum) are a terrific addition to an early season annual display but unfortunately once the heat of summer is upon us they tend to fade quite quickly. An easy solution to recapture the look of elegant vertical spires covered with blossoms is to swap them out with summer snapdragons (Angelonia).
This year in the Home Gardening Center our first Trial Bed is full of a number of varieties of summer snapdragons. There are two cultivars in this bed that I am unfamiliar with and am excited to watch them grow.
One is the cascading Angelonia ‘Carita™ Cascade Raspberry’. It reaches only 8-10 inches tall, yet spills over to form a 20 inch cascading mound. It doesn’t require any deadheading and like other summer snapdragons it is deer resistant and heat and drought tolerant. This is a candidate that would be ideal spilling over the edge of a container or at the front of a border. It would partner beautifully with a dark-leaved coral bell (Heuchera).
The other cultivar is called Angelonia ‘Serena™ Lavender Pink’. She gets 10 to 12 inches tall and just as wide. ‘Serena™ Lavender Pink’ has already filled out beautifully in the garden and formed a nice clump. The lavender pink color of the blossom will blend with just about anything. This cheerful annual looks genteel with the silvery foliage of trailing licorice plant (Helichrysum petiolare) and white fan flower (Scaevola ‘Bombay White’).
Other summer snapdragons in the Trial Bed are from the AngelFace® and AngelMist™ series. These summer snapdragons tend to be 18-24 inches tall and fill out beautifully during the course of the summer to form a substantial plant. The other year I accidentally paired the bicolored (purple and white) ‘AngelFace® Wedgewood Blue’ with an apricot nasturtium (Tropaeolum ‘Tip Top Apricot’) for a beautiful display.
While these summer snapdragons are advertised as requiring no deadheading, they do benefit from occasional deadheading which cleans them up and encourages more new growth. They will grow and flower profusely regardless. While they can handle drought they also grow well in average garden soil. This is an easy, no fuss annual that performs consistently all season long.
See a slideshow of the Home Gardening Center’s Angelonia below!
Recycled drain pipes used as planters in the Hampshire (U.K.) Garden of Pauline Thomas
By now your garden should be ablaze with color. If it’s not, and you’re finding that you have unsightly gaps in your border, don’t panic! There is still plenty of time for an easy fix: Add a container display to your garden! Don’t limit your container plantings only to the patio though, containers are also a great way to jazz-up any dull or quiet beds or borders you might have.
An attractive container display starts with a good foundation–a good looking container. Many containers these days are made of synthetic materials like poly resin and fiberglass. These materials are often transformed into believable reproductions of classic containers. Find one that suits your gardening style.
Wooden planters on the New York balcony of Devin A. Brown
If you are in the market for a rustic looking container try wood, faux wood or faux stone. If you prefer a more elegant look, then invest in terra cotta, faux terra cotta, reconstituted stone, or faux cast iron. Artistic souls will welcome the stunning array of colorful glazed pots as well as colorful lightweight synthetic substitutes that seem to be available everywhere these days. A few years ago I fell madly in love with a fiberglass reproduction of a bronze container that looked durable as well as lavish.
Colorful pots full of succlents in the Dallas patio garden of Shawn Ashmore
Maintaining appropriate moisture levels can be a challenge when gardening in containers, particularly if you like to escape for a few days during the summer. As common sense would dictate, the larger the container, the easier it is to keep it well-watered. There are many self-watering containers or contraptions on the market that you can outfit your container with. They are essentially water reservoirs that hold the water in the bottom of the container and slowly release it into the mix.
Another viable option is to add some of water retaining polymers or hydrogels to your potting mix. These polymers grab water from the soil, expand as they hydrate, hold onto the moisture, and then release it when the surrounding potting medium starts to dry. Friends of mine who plant narrow window boxes swear by them. Two brands that are easy to find are Terra Sorb® and Soil Moist™.
Whether you are placing your container in the garden or on your patio it is always advisable to raise it up onto bricks, blocks or feet to allow for good drainage. Next week we will take a look at some candidates for filling your lovely new containers.
Shade gardens call to mind stalwart plants such as hostas, ferns, and astilbes. While the Azalea Garden has an interesting array of exquisite hostas and intriguing ferns, it also includes less familiar shade-loving woodland inhabitants.
Many of these plants have interesting foliage that can add texture and color to a shade garden, and a number of them flower later in the season, providing color in the garden long after spring ephemerals and the majority of azaleas have finished their early season show. These woodlanders come in all shapes and sizes, from groundcovers to large perennials, and in a myriad of leaf colors–variegated, deeply veined, and color-tinged–and in a range of textures–fuzzy to matte and glossy.
Mukdenia rossii 'Karasuba' with Beesia deltophylla in the back
Mukdenia rossii ‘Crimson Fans’ (Karasuba) is one of two unusual plants in the Azalea Garden with foliage that gets a beautiful red tinge as the season progresses. A relative of the coral bell (Heuchera), mukdenia has been available for a few years from specialty growers and is now becoming more widely available. The main attraction of mukdenia is its spectacular fan-shaped leaves that turn red around the edges in mid-summer and continue coloring into fall. Panicles of small white flowers that resemble foam flowers rise above the plant in early spring. Mukdenia grows 12-16 inches tall and fans out 12-24 inches, like coral bells, into a nice clump. In the garden it will perform best in moist, well-drained soil in part shade. The plant pairs nicely with late flowering red astilbe such as Astilbe x arendsii ‘August Light’. Mukdenia is native to Korea and China, where it grows on slopes and in rocky ravines at the side of streams.
Beesia deltophylla, a native of China, is another plant that gets red hues as the summer progresses. Beesia makes a wonderful evergreen groundcover in a woodland garden when planted in drifts. The foliage is spectacular: The leaves are large, glossy, and heart-shaped, with deep veins that give them a rippled, puckered appearance. Beesia looks like a mutant European ginger (Asarum europaeum) on steroids (in a good way). Small white flowers appear in summer on tall stems and are fairly insignificant compared with the foliage. Beesia will grow in many soil types but does best in moist, well-drained soil in part to full shade; it grows 10-15 inches tall and spreads up to 24 inches wide.
Syneilesis aconitifolia, the shredded umbrella plant, pokes its head out of the ground in spring wearing a fuzzy white coat that disappears as it matures. The leaves open like an umbrella to reveal large, heavily dissected, lacy leaves, looking like a mayapple (Podophyllum – See “Geographic Diversity In the Azalea Garden” for more on these plants) that has passed through a paper shredder. The shredded umbrella plant will thrive in part to full shade and can tolerate relatively dry soil. It reaches 2 feet in height. Its dissected foliage looks great when paired with a broad-leaved hosta that has smooth or puckered foliage.
Cardiandra alternifolia
In the Azalea Garden are some unusual members of the hydrangea family, all recognizable by their hydrangea-like foliage. Two are perennials that reach about 18 inches tall. Cardiandra alternifolia flowers in late summer with pretty pale-pink flowers reminiscent of a lace-cap hydrangea. Deinanthe caerulea ‘Blue Wonder’ flowers in midsummer with large, nodding lavender flowers. It has the demeanor of a hellebore. Both these woodlanders like part shade and moderate to moist soil. The sub-shrub Platycrater arguta reaches 2 feet tall and 2 feet wide. It flowers in midsummer with white blooms that resemble mock orange (Philadelphus) or deutzia (Deutzia).
Dealing with Deer
Aconitum krylovii, a monkshood from Russia, is a woodland plant that is deer-resistant–or at least has the promise of being so. It can be grown in full sun to full shade and matures to a height of 2 feet. Its deep-green, deeply veined, maple-like foliage is attractive even when the plant is not in bloom. White to pale-yellow flowers tinged with green open mid to late summer.
Leucosceptrum stelipillum 'Ogon'
Both deer and rabbits tend to avoid members of the mint family and so may also pass up Leucosceptrum japonicum ‘Variegatum’ and Leucosceptrum stelipillum ‘Ogon’, Japanese shrub mints. The ‘Variegatum’ has brilliant chartreuse-and-green variegated foliage that brightens up any shade garden. ‘Ogon’ has yellow-green foliage that is equally as impressive. Both produce pale-mauve flowers late in the season, September to October, and reach 2-3 feet tall.
Trachystemon orientalis
Rabdosia longituba, trumpet spurflower, also in the mint family, looks similar to many late season ornamental salvias. This relative has an open and airy vase-shaped habit. It grows to 3-4 feet tall with long sprays of tubular lavender flowers that appear from October into November. It tolerates dry soils, does best in part shade, and pairs nicely with Japanese anemone (Anemone japonica).
The Azalea Garden has many other interesting exotic woodland plants to explore. Creamy-yellow flowered Salvia koyame blooms from September to frost while the penstemon-like purple-pink blooms of the Chelonopsis yagiharana begin in August and last into October. For early season color try the elegant Asian twinleaf (Jeffersonia dubia), with its lavender cup-shaped flowers and lobed, red-edged foliage, or the tough, weed-smothering Trachystemon orientalis, with its borage-blue spring flowers and large heart-shaped leaves.
There is nothing inherently complex about hostas. They are easy-to-grow, readily available, adaptable foliage plants for the shade garden. The problem with hostas is that they have a predisposition toward mutation, and there is a glut of similar looking cultivars on the market.
So how do you navigate the vast selection of these ubiquitous shade lovers to find a few outstanding specimens for your garden? The Azalea Garden provides an ideal opportunity for window shopping, offering ideas for choice cultivars and tips on how to integrate them into your woodland landscape design. In this new garden, azaleas are paired with ferns, sedges, grasses, and woodland perennials.
Hostas come from Japan, China, and Korea. The common name was once plantain-lily and the former Latin name, Funkia,was often used as a common name as well. There are around 45 species of hosta with over 7,000 cultivars. Two well-known species are the fragrant Chinese Hosta plantaginea and the waxy glaucous (blue) Japanese Hosta sieboldiana. Theyare parents to a myriad of successful cultivars on the market. Members of the plantaginea group tend to be heat lovers, while members of the sieboldiana group cannot take too much sun and warmth, their waxy blue coating starts to melt and turns green.
Hostas are notorious for having split personalities, meaning they sometimes change color during the course of the season. There are terms for this type of color instability: A hosta that changes from yellow or white to green is called viridescence; a change from green to yellow is called lutescence; and from yellow to white albescence.
Hostas are often classified by size: dwarf, miniature, small, medium, large, or giant. Each category has a different height range (given in inches) and average leaf size (given in square inches). For example, a giant hosta is over 28 inches tall and has a leaf surface area of greater than 144 square inches.
As you stroll through the Azalea Garden you will see a large number of North American native species and their closely related Asian cousins. Many of these plants share a genus, but have different species names. For example, the garden contains many interesting Asian Arisaemacommonly known as Jack-in-the-pulpits.
In botanical nomenclature, plants are identified by a two-part, or binomial, name. A plant’s genus denotes that it belongs to one group, while the species name marks it as a member of a sub-group of the genus. There are many Arisaema in the world, yet Arisaema triphyllum refers solely to a specific Jack-in-the-pulpit, one of North America’s native Arisaema.
Why are there so many closely related species on two continents separated by a large ocean? Many of these Asian/North American counterparts come from a common genetic pool. It is possible to imagine that over time seeds have been dispersed by glaciers, wind, birds, or other animals. While this certainly has occurred it would be more likely to have happened on a contiguous landmass.
The most compelling theory for why these closely related floras are found on the opposite sides of an ocean comes from the scientific theory of continental drift, the process by which the continents have moved apart over millions of years. About 250 million to 65 million years ago, during the Mesozoic era, the landmass Pangaea began to split apart; the northern part of the supercontinent broke off into Laurasia (North America and Eurasia). As Asia and North America drifted away from each other, the plants that had been one genus began to evolve. Time, combined with changes in climate, and range fragmentation helped these once related plants to diversify and evolve into new species. Why are there so many Asian Arisaema compared with only two Arisaema native to North America? During the last ice age, parts of eastern Asia remained ice-free. This resulted in a greater diversity in the flora there.
How do botanists know that these plants are closely related? Just looking at the plants can be deceptive, so they also collect evidence from the fossil record and analyze the plants’ genes in order to determine relationships.
In this video Kristen Schleiter, Curator of Outdoor Gardens and Woody Plants, discusses many of the Azalea Garden’s geographically diverse perennials.
The best pruning jobs begin with a goal, a determination of what needs to be accomplished–reducing size, controlling shape, rejuvenating growth. As with all pruning jobs, removing the dead and diseased wood is the first call of order. Then take a step back and look at the framework before moving ahead with your mission.
The best time to prune azaleas and rhododendrons is immediately after bloom into mid-July. If you wait too long, buds will already have formed for the following year. In general, azaleas and rhododendrons need minimal pruning.
Reducing Size
To reduce the height of an azalea while allowing it to retain its natural appearance, follow the branch targeted for removal down to a lower lateral branch, and make a cut just above the point of intersection. The cut should be slightly above where the two branches intersect so as not to cut into the tissue of the branch that will remain.
Another way of reducing the size of an azalea is to cut it back to just above a whorls of leaves. Also look for circular scars around the stem, where leaves once were. Cutting just above these areas should create good bud break. In either case, make the cut just above new buds, whether they are visible or latent.
Controlling Shape
Evergreen azaleas can be sheared back to form nice mounds if desired. If you are pruning the azalea into a mound, remember to occasionally open up the plant and let some light penetrate into the dense mass of foliage so that it doesn’t get too congested.
If you’d like to make a young azalea or rhododendron more compact and well-branched, the easiest thing to do is to pinch off the vegetative buds in spring. First take a look at the plant to familiarize yourself with the bud system. The fat swollen buds are flower buds. These form in the previous season and overwinter, and you’ll want to leave these alone. They are generally twice the size of the vegetative buds, which are the narrower, pencil-like, smaller buds.
The majority of azaleas native to North America hail from the states running down the Appalachian mountain range; from Maine to Florida. All of the North American natives are deciduous, tend to have open, loosely branched habits, are known for their hardiness, and for their exquisite fall foliage. Many are scented, with perfumes ranging from sweet to spicy.
Though azaleas in general prefer part sun and moist, humus-rich, well-drained soil, among species there is a broad spectrum of tolerance for heat, moisture, and hardiness. Flowering times are also wide ranging: from early April into August.
Following are some native species and their cultivars that can be found in the Azalea Garden.
There is nothing inherently complex about hostas. They are easy-to-grow, readily available, adaptable foliage plants for the shade garden. The problem with hostas is that they have a predisposition toward mutation, and there is a glut of similar looking cultivars on the market.
