Evergreen shrub

The Mystery of the Missing Holly Berries

I hate it when I answer a gardening inquiry and then later learn that my answer was only partially correct. Yet, that is what happened this week when a friend asked why her holly (Ilex genus) that normally has plenty of berries is berry-free this year. I will spare you the repetition of my half-wrong answer and offer up correct information. (I noticed today that one of my hollies that usually drips with berries is completely bare. Another, a few feet away, is heavy with fruit.)

Hollies are mostly dioecious, meaning that some plants are male and others are female. The females produce fruit only if there is a male in the vicinity so that cross-pollination can take place. There are a few that are self-fruitful, meaning they produce berries without a pollinating partner.  Ilex x ‘Nellie Stevens’ and Ilex cornuta ‘Burfordii’ are two self-fruitful varieties with plenty of berries. Even with a opposite-sex partner, hollies sometimes produce little or no fruit in a given year. This can be attributed to several possible reasons: (1) A juvenile plant. Seed-grown plants may need five years or more before they start fruiting. Plants grown from cuttings usually fruit within two years. (2) A late frost which damaged the blooms. (3) Poor pollination, even on a self-fruitful plant. Bad weather during flowering season can reduce bee activity. (4) Too much nitrogen in the soil, usually as a byproduct of applying heavy fertilizer to a lawn. (5) Missed connections. If males and females bloom at separate times, pollination may be reduced. I see this most often in winterberry holly (Ilex verticillata). Winterberry’s bright red fruits look stunning against their leafless branches in winter. Not all males bloom at the same time as the females. Check labels for a recommended pairing. It does no good to pair an early-flowering male with a late-flowering female, even within the same species. Heavy rainfall during the pollination window can have the same effect.

There are multiple species within the Ilex (pronounced EYE-leks) genus. American holly, Ilex opaca, is the one we think of as the traditional Christmas holly. It has sharp spines on the leaves and bright red berries. Don’t make the mistake of planting one where it will outgrow the available space. American holly can get up to fifty feet tall. Chinese holly or horned holly, Ilex cornuta, also has spiny leaves and red berries. Chinese holly cultivar ‘Burfordii” is popular because it does not need a pollinator to produce plentiful berries. While it is not as large as the American holly, it is still up to twenty-five feet tall at maturity. Don’t be misled by the description of “dwarf Burfordii.” A dwarf giant is still a large plant – up to ten feet.

Japanese holly, Ilex crenata, has small leaves with smooth edges and is often used in hedges as an alternative to boxwood (Buxus). They have black fruit. Inkberry holly, Ilex glabra, has longer leaves than I. crenata, with smooth leaf edges and black fruit. It is also used as a boxwood substitute.

My two favorite hollies are ‘Nellie R. Stevens’ and ‘Liberty.’ ‘Nellie R. Stevens’ is a heat tolerant hybrid that will produce berries without a partner, although fruiting will be heavier with a pollinator nearby. It can grow to thirty feet tall and less than half that wide, a slender garden feature. Most leaves have three points per side, like the holly leaf we learned to draw as children. It prefers a little more shade than other hollies. ‘Liberty’ holly is a hybrid that is pyramid-shaped, like the Liberty Bell. The dark green leaves have up to twenty pairs of small points. Given full sun, it will be dense and produce plentiful berries. In more shade, the plant becomes looser and has fewer berries. It can grow up to fifteen feet tall. The lower limbs can be removed to make it more tree-like and less shrub-like.

Cultural needs vary between the species, but almost all like well-drained, moist, slightly acidic soil in full sun to mostly sun. Winterberry holly is the exception to the well-drained soil requirement. It prefers wet soils, but will survive in dryer ground.

Fall planting is preferred for all species. Bees love tiny holly flowers, so shrubs are best planted away from walkways so they will not be brushed by visitors. Where space allows, the taller types make a fantastic evergreen privacy hedge and windbreak. Hollies are cold hardy in zones 7-9, at minimum.

The leathery leaves of this holly contrast with bright red berries.

‘Liberty’ holly leaves have many small points on each leaf edge.

Pretty Pittosporum Shrubs

We have had some trees removed to open up a mountain view. As a result, there is a new design opportunity in the Mary Snoddy garden. The steeply sloped area, approximately four acres, has scattered tall hardwoods, a few native Dogwoods, patches of Mountain Laurel, numerous Sourwood trees, and rocks for days. Big rocks. My vision for the future includes a meandering  path with decorative plantings on either side, all the way down to the creek. The path will need switchbacks due to the steep slope. Opportunities abound for plants in full sun, full shade, and everything between.

My tree and shrub choices need to be hardy in zone 7 with a tolerance for rocky, acidic soil.  They also need to be tolerant of heat and humidity while being deer resistant (a relative term, for sure). I started my plant selection Wish List by scanning photos of other gardens I have visited and admired. From this, I gleaned a small set of shrubs and trees to research. One of these is Pittosporum tobira ‘Variegata.’ I can still remember the wonderful fragrance of this evergreen shrub, a variegated cultivar clad in gray-green leaves with white margins. The clusters of flowers open white but turn yellow when pollinated. The homeowner had allowed the shrub to grown unpruned. It was four feet tall and about the same width.

I learned several things about Pittosporum. First, I have been pronouncing the name incorrectly for decades. It’s not pit-oh-SPORE-um. The correct pronunciation is pih-TOSS-pur-um. It is cold hardy in zones 8-10, although cultivar ‘Mojo’ is more compact and a bit more cold-tolerant. ‘Wheeler’s Dwarf’ is even more compact but less cold-tolerant than others. Mature height for most cultivars is 8-10 feet.

Pittosporum is tough, fast-growing, demands well-drained soil, and makes a good evergreen hedge. It is not particularly choosy about light (full sun to partial shade) or soil acidity. It is resistant to salt, making it a good choice for coastal gardens.

Unfortunately, deer are attracted to Pittosporum and frequently browse it year-round. This trait and its borderline hardiness in my area moved it from my ‘Wish’ list to the ‘Not For Me’ list.

Pittosporum has an interesting characteristic known as ‘sympodial growth.’ This means that the terminal bud will stop growing and lateral buds will keep on growing, giving stems a zig-zag look. This constant forking is also seen in some orchids and Beech (Fagus) trees. For Pittosporum, the terminal bud usually ceases growth because a flower has formed at the tip.

To prevent leaf spots and fungus problems, provide good air circulation, avoid overhead watering, and remove fallen leaves. Note that Daconil®, a common fungicide, is not labeled for use on Pittosporum and will damage or kill the plant. Counter aphid attacks with spray-on horticultural oil.

Pittosporums are easy to propagate from cuttings taken in late summer. Use a talc-based rooting compound to increase success rate.

Clemson University has an excellent fact sheet: https://hgic.clemson.edu/factsheet/pittosporum/

Pittosporum in flower.

Photo by Jean-Pol GRANDMONT - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=4561211

Evergreen Shrubs for Shade

Evergreen shrubs give life to the winter garden. In warm weather, they provide a background that makes other plants, especially flowers and variegated specimens, look better by contrast. Last week we looked at several good choices for sun. Today, let’s a look at a couple of good background evergreens for shadier areas.

While most Viburnum (pronounced vih-BUR-num) are deciduous, evergreen Viburnum awabuki ‘Chindo’ has large, glossy leaves that are equally attractive as a backdrop or a featured specimen. ‘Chindo’ grows fast – one to two feet per year – and will thrive in almost any soil. It won’t do well in deep shade, but dappled shade or partial shade prevents leaf scorch. Mature specimens will have clusters of small white flowers and clusters of red berries that look fabulous against its deep green leaves. ‘Chindo’ naturally forms a pyramidal shape. It will be loose in part shade, dense with more sun. It will grow in zones 7 through 9, and is drought tolerant once established. Allow plenty of space, because a mature plant will reach 12 feet tall and 8 feet wide. Deer tend to avoid the thick leaves of this easy shrub.

Camellia sasanqua and Camellia japonica (pronounced kah-MEE-lee-ah jah-PON-ih-kah) are well known and beloved for their shade tolerance and their beautiful blooms. Camellia japonica prefers partial to full shade. It is a good choice for woodland gardens. C. japonica leaves are larger than C. sasanqua, probably to increase photosynthesis in lower light levels. There are numerous cultivars. These tall shrubs are slow growing but will reach 12 feet or more.

Camellia japonica ‘Professor Sargent’ is popular and widely available.

Camellias grow in zone 7 through 9, in well-drained acidic (pH 5.5 to 6.5) soil containing plentiful organic matter. They produce showy flowers in winter, in shades of red, rose, white, pink, and bi-colors. Flower forms range from singles with prominent yellow stamens to “formal double” types with overlapping petals and no visible stamens.

Very cold temperature or ice and snow may damage Camellia flowers, causing them to brown and drop off. Buds are numerous, so flowering will resume when weather extremes abate. It is best to rake up and discard fallen flowers, to help prevent diseases and insect problems. Yellow leaves are a symptom of too alkaline soil. Purchase plants that are actively blooming to ensure your selection is your preferred color. My favorite cultivar is ‘Nuccio’s Pearl,’ a formal double white flower with a slight pink flush. Gorgeous! Until blooms get zapped by cold, that is. Then they turn a sickly tan and fall off a few days later.

The Cephalotaxus genus (“Yew” or “Plum Yew”) offers species that fit any growth habit desired - spreading, upright, skinny. The fernlike, needled foliage emerges light green and matures to a deep, rich green. All forms are slow growing and happy in shade. I decided to take a chance and planted Cephalotaxus harringtonia ‘Fastigiata’ in a sunny area next to my home. I have given it supplemental irrigation during drought. Despite being recommended for shade, it happily matured to 15 feet tall, four feet wide. It is a good source of holiday greenery, since cut stems last a long time in water and provide good contrast to the more traditional Christmas greens. Its narrow mature width makes it a good alternative to ‘Sky Pencil’ holly.

My favorite evergreen shrub for shade is Osmanthus (pronounced oz-MAN-thus), or Tea Olive. Shrubs flower in late summer to autumn, a clean, fruity fragrance that every nose enjoys. The white flowers are tiny but numerous. An orange-flowered variety is available but it blooms less profusely than the white.

Osmanthus fragrans will reach heights of 20 feet, in zones 8b through 11. Its leaf edges are smooth or very slightly toothed. Osmanthus x fortunei, Fortune’s Tea Olive, tolerates more sun and more cold than O. fragrans. It will reach heights of 25 feet, in zones 7b through 10. Juvenile leaves are toothed while mature leaves tend to have smooth margins. The cultivar ‘Fruitlandii’ has outstanding fragrance.

Osmanthus heterophyllus has leaves that strongly resemble Holly (Ilex). It is sometimes called “Holly Tea Olive.” It matures at 15 feet, which makes it easier to incorporate into a mixed border. It will tolerate a more alkaline soil than the first two. A variegated form, ‘Goshiki,’ is a favorite in the Mary Snoddy garden. ‘Goshiki’ means “five colors,” an allusion to the dark green, light green, cream, and white leaves. New growth is a rosy pink. I find that ‘Goshiki’ blooms less than the others, but it may be because I keep it sheared into tight cones. You may have noticed that I have an affinity for gumdrop-shaped topiary. Deer usually ignore all members of the Osmanthus family, especially after they gain size.

I cannot leave the subject of evergreen backgrounds without a mention of narrow choices. If your home is site on a narrow lot with neighbors close on either side, the space between houses is shaded by the structures themselves. When seeking “skinny” shrubs, look for “fastigiate” or “columnar” on plant tags. Both these mean the shrub has a narrow profile. If space is super tight, consider growing vine Confederate Jasmine or Clematis armandii on a fence to provide privacy and a solid green backdrop.

Better Behaved Abelia

Modern Abelia cultivars are a vast improvement over the version that was common in every garden several decades ago. Those evergreen or semi-evergreen shrubs grew to heights of six feet or more and threw unruly sprouts that reached for the sky, creating an unkempt appearance. There was a pair of them planted either side of the rear entrance of a local church. Their whippy tentacles waved around like something from The Little Shop of Horrors. You could almost hear them whisper, “Repent!” But I digress.

Glossy Abelia of yesteryear (Linnaea x grandiflora, pronounced LIN-ay-ee-uh gran-duh-FLOR-uh, formerly known as Abelia x grandiflora) was appreciated for its tolerance to heat, drought, humidity, and poor soil. New growth was a bronzy pink, and honeybees swarmed over their nectar-rich tubular pink and white blooms. Unfortunately, to keep them in check, homeowners regularly pruned their arching stems into ugly, tight meatballs.

Current Abelia cultivars have two advantages over the older generations. First, many are available in mature sizes of four feet or less, making them ideal for foundation plantings. ‘Edward Goucher,’ ‘Rose Creek,’ and ‘Little Richard’ are all dwarfs, reaching heights of 36 inches or less. Second, there is a entire rainbow of foliage colors available. ‘Kaleidoscope’ has multicolored foliage with yellow leaves in spring and orange-red in fall. ‘Sunrise’ has green, yellow and white variegated foliage. ‘Confetti’ has pink, green and white foliage (a real stunner, in my opinion).

Abelia is hardy in zones 5-9. It prefers well-drained soil, acidic to neutral, and will accept some drought once established. The bell-shaped pink, rose, white, or lavender flowers attract bees, butterflies, and hummingbirds. Flowers open over several weeks in summer, but may appear sporadically at any time. Shrubs are rarely bothered by deer and resist damage from pollution, drought, or salt.

In upstate South Carolina, this ‘Kaleidoscope’ Abelia has scattered blooms on the last day of November . The foliage is yellow, green, orange, and pink.

Same shrub as above. From a distance, the color reads as green and salmon.

Abelia ‘Rose Creek’
Image by Jan Haerer from Pixabay