What Grows There :: Hugh Conlon, Horticulturalist, Garden Advisor, and Photographer

Three Native Azaleas That Should Be Included In Mid- Atlantic and Southern Gardens

Posted by Hugh on March 25th, 2024

About Native Azaleas: Flowers appear from April to September depending on species. Flower clusters (called “trusses”) appear just before the leaves emerge. Each truss may bear 3 – 12 blooms, which open 1.5 – 2 inches wide. Flower colors vary among native species from white, pink, orange and red shades. In many spring blooming species, the open petals curve back to show off the long stamens and styles that protrude from the flowers. Among the 15 azaleas native to the Eastern and Southern U.S., flower fragrance is wonderfully aromatic in some; others emit no fragrance.

Three of my early spring blooming favorites are highlighted here.

Coastal azalea (Rhododendron atlanticum) is a compact, loosely branched, stoloniferous, suckering, deciduous shrub that typically matures to 2-3 feet tall and as wide, but infrequently grows to 6 feet. In April 1.0-1.5-inches long white flowers are flushed with pink, bloom in multiple clusters of at the time of or slightly before the appearance of new leaves. Stamens protrude well beyond the corolla mouth. Flowers have a wonderful musky fragrance. This azalea is native to coastal plain areas from New Jersey and Pennsylvania south to Georgia. It spreads by underground stolons. (Zones 5-8).

Florida Flame Azalea (R. austrinum), not to be confused with Flame azaleas (R. calendulaceum) blooms within days after Coastal Azalea in shades ranging from sunny yellow to deep gold, tangerine, or apricot. Blooms strut showy protruding stamens and are highly fragrant. It is native to woodland slopes and mountain balds in the Appalachian Mountains from Pennsylvania to Georgia. (Zones 6-9). Shrubs are upright branched and typically grow 4 to 8 feet tall (infrequently to 10 to 15 feet) and 8 to 10 feet wide.

Pinxterbloom azalea (Rhododendron periclymenoides), formerly R. nudiflorum, is a hardy deciduous azalea native to a large geographic area of the eastern U.S. Pinxterbloom prefers a humus-rich, well-drained soil. Pinxterbloom grows to heights from 4-8 feet. The slightly fragrant flowers are generally pale pink but colors may range from white to deeper purple in natural populations. It spreads by underground stolons and shrub may become densely branched. (Zones 4-9).

General Care: A partly shaded or dappled sun site is preferred. Heavy woodland sites limit flower numbers. Deciduous azaleas prefer consistent moisture, and well-drained soil. Water after planting and every 5 days over dry periods lasting 10 or more days. Mulching with 3–4-inch layer of pine needles, wood bark, or compost helps conserves soil moisture and maintains cooler soil temperatures.

Deciduous azaleas are pruned within 4-6 weeks after seasonal flowering has finished. Prune to desired shrub size and remove broken or dead wood. Protect against strong winter winds and spring frosts to prevent leaf scorch and blossom injury. Disease and insect problems are infrequent when these 3 native azaleas are properly sited. Flowers will attract butterflies, bees, and hummingbirds.

Ten Favorite Viburnums

Posted by Hugh on March 18th, 2024

Viburnums are versatile landscape shrubs that flower, fruit, and fall color. Several species have fruit that attracts birds and may persist most of the winter. To have the best cross-pollination and fruit display plant in groups rather than as specimens. Viburnums tend to prefer slightly acid soil. They have few pest or disease problems and need little pruning if they are selected and properly sited.

Korean Spice (V. carlesii) small white flowers, opening from pink buds, are highly fragrant from several feet away. sweet, rich, and complex with a hint of cloves. It has an attractive wine-red fall foliage on a compact, spreading 4- to 5-foot-high shrub. (Zones 4-7).

Mohawk hybrid viburnum (V. x burkwoodii ‘Mohawk’) has showy fragrant flowers and will attract wildlife to your yard. (Zones 4-8). Mature plants have excellent heat and drought tolerance; foliage turns maroon in fall but remains evergreen in zones 7 and 8.

Cayuga viburnum (V. x carlecephalum ‘Cayuga’) has a 4-10 feet tall and wide compact growing habit along with 4-inch snowball-shaped fragrant blooms in spring. (Zones 4-8).

Doublefile viburnum (V. plicatum f. tomentosum), with stately horizontal branches on a 10-foot-tall shrub. ‘Shasta’ and ‘Mariesii’ are beloved for its layers of broad, flat, white flower clusters, though it bears little fruit. Its crinkled deep green leaves take on a burgundy tint in autumn. (Zones 5-8).

Judd viburnum (V. x juddii) grows only 6 – 8 feet tall and 6 -10 feet wide, with an upright rounded form. pink buds open to snowball clusters of fragrant white blooms in the spring, reds and purple fall color. In some years its dark green leathery foliage turns red in autumn. (Zones 4-8).

Chinese Snowball viburnum (V. macrocephalum) grows up to 25 feet tall and 20 feet wide with a rounded vase-shaped form. Flowers are the largest of the snowball viburnums with profuse dome-shaped, rounded, infertile flowers in spring and some secondary bloom in the fall. The flowers emerge chartreuse and quickly turn white, sterile, and no fragrance. (Zones 6-9).

American cranberrybush viburnum (V. trilobum). Shiny red fruits (not true cranberries) follow the white flowers if they are pollinated from another plant, and broad leaves, almost maple-shaped, has distinctive trilobed leaves that turn bright red in autumn. Redwing (‘J. N. Select’) grows up to 10 feet tall and 8 feet wide. (Zones 2-7).

Arrowwood viburnum (V. dentatum) grows in full sun to part shade and range from 5-10 feet in height depending on cultivar. The broad white flower clusters that come in June are fragrance-challenged, but they mature into blue-black berries that birds love. ‘Blue Muffin® and Autumn Jazz® (‘Ralph Senior’) have reliable fall color. Chicago Lustre™ (‘Synnestvedt’) produce shiny blue berries in autumn. (Zones 2-8).

Blackhaw viburnum (V. prunifolium) is a 15-20-foot-tall tough utility shrub or small tree. It produces creamy flower clusters in May and pink fruits that eventually ripen to black; fruits are edible for humans as well as birds. (Zones 5-9)

Possumhaw, Witherod viburnum (V. nudum) is represented by two outstanding 5-6 feet tall cultivars– Brandywine™ (self-fruitful) and ‘Winterthur’ bear 2-5-inch-wide flat-topped flower clusters in May-June attractive glossy dark green leaves thru summer, and a stunning display of rosy pink and dark blue fruits in fall. Both varieties follow up with plentiful clusters of tart berries that start out light pink to deep pink and ripen to blue to purplish-black fruits; plant two or more for best fruit numbers. (Zones 5-9).

Woodland (Snow) Crocus

Posted by Hugh on March 13th, 2024

Snow crocus in early March at Longwood Gardens in Kennett Square, PA

Snow Crocus, aka early crocus (Crocus tommasinianum) is a late winter to early spring blooming bulb (corm) that is native to southeastern Europe into Asia. These tiny crocus are generally the first to pop its leaves above the ground and even bloom when there is snow on the ground, hence its common name. Snow crocus are the earliest crocus to flower, approximately the same time as snowdrops (Galanthus spp.) and dwarf / netted iris (Iris reticulata). They hold up to a surprise spring snowfall and recover rapidly.

In early fall, plant them 3 – 4 inches deep and 3 – 4 inches apart in average well-drained soils. They prefer sandy soils but grow well in clay soil. They perform best in full sun but tolerate partial shade. Blooms unfurl in mid-morning as day warms up and close around sunset. Blooms remain closed on cloudy days.

Mass plant corms along walkways, in front of trees or shrubs, in woodland or rock gardens, or let them naturalize in a lawn. If planted in a lawn wait until the leaves turn yellow before mowing. Snow crocus tolerate browsing from deer, are resistant to foraging by squirrels, and grow around black walnut trees.

Crocus are also good for forcing indoors over the winter. Pot them up in mid-October and precool them at a consistent, dark 38 to 45°F for 8-10 weeks with moderate weekly watering. Gradually bring pots into the house and crocus will bloom about four weeks later. Once they finish blooming, set them outdoors and plant in your garden.

Blooming about two weeks before their larger flowering kin. To help these tiny corms to grow and naturalize, hold off mowing the lawn until the crocus foliage has died back completely, usually in six weeks. Lots of sunlight helps to create new bulb divisions (bulblets) with increase blooms in subsequent years.

These lovely six-petaled, 4-inch-tall flowers open and close on sunny days, and grass-like foliage that often has narrow, median silver stripes. Crocus naturalize readily in well-draining soil and in full- to part-day sunlight. Woodland crocus are squirrels that may dig up newly planted bulbs for a snack, or to transplant elsewhere for surprise spring pop-up clusters.

Plant 9 corms per square foot for a dense planting. Bulb size: 5 cm/up. Full to partial sunlight. Bloom time in horticultural zone 5: Late March/early April. Plant 4 inches deep and 3 – 4 inches apart. (USDA hardiness zones 3-8).

Tulip Poplar

Posted by Hugh on March 7th, 2024

Tulip-like flowers mostly hidden within foliage

Tulip poplar (Liriodendron tulipifera), aka yellow poplar and tulip tree, is a large stately deciduous tree of eastern North America (USDA hardiness zones 4-9). This fast growing native typically grows 60-90 feet tall and it is not unusual to see tulip trees over 100 feet. It is also an important timber tree.

A member of the magnolia family, flowers attract large numbers of bees. Ornate 2-inch-wide goblet-shaped flowers are yellow with an orange band at the base of each petal. Most flowers go unnoticed, hidden among the 8- inch-wide leaves that emerge a week or two prior to bloom. Dry, scaly, cone-shaped brown fruits follow, each bearing numerous winged seeds. In some years (not all), bright green tulip shaped foliage turns golden yellow in fall.

Double row allée at Biltmore Estates in Asheville, NC

Young tulip poplars grow with a pyramidal form and mature with a broad rounded canopy. Mature trees may reach 4-6 feet in trunk diameter, rising column-like and devoid of lower branches. Tulip poplars grow rapidly and become too big for an average residential property. In general, branches are not weak wooded in the early years, but weighty branches on older trees tend to snap off branches in wind and ice storms. Surface roots grow in lawns and tend to uplift sidewalks in urban areas.

Overall tree size becomes too menacing to many homeowners. Young tulip poplars grow with a pyramidal form and mature with a broad rounded canopy. Trunks of mature trees may reach 4-6 feet in diameter, usually rising column-like and devoid of lower branches. Tulip poplars grow rapidly and become too big for an average residential property. Branches are not weak wooded in the early years, but weighty branches on older trees tend to snap off branches in wind and ice storms. Its shallow root system competes in turf areas and likely will uplift sidewalks in urban areas.

Although not prone to serious disease and insect problems, leaves may be plagued by sap feeding aphids which exude sticky sap over decks, patios and cars beneath. Over a dry summer tulip tree may shed up to one-third of their leaves, perhaps abit messy for some homeowners. Shallow root systems compete with most kinds of plants planted within its drip line. During hot, dry weather the leaves tend to turn yellow and drop off.

Not prone to serious disease and insect problems, leaves may be plagued by sap feeding aphids which exude sticky sap over decks, patios and cars beneath. Over a dry summer tulip tree may shed up to one-third of their leaves, perhaps abit messy for some homeowners. Tuliptree provides food and shelter for insect pollinators. including hummingbirds and small critters.

Leading cultivars:

‘Arnold’ – columnar 50 feet tall and 20-25 feet wide

Majestic™ (‘Aureomarginatum’) – 75 feet tall tree with green leaves variegated edged with yellow margins

‘Little Volunteer’ – compact 30-35 feet tall and 20-25 feet wide

Emerald City™ (‘JFS-Oz’) upright oval shape to 55 feet high and 25 feet wide

Wonderful Carolina Silverbells

Posted by Hugh on March 1st, 2024

Carolina silverbell (*Halesia tetraptera*)

To start, the botanical literature is a little confusing regarding the two silverbell species. Mountain silverbell (Halesia tetraptera; formerly H. carolina) and two-winged silverbell (H. diptera) are native to the Appalachian Mountains of Tennessee, North Carolina and Georgia. (Zones 6-9).

Silverbells are either small- to medium-sized deciduous trees or large, multi-stemmed shrubs. It blooms in the spring (late-March to late-April) with white bell-shaped flowers that hang in clusters on year-old branches. Silverbells are in the Styrax plant family (Styracaceae) along with the snowbells (Styrax spp.).

Silverbell spring flowering is stunningly beautiful when set on or nearby a patio or planted at the edge of a woodlands. They’re naturally understory trees with a medium growth rate. Mountain silverbell may reach heights of 30 – 40 feet, whereas two-winged silverbell is smaller with a mature height between 20 – 30 feet. Both have a rounded tree canopy.

Flowers on two-winged silverbell average ¾-inch long. Mountain silverbell (H. tetraptera var. monticola) has larger white flowers than Carolina silverbell. It bears 4-winged green pods mature to brown. 2 inches long in fall. At the nursery, producers train them into a multi-stemmed small tree or a single trunk tree.

Silverbells thrive in rich, well-drained soil containing abundant organic matter. In their natural habitat silverbells grow moist acidic (pH 5.0 to 6.0), and the woodland floor is organically littered (mulched). Guard against the late summer foliage becoming chlorotic (yellow), a sign that the soil pH is not low (acidic) enough. A two-year old established tree is moderately drought tolerant.

Fertilize once in the spring with a slow-release acidic organic fertilizer. Silverbells tend to transplant well, preferring containerized rather than balled-and-burlapped (B&B) trees. Do not (never) attempt to dig a silverbell tree out from the wild.

Fall foliage often turns an attractive yellow before abscising and the bark adds winter interest with its contrasting striations. Silverbells generally have no pests of major concern. The species is susceptible to Phytophthora root rot that can be problematic in organically deficient and poorly drained soils.

Cultivars To Look For:

‘Arnold Pink’ forms large 3/4 in. rose pink pendulous flowers hang from the branches in spring.

‘Magniflora’ produces larger flowers (to 1 1/2″ wide) and reportedly flowers.

H. tetraptera var. rosea bears pink-blushed flowers.

‘Jersey Belle’ (H. tetraptera) bears extra-large white bell-shaped flowers.

‘Wedding Bells’ is a 20-foot smaller tree that is highly floriferous.

Easter Cactus

Posted by Hugh on February 26th, 2024

A native of southeastern Brazil, Easter cactus (Schlumbergeri gaertneri), formerly Hatiora gaertneri, is a tropical succulent cactus. It is often confused with Thanksgiving (Schlumbergera truncata) and Christmas Cacti (S. x buckeyi) both of which have very difference flattened stems with rounded or spiney-edged scalloped foliage. In the wild, this tropical grows almost shrub-like on trees or rocks.

Easter cactus may be identified for its single, squat stem. From this, elongated leaf segments grow. Unlike other holiday cacti, the Easter form has no scallops or teeth on a healthy leaf. Foliage color darkens as they age, beginning life as pale green and grow wider and flatter with age, with fully grown segments measuring 1.5 – 3 inches and up to 1 inch wide. When fully grown, segments will arch downward under their own weight.

Easter Cactus is an epiphytic house plant that asks for light shade and well-drained soil. The plant tolerates dry soils and overly wet potting media will cause root rot. Indoors, Easter cacti prefer a bright East-facing window, one not in direct sunlight. Plants prefer high humidity; mist every 2-3 days and set the pot in a tray of moist pebbles.

Flower buds start to set up in February-March as photoperiodic daylengths get longer. Flower buds form on the end of branches and open between late March and May. Bright starburst shaped flowers are available in scarlet red, light lavender and pink hues, depending on variety. These large blooms typically measure 3-inches across, with yellow stamen in center. Flowers that have been pollinated may produce oblong red fruit bearing seeds.

After flowering, Easter cactus enters a one-month resting period when water amounts are reduced. You may move the plant outdoors to a shady spot under a tree over most of spring and through the summer months. Treat the plant as you do most succulents in your house plant collection; water every 5-7 days and fertilize bi-monthly with a water-soluble product such as Miracle-Gro®, Jacks®, or Schultz® House Plant Food. In early January initiate flowering in early spring, set the plant, move the plant to cool room: 50-65°F during the day and night. Each night, set the plant in 14 hours of darkness daily by covering the plant with a box or moving it to a closet.

From late October through February, do not fertilize during its winter resting period. Never re-pot during bloom or immediately following resting period. Re-pot by removing only the loose soil around the roots. Transfer to a slightly larger pot and add potting mix. The best soil blend for Easter cacti contains about 50% peat/perlite potting, 25% garden soil, and 25% bark chips or gritty sand.

Cranesbills (Hardy Geraniums)

Posted by Hugh on February 19th, 2024

Cranesbills (Geranium spp.) comprise a large genus of super hardy herbaceous perennials. (USDA hardiness zones 5-8). These are not your annual geraniums which is the genus Pelargonium. They grow happily in partial sun to full shade and in moist, humus-rich, well-drained soil. Cranesbills tolerate full sun in cool northerly areas. Plants may produce fewer flowers in deep shade.

Plants grow from basal rosettes of palmately lobed leaves. Cranesbills benefit from annual mulching and tolerate moderate drought periods due to thick rhizomes. Over 250 varieties species worldwide, popular varieties grow 12-18 inches high and others to 24 -30 inches in height Utilize them as groundcovers and low garden borders. Clip (deadhead) plants back in mid-season for a clean appearance and to stimulate additional flowering.

Most cranesbills easily spread in the garden via rhizomes. Some varieties may self-seed and some cultivars may not come true from seed. Clumps may be divided every 3-5 years.

Personal Favorites: ‘Rozanne’ geranium (G. ’Gerwat’), Bloody cranesbill (G. sanguineum), G. maculatum ‘Espresso’, G. maculatum ‘Espresso’, G. x cantabrigiense ‘Biokova’, G. clarkei x pratense ‘Brookside’, and G. macrorrhizum ‘Ingersen’s Variety’).

‘Rozanne’ (G. ‘Gerwat’ is a hybrid clump-forming geranium that typically grows in a mound to 20 inches tall x 24 inches wide. It blooms almost non-stop flowering throughout the growing season. Large, 5-petaled, violet-blue flowers (to 2.5 inches in diameter) with purple-violet veins and small white centers bloom profusely from late spring to early summer, generally into the fall in zones 7 and parts south. Its deeply cut holds up well to summer heat and humidity. Perennial Plant of the Year in 2008 and highly pest and disease resistant.

Bigroot Geranium at Cheekwood Gardens in Nashville, TN

Bigroot geranium (Geranium macrorrhizum) is a rhizomatous semi-evergreen perennial that typically grows to 12 inches tall but spreads to 24 inches wide to form a thick, weed-resistant ground cover. Deeply lobed and rounded, grayish-green leaves (4-8″ long) have 5-7 lobes, with each lobe having 3 to 5 notches at the tip. Leaves are strongly aromatic when crushed. Leaves acquire attractive red tones in autumn. Long-lasting purple-pink flowers (to 1″ wide) with inflated dark red calyces bloom in umbel-like clusters above the foliage in late spring to early summer, often with some sporadic rebloom occurring throughout summer.\

Bloody cranesbill (G. sanguineum) is an herbaceous, clump-forming perennial that typically grows in a mound to 9-12 inches tall with white-hairy trailing stems eventually to 24-inches wide over time. The dark green summer foliage usually takes on a reddish look in the cool autumn season. ‘Ingwersen’s Variety’ has highly aromatic, bright green leaves that turn red and orange in fall. Its purplish red (mauve) buds open into soft pink, 5-petaled flowers with darker sepals and elongated stamens.

‘Brookside’ Geranium at Chicago Botanical Gardens

G. clarkei x pratense ‘Brookside’ is an award-winning cranesbill in English gardens covered with violet blue flowers with a white eye in June and July. Brookside geranium grows to a height of 24 inches; cut back after first bloom to promote a second flush of late season flowers.

Seven Winter Blooming Shrubs

Posted by Hugh on February 12th, 2024

If you live where winter temperatures are generally moderate in the low teens, a number of shrubs bloom in winter. In the Delmarva and mid-South regions (USDA hardiness zones 6-7), these seven plants bloom reliably for 2-3 weeks before spring officially arrives.

Fragrant honeysuckle (*Lonicera fragrantissima*)

1. Winter honeysuckle (Lonicera fragrantissima), aka fragrant honeysuckle, are covered with small fragrant white flowers in midwinter on this vigorous 10-12-feet-high shrub. Note: winter honeysuckle is listed as invasive in some southern states because they are prolific seed producers. In the Tri-Cities area of Tennessee (Zones 6b-7a), flowers rarely produce viable seeds.

2. Wintersweet (Chimonanthus praecox) are covered with highly fragrant yellow/slight red blotched flowers in late January into February. This deciduous shrub grows 12 feet high by 10 feet wide and is moderately drought resistant.

3. Sweetbox (Sarcococca hookeriana ‘Humilis’) is a low-growing evergreen ground cover. During warm spells in February or March, small fragrant white flowers emerge from within the glossy boxwood-like evergreen foliage. It spreads slowly by underground runners where it prospers around woodland trees and dry sites.

4. Chinese paper bush (Edgeworthia chrysantha) is a deciduous suckering shrub that typically grows to 4-6 feet tall and wide. Clusters of tiny, apetalous, tubular, yellow flowers open in February. Blooms are also delightfully fragrant. Dark blue-green, lanceolate-oblong, 3-6-inches long deciduous leaves are an added plus in the spring-summer landscape. Irrigate every 7-10 days during prolonged dry spells.

5. Carolina Jessamine (Gelsemium sempervirens) produce sweet scented, golden yellow flowers February – March. This vine is trained to a trellis or vertical wall. It is often seen growing wild as a ground cover or pruned into 3-6 feet cascading mound. Many people wrongly call them forsythias which bloom in April.

6. Chinese Witchhazel (Hamamelis x intermedia) are hybrids of two Asian witchhazels (H. japonica x H. mollis). Shrubs grow 6-12 feet tall and wide and sucker freely at the base. Some of the better cultivars include ‘Diane’, ‘Gingerbread’, ‘Jelena’, ‘Orange Beauty’, ‘Primavera’, and ‘Westerstede’.

7a. Cornelian Cherry Dogwood (Cornus mas), native to central and southern Europe and western Asia, is a multi-stemmed, low-branched dogwood tree or shrub. Tiny, golden yellow flowers cover the branches during most of March despite some cold wintery nights. ‘Golden Glory’ and ‘Spring Glow’ are popular cultivars.

7b. Japanese cornel (C. officinalis) is filled with golden yellow flowers in very early March along with an attractive exfoliating winter bark. Both species grow 20-25 feet tall and slightly less in width. Leading varieties: ‘Kintoki’ (smaller 15 x15 feet specimen and heavy bloomer) and ‘Sunsphere’ (heavy blooming).

Rarely will you find these flowering shrubs for sale at local garden centers. It is best to buy these shrubs in late winter a number of fine on-line nurseries that do list them for spring planting. Plan on a 1-2 year waiting period before shrubs bloom for the first time.

These shrubs are also valued by early pollinating bees and butterflies. Birds attracted to red fruits in September. All shrubs are also moderately deer resistant.

Foamflowers For Your Shade Garden

Posted by Hugh on February 6th, 2024

Foamflower (Tiarella cordifolia) is a low-growing, clump-forming woodland perennial groundcover. It grows naturally in moist forests, coves, and well-drained bottomlands where it spreads by slender runners (stolons) to form dense, 1-2 feet wide clumps of foliage or colonies. Small spikes of creamy white spring flowers and its attractive bright green foliage are solid pluses in a shady garden. (USDA hardiness zones 3-8).

Semi-glossy, heart-shaped, 3-5 lobed leaves (3-4 inches across) sprout directly from the stolons. Leaves may have reddish variegation along the veins. Foliage stays evergreen in mild winters, often taking on a reddish bronze tint in autumn and winter. Tiny, white flowers with very long “foamy -like” stamens appear in airy racemes in spring for 4-6 weeks; erect, wiry, mostly leafless floral stems stand tall above the foliage clump to a height of 10-12 inches. Flower buds start out pinkish before turning creamy white.

Foamflower is easily grown in average, medium, well-drained soil in part shade to full shade. It thrives in humus-rich, moist, well-drained soil. Poorly drained or dry soils can be fatal for this shade groundcover. Fertilizing is rarely necessary. Mow high over the spent flower spikes for a neat appearance to the foliage mound. It is semi-evergreen in zone 6 and points further south where tiarellas are evergreen in winter.

A southern variety (var. wherryi), sometimes listed as a separate species, does not send out runners and the deeply lobed leaves resemble oak foliage.

Landscape Attributes: An excellent ground cover for heavy shaded sites; airy white flowers attract early pollinating small bees and flies. The heart-shaped foliage is generally passed up by deer and rabbits. Plants offer minimal wildlife value providing food or cover.

Foamflower is a great for woodland gardens and planted as a groundcover nearby the shade of acidic-loving shrubs and trees such as azaleas (Rhododendron spp.), mountain laurels (Kalmia latifolia), woodland phlox (Phlox divaricata), and flowering dogwood (Cornus florida).

Christmas Fern

Posted by Hugh on January 31st, 2024

Christmas Fern (Polystichum acrostichoides) is an evergreen native fern that grows tough as nails. This native fern, also called the Christmas dagger fern, is indigenous to much of eastern North America; it grows in every U.S. state east of the Rocky Mountains (USDA hardiness zones 3 – 9). This durable fern has long been associated with Christmas, its evergreen fronds (foliage) once in popular use in making holiday wreaths. Fronds (foliage) provides winter landscape interest.

Christmas ferns are long-lived plants. They grow to about 18 – 24 inches tall and wide with all fronds emerging from a central crown. As the plant ages, it produces additional fronds, usually numbering 20 or so per plant. Transplant them almost any time that the ground isn’t frozen. They prefer light to full shade, although in most northern states can handle full sun. Plants grow larger in humus-rich soil and are not finicky if planted in heavy clay soil.

The base of the frond and the central crown is covered with brown scales. The fronds are pinnately compound, meaning there is a central axis with the individual leaflets (called “pinnae” in fern lingo). Pinnae are about 2 inches long but are proportionally smaller as you move down the midrib. Two rows of spore dots (sori) run down their length.

Christmas fern grows in a fountain-like clump with leathery, lance-shaped, evergreen fronds. In early spring, new fronds uncurl, and the old fronds wither away. Best grown in organically rich, dry to medium moist, well-drained soils in part to full shade. This rhizomatous fern does not spread or naturalize. Individual clumps increase in size over time.

Young silvery and scaled fiddleheads, referred to as “croziers”, appear in the spring. Sori, containing fruiting bodies of ferns, appear on the undersides of the pinnae only at the ends of the fronds.

Christmas ferns have no serious insect or disease problems. They are rabbit and deer resistant. Crown rot can be problematic in poorly drained soils, particularly during the winter.

Why Called “Christmas Fern”? If you pull off a single leaflet (pinna) and turn it horizontally, it looks like Santa standing up on the back of his sled; hold it vertically, it resembles a Christmas stocking or a mitten.