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

Unusual Forms Of Umbrella Pine Are Really Cool

Posted by Hugh on December 11th, 2018

Umbrella Pine at NC Arboretum in Asheville, NC

Gold shrub form of Umbrella pine

Japanese Umbrella Pine (Sciadopitys verticillata) is a prized ornamental evergreen (USDA hardiness zones 5b -9). It is not actually a pine. The only species within genus Sciadopitys, this conifer dates back to the dinosaurs. Umbrella pine is a mid-sized landscape tree with several fine attributes: 1. glossy green long narrow needles arranged like the spokes of a wheel; 2. peeling reddish brown bark; and 3. conical form.

In its early years after planting, umbrella pine is a notoriously slow grower. Eventually, it reaches 30 to 40 feet in height and 20 feet wide. Specimens 70 feet tall are not unusual. Shedding reddish brown bark is noticeable on mature trees. Umbrella Pine prefers full sun with light shade around mid-day. Plant the tree in humus-rich, moist, well-drained soil with slightly acidic to neutral pH. Their long rigid needles, along with a sturdy limb structure, allow the tree to withstand heavy snow and ice loads.

Several forms, including variegated, pendulous, columnar, and dwarf cultivars, along with striking foliage are available at specialty conifer nurseries.

Four Unusual Forms of Umbrella Pine:

‘Gruene Kugel’ – slow-growing compact form from Germany (30 inches x 18 inches in 10 years); rounded form when young, develop slowly into a small compact tree with glossy deep green foliage year-round.

‘Mr. Happy’ – upright coniferous tree with lush dark-green needles and /or clear yellow variegation. According to Buchholz & Buchholz Nursery in Gaston, OR, needles may be entirely green or entirely yellow or variegated half-and-half. It prefers sun/partial shade in well-drained soil; 5 feet tall x 3 feet wide in 10 years. Zone 4

‘Joe Kozey’ grows tall and very narrow at 20 feet high and 6 feet wide. Needles are held more tightly to the trunk than other types. At maturity, this slow-growing variety becomes a large, spire-like tree.

‘Picola’ – a dwarf, conical selection with short, 2 inch (5 cm) long, shiny dark-green needles. After 10 years years of growth, a specimen will stand only 30 inches (80 cm) tall and 15 inches (35 cm) wide, suggesting an annual rate of growth of 2.5 inches (8 cm).

Outdoor Holiday Decorating With Poinsettias and Cyclamens

Posted by Hugh on December 6th, 2018

Outdoor planting of hardy cyclamen

Poinsettia in Jacksonville, FL landscape

If you live in U.S. hardiness zones 3-7, December weather is ordinarily is too frigid to grow poinsettias and cyclamen outdoors. Southeastern U.S. cities like Charleston, SC, Savannah, GA, and northern parts of FL like Jacksonville, Tampa and Orlando enjoy mild December temperatures 50 º F. lies in zone 8 as well as most of the Dallas TX.

Whether planted in front of a shopping center, a restaurant, or your home, these brightly colored plants should put you into the holiday spirit. Poinsettias are native to Mexico (USDA hardiness zones 9 to 11. If poinsettias and cyclamens are planted nearby a building foundation, they often enjoy a micro-environment protection of 4-5 º F.

Hardy cyclamen (Cyclamen spp.) are native to the Mediterranean region and flowers are available in a wide range of white and pink shades. Breeders have developed several plant sizes ranging from small, medium and large. Some varieties are fragrant. At Black Friday sales around Thanksgiving, poinsettias may sell for less than $2.00 at the big box stores.

Here are some basic care tips for outdoor care:

Place poinsettias and cyclamens in bright natural light to morning only sunlight.
Keep plants away from high winds.
Brightly colored poinsettia bracts should remain fresh if outdoor temperatures do not exceed 80 º F or drop below 50 º F in November and December.
Water plants thoroughly weekly if set bare-root in planter beds or every 3-4 days in pots if natural rainfall is low. Never leave plants sitting in water over several hours.
Feed plants every 2-3 week with a water soluble fertilizer such as Schultz™ and Miracle-Gro™ at recommended rates for house plants.
Plant quality will begin to decline in early January. You may opt to discard plants or grow them on for their foliage.

Spring Star Flowers (Ipheion)

Posted by Hugh on November 28th, 2018

Starflower (Ipheion)

Spring star flowers (Ipheion uniflorum), native to Argentina and Uruguay, feature grass-like foliage and 6-petaled star-shaped flowers on 3-6 inches tall stems in early spring (April). Each bulb produces multiple flowering stems. Flowers range in color from almost white to violet blue and emit a mild spicy fragrance. In addition the grassy foliage gives off an oniony or garlic aroma when crushed. They are in the Liliaceae plant family and their scent repels deer and rabbits.

Star flowers are one of the easiest bulbs to grow. These minor bulbs grow in average, medium, well-drained soils in full sun to part shade. They’re tolerant of a wide range of soils. In fall, sow bulbs 2-4 inches deep and 2-4 inches apart. Bulbs naturalize rapidly by bulb offsets and also by self-seeding. Plants go dormant by late spring. Lightly feed the planting in early spring with 10-20-10 or equivalent fertilizer.

Bulbs may start out slowly the first year, but star flowers eventually naturalize. Once established, star flowers produce masses of quarter size blooms lasting 3-4 weeks even if planted in the home lawn. Star flowers flourish in the Southeastern U.S. west to Texas (USDA hardiness zones 4-9).

Star flowers are great planted in a rock garden, containers, front borders or mixed among peonies, heucheras, hostas, et al. Sow masses of bulbs under recently planted shade trees. Branches should be limbed up high enough to permit the early spring sunlight to filter down to the bulb foliage.

I have found the largest variety selection listed in Brent and Becky’s fall catalog @Brent and Becky’s Bulb, Inc. in Gloucester, VA. A few favorites include: ‘Jessie’ (described as the darkest blue); ‘Rolf Fiedler’ (bright deep blue), ‘Tessa’ (light pale blue), ‘White Star’ White stars), and ‘Wisley Blue’ (variable shades of blue).

Decorate your spring kitchen table with a small vase of these beauties.

Hardy Sedum Groundcovers

Posted by Hugh on November 25th, 2018

Sedum ‘Lidakense’ at Kingwood Center in Mansfield, Ohio

S. rupestre ‘Angelina’

Sedums (Sedum spp.) are tough, easy to grow perennials (zones 3-9). Plants prefer average dry to moist well-drained soils and full to partial sun. Most sedums do not tolerate wet soils. Their thick succulent glossy leaves lead to the plants’ exceptional drought resistance. Sedums are exceptionally easy to root from leaf and stem cuttings.

Low groundcover types are featured here. These creeping beauties fill in spaces between taller plants or creep into crevices in rock garden or on steep cliffs. These sedums produce masses of tiny, star-like floral heads and attract lots of pollinators. Some creeping sedums are evergreen or semi-evergreen with thick leaves of many shapes, sizes and colors. Most are deciduous. These undemanding plants love hot dry garden sites and thrive as well in containers, on rock walls and rooftop gardens.

Eight of the best low growing groundcover types:

S. cauticolum ‘Lidakense’ – round blue foliage on low 3-4 inch tall spreading plants with gracefully arching stems; tiny brilliant pink star flowers in late summer.

S. floriferum ‘Weihenstephaner Gold’ –4-6 inches tall dense groundcover; covered in canary yellow star-shaped flowers in late spring.

S. kamtschaticum – 3-6 inch tall with needle-like foliage that emerges chartreuse, turns golden yellow in summer, and orange and red shades in fall; yellow flowers in mid-summer.

S. reflexum ‘Blue Spruce – ground-hugging 3-6 inch tall dense mat of conifer-like blue foliage; deep mauve pink stems rise to 10 inches high, topped by brilliant yellow flowers.

S. rupestre ‘Angelina’ – 6-10 inch tall aggressive spreading; needle-like foliage that emerges chartreuse, turns golden yellow in summer and to rich shades of orange and red in fall; yellow flowers in mid-summer.

S. spurium ‘John Creech’ – 3-6 inch tall dense mat of small, scalloped green leaves, topped with rose pink flowers in late summer.

S. spurium ‘Red Carpet’ – vigorous grower that starts red in spring, holds its color all season; rosy red flowers in summer.

S. ‘Vera Jamison’ – low, spreading grower with arching stems of round, smoky blue foliage that gradually turns deep burgundy purple; dusky pink flowers in late summer.

Tips for Growing Abutilon (Flowering Maple)

Posted by Hugh on November 20th, 2018

‘Ball Gown’ plants for sale at Biltmore Estates

Abutilon (Abutilon x hybridum) is a group of tender evergreen perennials (USDA hardiness zones 9-11). In USDA hardiness zones 6 thru 8, abutilon is grown outdoors from mid-spring to mid- autumn, when it is moved indoors and grown as a tropical houseplant. When moved indoors, partially cut back to fit its indoor space. In early spring prune the plant back hard.

Abutilon -flowering maple

Abutilon is known by several names including Chinese bellflower, Chinese lantern, Parlor maple, and flowering maple. It’s related to mallows and hibiscus (plant family Malvaceae). Albutilon has maple-like palmate deeply lobed leaves and bears colorful delicate looking flowers. Abutilon may flower almost non-stop in shades from white, pale yellow, orange, red, and bi-colors.

Abutilon is not too particular about soil (potting media). It should be well-drained, moist, and pH near neutral (6.2-7.2). Re-pot a container grown plant(s) into new larger containers and in new potting soil. Feed every two weeks with a dilute, water-soluble fertilizer such as Miracle-Gro™, Jack’s™, or Schultz™.

During the summer abutilon may be infested with whiteflies, spider mites, scale and mealybugs. Spray leaves and stems with water to wash pests off or spray with insecticidal soap or neem oil. Plants should be adequately spaced and keep foliage dry to prevent leaf spots and rust diseases.

Some gardeners opt to train abutilon into a tree or topiary form. Flowering maple is also great in a garden bed or a hanging basket. Butterflies and hummingbirds are attracted to their pendent bell-shaped flowers, available in many colors including yellow, orange, pink, red, and bi-colors.

Today’s flowering maples are the result of hybridizing between four species A. darwinii, A. striatum, A. pictum, and A. megapotamicum. One of the finest is ‘Biltmore Ballgown’, an heirloom variety sold by Biltmore Estate in Asheville, NC. It grows 2-4 feet high and 1-2 feet wide with showy orange-netted lantern flowers.

Abutilon is propagated by softwood cuttings. Beware: Leaf sap may cause mild dermatitis in susceptible individuals.

Fertilizing Trees And Shrubs

Posted by Hugh on November 15th, 2018

Fertilize area under tree 1.5 times the tree’s spread

Apply fertilizer in planting area under the sweetgums

Maintaining good plant nutrition is of key importance. A tree and shrub which is growing vigorously can resist infestation from most diseases and insects. Symptoms of poor nutrition: pale green or chlorotic leaves; undersized plants; slower annual growth rate; many dead or dying branch tips; increased insect/disease problems.

Trees under 10 years of age should be fertilized annually. There is little need to feed newly planted specimens and those suffering root damage from recent trenching or construction. Yard shade trees generally receive adequate fertilizing if the lawn is fed twice annually. Old established trees do not need to be fertilized every year.

High pH (alkaline) soils can result in chronic deficiencies of nutrients in some tree species, such as red maple, birch and pin oak, as well as nitrogen-deficient soils. Nitrogen (N), phosphorus (P), and potassium (K) are essential plant nutrients found in bags of fertilizers. The analysis will vary from one fertilizer manufacturer to another. Some products may be organic-based and are “slow-release”.

The fertilizer label on the package lists the exact proportions of available nutrients. For example, a bag label of 20-10-10 contains 20% N, 10% P (phosphoric acid), and 10% potassium (K) as potash. A 50 pound bag containing 20% nitrogen fertilizer (10 pounds of actual nitrogen) and also 5 pounds each of P and K.

Your soil should be tested every 4-5 years to check and correct (if necessary) a nutrient deficiency or soil pH that may be out of balance. Many land grant universities and full service garden centers offer fee-based soil testing.

General Fertilizer Program for trees and shrubs:

Here in Tennessee or Virginia, the best time to fertilize is late March or early April or in late fall once plants are dormant. In New England or Midwestern states, application time may be 2-4 weeks later. Weigh out the recommended fertilizer and distribute it evenly under the tree or around the shrub. Do not fertilize within 12 inches of the main trunk. Do not exceed rate of 3 lbs. of actual nitrogen per 1,000 square feet. Tree roots usually spread 1.5 times the diameter of the branch spread or that of the shrub width. Around mass groupings of plants, calculate the surface area around the entire planting to be fertilized (see photos above).

Information Source: Morton Arboretum in Lisle IL

Beware Of Fast Growing Trees

Posted by Hugh on November 10th, 2018

Platanus x acerifolia

Silver maple in autumn

Many property owners choose fast growing landscape trees. These large shade trees increase the value of your property. Their summer shade and wintry wind protection may reduce utility bills by 20 – 25% . Trees attract wild birds for nesting, protection, and as a food source. Some brighten up your landscape with dazzling fall color. However, we may pay a price for the fast growth.

Trees listed here are rated as fast growing. In general, most (not all) fast growing trees are weak wooded. Branches may break apart under ice or snow loads and in high winds. Their shallow roots may uplift or crack sidewalks. Do not plant fast growing species within 50 feet of your home as tree roots may penetrate foundations and septic fields. This is particularly true for silver maples, cottonwoods, poplars, and weeping willows. Some species are also susceptible to verticillium wilt, leaf anthracnose, and cankers; pests like scale and borers may be troublesome at times.

Do not assume that all listed species are troublesome. Those marked by an asterisk (*) are superior trees and are highly recommended. All species are rated hardy in USDA zones 5-8. Better cultivars are listed for a few species.

Fifteen Large Fast Growing trees (25 feet or more high after 10 years):

Box elder (Acer negundo)

*Silver Maple (Acer saccharinum) ‘Silver Queen’

Tree of Heaven (Ailanthus altissima) – rated an invasive species in some states

Eastern cottonwood

Common hackberry (Celtis occidentalis)

*Tulip poplar, tulip tree (Liriodendron tulipifera)

Empress tree (Paulownia tomentosum) – rated an invasive species in some states

*London Planetree (Platanus x acerfolia)

Sycamore, planetree (Platanus occidentalis)

Eastern Cottonwood (Populus deltoides)

Lombardy poplar (Populus nigra ‘Italica’)

Quaking aspen (Populus tremuloides)

Weeping Willow (Salix babylonica)

*Basswood, American linden (Tilia americana)

*American Elm (Ulmus americana) ‘Washington’, Princeton’, ‘Jefferson’

Siberian elm (Ulmus pumilo) -rated an invasive species in some states

Dieback Shrubs

Posted by Hugh on November 5th, 2018

Buddleia

Dieback shrubs are a group of hardy landscape shrubs that emerge and grow vigorously from mid-spring through early summer. They bloom reliably from late summer into early fall. Plants are near the edge of their hardiness range, and often die back to the ground in the winter. They act more like herbaceous perennials. The above-ground shoots are not dependably winter hardy.

Stated another way, a dieback shrub is a woody deciduous species that grows one full plant zone lower (colder) as a perennial. A zone 7 hardy woody shrub performs more like a herbaceous perennial in zone 6. It dies back to the ground in winter and re-grows and blooms the following year. Prune the shrub back in early spring before the bud break. Their colorful flowers attract bees, butterflies, and other pollinators, and are mostly deer resistant.

Four Reliable Dieback Shrubs:

Butterfly bush (Buddleia x davidii) is cold hardy to zone 5 which makes it suitable for most gardeners in the United States. These shrubs generally grow 2-3 feet tall, usually as wide and tall. They’re tough plants that can tolerate lean and alkaline soils. Plants perform at their best in average well-drained soil with a pH range of 5.5 to 8.5.
Bluebeard shrub (Caryopteris spp.), also called blue mist or blue spirea, produces gray-green foliage and bright blue flowers in early summer through fall (USDA hardiness zones 5-9). Leading varieties include Petit Bleu® (rich blue blooms), ‘Worcester Gold’, and ‘Longwood Blue’.
Chaste tree (Vitex agnus-castus) include short growing varieties like Blue Puffball™ (3-4 feet tall and wide in zones 6-9) and Blue Diddley® (3-6 feet tall in zones 5-9).
Crape myrtle thrives in the southeast U.S. (zones 6-10), but are at risk in colder northern areas. Grow them as perennials in full sun and average well-drained soils. Select the hardiest forms from the U.S. National Arboretum. I recommend these 4 varieties such as ‘Natchez’, ‘Muskogee’, ‘Acoma’, and ‘Osage’ to try in zones 5b -6a as herbaceous perennials.

Fall – Winter Pruning Dos and Don’ts

Posted by Hugh on October 30th, 2018

Bad cuts (sap leakage in winter)

Hand tools for pruning

Pruning is a chore that you don’t need to put off until spring. Many trees and shrubs may be pruned this autumn. However, NOT all landscape trees and shrubs are pruned. Here are some pruning guidelines to follow:

WAIT to prune spring flowering deciduous shrubs such as Forsythia, Lilac, Bridal Wreath & Vanhoutte Spireas, Quince, Viburnums, Fothergilla, Weigela, Deutzias, and some others. Add some evergreen flowering shrubs including all azaleas (both evergreen and deciduous) and rhododendrons, Japanese andromeda (Pieris japonica), Mountain laurel (Kalmia), Daphne, and Mahonia. Wait 3-4 weeks after spring flowering to prune all the above shrubs plus a few others not listed.

DO PRUNE NOW: Summer flower shrubs should be pruned now while they are dormant to manage size, shape, balance, and uniformity prior to spring growth. These include Summer Spireas, Panicle hydrangeas (H. paniculata) & Smooth hydrangeas (H. arborescens), Rose of Sharon (Hibiscus syriacus), Bluemist (Caryopteris), Butterfly bush (Buddleia), Potentilla (cinquefoil), Summersweet (Clethra). and others.

Hold off pruning Big Leaf Hydrangeas (H. macrophylla). They bloom both on old last year’s wood and on new wood. Wait until spring to determine if winter climes have injured the old wood. After harsh winters Big Leaf hydrangeas may be cutback to 3-5 feet and will bloom mostly on new wood later in summer.

ROSES: Pruning varies according to the species of roses. Hybrid Tea, Grandiflora and Floribunda types can be lightly prune back by 25 to 30%. In the early days of spring, prune to the desired height and width, remove diseased or broken canes, and thin out the interior of the bush. Shrub roses including Knock Out™, Home Run™, and Carefree™ series are pruned down to 18-36″ in height. Shorter types like OsoEasy™ and Flower Carpet™ are pruned to 12-18 inches in height.

Don’t Prune Crape myrtles until late winter

CRAPE MYRTLES: Predicting winter cold is foolhardy, so hold off until spring. In general, crape myrtles need for little annual pruning other than removing dead, diseased, weak wood, and the old seed heads.

DECIDUOUS SHADE TREES: Prune them now before or after leaf drop. For young, newly developing trees, thin out excess branches, remove lower limb, and shape of the tree’s upper crown.

SPRING FLOWERING TREES: Wait 3-4 weeks until after spring flowering to prune, mostly for appearance. Remove dead, diseased, and weak branches and twigs.

Special note: Maples (Acer spp.), Birches (Betula spp.), Yellowwood (Cladrastus), and Dogwoods (Cornus) exhibit a high sap pressure and often bleed when pruned in late winter and early spring. If you prune them now, they will “bleed” sap.

Stoloniferous Dogwoods Jazz Up The Winter Landscape

Posted by Hugh on October 25th, 2018

Redtwig Dogwood Brightens Up The Winter Garden

White fruits in September

Red osier dogwood (Cornus sericea) is a medium-sized, deciduous shrub native to much of the Northern and Western United States (USDA hardiness zones 2-7). Without question these shrubs standout in winter by their colorful stems (see pruning recommendations below). Cut branches are an added plus for indoor arrangements. The yellow-twig form (C. sericea ‘Flaviramea’) is also available.

Leaves are oblong-lanceolate (up to 5 inches long), oppositely arranged with 5-7 pairs of lateral veins, and entire margins. Species may grow up to 10 feet tall and spread voraciously by underground stolons to form large clumps. One landscape idea is to mix red and yellow–twig dogwoods together for a winter color blast. Osier dogwoods grow well in very large containers, but quickly outgrow their pot space in 2-3 years.

These stoloniferous dogwoods bloom in mid-spring (in Tennessee). The terminal creamy white (cyme) flowers measure 1.5 to 2.0 inches across and white berries follow in late summer.

Plant shrubs in full sun (in northern areas) and in partial shade (in zone 7) and average soil. Fertilize in early spring before buds break and irrigate during long dry summer spells. Shrubs establish quickly and are very drought tolerant after one year. Many cultivars are available, and are highly variable in leaf and stem color. This shrub dogwood may be confused with C. amomum which has a similar red bark, but C. amomum has blue fruits and brown pith.

Arctic Fire® is a non-suckering compact form with dark red winter stems. It grows 4-5 feet tall and 4-5 feet wide. It puts on a spectacular show in the wintert. Most varieties of stoloniferous dogwoods grow 8 to 10 feet, making Arctic Fire a great breakthrough for smaller gardens or residential landscapes.

Stoloniferous dogwoods are disease and insect resistant and deer generally overlook them. They make great landscape additions; utilize them in perennial or shrub borders, masses and groupings, container gardens and winter gardens.

Pruning tip: cut 2-3 year old shoots back to the ground each spring immediately after flowering to ensure a good display of the winter branches.

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Eight of the best low growing groundcover types:

S. cauticolum ‘Lidakense’ – round blue foliage on low 3-4 inch tall spreading plants with gracefully arching stems; tiny brilliant pink star flowers in late summer.

S. floriferum ‘Weihenstephaner Gold’ –4-6 inches tall dense groundcover; covered in canary yellow star-shaped flowers in late spring.

S. kamtschaticum – 3-6 inch tall with needle-like foliage that emerges chartreuse, turns golden yellow in summer, and orange and red shades in fall; yellow flowers in mid-summer.

S. reflexum ‘Blue Spruce – ground-hugging 3-6 inch tall dense mat of conifer-like blue foliage; deep mauve pink stems rise to 10 inches high, topped by brilliant yellow flowers.

S. rupestre ‘Angelina’ – 6-10 inch tall aggressive spreading; needle-like foliage that emerges chartreuse, turns golden yellow in summer and to rich shades of orange and red in fall; yellow flowers in mid-summer.

S. spurium ‘John Creech’ – 3-6 inch tall dense mat of small, scalloped green leaves, topped with rose pink flowers in late summer.

S. spurium ‘Red Carpet’ – vigorous grower that starts red in spring, holds its color all season; rosy red flowers in summer.

S. ‘Vera Jamison’ – low, spreading grower with arching stems of round, smoky blue foliage that gradually turns deep burgundy purple; dusky pink flowers in late summer.

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