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

Muhly Grass Pink Color Emblazens The Autumn Season

Posted by Hugh on September 12th, 2012

Muhly grass in November at NC Arboretum in Asheville

For most of the season Muhly grass (Muhlenbergia capillaris) grows pretty much unnoticed. Muhly exhibits a semi- erect growth habit, 3-4 feet in height and 3-4 feet in spread.

Walking past a pink billowy inflorescences of Muhly on a brisk sunny October morning is nothing short of “wow”. For 10- 12 weeks, from early September thru late November, a pink haze arises 12 inches or more above the narrow bladed green foliage. Muhly stands up well to rainfall and early frost. By late autumn the vibrant purple to pink hues gradually fade to beige.

Muhly grows best in full or partial sunlight (6- hour minimum) in average moist well-drained soil. Its native range extends from southern New England to southern Florida, west to Texas. Mulhy prospers in dry, gravely, often poor soils. Muhly stalls out in wet soggy winter soils.

Selecting a hardy seed source is very important. Muhly is marginally hardy in zone 6. Buy plants or seeds from a nursery which has checked on seed provenance. Foliage is semi-evergreen in parts of zone 7 and further south. Old growth should be cut back to 5-6 inches above ground in late winter.

Plant Muhly as a single specimen or group several for a larger display in a garden border or meadow setting. Muhly does not aggressively spread to other areas of the garden.

Three cultivars: Pink Cloud™ (shorter 2 ft. height, pink inflorescence); White Cloud ™ (4-5 ft. tall, more upright habit, and white inflorescence); and Regal Mist™ (3-4 ft. height, dusky pink inflorescence)

Leyland Cypress For Fast Growing Evergreen Privacy

Posted by Hugh on September 9th, 2012

: Leyland Cypress

Leyland cypress (xCupressocyparis x leylandii) is winter hardy in the Southern Appalachian region (USDA zones 6 and 7). It is frequently regarded as “the” conifer for Southern states. Its growth rate, compared to other evergreen conifers, is horrendously fast, with young established plants growing 3 feet or more annually. A young 2-3 foot specimen may reach 25 to 30 feet tall in only ten years. A 50 to 60 foot tall Leyland screen is a common sight.

At planting time Leyland should be spaced 16 to 18 feet apart and no closer. An alternative design is to plant each 8 foot apart and eliminate (or transplant) every other Leyland within 3-4 years.

Plant Leyland in full day sun and in fertile well-drained soil. A new planting should start off irrigated the first two summers. Backup irrigation during severe summer dry periods is highly advised to prevent disease flareups.

What attracts gardeners to plant Leylands is the soft green sprays of evergreen foliage. Numerous cultivars are available, and three commonly planted include: ‘Haggerston Grey’ (green needles with slight gray cast), ‘Leighton Green’ (rich green), and ‘Gold Rider’ (yellow with green tips).

Crowded and/or shaded plants are susceptible to any of three serious fungal diseases: Cercospora needle blight, Botryosphaeria canker, and Seiridium canker. Occasionally, bagworms populations may ravage Leyland foliage in late spring. Fungicide and pest spraying are mostly ineffective due to the enormous size of Leyland cypress.

Leyland is now commercially grown as a Christmas tree in the deep South, where fraser fir trees do not thrive. Leyland’s foliage displays exceptional sea salt tolerance, making it a good wind barrier around coastal areas.

This Korean Maple Deserves To Be Planted More

Posted by Hugh on September 4th, 2012

Acer pseudosieboldianum ‘Takeshimense’

Ullung-do Island Korean maple (Acer pseudosieboldianum ‘Takeshimense’) is a small deciduous tree which will grow to be 20 -25 feet tall tree, with a spread of 15-18 feet. It tends to branch low to the ground. It originates from the Ullung-do Island in the sea of China.

Korean maple is one of the best maples for fall color in the Southern Appalachian region (USDA zones 6 and 7). For a short time, new spring foliage emerges with a reddish tinge. Its forest green foliage lasts all summer long and stays disease and pest free. Autumn leaf colors are exceptional with reds, oranges and yellows throughout the tree.

It features subtle clusters of creamy white flowers with purple bracts rising above the foliage in early spring before the leaves appear. The two winged samaras turn purple in mid-summer. The rough gray bark and brick red branches add an interesting dimension to the winter landscape.

Korean maple excels in full sun in northerly areas (USDA hardiness zones 4) where few Japanese maple (A. palmatum) cultivars, if any, will grow. In northerly areas Korean maple grows in full sunlight and a compost rich, well-drained, and slightly acidic soil. Further south (zones 6 and 7), partial day or full morning sunlight is the rule. The tree shouldn’t be permitted to dry out. Irrigate during extended dry periods and cover the ground with 2-3 inches of mulch.

This is a relatively low maintenance tree, and is best pruned in the summer after the leaves have fully developed. Korean Maple is an open multi-stemmed low canopy deciduous tree which makes it ideal for planting under power lines.

Availability of Korean maple is limited to e-commerce nurseries on-line.

Growing Full Moon Maple in the Southeast U.S.

Posted by Hugh on September 1st, 2012

Acer shirasawanum 'Aureum'

Simply put, golden full moon maple (Acer shirasawanum ‘Aureum’) is a stunner (USDA hardiness zones 5-7). It is a slow growing maple, eventually reaching 18-20 feet in height and spread at maturity. It tends to be a long-lived tree if properly cared for. Leaves are circular with 9-13 short pointed lobes. Each lobe does not cut deeply into the leaf. The circular gold leaf creates a “full moon” design.

Foliage color is changeable with the seasons. Spring foliage starts out bright yellow and darkens to lime green in the summer. Clusters of tiny delicate flowers emerge in April for a brief period. The golden foliage serves as a bright background for tiny reddish purple flower clusters. Leaves may be tinged red along the edges. In early autumn leaves display a mix of orange and red tints. Small double winged samara color up red against the lime green foliage in late summer.

Growth rate starts off moderately, but slows down after 8-10 years. Full moon maple has a long life span. Plant it in a compost rich, slightly acidic, well-drained soil. In the Southeast U.S. full moon maple prefers morning sunlight to avoid leaf scorching in the summer heat. Irrigating during excessive dry spells is also warranted. Leaves may turn green in heavy shade. Protect from strong winter winds which may desiccate the dormant growth buds.

Full moon maple is a relatively low maintenance small garden and patio tree. Pruning, when needed, is best performed anytime from mid-spring through the summer.

‘Northwind’ Switchgrass Is Environmentally Tough and Beautiful

Posted by Hugh on August 28th, 2012

: Young Clump of ‘Northwind’ Switchgrass

Northwind switchgrass (Panicum virgatum ‘Northwind’) is a medium sized 5 to 6 feet tall ornamental grass. This tall native prairie grass grows best in full sunlight for most of the day. Its tight narrow posture seems to fall apart in shade. There are many good switchgrass varieties. Northwind makes a strong vertical presence, perhaps the best of the lot.

Northwind grows tall and narrow, with steely blue foliage and a lacy inflorescence. Beginning in mid-summer the soft pinkish white inflorescence rises 1-2 feet above the foliage (USDA hardiness zones 5). By early autumn floral heads fade to a silvery gray tint and look great in floral arrangements. The narrow grass blades turn many shades of yellow in autumn.

Switchgrass prefers a moist fertile ground, but adapts to most soil types, and either wet or dry conditions. This tough prairie inhabitant is heat and drought tolerant and is disease or pest resistant. Vigorous overcrowded crowns should be divided every 4-5 years, which is no easy task. Overwintering clumps stand rigid like sentinels and provide shelter for birds and other wildlife.

Take advantage of its natural form and foliage color in residential and commercial properties. Northwind is attractive alone or mixed with other plants in containers, massed along a stream bank, or set on steep slopes or reclamation lands. Switch grass is utilized in dune stabilization along coastal beaches and tolerates high winds and salt spray. Incorporate switchgrass in highway median strips; the dense upright vegetation effectively blinds headlights from opposing traffic.

Apples Ready To Pick?

Posted by Hugh on August 27th, 2012

'Gravenstein' apples espalier trained to wall

This unusually hot summer has sped up the harvest time of your backyard apple crop. Here are five good indicators that the apples are ready to harvest.

Change in skin color is one of the easiest for gardeners to spot. The green skin pigment gradually matures to red, yellow or oft green, depending on variety. Photos in fruit nursery catalogs, many available on-line, are good resources for fruit color. Some varieties will develop red skin color before they’re fully ripened, so color should not be your only indicator of maturity. The bottom of the apple (calyx end) turns from green to light-yellow.

On some varieties fruit shape is another change. Red Delicious and many varietal sports form 4-5 nubbins (raised bumps) on the bottom. The nubbin formation is dictated by the region where the variety is grown. Red Delicious from the Northwest U.S. is most to type, while those produced in the warm southeastern states less so.

Next harvest tip is flavor. Bite into an apple and determine its taste. You may not know what kind of apple that you’re eating, but its flavor and sweetness may be what you like. Apples which are hard to bite into or have a sour or starchy flavor are not ready. The inside flesh color often changes from oft-green to white, sometimes to yellow.

The number of days (interval) from bloom period to harvest date can be a reliable guide. Extremely hot summer weather may move up the harvest interval by 7 to 10 days. The approximate picking intervals of popular varieties are: Gala and McIntosh @ 110-115; Empire, Jonagold, and Jonathan @135-140; Red Delicious and Golden Delicious @ 145-150; and Rome, Granny Smith, and Winesap @155-160 days.

Finally, if you harvest too early, apples will be of smaller size, but will ripen off the tree indoors.

Winter Hardiness of Crape Myrtles

Posted by Hugh on August 25th, 2012

Awesome bark on Lagerstroemia fauriei

If you garden in USDA zone 6, certain crape myrtle cultivars are rated as reliably winter hardy perennials. Most dependable are the U.S. National Arboretum cultivars released starting in the 1980’s to date. Each one is named for an Indian tribe. Most of the National Arboretum cultivars are selected for cold hardiness as well as for disease and insect resistance.

Among the cold hardiest (zone 6-b) are the popular ‘ Natchez’ (26-28 feet/ white flowering tree form). This should be the first crape myrtle to trial in your landscape. Also worth trying are ‘Acoma’ (5-10 feet/white flowering), ‘Apalachee’ (11-16 feet/light lavender), ‘Hopi’ (8-10 feet/medium pink), ‘Sioux’ (10-16 feet/dark pink), ‘Tonto’ (8-10 feet/maroon red flowers), ‘Tuscarora’ (26 feet/dark pink), and ‘Pocomoke’ (3-5 feet/dark pink flowers).

Plant crape myrtles in well-drained soil and in full day sunlight. During the initial year of planting, water and mulch the crape myrtle when natural rainfall falls short. Fertilize with 10-10-10 fertilizer or equivalent following spring planting and repeat every spring hereafter.

Living in zone 6, expect that out of every three winters will kill crape myrtle(s) to the ground. To prevent winter injury, never prune a crape myrtle in the fall or early winter. The pruning cuts often do not heal over and the wood may be killed. Sudden spring cold snaps may also injure the growth buds. Wait until mid-spring to evaluate the harshness of the past winter before acting.

The rootsystem is very hardy and will push up new shoots in the spring. Crape myrtle blooms on new wood, and summer flowering is not lost. Yes, your winter injured crape myrtle may be smaller, but it often survives and flowers.

‘Senorita Rosalita’ – A Welcome Spider Flower Addition

Posted by Hugh on August 23rd, 2012

Señorita Rosalita spider flower

Cleome or spider flower (Cleome hassleriana) is the 5-6 foot flowering annual that your grandmother grew in her garden. Long stamens extending from the flowers look like spider legs, hence the common name. The old fashioned varieties produced lots of seed pods which meant lots of weed seed in next year’s garden. As summer temperatures rose, flower power declined and lower leaves dried up.

Señorita Rosalita is a vastly improved cultivar, displaying medium green leaves on a 3 to 4 feet tall upright branched plant, topped by brightly colored flowers. It flowers continuously through the heat of summer up to autumn frost. Flowers are spidery clusters of 4-petaled lavender-pink flowers 3 to 5 inches across. The gorgeous blooms should catch anyone’s attention in flower borders and in large planters.

Señorita Rosalita flowers are sterile, which means no seeds. It exhibits tremendous heat and drought tolerance which means no leafless stems in late summer. Señorita Rosalita has no sticky stems or thorns. Flowers are produced all over the compact plant. Plants exhibit an upright growth habit, maturing from 24 to 48 inches tall, depending on soil moisture and nutrition over the growing year.

This South American native grows best in full sun. Space transplants 18-24 inches apart in well-drained soil. Add 1-2 lbs of 10-10-10 or equivalent fertilizer per 100 sq. ft. of garden bed at planting time. Supplement with a water soluble fertilizer (Miracle-Gro®, Schultz®, or Hollytone®) at the start of summer and 6 weeks later. Señorita Rosalita is self-cleaning, and requires no special deadheading. Irrigate regularly for the first 3-4 weeks until established so that cleome can handle summer’s heat and humidity. The foliage and flowers stay mostly disease and pest free all summer long.

How To Re-Bloom a Moth Orchid (Phalaenopsis)

Posted by Hugh on August 22nd, 2012

Phalaenopsis moth orchids for sale at garden center

Perhaps this past year a friend gifted you a lovely moth orchid (Phalaenopsis spp.). Late summer and early fall is an excellent time to re-bloom it, if you live in USDA hardiness zones 6 through 8. The overall health of the plant should be good. Moth orchids require a fluctuation of between 15 – 20°F in day/night air temperatures for 4-6 week period to initiate flowering. Flower stalk(s) should appear 4-6 months later.

Moth orchids thrive outdoors in the spring and summer months at temperatures between 50 and 90°F. By late summer, the cooler temps have triggered the flowering mechanism. Occasionally plants must be moved indoors on cool (<50°F) nights. In the fall moth orchids are moved to a window with an eastern exposure to the morning sun. Direct morning sunlight may burn orchid leaves in the spring and summer months, but not in the fall and winter.

In the fall plants do benefit from re-potting. Use a commercial orchid mix available at many local garden centers and big hardware store chains. Remove the pot and inspect the quality of the root system. Clip off broken, shriveled or rooted roots using a sharp knife or shears. If the roots are over-crowded in the old container, re-pot in a container slightly larger. Water the orchid thoroughly after potting, and wait 2-3 weeks before fertilizing it the first time.

Fertilize orchids weekly in spring, summer and fall with a high phosphorus-based orchid fertilizer. During the winter, feed once monthly. Group plants together sitting in shallow trays filled with moistened gravel. Mist leaves one or more times daily to raise room humidity around the orchids.

In the late winter and spring one or more flower stalks should emerge. Use a twist’em to tie stalk(s) to a 12-18 inch tall stake as needed. Rotate the plant every 2-3 days to keep floral stalk growing straight. After all flower petals have fallen, remove the spent floral stalk.

Star Zinnias Handle Heat and Dry Weather

Posted by Hugh on August 21st, 2012

'Zahara Starlight Rose'

Wanting two seasons of spring-summer color, heat and drought tolerant, and no disease or pest problems? You should be planting Profusion and Zahara zinnias, also called “star zinnias”. They are very resistant to powdery mildew, a disease which plagues many kinds of zinnias.

Profusion and Zahara zinnias bloom non-stop for almost 6 months (mid-May thru October) in the Southern Appalachian region (USDA hardiness zones 6 and 7) before losing out to a November freeze. My favorites in the Profusion series are Apricot, Orange and Cherry. White, Yellow, Fire and Double Cherry Red are also available.

Zahara bears flowers 20% larger than the Profusion series. Zahara zinnias come in a wide range of colors, from white to scarlet. ‘Starlight Rose’ (photo) features white petals splashed with bright red around its floral button center. ‘Double Cherry’ (deep magenta) and ‘Double Fire’ (scarlet orange) are double flowered cultivars.

Flower sizes range from 2 to 3 inches in diameter. The colorful daisy-like blooms will attract numerous butterflies to your garden. Flowers are self-cleaning, requiring very little deadheading. Plants grow compact and well-branched at 18 to 20 inches high and wide. Plants should be spaced 8 to 10 inches apart in flower garden beds or in containers.

Star zinnias perform best in the full sun with good fertility. Add 2 to 3 inches of mulch to improve soil organic matter and to reduce soil moisture loss. Irrigate during extreme dry spells to maintain plant health, vigor, and flower numbers. At spring planting, feed with a slow-release fertilizer. Supplement nutrition with a water-soluble fertilizer (such as Miracle-Gro®, Schultz®, or Hollytone®) every 2-3 weeks during the summer period.