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

Move Over AJ, Here Comes T-Rex

Posted by Hugh on July 26th, 2011

'T-Rex' Sedum (photo credit-www.PerennialResource.com)

For nearly half a century, ‘Autumn Joy’ has been the leading “stonecrop” or “live forever” sedum cultivar planted. More than once I’ve heard this saying: “if Autumn Joy won’t grow in your garden, you should try another hobby. ‘T-Rex’ is a terrific new hybrid and ‘Autumn Joy’ is one of its parents. ‘T Rex’ has better resistance to stem rot than many veteran sedum cultivars, including ‘Autumn Joy’.

Compact growing T-Rex barely reaches over two feet in height and its stout sturdy stems support the massive flower heads. The serrated blue-green foliage of T-Rex is another plus.

By mid-July across the Southern Appalachian region (USDA zones 6 and 7), cream colored floral buds have formed, open to light rose pink flowers in late summer, and finish reddish pink in mid-autumn. If left standing, the seed heads provide winter interest and food for birds. Sedums flowers attract copious numbers of bees and butterflies.

T-Rex thrives in any average well-drained garden soil in full to partial (minimum 6 hours) sunlight. It requires no trimming, no deadheading, and no pinching. Very little, if any, watering is required once plants become established. Stonecrop sedums behave very shrub-like and are one of the easiest low maintenance choices.

Torch Lily Has Long Bloom Life

Posted by Hugh on July 23rd, 2011

Torch Lily (Kniphofia spp.)

Torch lily (Kniphofia spp.), aka “red hot poker”, is an easy to grow long-lived perennial from South Africa. Its colorful floral spike (and a little imagination) resembles a fiery torch or sizzling poker, visited often by hummingbirds, bees and butterflies.

New cultivars are mostly hybrids and vary in plant height and flower color. Starting in May one or more floral spikes arise 18 inches to 4 feet in height, depending on the cultivar(s) planted. Color choices include off-whites, yellows, oranges, reds, and blends of two or more tints. From the months of June thru October additional re-blooming follows soon after the spent floral scapes are pruned off.

Torch lily excels when planted in an average well-drained soil. Full to partial (6 hours minimum) sunlight is ideal. Most, but not all, cultivars are cold hardy in the Southern Appalachian region (USDA zones 6 and7). The sharp edged grass-like foliage is evergreen, but tends to take a beating in rough winters. Prune back the entire plant near the soil line in late winter for a fresh start.

A 2-year and older plant clump is both heat and drought tolerant. Every 3-4 years rhizomes are dug and divided either in early fall or late winter. Torch lily has few serious disease and insect problems. Root rot may become a significant problem when planted in a poorly drained soil.

To Grow Crocosmia Or Not?

Posted by Hugh on July 19th, 2011

'Lucifer' Crocosmia at Kingwood Center, Mansfield, Ohio

This South African native, also called ‘montbretia”, thrives in full sun in well-drained average garden soil. A richly composted soil tends to boost foliage size and bloom count, but often weakens bloom stems, requiring some staking. Crocosmia may struggle in a wet soggy wintry soil. Established plants are exceptionally summer heat and drought tolerant.

Brightly colored flowers rise on wiry stems above the sword-like leaves in early July in the Southern Appalachian region (USDA zones 6 and 7). The foliage closely resembles gladiolus. Most cultivars are hybrids and vary in flower color, height and plant vigor.

Flower stalks arise from fast-multiplying underground bulbs (they’re really corms) in red, orange, yellow and mixed colors. The most popular cultivar is ‘Lucifer’, a Blooms of Bressingham introduction. ‘Lucifer’ produces vivid red flowers on 4-5 foot arching wiry stems. Crocosmias make excellent cut flowers.

Corms are planted 3 to 4 inches deep in fall or early spring. In northerly zone 5, either plant corms 6 inches deep or lift and store them by late fall. Container-grown plants are also sold at most garden shops.

Many low growing forms (not ‘Lucifer’) tend to start slow their first year, but wind up as long-lived perennials. Over the years crocosmia may become a nuisance (perhaps invasive?) as corms spread to other garden areas. Mites may draw sap (stipple) leaves in a dry summer.

Panicled Raintree Promises Showy Lantern Pods

Posted by Hugh on July 15th, 2011

Chinese Flametree With Autumn Lantern Seed Pods

Chinese flametree (Koelreuteria bipinnata) is also called bougainvillea raintree. This rare tree, available primarily from internet nursery commerce, deserves to be planted more. It has performed well in the Southern Appalachian region (USDA zones 6-b and 7) and is questionably hardy further north.

Flametree is less popular in Southeastern landscapes than goldenrain tree (K.paniculata). Low branching and broad canopy limits its landscape use to a small 25-30 foot tall specimen tree. Very showy dense terminal panicles of small fragrant yellow flowers appear in mid- to late summer, nearly 3-4 weeks after goldenrain tree (K.paniculata).

Large clusters of two-inch-long showy rose-colored “Chinese lanterns” form quickly after flowering which persist to mid-October. The papery thin seed husks retain their pink color indoors in dry flower arrangements. The bark on Chinese Flame-Tree is smooth and light brown when young, becoming more ridged or furrowed as the tree matures.

Flametree’s dark green summer compound leaves, each 1-2 feet long, turn yellow for a short autumn interlude before falling. Later, numerous fertile seeds drop, which potentially, may raise invasive issues for this species.

(See also blog on Goldenrain tree (K. paniculata) published 7-1 -11)

Galinsoga -The Gardener’s Weed

Posted by Hugh on July 13th, 2011

The dreaded galinsoga

Thirty plus years ago a gardening friend passed along this tidbit: “galinsoga (Galinsoga parviflora) is the gardener’s weed”. Galinsoga grows only in cultivated soils such as in your vegetable and/or flower garden from part shade to full sun. It prefers moist soil but grows almost anywhere, even between cracks in a sidewalk. Its thin leaves may wilt in the hot midday summer sun, but recover by nightfall.

The rule is to never allow galinsoga to bloom. It produces abundant seed and those seeds frequently germinate within days, potentially producing multiple generations in one growing season. The seeds overwinter in the soil and become a bigger nuisance in subsequent years.

The hairy leaves and stems grow rapidly to 18-24 inches in height and begin blooming when plants are only 6 inches tall. Tiny 5-petalled white ray flowers surround a yellow disk center. Flowers are less than ½ inches wide.

Hand pulling or hoeing, followed up by mulching, is most effective control measure. Remove galinsoga before it flowers. Seeds already in the soil continue to germinate throughout spring and summer. Pine straw, grass clippings or compost serve as excellent mulches.

Preen® (trifluralin) is a pre-emergent herbicide for garden use. Read and understand the label before using.

Summer Blooming Oyama Magnolia

Posted by Hugh on July 10th, 2011

A friend on vacation sent me the attached photo from Wooster, Ohio. When I told him that it was Oyama magnolia (Magnolia sieboldii), he asked why gardeners are not growing it. Good question!

Oyama magnolia is a 10-15 feet tall (and equal spread) deciduous tree or large shrub from eastern Asia. It prefers to grow in partial sunlight and in moist, well drained loamy soil (USDA zones 6 -8). Oyama is an ideal tree/shrub magnolia for a small garden. Spring bloom is in May, avoiding the threat of frost injuring the flower buds of this later blooming magnolia.

The 3-6 inch long medium green foliage is first to appear in April, coated with a silvery pubescence. White nodding egg-shaped flower buds appear in late June, and blooms appear intermittently thru most of the summer. The 1-3 inch wide saucer shaped flowers are white, centered by crimson stamens within. Oyama begins to flower at an early age.

Leaves turn pale yellow before abscising in mid-autumn. Small pink fruits appear in late summer, and split open to reveal orange-red seeds in late September. Branch bark wood is light gray.

Feed magnolias with a slow release fertilizer in early spring. They benefit from annual mulching. Pruning shrub to desired shape and size, and to remove dead or broken branches.

Oyama magnolia is available from a few on-line specialty nurseries.

Invite Sonata Cosmos Into Flower Beds

Posted by Hugh on July 7th, 2011

'Sonata Pink' Cosmos at BuGa Show, Koblenz, Germany

Over the past few years a flower bed containing cosmos (Cosmos bipinnatus) has become a rare sight across the Southern Appalachian region (USDA zones 6 and 7). Not so, at the recently visited BuGa National Gardening Show 2011 in Koblenz, Germany.

Called by some “Mexican asters”, cosmos produces big 3- inch wide red, white, pink or purple blooms. Their lacy or fern-like foliage lends a different textural feel to a flower garden.

Cosmos blooms from the late spring thru summer. The 18 – 24 inch tall ‘Sonata’ series are personal favorites. These dwarf cosmos look super planted in front of garden beds and in containers. Add a fresh bouquet of cut cosmos flowers to your dining room table this summer.

Cosmos grows in any soil type and flourishes without special soil enrichment and heavy feeding. Overwatering tends to reduce overall plant vigor and flowering. Cosmos are sun lovers and do irrigate over exceptionally long summer dry spells.

Deadheading promotes renewed flowering and reduces the dread of self-sowing in the garden. Tall growing (3 feet or more) cosmos may require staking, whereas the shorter Sonatas do not.

Species cosmos are popular in wildflower and meadow gardens where they attract butterflies and honeybees.

Tough And Reliable Chinese Astilbes

Posted by Hugh on July 4th, 2011

Astilbe chinensis at Kingwood Center, Mansfield, Ohio

Astilbes (also called “false spireas”) are favorite late spring flowering perennials. The Astilbe x arendsii hybrids from Germany are most popular and available at local garden centers. Astilbes are very hardy in the Southern Appalachian region (USDA zones 6 and 7).

If low maintenance is your goal, try Chinese astilbe (Astilbe chinensis var tacquetii). Their care is less demanding than the Arendsii hybrids. Chinese astilbes bloom nearly two weeks later. Group many together for mass effect of plume flowers and dense compound foliage.

The ‘Visions’ series are personal favorites. The original ‘Visions’ bears raspberry plume flowers. Later cultivars, ‘Visions in Red’ and ‘Visions in Pink’, are also nice. Plants form a 9- inch tall mound with bronze-green leaves and dense panicles of raspberry colored flowers on 12-15” tall stems.

‘Pumila’ forms a thick ground cover with 8-12 inch tall lavender purple flowers in mid- summer. ‘Superba’ is a taller flowering form and more available in nursery commerce.

Chinese astilbes grow in moist, well drained soils and partial sunlight. Two –year old established plants are exceptionally drought tolerant, have no serious disease or pest problems, and are generally not a favorite of deer.

Goldenrain Tree – A Golden Shower of Bloom

Posted by Hugh on July 1st, 2011

Golden Raintree in Urban Parking Lot

Goldenrain tree (Koelreuteria paniculata) is a medium sized landscape tree maturing to 30-40 feet in height and spread with rounded canopy. A native of China, Japan, and Korea, the tree is winter hardy in the Southern Appalachian region (USDA zones 6 and 7). Large panicles of dark yellow flowers set off a golden fireworks for your 4th of July celebration.

Individual flowers barely measure a 1/2″ wide, but the multi-branched floral panicles measure 10-15 ” across. The bipinnately compound leaves are also large at 8 to 14 inches in spread. The medium green colored spring/summer foliage turns pale green in autumn before dropping.

Yellow-green triangular 1 to 2 inches long seed capsules soon follow after flowering. The papery seed capsules are often called “Chinese lanterns” and are a significant ornamental feature. Each lantern may contain 1-3 hard black globular seeds. By early fall the capsules have turned dark brown. Bark of old trees is ridged with shallow reddish brown furrows.

Goldenrain tree grows in a wide range of soils, including high pH soils. It’s rarely bothered by pests and demonstrates exceptional heat and drought tolerances. It excels as a specimen yard tree, or utilize planted along wide avenues or in parking lots with their lower branches limbed high.

Seed viability may potentially be an invasive plant issue in some Southeastern states.

Looking ahead: see also blog on Chinese flametree to be published 7-15-11

Biltmore Estate and Gardens

Posted by Hugh on June 30th, 2011

Biltmore House

I have visited the Biltmore Estate on several occasions, but my May visit this year was special. I had the opportunity to interview Parker Andes, Biltmore’s Director of Horticulture, and Bill Alexander, Landscape and Forest Historian.

Few properties match the overall grandeur of Biltmore Estate and Gardens in Asheville, North Carolina. Biltmore is a historical perspective of America over a century ago. The property was designed by Fredrick Law Olmstead, Sr., deigned the father of American Landscape Architecture. Famed botanist and horticulturist Chauncey Beadle maintained the grounds nearly 60 years.

Olmstead took on over 1000 acres, an area some 50 times larger than another of his grand projects – New York’s Central Park. The 3- mile entry driveway winds through dense woodlands to the estate home and gardens of tycoon George Vanderbilt. Along the drive are native rhododendrons and azaleas (Rhododendron spp.), mountain laurels (Kalmia spp.), hemlocks (Tsuga spp.), pines (Pinus spp.) and thick stands of bamboo (Bambusa spp.).

Espanade of Replanted Tulip Poplars

A double lined esplanade of 2^nd generation tulip poplars (Liriodendron tulipifera) frame the entrance to Biltmore House. The four-acre Walled Garden and the 16th-century Italian garden are adjacent to the house.

The Spring Gardens Festival had just ended, and newly-planted summer annuals replaced thousands of tulips, hyacinths, etal. The adjacent rose garden was fully in bloom. According to Bill Alexander, the garden staff is launching a multi-year rose trial of varieties gathered worldwide.

Rose Garden at Biltmore

Many mature specimen trees and shrubs are found on the property: one of the first dawn redwoods (Metasequoia glyptostroboides) brought to the U.S. from China in the early 1940’s; a century-old Persian ironwood (Parrotia persica) with its mosaic patterned bark, and a mature Katsura tree (Cercidophyllum japonicum). The enormous size and majesty of the Olmstead- planted beeches and oaks is always breathtaking.

Growing Berries at Antler Hill Farm

I concluded the delightfully full day with a trek through the new Antler Hill area, where the Winery and Creamery (not the original) are situated. Close by is the Historical Farm, which includes the livery, coppersmith, and woodworking shops. Visitors have the opportunity to play games popular in the 19^th and early 20th centuries. An antique farm equipment museum was recently added near the fruit, vegetable and herb gardens.

Magnificent Mountain Laurels (Kalmia)

Bringing Biltmore Gardens home to your garden is no longer wishful thinking. The horticultural team has partnered with several nurseries around the world to reproduce many of the fabulous plants which have grown on the grounds for over a century. Periodically, I plan to feature these horticultural treasures in my blog: whatgrowsthere