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

Fall In Love With Sweetheart Tree

Posted by Hugh on August 20th, 2012

Korean Sweetheart tree (Euscaphis)

The late J.C. Raulston introduced euscaphus tree (Euscaphus japonica) to gardeners in the 1980’s. Tennessee nurseryman Don Shadow is credited with naming it “Korean sweetheart tree” which has become its more popular name. It is reliably winter hardy to USDA zone 6-b.

Sweetheart tree is a small 15-20 foot tree or large shrub. The pinnately compound foliage is comprised of 7-11 leaflets which are glossy and feel thick to the touch. Leaflets hold their dark green color through the summer months. Foliage reportedly turns burgundy red in the autumn, but my tree of 20 years has finished greenish yellow every year.

A young tree branches low to the ground and its bark has a brownish purple skin with thin white lines running vertically. A 25 years and older tree exhibits a dark gray bark.

Small terminal clusters of creamy white flowers open in late May and early June. While flowers are noticeable through the compound foliage, they are not stunning compared to many showier trees and shrubs also blooming at this time.

In late summer the bright red fruits will likely capture your attention. Multiples of 1/2 inch wide, heart shaped seed capsules are grouped together, and turn cherry red in early September. The capsules open to reveal 1-3 shiny black seeds within.

Sweetheart tree grows best in a compost rich, well-drained, and moderately acidic garden soil. Grow sweetheart tree in full sun (under irrigation) or in part shade (2-3 hours sunlight and no irrigation).

Strong Vertical Presence of Serbian Spruce

Posted by Hugh on August 17th, 2012

Serbian spruce at Arnold Arboretum in Boston

Serbian spruce (Picea omorika) rises as a tall spire in the urban landscape. A mature tree may reach 50 to 60 feet high and it creates a narrow footprint of 15 to 25 feet wide. Lateral branches uniquely bend downward while the growing tips sweep gracefully upward.

Annual growth rate is slow at 12-15 inches. Two-thirds of the short dark green needles lay flat. Needles are lustrous on the upper surface with two prominent white bands on the underside. Oval-shaped 2 ½ inches long cones hang downward, bluish-black early and light cinnamon at maturity.

Serbian spruce is highly adaptable. It grows well in full or partial sunlight (6 hours recommended) and rooted in moist well-drained soils with a wide pH range. A 3-year and older established tree handles summer dry spells and rough urban environs. A nursery-grown tree transplants well in the early fall or late winter periods from container or balled and burlapped (B&B) stock. It is northern hardy to USDA hardiness zone 4 and with good heat tolerance to zone 7-a. It becomes heat challenged past this point.

Serbian spruce deserves a more prominent place in commercial and residential landscapes. Few diseases and pests trouble this staturesque tree. You can group several together as a windbreak or privacy screen or plant a single specimen, where ground space may not be plentiful.

If you are searching for an alternative to the oft-used Norway and Colorado spruces, try Serbian spruce. Dwarf and weeping cultivars are also available through e-commerce specialty conifer nurseries on-line.

Common Ditch Lilies

Posted by Hugh on August 14th, 2012

Hemerocallis fulva

A native of eastern Asia, tawny daylilies (Hemerocallis fulva) are often called “ditch lilies”. You see them growing along roadsides, in back alleys, and in old gardens, often in very poor soil. Their tenacious root system helps to stabilize steep slopes. They seem to thrive in places too difficult for most plants. They’re grow so easily that they eventuallyspread and become a nuisance.

They start blooming in late June in USDA zones 6 and 7. The 4 ½ inch diameter pale orange flowers are borne on sturdy 5- 6 foot tall floral scapes. Flowers last one day, and each scape bears multiple floral buds which open over a 3-5 week period. They come in a rainbow of flower colors, but orange is the most common. Some H. fulva cultivars are sterile and are less of a potential nuisance.

Ditch lilies prefer full or partial sun. In the lower South (USDA zones 7-b thru 9), ditch lilies are best sheltered from direct sunlight. Soils should be moist, loamy, slightly acidic, and well-drained. Fertilize with 10-10-10 or equivalent in early spring when new growth starts up and again in midsummer.

Ditch lilies form large thick clumps of arching, strap-like bright green leaves. Established clumps cope with summer heat and drought spells. Ditch lilies will grow in semi-shade, but produce more foliage and less flowers.

Group ditch lilies together in the wide border to naturalize. Because of their invasive tendencies, ditch lilies are ideal for planting in confined spaces such as in parking lot islands or in median strips on a busy highway.

They have few problems with pests and foliar diseases. Clumps spread quickly and should be dug up and divided every 4-5 years in early autumn. Occasionally, flower scapes develop aerial plant/root proliferations which can be easily rooted.

‘Hot Lips’ Turtlehead – A Late Summer Flowering Native

Posted by Hugh on August 8th, 2012

Turtlehead (Chelone) in late August

Turtlehead (Chelone spp.) is a U.S. native. Turtle-head shaped flowers appear in August and September. The 1 inch flowers open from bottom to top along the stem (s). Colors vary from bright white, creamy white, and white tinged with pink (depending on species and cultivar grown).

Pink turtlehead (C. lyonii ) is native to the Southern Appalachian region (USDA zones 5-8) and is an upright, clump-forming, rhizomatous perennial. It typically grows 2-4′ tall on stiff, square stems. New leaves emerge bronze green in early spring and quickly turns dark green. Full leaves are coarsely-toothed and up to 6 inches long.

Turtlehead grows sturdy in a compost rich, medium to wet soil in full or partial sunlight (6-hours minimum). Plants become floppy when grown in part to deep shade and often require staking. Be wary that turtlehead disperses seeds around the garden. No disease and pest problems are generally the rule, but powdery mildew may pop up if turtlehead becomes stressed out in dry soils or air circulation around plants is poor.

Butterflies, hummingbirds and other pollinators are attracted to turtlehead, and the plants are deer resistant. ‘Hot Lips’ turtlehead is an outstanding selection of C. lyonii with dark green foliage and knockout deep pink colored flowers. ‘Hot Lips’ stands 2-3 feet tall on sturdy deep red stems.

Ostrich Fern Likes It Moist And Cool

Posted by Hugh on August 6th, 2012

Slight Drought Injury on Ostrich fern (Matteuccia struthiopteris)

For sheer toughness ostrich fern (Matteuccia struthiopteris) handles most landscape situations (USDA hardiness zones 2-7a). Ostrich fern is commonly seen growing naturally in cool moist river bottom soils, 3-5 feet in height and spreading aggressively. Roots have a clumping rhizomatous nature. The fronds grow upright with a slightly arching form, typically to 2-3 feet in height under average garden care.

Ostrich fern is a deciduous fern which prefers moist, well-drained, slightly acidic to low alkaline pH soils in full to partial shade. It is no fan of drought, high heat and humidity and can only survive in cool moist shade in southern zone 7-a.

Ostrich fern earns its name for their feathery long “ostrich -like plumes”. In early spring the vegetative fronds emerge from a narrow pedestal or base as “fiddleheads”, which unfurl to a maximum length of 3-4 feet. The emerging fiddleheads (new fronds) are said to be quite delicious sautéed in oil or butter. By mid-summer the 2 foot spike-like fertile fronds arise in the center and turn dark brown and woody by late summer.

Well-established 2-3 year old clumps can survive in non-irrigated ground, but the vegetative fronds may appear brown and tattered. Medium green fronds mature to dark brown in mid- to late autumn.

No serious insect or disease problems trouble them. Group several together in moist woodland areas or adjacent to streams or ponds. Plant ostrich ferns with other shade garden favorites such as heucheras, astilbes, lungworts (Pulmonaria), hostas, and hakone grass.

The Boys Or Girls of Summer

Posted by Hugh on August 3rd, 2012

Shasta Daisy, Purple Coneflower, Black-eyed Susan

Gardeners are looking for simple plant combinations and this photo, shot at Kingwood Center in Mansfield, Ohio, shows three easy to grow perennials, “no-brainers” as some might call them. Originally, all three plants emigrated from the prairie where each coped with hot summers without much rainfall.

In the hands of modern plant breeders, each perennial has been greatly improved. All are disease and pest resistant. Some cultivars are fairly new, others are old-timers, and all are reliable:

‘Goldsturm’ or ”Little Goldstar’ black eyed Susan (Rudbeckia fulgida)

‘Becky’ or ‘Amelia’ Shasta daisy (Leucanthemum superbum)

‘Kim’s Knee High’, ‘Magnus’ or ‘Pow Wow Wild Berry’ coneflower (Echinacea purpurea)

Buy from local greenhouse growers or garden centers where you live. You may also order from reliable plant dealers on-line. All perennials should be purchased as vegetative cuttings and from “true to type” seed sources.

Prepare the planting bed in late winter. All perennials listed above grow in average garden soil, although they do benefit from generous additions of compost. Fertilize (10-10-10 or equivalent @2 lbs. per 100 square feet of garden bed) after planting the perennials. In addition, spread Preen® weed preventer over the bed after planting and irrigate after all chores are finished. Water your new perennial bed as needed through long dry spells during the first 6 weeks. Usually these tough prairie plants should handle the summer weather conditions ahead.

By mid-autumn after frost, cut (mow) the bed to prevent the distribution of perennial seeds. Rake up the plant debris and apply a fall application of Preen® to prevent germination of winter annual weeds.

Over the next 3-4 summers your new perennial bed should look glorious.

Dawn Redwood Is Back From Extinction

Posted by Hugh on August 1st, 2012

Dawn redwood (Metasequoia)

Dawn redwood (Metasequoia glyptostroboides) was thought to be extinct until the mid-twentieth century. In 1948 dawn redwood was re-introduced into North America from Sichuan-Hubei Provinces in China.

Dawn redwood grows in full sun and in well-drained, compost-rich soil. The tree struggles in dry or high pH soils. Dawn redwood will tolerate standing water for a brief period. It is often confused with bald cypress (Taxodium distichum) which grows in swampy ground as well as average landscape soils. If branched low to the ground, the trunk of dawn redwood may develop large swollen areas called “boles”.

Dawn redwood is a deciduous conifer. New spring leaves emerge bright green and darken to a medium green. In autumn the fine textured foliage initially turns pinkish tan and finishes reddish bronze before dropping. An attractive shredded reddish brown bark clothes a tapered trunk. Dawn redwood possesses distinctive “arm pits” or depressed areas under each branch, where it is attached to the main trunk. The straight trunk and redwood bark are dominant winter features.

Dawn redwood foliage remains fresh and clean all summer and is not plagued by disease and pest problems. Spider mites and Japanese beetles may injure the foliage occasionally, but its quick growth rate leads to a swift recovery. Dawn redwoods often mature to 90-100 foot tall specimen trees, and are suited for large properties such as public parks, golf courses and college campuses.

Gold Rush® (‘Ogon’) metasequoia is a gold-leaved form. It has a slower growth rate and matures to 50-60 feet.

Boxwood Blight Discovered on Pachysandra

Posted by Hugh on July 30th, 2012

Healthy Pachysandra Planting at Biltmore Estates in Asheville, NC

In June 2012 plant pathologists at the Connecticut Agricultural Experiment Station have confirmed a natural infection of pachysandra in the landscape by boxwood blight (Cylindrocladium pseudonaviculatum), the boxwood blight fungus. The infection originated from recently installed balled and burlapped (B&B) boxwood plants. A plant inspector in Fairfield, CT noticed that an established bed of pachysandra bed near the infected boxwoods exhibited unusual foliar symptoms.

Symptom on the pachysandra foliage included small to larger necrotic lesions with well-delineated margins. All of the necrotic lesions had well-defined, diffuse yellow haloes. No lesions were observed on the stems and no defoliation had occurred. The overall color of the pachysandra leaves were normal and dark green.

Source: NMPro Magazine (July 2012)

‘Morning Grace’ Spiderwort Is A Delicate Beauty

Posted by Hugh on July 26th, 2012

Tradescantia rosea 'Morning Grace' (photo supplied by North Creek Nurseries)

Morning Grace spiderwort (Tradescantia rosea ‘Morning Grace’) is a short growing spiderwort native from Maryland south to Florida. Its small size and clumping nature makes it a wonderful rock garden plant. It grows into 8″ tall x 8″ wide clump of narrow medium green leaves. At first glance this spiderwort’s foliage appears very grass-like.

Morning Grace has a long flowering period from May thru August in the Southern Appalachian region (USDA hardiness zones 6 and 7). Tiny triangular 3- petalled pink flowers stand just above the foliage. The blooms open early in the morning and close late in the afternoon. The lightly fragrant flowers attract numerous pollinating insects. Spiderwort is not troubled by deer.

Unlike the commonly grown spiderworts (T. virginiana), Morning Grace is far less aggressive and is welcome into my garden over other spiderworts which frankly become a weedy nuisance.

Spiderwort prefers a moist, rich, acidic soils in part shade, not in full sun or deep shade. It grows and flowers poorly in dry shade.

At a recent perennial plant show Morning Grace attracted rave interest. Attendees spotted tiny pink blooms and they liked to brush the slender foliage.

Tradescantia ‘Morning Grace’ was selected by Michael Jenkins.

Yellow Nutsedge Control Is In Your Hands

Posted by Hugh on July 21st, 2012

Yellow nutsedge

Yellow nutsedge, aka “nutgrass” (Cyperus esculentus) is a nasty weed found in lawn and garden areas. It is a sedge, and not a grass, and methods of eliminating it vary. Yellow nutsedge is easily identified by its yellow to light green glossy leaves and the triangular shape of the stem. It grows most actively during the warm spring and summer months.

Yellow nutsedge is a perennial which reproduces primarily by small underground tubers or nutlets. It also spreads by rhizomes (underground stems). The nutlets often spread from contaminated soil which you have transported into your garden.

Maintaining a healthy dense growing lawn or garden bed is best way to avoid yellow nutsedge infestations. For small infestations, judicious hand pulling will eliminate it. This may take several weeks as the underground nutlets may re-sprout.

Mid-spring thru early summer is the ideal time to control yellow nutsedge in the Southern Appalachian region (USDA hardiness zones 6 and 7). The plant is young, actively growing, and the nutlets have not matured. By late summer the seedheads have formed and is very difficult to control at this time.

For treating large infested areas, use of chemical weed killers (herbicides) may be your best option. Available to homeowners are herbicide products containing the ingredient MSMA (methanearsonate). MSMA is packaged under several product brand names. The herbicide works better if the lawn or garden area is irrigated a day or two prior to application. Continue to repeat herbicide applications until all nutsedge plants are eliminated.

For selective control of nutsedge in lawn areas, without injuring the lawn grass, Basagran™ (bentazon) and Manage® (halosulfuron) are available. However, these two products are not available to homeowners and are applied solely by certified landscape professionals only.