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

Delightful Dragonflies And Damselflies

Posted by Hugh on June 27th, 2015

Dragonfly (Photo by Dr. Frank Hale, UT Entomologist, Nashville)

Damselfly (Photo from Dr. Frank Hale, UT Entomologist, Nashville, TN)

Watch them flitter… Dragonflies and damselflies, also called “darning needles” and “dining needles”, are common spring/summer inhabitants in many U.S. gardens, particularly around water gardens, streams and other water features, where they reproduce. Adults lay eggs on the plants around the water’s edge; the nymphs hatch from the eggs and live under water for months or years before they mature and fly. These insects are in the order Odonata.

Dragonflies and damselflies are beneficial insects and delightful to watch. Young children enjoy seeing them flit around reeds, lilypads, and flowers; children frequently cause panic when they fly to close. However, they do not sting or bite people. Dragonflies and damselflies are predators of other insects, including mosquitoes and beetles. They have excellent eyesight and are fast nimble fliers.

Both dragonflies and damselflies tend to stay close to where they were born. Key differences between them is that dragonflies rest with their wings held open; damselflies fold their wings back over their abdomens while resting. Some people refer to dragonfly nymphs (immatures) as “skimmers”.

Dragonflies live around water ponds and features, such as a large urn or half whiskey barrel filled with water. Dragonflies are most active on warm spring and summer days. They prefer ponds with plants growing in or around it where the nymphs can hide and hunt. Young fliers will rest (bask) on rocks and twiggy shrubs; tall cattails, reeds and grasses are great places to perch on.

Dragonflies and damselflies are an important food source for various birds. Pond fish or frogs will prey on the nymphs.

Credit: idea for blog originates from writings of Rick Darke and Doug Tallamy whose books on garden ecology should be general reading for children and adults.

Persian Shield Offers Radiant Foliage Color

Posted by Hugh on June 24th, 2015

Persian shield and coleus at Biltmore Estate, Asheville, NC

The iridescent purple foliage of Persian shield (Strobilanthes dyerianus) radiates in a warm summer garden in the U.S. Here it is treated as an annual (USDA hardiness zones 9-11). Persian shield is native to tropical Myanmar (formerly Burma), where it is a 3-4 feet tall soft-stemmed evergreen shrub or subshrub. In temperate regions it grows only 1-3 feet.

Dark green leaves (to 8 inches long) are flushed with silvery-purple variegation above and dark purplish tints beneath. In the tropics, tiny violet 5-lobed flowers appear in short cone-shaped inflorescences. It rarely blooms in non-hardy regions.

Persian shield prefers compost-rich, moist and fertile soil. Two keys to successfully growing Persian shield are light exposure and plentiful soil moisture. Depending where you garden, plant in full sun or partial sun or moderate shade. It thrives in the heat and humidity of the southeastern U.S. In cooler areas (zones 4-6), full day sunlight is ideal. Where summer temperatures sizzle, a few hours of early morning sunlight is adequate. Partial shade brings out the deepest purple in the leaves.

From spring through summer Persian shield plant responds to constant feeding. Fertilize it with a water soluble products such as Miracle-Gro™, Nature’s Source™, or Daniels™ at half rate and twice as often (contrary to package directions) to maximize shoot growth and not to burn the roots.

Pinch stems every few weeks to develop a compact, bushy plant. Use the pinched cuttings to start new plants (see below). Otherwise, Persian shield will develop a 3 feet stem, that will likely need staking to prevent flop over. Persian shield has few, if any diseases and pest problems. Occasionally, spider mites may discolor the leaves.

In the fall, with killing frost pending, take cuttings from garden plants and grow them as house plants over winter. Cuttings easily root within 3 weeks in moist sand and/or vermiculite and held in a plastic tent for high humidity. Provide moderate light, but not direct sunlight, so as not to burn the tender unrooted cuttings. Transplant into good potting soil and keep adequately watered and fertilized until mid to late spring.

Obedient Plant For Late Summer Blooming

Posted by Hugh on June 21st, 2015

Late Summer Blooming Obedient Plant

Obedient plant (Physostegia virginiana) is native from the Central to Southern U.S. and northern Mexico (USDA hardiness zones 3-9). It is called “obedient plant” because each tubular flower will, upon being pushed in any one direction, stays in new position.

From July to September obedient plant is valued for its late season pink or white flowers. Tubular, two-lipped pink flowers in upright terminal spikes (each to 12-18 inches high) bloom throughout summer atop stems rising to 3-4 feet high and 1-2 feet wide. Flowers attract numerous pollinating insects.

Obedient plant tends to seed-in and also spreads prolifically by rhizomes. The leading cultivar is a non-spreading form appropriately named ‘Miss Manners’; it grows more tidy and is better behaved; its snapdragon-like flowers are pure white. It selected by Darrell Probst of Garden Visions in Hubbardston, MA. Miss Manners is a shorter grower, 18 inches high and 12 inches wide. It has a clumping habit, good secondary branching, and will rebloom when deadheaded. Foliage is deep green, glossy foliage.

Obedient plants grow best in average well-drained soil and in full sun. Plants growing in light shade or in rich, highly fertilized soils tend to flop and need staking. Prune back plants by half in late spring to improve branching and minimize possibility of floppiness. Plants should be divided every 2-3 years to keep beds neat.

It has no serious disease or pest problems and deer generally avoid it. In wet summers rust disease may be troublesome. Obedient plant naturalizes freely and eventually becomes overcrowded in a wildflower or meadow garden. It may be sited in rain gardens as plant tolerates temporary flooding. Flowers are a welcome addition in floral arrangements because flowers obediently hold in almost any position you desire.

Vanilla Strawberry™ Hydrangea

Posted by Hugh on June 18th, 2015

‘Vanilla Strawberry’ Hydrangeas at Biltmore Estates, Asheville, NC

Vanilla Strawberry™ hydrangea (Hydrangea paniculata) is a new peegee hydrangea selection introduced from France and it is really catching on with U.S. gardeners (USDA hardiness zones 4-9). This exceptionally cold hardy hydrangea blooms from late June thru early September. Blooms are enormous and stand upright. Following a heavy summer shower, saturated floral trusses temporarily bow down under their sheer weight, but gradually recover.

Flower color varies with age: new blooms open green, turn creamy white, to blushing pink, and finish rosy pink! New blooms are produced over 3 months. Cut flowers make great additions to fresh and dried floral arrangements.

Vanilla Strawberry is a vigorous grower and low-maintenance. Shrub is a well-branched and reaches 6 to 7 feet high and 4 to 5 feet wide in only 2-3 years. Grow panicle (“peegee”) hydrangeas in full sun in zones 6 and further north; in southerly climes, provide full morning sunlight and moderate afternoon shade. Hydrangeas thrives in moist, well-drained soil. Feed hydrangeas in early spring with a season-long slow-release fertilizer. Apply 2-3 inches of an organic mulch in the spring to conserve soil moisture. Irrigate during long summer dry spells.

Peegee hydrangeas look great as a deciduous hedge, or scattered in an open woodland garden, or as an individual specimen shrub. It can also be trained as a single trunk tree. They are troubled by few disease or pest problems. Since they bloom on current season’s wood, prune in late winter to reduce plant height and spread and to remove weak thin branches. Hydrangeas attract several kinds of butterflies.

Lots Of Stokes Asters To Pick

Posted by Hugh on June 15th, 2015

Stokesia ‘Peachie’s Pick’

Stokes aster (Stokesia laevis) is an underutilized herbaceous perennial. It is indigenous to the southeastern United States (USDA hardiness zones 5-9 and AHS heat zones 4-11). Many attractive cultivars are now available (see below). Most stokes asters produce mostly blue and purple colored floral cultivars, but violet, yellow, white, and blended color forms are also available.

Stokes aster prospers in full sun but does tolerate very light shade. A well-drained soil is absolutely essential; it tolerates a wide range of soil types. A one year-old established clump is moderately drought tolerance. Soppy winter soil is the usual cause of losing Stokes aster; few garden diseases and pests trouble this perennial.

It bears large showy flowers from late spring through summer. Blooms are attached to short stalks and sit slightly above the foliage canopy. Most cultivars produce two and more flushes of flowers if deadheaded immediately and irrigated over dry periods. Fertilize at planting time or in early spring with a slow-release product such as Osmocote™, Nutricote™, or Nursery Special™.

Cultivars:

White flowering – ‘Alba’ and ‘Silver Moon’

Blue-flowering – ‘Blue Danube’, ‘Blue Moon’, ‘Blue Star’, ‘Klaus Jelitto’, and ‘Wyoming’.

Yellow flowering – ‘Mary Gregory’ (large 3-4 inch wide lemon yellow).

Deep purple flowering – ‘Honeysong Purple from Wayside Gardens of Hodges, SC; the tint deepens as the flower ages, contrasting with white stamens and red overtones.

Lavender-blue flowering – ‘Omega Skyrocket’ bears on long stalks, a trait that endears it with cutflower enthusiasts. A white selection is also available.

‘Peachie’s’, often listed as ‘Peachie’s Pick’ in nursery catalogs, is the cultivar that gets the most buzz. It was selected by Peachy Saxton in Meridian, MS. It bears large lavender-blue flowers that stand tall above the plant foliage. It blooms repeatedly from mid-June to frost.

It has large 2- inch diameter lavender-blue flowers on erect 18-inch stems from mid-summer onward. Peachie’s Pick forms a tidy 10-12 inches tall and 18-20 inches wide mound of deep green foliage; foliage is evergreen during most winters in zones 7-9.

Swamp Azalea Deserves More Garden Space

Posted by Hugh on June 12th, 2015

‘Lemon Drop’ Swamp Azalea (Photo by Jay Jackson)

‘Miss Lindy’ -pink selection from Jay Jackson (his photo)

Swamp Azalea (Rhododendron viscosum, formerly R. serrulatum) is very different among deciduous azaleas. Most rhododendrons (azaleas) do not care for soppy, poorly drained soils. This U.S. native is an exception, indigenous to swamps, bogs, stream edges and wet lowlands from southern Maine to northeastern Ohio south to Florida and Alabama. Add that it is also exceptionally winter hardy (USDA hardiness zones 4-9). If your property has a stream, pond, or leach field, this species is a good choice.

Swamp azalea grows 8-10 feet tall and 6-8 feet wide. It is an early summer bloomer with abundant long tubular flowers that some might confuse as wild honeysuckle (Lonicera spp.). Its spicy, clove-scent fills the late June-July garden air and attracts butterflies and hummingbirds. The 1 to 2 inches long white flowers are sticky to the touch. Pale pink and lemon yellow forms can be observed in the wild.

Two-year old established plants are highly drought tolerant. The glossy green summer foliage is highly disease and pest resistant; some wild forms emerge with bluish green leaves in the spring. All plant parts are poisonous and deer usually keep their distance. Among the native deciduous azaleas, swamp azalea’s flame red foliage color is exceptional. Pruning is best after flowering to manage plant height and spread.

Swamp azalea is best grown in acidic (pH range between 5.0 – 6.0), compost-rich, well-drained soil and under partial shade. Full morning sunlight in northerly zones (zones 4-7) is adequate. Some seaside selections are very salt tolerant, and is best sited away from strong winter winds.

Roots are fibrous and grow near the soil surface. They benefit from annual mulching (wood chips or pine bark or needles). Plants slowly naturalize from root suckers.

Cultivar list includes ‘Lemon Drop’ , ‘Parade’, ‘Pink Mist’ , ‘Pink Rocket’ among others.

Japanese Hydrangea Vine Worth The Wait

Posted by Hugh on June 10th, 2015

Flower/foliage of cultivar ‘Moonlight’

5 year old Schizophragma hydrangeoides

Japanese hydrangea vine (Schizophragma hydrangoides) ‘Moonlight’ is a deciduous woody vine (USDA hardiness zone 5 to 8). It is closely related to climbing hydrangea vine (Hydrangea anomala ‘Petiolaris’).

This ornate climbing vine is valued for its silvery, silvery-green, heart-shaped foliage and large, flat-topped, lace cap hydrangea-like clusters (8-10 inches across) of creamy white flowers. Initially, it starts out slowly, but will cover a 5 square foot area on a wall and puts on a fabulous flowering show after 5 years.

The 8-10 inch wide creamy -white panicled blooms are comprised of numerous fertile florets surrounded by sterile outer flowers that each have only one spade-shaped petal. They appear in late June into July in Tennessee bloom for 6 to 8 weeks. Flowers are lightly fragrant up close. Leaves measure 3-5 inches across with good yellow fall color.

This woody grows against a wall, fence, or large tree. Fine adhesive rootlets emerge from young stems and attach to the mortar or brick surface. Reddish-brown stems provide a little winter interest. The silver-green leaves have long petioles with deep-green veining.

Japanese hydrangea vine is planted in part sun to partial shade for best flowering and foliage. Grow it in rich, medium moisture, well-drained soil. Fertilize lightly in early spring, but do not over stimulate. Prune in late winter to early spring to remove any winter injured stems and to contain growth. A single plant will eventually grow 20 to 30 feet or more wide. Space multiple plants 6-9 feet apart along any long wall to be covered. Insect or disease problems are rare.

Vine growth rate: over the first two years growth rate is slow, but gains speed in subsequent years. Plants begins blooming within 3 years which is a lot better that hydrangea vine. It is not as pH sensitive as hydrangea vine.

Managing Leaf Spot Infections

Posted by Hugh on June 8th, 2015

Leaf spotting on Hosta

There are nearly 1,000 fungal pathogens that cause leaf spot diseases on garden plants. Fungal leaf spots vary in size—from the size of a pinpoint to lesions that consume the entire leaf. Many leaf spots are tan to dark brown in color and may be circular, angular or irregular in shape.

Some of the common leaf spot-causing fungi are Alternaria, Ascochyta, Cercospora, Colletotrichum, Fusarium, Gloeosporium, Helminthosporium, Phyllosticta, Ramularia and Septoria. Generally, they do not kill plants but mar their attractiveness.

Most leaf spot diseases require cool conditions, wet foliage, high humidity and little air movement. Crowded plants often lead to leaf spot infections. Long intervals of wet weather in spring and summer or overirrigating enhances infection outbreaks.

The first rule is to keep foliage as dry as possible. Water at times of the day when the foliage will quickly dry out; avoid late night irrigation. Secondly, increase air movement around plants.

Learn to properly identify leaf spots by the symptoms and adopt the best control strategies. Leaf samples may be sent to a diagnostic clinic at your state’s university lab or local Extension office.

A number of fungicides are labeled for controlling a wide range of leaf spot diseases. Some of the most effective for leaf spots include Pageant (pyraclostrobin + boscalid), Medallion (fludioxonil), Eagle/Systhane (myclobutanil), Chipco 26 GT (iprodione) and Daconil (chlorothalonil).

Remember that fungicides are protectants and not cure-alls. Applied the fungicide before symptoms (leaf spotting) is detected. These products can prevent fungal leaf spots from spreading. Good cultural practices and irrigation timing, along with proper preventative or control strategies will greatly reduce leaf spot severity.

Credit: Thank you to Paul Pilon, Ball Horticulture, Chicago for information in this blog.

Sunset Cutie® Gaillardia

Posted by Hugh on June 5th, 2015

‘Sunset Cutie’ Gaillardia (photo by Paul Pilon)

New from PlantHaven is a new 15-inch gaillardia (Gaillardia x grandiflora) called Sunset Cutie® with red-bronze flowers edged in creamy yellow. It will leave a bright fiesta feel to our home landscape.

Sunset Cutie has a compact mounding plant habit. It will bloom nonstop on your patio this summer or in your perennial flower bed. It is hardy to Zone 5 to 9.

Grow gaillardias in full sun and well-drained soil or container media. Soil (media) drainage is an absolute key to plant and flowering longevity. Keep plant(s) adequately watered and fertilized. Feed container grown plants monthly with a water soluble fertilizer such as Miracle-Gro™, Schultz™, or Nature’s Source™.

Gaillarida or “blanket flower” is seldom bothered by deer. Deadheading keeps plant(s) blooming from late spring to autumn’s first frost.

Winter Damage On Crape Myrtles

Posted by Hugh on June 2nd, 2015

Crape myrtles suckering from base

Winter damaged crape myrtle

Extremely cold winters of 2013-14 and 2014-15 have damaged many cultivars of crape myrtles (Lagerstroemia x indica). Don’t assume that new crape myrtles are hardy; many are rated hardy only to zone 7. Several of the U.S. National Arboretum cultivars are hardy in zone 6. Gardeners living in the Mid-Atlantic or the lower Midwest states, where crape myrtles are iffy, frequently start over by cutting them back near the ground in spring and fertilizing.

Is your crape myrtle dead? First, determine if the tree (shrub) is alive? Nick the bark with your fingernail or a knife to determine if the wood is still green (living). Use a chain saw, pruning saw or loppers to cut the trunk(s) close to the ground. Within a few weeks green shoots will begin sprouting around the base. Choose 3 – 5 well-spaced shoots to become the new main trunk(s) and cut off the rest. Large specimens can sucker back and even bloom in late summer and the early days of autumn.

Fertilize every 6 – 8 weeks with a high-nitrogen fertilizer until mid-August and no more through the end of the year. Maintain 2 – 3 inches of mulch and keep soil and mulch away from the shrub/tree base. Irrigate crape myrtles bi-monthly in the absence of rainfall.

When replanting, set crape myrtles in the ground shallow and never deep in the planting hole. Stop the practice of hat-racking, commonly called “crape murder”, as it places a tree under stress and more susceptible to winter freeze damage. Do not prune crape myrtles in the winter months (early March in most areas).

Finally, select exceptionally cold-hardy cultivars, such as ‘Natchez’ (tree form, white blooms), ‘Hopi’ (shrub, medium pink), ‘Acoma’ (shrub, white).