My Search Continues For A Hardy Gardenia

 

Gaardenia As Hedge Plant At Fast Food Restaurant in NC

Gardenia As Hedge At Fast Food Restaurant in NC

Non-hardy Gardenia in Tree form

Non-hardy Double Flowered Gardenia in Tree Form

 

 

 

 

 

 

 

The longer you garden, many plant species keep improving, including their winter hardiness. A few years ago, growing gardenias (Gardenia jasminoides) in a U.S. zone 6 garden was a dream. Today, hardy gardenias are a safe bet in zone 7 or in zone 6 in a protected area of the garden, away from wintry winds. Otherwise, gardenias make good houseplants.

Pure white fragrant flowers cover this lovely evergreen shrub in early summer. Single pinwheel shaped flowers are most common, but semi-double and double flowering types are also available. Cultivars vary in flower fragrance from a hint to highly scented.

Gardenias grow 2 – 6 feet tall and 3 – 6 feet wide, depending on cultivar and desired size after pruning. Gardenia care is similar to that of rhododendron or camellia. Provide morning sun and afternoon shade or in full day dappled sunlight. Locate gardenias near a home entry door, patio or deck, where you and your guests may fully enjoy their fragrance.

Whether planted in a container or garden bed, gardenias require moist, well-drained, acidic medium (soil) that contains lots of organic matter. Gardenias need watering when rainfall is less than an inch per week. Fertilize plant(s) every spring with an acidic type fertilizer such as water-soluble Miracle-Gro™ or Espoma Hollytone™.

Yellowing leaves indicates any of three possible problems. If it is the bottom foliage turning yellow, it could be under- or over-watering. If the upper leaves show interveinal chlorosis (yellowing), your gardenia plant needs an iron supplement or the soil is not be acidic enough. Gardenias are subject to a number of pests which can be managed using insecticidal soap.

‘Frost Proof’ and ‘Daisy’ are two that I have trialed in my zone 6 garden. The harsh winter of 2013-14 killed both varieties to the ground. By late June both cultivars had sprung back to life from the crown but did not bloom. A year later both cultivars were dead.

Hummingbird Favorite Plants

Salvia elegans favorite hummingbird plant

Salvia splendens favorite hummingbird plant

Albizia julibrissin is hummingbird magnet, potentially invasive in some areas

Albizia julibrissin is hummingbird magnet, potentially invasive in some areas

 

 

 

 

 

 

 

Many lists of hummingbird plants available in books, on the internet, and at garden centers aren’t very good hummer plants (e.g. petunias, daylillies).  Inclusion of whole genera (e.g. Penstemon or Aquilegia) is not correct as only a few species supply ample quality nectar to hummingbirds.

Creating a definitive list of the best hummingbird plants is nearly impossible as hummer species have different taste buds regionally. Note that preferred flowers  are tubular shaped and bloom in the summer. In addition, North American native plants are more to their liking than Asian or European species. Warning: some plant genera may be potentially invasive.

There are 115 genera and 330 species of hummingbirds worldwide. However, fewer than two dozen species spend summers in the U.S. and Canada, and very few species remain year-round. Most spend winters in Central America or Mexico and migrate north to their breeding grounds in the southern and western U.S. as early as February, and to areas further north later in the spring.

Perennials

  • Native Columbine (Aquilegia canadensis)
  • Coral Bells (Heuchera sanguinea) – fancy-foliaged cultivars provide less nectar
  • Red Beardtongue (Penstemon barbatus)
  • Bee Balm (Monarda didyma)
  • Cardinal Flower (Lobelia cardinalis)
  • Hollyhock (Alcea)
  • Delphinium

Annuals—some are perennials in southern climes where they are and bloom in the summer and early fall.

  • Salvia –several species such as Pineapple Sage (Salvia elegans), Scarlet sage (S. coccinea) or (S. splendens), Anise sage (S. guaranitica), Autumn sage (S. greggii)
  • Flowering Tobacco (Nicotiana)  – some, but not all attract hummers.
  • Canna (Canna indica) – short growing, small red flowers.

Vines—many good options here, both woody perennial vines and annuals

  • Crossvine (Bignonia capreolata)
  • Coral Honeysuckle (Lonicera sempervirens)
  • Trumpet Creeper (Campsis radicans) – Hybrid and Asian cultivars not as attractive to hummers.
  • Annual vines  - Spanish Flag (Mina lobata) and Cardinal vine (Ipomoea x multifida)

Trees/Shrubs

  • Red horsechestnut (Aesculus pavia)
  • Silk Tree (Albisia julibrissin)
  • Butterfly bush (Buddleia)
  • Catawba Rhododendron (Rhododendron catawbiense)
  • Rose of Sharon (Hibiscus syriacus)
  • Weigela (W. florida)
  • Asian honeysuckles (Lonicera)
  • Lilacs (Syringa spp.) -  select brightly colored

Delightful Dragonflies And Damselflies

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

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

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

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

Persian shield and coleus at Biltmore Estate, Asheville, NC

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

Late Summer Blooming Obedient Plant

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

 

'Vanilla Strawberry' Hydrangeas at Biltmore Estates, Asheville, NC

‘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

Stokesia 'Peachie's Pick'

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

'Lemon Drop' Swamp Azalea (Photo by Jay Jackson)

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

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

‘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

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

Leaf spotting on Hosta

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.