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

Spider Flowers Excel In Summer’s Heat And Humidity

Posted by Hugh on July 21st, 2016

Spider flower (Cleome) at Dallas Arboretum in Texas

Cleome ‘Senorita Mi Amor’ at Univ. of Tennessee Gardens, Knoxville, TN

Spider flowers (Cleome x hybrida) are top performing summer flowering annuals. Each year plant breeders introduce compact varieties to beautify flower beds and container gardens. Select among vegetative and seed produced types.

Spider flowers ask for weekly watering and full day sunlight (best) to achieve maximum blooming potential. They will grow in a partially shaded beds but bloom less and the plants tend to stretch.

Cleomes grow in average soil that is well-drained. Amending the soil with compost at planting and mulching are highly recommended to keep them highly floriferous. Rated as moderately drought tolerant, spider flowers prosper under weekly irrigation. Before planting work in lots of compost into garden soil or container media; broadcast a slow release fertilizer over the entire bed.

By mid-summer heavy feeding plants, particularly those in containers, become nutritionally deficient. Bottom leaves are first to turn yellow and bloom count becomes more sparse. Summer- feed container plants twice monthly with a water soluble fertilizer such as Miracle-Gro®, Peters®, or Schultz® at label rates.

Spider flowers are highly disease and pest resistant. Low compact forms require no staking compared to old-fashioned tall varieties that your grandmother used to grow.

Leading Cleome hybrids are:

Cleome Clio Magenta – 18 – 36 inches tall and 12 – 24 inches spread violet spider-like flowers with pink overtones.

Senorita Rosalita – 24 – 48 inches tall and 18 – 24 inches wide; do not self seed, keeps its lower foliage all season long; not prickly.

Sparkler series -reach 3 1/2 – 4 feet tall; plants are vigorous, and bloom heavily from spring to early fall; choice of white, blush and lavender.

Do Not Call Them “Weeds” Any Longer

Posted by Hugh on July 18th, 2016

‘Gateway’ Joe Pye in East Tennessee Garden

Helenium ‘Moerheim Beauty’

Butterfly weed (Asclepias)

Some plants deserve more respect. Over the years several U.S. native species have been tamed or domesticated. Yet, they retain their common name “weed”. Four popular former “weeds” are:

butterfly weed (Asclepias tuberosa)
ironweed (Vernonia lettermannii ‘Iron Butterfly’),
sneezeweed (Helenium autumnale), and
Joe-Pye weed (Eupatorium spp.).

Butterfly weed (Asclepias tuberosa) is a tuberous rooted long-lived perennial found in dry/rocky open woods, glades, prairies, fields and roadsides across the Eastern and Southern U.S. Plants are slow to establish and may take 2-3 years to produce flowers. Mature plants may freely self-seed in the landscape if seed pods are not removed prior to splitting open. Butterfly weed does not transplant well due to its deep taproot, and is probably best left undisturbed. It typically grows in a clump to 1-3 feet tall and features clusters (umbels) of bright orange to yellow-orange flowers atop upright to reclining, hairy stems with narrow, lance-shaped leaves.

Joe-Pye (Eupatorium spp.) has 4 to 5 feet select varieties which grow much shorter than the wild species. Sturdy stems are clothed with whorls of green leaves and topped with dome-shaped heads of lavender to pink flowers in mid-summer . Leading cultivars are: ‘Gateway’ -tiny, dusky rose-pink flowers form a huge, terminal, domed, compound inflorescence (12-18 inch diameter) in mid-summer to early fall, ‘Chocolate’, and ‘Little Joe’.

Ironweed (Vernonia lettermannii) is a compact, well-branched and vigorous plant. In late summer its vivid purple flowers are covered with butterflies and other pollinators. Ironweed is found growing in poor rocky soils, tolerates long periods of submersion (flooding), yet it is highly tolerant of hot dry sites. Cultivar ‘Iron Butterfly’ is a low mounding perennial form with narrow fine textured foliage. Plants are 2-3 feet tall and equal in spread. Sturdy plants are strongly anchored by a sturdy taproot. Branch terminals are covered by small clusters of deep purple disc florets in late summer.

Sneezeweed (Helenium autumnale) is an erect, clump-forming perennial which typically grows 2-3 feet tall (sometimes to 4 feet) on sturdy stems. It has a lengthy bloom season from summer into to early fall. Daisy-like 2 inch wide flowers have wedge-shaped, coppery-red (or yellow) rays that are notched at the tip and prominent, dark dome-like center disks. Leading cultivars are ‘Moerheim Beauty’.

All four perennials are favorite nectar plant of bees and butterflies, particularly the Monarch butterfly larvae. They prefer sunny sites with average to dry soils. Grow in average, medium to wet, well-drained soil in full sun. Over-fertilization may force plants to grow too tall. Although not required, three species, not butterfly weed (Asclepias) may be cut back in early July (at least 6 weeks before normal flowering) to reduce plant height and encourage branching, thus increasing bloom count, healthier foliage, and less need for support. Remove spent flowers to stimulate additional bloom. Divide clumps every three years to maintain vigor. They are disease and pest resistant and is not bothered by deer or other herbivores.

Late Summer Planting of Vegetables

Posted by Hugh on July 15th, 2016

Two Varieties of Cabbage for the Late Summer Garden

Cauliflower seedlings for sale at local Garden Center

Mid to late summer is the second season for planting many (not all) kinds of vegetables and herbs in many parts of the U.S. There is still 3 months or more of great growing weather ahead to harvest veggies planted now. You’ll enjoy great harvests for the Thanksgiving and perhaps the Christmas/winter holiday table (USDA zones 5-7).

Start with leafy greens for salads or garnish such as lettuce, pak choi, chard, and parsley. Carrots, beets, peas, green onions, spinach, radish, and some brassicas (cabbage, broccoli, cauliflower, and turnips) are good picks for the fall garden. Long season veggies such as tomatoes, cucurbits (cucumber, pumpkins, squash, and others), and sweet corn are not included.

Diseases, insects, and weeds are less problems. Crops like cabbage, cauliflower, and broccoli can be store outdoors in the garden row through most of the winter without them going to seed (bolting) or developing a bitter taste. Pick them as you need them for the dinner table. Transplants of lettuce, cabbage, broccoli, cauliflower, and others are available at local garden centers starting in August, depending on locality.

In summer start seedlings in pots, flats, or other containers in the cool home basement under gro-lights or in an outdoor cold frame; or directly sow seeds directly into the garden in dappled sun or light shade, but not in direct sun.

Set your new veggie transplants in a moist garden or raised bed, preferably around twilight when it is cooling off. In the mid-South protect new transplant seedlings under row covers or shade cloth for several days to acclimate them to sun and heat. Light sprinkling (spritzing) seedlings 2-3 times daily also cools seedlings.

Seedlings should adapt to outdoor beds within a week. Keep them adequately watered and fertilized. In USDA zones 8, 9, and 10, some fall-planted crops are harvested all winter long.

Comparing Oriental Lilies To Asiatic Lilies

Posted by Hugh on July 13th, 2016

‘Black Beauty’ Orienpet Hybrid Lily

Asiatic Hybrid Lily

Both Asiatic and Oriental lilies (Lilium spp.) are popular lilies in U.S. gardens. Hybrid cultivars share traits of both species. Lilies grow in a wide variety of soil types and are not pH sensitive. They flower in full to part partial sun (5 hours minimum of sunlight). Both prefer a well-drained soil and mulch to keep roots moist and cool.

Both Oriental and Asiatic lilies are top-notch garden performers. Oriental lilies enjoy cooler summer temperatures and are best planted in afternoon shade or all-day dappled sunlight in hotter climates. In mild climate summers, where the average temperature doesn’t usually exceed 90 degrees during July and August, Oriental lilies do equally well in full sun or light shade. No winter mulch is required if your climate is warmer than USDA hardiness zones 6-9.

Flower Fragrance: Asiatic lily flowers have little or no fragrance, and oriental lily flowers are large, exotic (often frilly), and heavily scented.

Cold Hardiness: Asiatics prefer colder winters to reset bloom (zones 1 to 9); Orientals (zones 6 to 9), down to zone 4 (if roots are mulched). Asiatic roots are not heat tolerant. Plants grow shorter and rarely require staking.

Staking: Asiatic lilies grow 1 to 6 feet tall. Oriental lily plants can grow 2-8 feet tall. Although stems are sturdy, Oriental lilies frequently need staking because their heavy trumpet flowers may topple over in windy or rainy weather.

Foliage: Asiatics generally have shiny 4 to 5 inch long leaves clustered close to one another on the stem. The leaf color is typically bright green. Oriental leaves are wider in the middle and longer, spaced further apart on the stem. Leaf color is typically dull green.

Dividing Bulbs: Asiatic lilies tend to double themselves from one year to the next. Oriental lily bulbs also increase in size and increase in bloom count each year. Bulbs should be harvested and divided every 3 to 5 years to prevent over-crowding in the bed.

Varietal Choices: Asiatics offer the widest choices of flower colors and choices from pastels to almost any colors of the rainbow. Asiatics usually come in single colors, while Orientals blooms are white, yellow and pink, with a different color on flower edges.

Bloom Season: Asiatics tend to bloom earlier in late spring. Generally, Orientals start blooming as Asiatic cultivars are finishing up. Mix the two, including hybrids, for a longer show in your garden.

Spice Up Dark Garden Spots With Heucherellas

Posted by Hugh on July 10th, 2016

‘Alabama Sunrise’ Heucherella (photo from Walters Gardens)

‘Buttered Rum’ Heucherella (Photo from Walters Garden)

Here come the heucherellas (x Heucherella), also called “foamy bells”. Heucherellas are hybrids that result from crossing two U.S. native genera: foamflower (Tiarella spp.) and coral bell (Heuchera spp.). Terra Nova Nurseries, a wholesale grower in Oregon, were the first to develop these hybrids. They possess the awesome foliage from both species parents.

One of my all-time favorites is ‘Sweet Tea’ foamy bells (Heucherella x ‘Sweet Tea’). It is a true garden performer. Large 4-inch wide palmate leaves become an orange colored tapestry which looks better from one month to the next. New spring foliage is bright orange. Some gardeners may opt to clip off flower stems to emphasize the rustic orange foliage colors. Leaves darken in the summer, and become a blend of orange and coppery shades in the autumn. Winter foliage is semi-evergreen in zones 6 and 7 and is fully evergreen further south.

Tiny creamy white, bell-shaped flowers open in late spring to early summer on sturdy stems, stand tall above the colorful foliage, and attract bees and butterflies.

Foamy bells want very little maintenance. They’re best planted in organically rich, well-drained soil and in a partially shaded area. Full morning sunlight and irrigation (or 1 inch rainfall weekly) are ideal condition. A new planting benefits from irrigation the first year; mulch plants to conserve soil moisture. Sweet Tea tolerates summer’s heat and dry periods because of its H. villosa bloodline (USDA hardiness zones 4–9).

Foamy bells are semi-evergreen through winter. Plants should be divided every 3-4 years in early spring before spring growth resurgence; remove and discard the old woody parts of the crown.

Leading cultivars at this time:

‘Sweet Tea’ – rustic orange leaves on 20 inch tall and 28 inch wide plants; tiny white flowers in early summer.

‘Buttered Rum’ – deeply cut, maple-shaped leaves begin caramel, changing to a rose-red for the fall. Sprays of small white flowers appear in late spring

‘Stoplight’- bright yellow leaves have a large, dark red blotch in the center which feathers out through the veins. Tiny white flowers on 12 inch tall stalks in late spring into early summer.

‘Sunrise Falls’ – brilliant chartreuse leaves with red veins; plants 8-12 inches tall

Oriental Spruce Stands Up to Southern U.S. Heat and Humidity

Posted by Hugh on July 7th, 2016

Oriental spruce at UNC Charlotte Botanical Gardens

Oriental spruce (Picea orientalis) stands as a tall spire in the urban landscape. A mature tree may reach 50 to 60 feet tall and makes a narrow stature or footprint of 15 to 25 feet in spread. 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.

Oriental 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 in zone 7.

Their branch silhouette is unique. Few diseases and pests trouble this statuesque tree. Group several together as a windbreak or privacy screen or plant a single specimen in a prominent place in commercial and residential landscape. Where ground area is not plentiful, capture the vertical nature of this unique conifer.

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

Dreaded Japanese Beetles Are Back

Posted by Hugh on July 4th, 2016

Japanese beetles on rose bush

Severe intraveinal feeding of JB on Rose foliage

In many areas of the Eastern U.S. Japanese beetles (JB) devastate the foliage, fruits and flowers of more than 300 plant species, particularly those in the rose family (Rosaceae). Adult beetles are approximately 3/8 inches in length with a dark metallic green head and metallic dark tan wings. In the soil JB grubs appear “C” shaped and feed primarily on grass roots, but also will feed on roots of corn, beans, tomatoes, and strawberries.

Grub populations between 7 and 15 per square foot can cause significant damage to non-irrigated turf. Grubs chew off grass roots and large dead patches of lawn result. Dead lawn patches can be rolled back like a carpet to expose the grubs in adjacent green areas. Natural predators such as moles, shrews, skunks, and crows may be also observed digging up grubs and causing damage to home lawns.

Japanese beetle life cycle

Adults emerge from the soil in late June (zone 7) to early July (zone 5), feed, mate, and lay eggs. Adult beetles mate and feed over a 6 to 8 week period and gradually die off. Each JB female can lay up to 60 eggs. She lays eggs in the turf. By late September grubs have grown to almost full-sized (about 1 inch long). In the fall, grubs begin to move deeper and spend the winter in a dormant state 2 to 8 inches below the surface. They begin to feed again in late April.

Inspect areas of brown turf and search in adjacent green areas for grubs and pupae. Insecticides are needed to control grubs and adults. Irrigating after applying an insecticide improves its action in the soil. However, too much rainfall (or over-irrigation) following an application may dilute the amount of insecticide in the soil. Grub infestations should be checked one week after an insecticide is applied. If after 10 days the grubs are still alive, apply a different product. Always read the pesticide label carefully before using.

The best time to apply insecticides for grubs is from mid-July to the end of September. Granular applied insecticides are generally applied with a spreader. Insecticides that kill grubs include products that contain imidacloprid, or biorational insecticides that do not harm beneficial insects in turf areas such as Ortho Grub-B-Gone™ ((halofenozide) and Acelepryn™. Milky spore disease (Bacillus popillae) has met with mixed success in killing JB grubs. It is sold under the brand names: Japidemic Doom™ and Milky Spore®.

Foliar sprays of contact insecticides kill JB adults, such as carbaryl (Sevin®), acephate (Orthene™), pyrethrins, and pyrethroids. Examples include pyrethroid products such as cyfluthrin (Tempo, Bayer Advanced Lawn & Garden Multi-Insect Killer), bifenthrin (TalstarOne), and permethrin (Spectracide Bug Stop Multi-Purpose Insect Control Concentrate™ and others).

‘Silk Tassel’ Sedge Shimmers In Shady Gardens

Posted by Hugh on July 1st, 2016

Carex-morrowii- ternofolia 'Silk-Tassel' at Ohio State Univ Gardens in Columbus, OH

Carex morrowii temnolepis ‘Silk-Tassel’ at Ohio State Univ Gardens in Columbus, OH

‘Silk Tassel’ Japanese sedge (Carex morrowii var. temnolepis) is an ornamental sedge from Japan (USDA hardiness zones 5 to 9). It is grown in shady areas for its narrow, variegated foliage. It grows slowly as a dense, grass-like clump to 12 -15 inches high and up to 2 feet spread.

Foliage bubbles up like a shimmering water fountain of fine-textured variegated foliage. Silk Tassel has ultra narrow, 1/8 inch wide thread-like leaves. Fine-textured leaves spill out over the ground. It has a soft, flowing, iridescent look and at first glance, may appear to be a sparkling, silvery green mound. A silvery white stripe at center with dark green margins runs the length of the narrow blade. Tiny greenish-brown flower spikes appear in mid-spring and are inconspicuous, supported on triangular stems. Silk Tassel is evergreen in the deep South.

Silk Tassel offers a great accent for patios and decks in decorative containers, or plant close together in masses. It looks super planted in a rock garden, perhaps nearby a dark igneous rock. It is easily grown in moist, moderately acidic, well-drained soils in partial day sunlight, preferably in morning or dappled light. Soil moisture is key, not too much(soupy) and never too dry.

Mix this fine textured beauty with bold leaf perennials such as hostas, lungworts (Pulmonaria spp.), brunneras (Brunnera) and other broad-leaved shade loving perennials.

Sedges may occasionally be troubled by aphids, and soil borne diseases such as Rhizoctonia. Deer leave most sedges alone.

Silk Tassel was introduced and named by Barry Yinger who brought it from Japan almost 30 years ago. It is primarily sold by mail order nurseries.

Yarrows Come In Many Size And Colors

Posted by Hugh on June 28th, 2016

Yellow flowering form of Yarrow

Salmon-Red Cultivar

Yarrow (Achillea millefolium) is a rhizomatous spreading perennial (USDA hardiness zones 3 to 9). The species originates from Europe and Asia and was introduced to America in colonial times. Today, yarrow is frequently seen naturalized along roadsides, fields, and gardens throughout the U. S.

Yarrow has fern-like, aromatic, foliage. Floral heads of 2-4 inch wide flattened corymb white flowers (and lots more colors) bloom from late spring through summer. Foliage emits a strong, somewhat spicy aroma that lingers when used in dried arrangements. Depending on cultivar, long-lasting flowers rise 1 ½ to 3 feet high.

Modern day cultivars possess strong stems, more upright forms and larger flowers. Flower colors range from pinks, reds, yellows, whites, and bicolor pastels. Showy flowers are irresistible to butterflies and make great cut and dried flowers.

Yarrow is a sun-loving, easy to grow, and performs well in any garden soils that is adequately drained. Where summers are hot and humid, plants are highly drought tolerant. Stems tend to flop over when grown in moist, rich soils. Protect plants from strong winds. Fertilize at planting time and in early spring as new growth begins to emerge.

Before flowering begins in late spring, reduce tall flowering cultivars by one-half to increase bloom count on more compact plants. Deadheading old spent flower heads will regenerate new blooms on stronger stems. Divide clumps every 2-3 years to maintain plant vigor. Yarrow spreads aggressively by rhizomes and self-seeding.

Stem rot, powdery mildew, rust and aphids are occasional problems, particularly where are poorly sited. Deer and rabbits stay away and the fern-like foliage tolerates air pollutants.

Herbal folklore: Achillea is derived from Achilles, hero of the Trojan Wars in Greek mythology, who used the plant medicinally to stop bleeding and to heal wounds.

‘Little Moonshine’ (new in 2015) – earlier and longer flowering (May-September); very compact 9-12 inches tall by 10-12 inches wide.

‘Peachy Seduction’ – 1 ½ – 2 feet in height and width lovely dense flat clusters of peach to rose-pink flowers; plant forms a tidy mound.

‘Strawberry Seduction’ (the Seduction Series™) – lovely densely packed strawberry-red/golden-yellow centers; dense dark green foliage on sturdy stems; 1 ½ -2 feet high and 2-3 feet wide.

‘Pomegranate’ -red-purple flowers atop 2-3 feet tall and 2 feet wide stems.

‘Pink Grapefruit’ –new cultivar in the Tutti Frutti series; large, slightly domed, deep rose-pink flower heads atop compact 2 foot stems.

‘Peggy Sue’ –2-3 foot tall, low-mounding plants with robust growth habit and apricot-orange blooms.

Nandinas Are Never Old-fashioned

Posted by Hugh on June 25th, 2016

Brightly colorful Nandina foliage in late winter in zone 6

Old-fashion species nandina in Jonesborough, TN

Nandinas in Planter Box in Winter at Biltmore Estate, Asheville, NC

Aka “heavenly bamboo”, nandinas (Nandina domestica) are broadleaf evergreen shrubs with several landscape attributes that include white spring flowers, color changing leathery foliage, and enormous clusters of colorful berry fruits in fall and winter (USDA hardiness zones 6-9).

This member of the Barberry family (Berberidaceae) is native to Japan, China and India. Foliage is variable, semi-evergreen to deciduous in northern areas in zones 6-7, and evergreen in zones 8-10. Some cultivars may die back to the ground during harsh winter and grow fully back by late spring.

Depending on cultivar, nandinas grow 4 to 8 feet tall and 2 to 4 feet wide with upright branching. Shrubs form erect, cane-like stems and compound leaves that some people may mistake as bamboo. Leaves comprise bi- or tri-pinnately compound that give it a fine textured appearance. They possess a rhizomatous rootsystem.

Depending on location, white panicle flowers appear in mid- to late-summer, 8-15 inches in length. Bright red ¼ inch berries follow in the fall and persist through winter. Cultivars ‘Leucocarpa’ and ‘Alba’ produce cream-colored berries. Deer leave nandinas alone. Fruits are rated poisonous to deer, other grazing animals and house pets.

Nandinas grow in average, medium moist, well-drained soils and in full sun to partial shade; they are shade tolerant. Soil pH may be either acidic to slightly alkaline. Leaves turn chlorotic in high pH (alkaline) soils.

Group or mass nandinas for optimum effect in shrub borders, home and building foundations, or open woodland areas. Nandinas are frequently utilized as low informal hedges in warm winter climates where foliage remains evergreen.

Note: nandinas are considered highly invasive in some southern states.

Popular Cultivars:

‘Firepower’ – popular dwarf, very compact 2 feet tall and wide shrub; lime-green foliage turns bright red in late fall thru winter; fruits sparingly.

Harbour Dwarf™ – compact 18 to 24 inches shrub; spring leaves emerge with coppery tints, green in summer, and bronzy-red in fall and winter; fruits sparingly.

Harbor Belle™ – dwarf, compact 18 to 24 inches shrub; spring leaves glossy green with pink tint, dark green by early summer; burgundy splashed in fall through winter; heavy load of bright red fruits in fall thru winter.

Gulfstream™ – compact growing 3-4 feet tall non-suckering shrub; medium green summer foliage turns orange-red winter in fall through winter; fruits sparingly; non-suckering.

Moonbay™ – sister seedling of ‘Gulfstream’, this dwarf variety grows 3-4 feet tall and wide; spring foliage emerges lime green, turns to medium green by early summer, and orange to red color in fall-winter; fruits sparingly; non-suckering.