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

Mexican Bush Sage

Posted by Hugh on August 6th, 2021

Mexican bush sage (Salvia leucantha), aka velvet sage, is a perennial that lights up the late summer / fall garden (USDA hardiness zone 7b-10). Indigenous to Central America and Mexico, it can be grown as an annual that grows to about 3-4 feet tall. In the U.S., bush sage is only hardy from the lower Piedmont to the coastal plain, and extreme winters may kill it.

Bush sage is prized for its dense, arching spikes of showy flowers. Choice of flower colors include purple, blue, and white. Bloom stalks bear persistent flower bases which are velvety and purplish. Bicolor flowers (white corollas and purple calyces) are stunningly spectacular. The individual flowers maybe short-lived and very abundant.

Bicolor flowers — white corollas and purple calyces

Plants prefer full sun (6 or more hours of direct sunlight daily) and humus-rich well-drained soil. Plants are moderately drought tolerant. Bush sage should be kept adequately water during hot dry intervals of summer; irrigate weekly the first growing season if rainfall is less than 1 inch.

Bush sage may freeze and experience crown death in wet soggy winter soils. Wait to cut back dead stems from late February thru early April as new growth emerges. Plants may be trimmed back 2 or 3 times during the spring and summer months to promote dense, more compact plant with heavier late seasonal bloom.

Bush sage may be propagated by seed or overwintering cuttings collected in late summer. Purchase potted plants at garden centers in spring or start seedings indoors 6-8 weeks prior to the last spring frost date in your area.

In Tennessee, North Carolina, and Virginia when winters are exceptionally mild, plants may survive in protected locations covered with leaf mulch. When winter temps are severe, expect plants to die.

Flowers are attractive to hummingbirds and butterflies and ignored by deer and rabbits.

Mexican Bush Sage

12 Plants With Silver Foliage

Posted by Hugh on August 1st, 2021

Silver King Artemisia (Artemisia ludoviciana ‘Silver King’) is an aggressive form with bushy, upright patch of fragrant silvery foliage and loose sprays of grey flowers in midsummer. Prune back hard after flowering to rejuvenate foliage. Deer and drought resistant. (z 3-7).

Silver Mound Artemisia (Artemisia schmidtiana ‘Silver Mound’) – soft feathery leaves grow into compact, cushion-like mounds. It has multiple
landscape applications including edging, rock gardens or containers. Deer and rabbit resistant. (z 3-7)

Heuchera ‘Dolce Silver Gumdrop’ –a compact, tidy mound of silver metallic foliage brightens up any shade garden along with multiple stems of tiny pink flowers. This H. villosa hybrid develops a rosy blush as the season progresses. (z 3-8).

Brunnera macrophylla ‘Jack of Diamonds’ – giant version of the classic ‘Jack Frost’ – with a twist. Huge 9-10 inch, dark green veined leaves, have a heavy silver overlay and overlap at base. Clusters of baby blue, forget-me-not type blossoms rise above the spring foliage. (z 3-8).

Cheddar pinks (Dianthus gratianopolitanus ‘Firewitch’ (Fuerxe’) – ground hugging low mats of silvery blue evergreen foliage grows about 4-6 inches tall (flowers top out at 7-8 inches tall), and 18-24 inches in diameter. (z 3-8).

Licorice Plant (Helichrysum petiolare) is grown for its silvery, densely-felted foliage and trailing habit. It is a shrubby, woody-based tender perennial grows 1-2 feet high (3-4 feet wide) on upright to trailing stems densely clad with soft, woolly, oval-rounded, gray-green leaves (1.5” long). Tiny white flowers are insignificant and often removed by gardeners as they appear. Plant foliage has a slight licorice aroma in the heat of the summer. (z 9-11).

Lavender (Lavandula angustifolia) is an evergreen 3 feet tall perennial
is a dwarf shrub that blooms in the summer and has aromatic leaves, flowers, and dry seed heads. Utilized as a border, a low hedge, in massing, in containers, and in herb gardens. (z 5-9).

Spotted deadnettle (Lamium maculatum ‘White Nancy’) – a silvery leaf groundcover that grows 6-8 inches high and spreads 2-3 feet wide. If foliage declines in mid-summer, mow back or shear plants to stimulate fresh new growth. White flowers in late spring is an additional asset. (z 3-8).

Japanese Painted fern (Athyrium niponicum var pictum) is a lovely deciduous fern with soft blue-green fronds with a silvery overlay accented by contrasting dark burgundy midribs. (z 3-8)

Dusty Miller (Senecio cineraria), also called Silver Ragwort, is a hardy herbaceous perennial typically grown for its grayish ornamental foliage. Leaves are covered with fine matted hairs, giving them a felted or woolly, silver or white. (z 7-10)

Dichondra ‘Silver Falls’ – is a vigorous annual vine with round silver foliage on silver stems. It is very heat and drought tolerant often used as a trailing plant in baskets, window boxes and other planter containers. (z 9-11).

Lamb’s Ears (Stachys byzantina ‘Helene von Stein’) is an improved non-blooming form that results in larger fuzzy, silver foliage (8 inches tall x 15-18 inches wide). Helen von Stein, aka “Big Ears” makes a great edging plant with mounding habit. Neat, non-blooming plant that does not reseed. (z 4-9).

Plants With Silver Foliage

Elephant Ears In Motion

Posted by Hugh on July 21st, 2021

Elephant ears (Colocasia esculenta) and their aroid cousins have become commonplace in not only hot, humid southern gardens, as well in temperate landscapes. Gardeners grow them in large containers and overwinter them indoors in a non-freezing environ. Also, my neighbors in zone 6 blanket in-ground plantings with several inches of loosely packed leaves overwinter.

Colocasia ‘Coffee Cups’ develops into a stunning 3 to 6 foot tall clump glossy olive green foliage with jet black stems. Leaves fold and form into a cup-shape. As the leaf fills with water, the stem gives enough for the leaf to dump out its catch before refilling… totally fascinating. Elephant ears thrive in an organically-rich garden soil or in large containers or urns.

A similar variety, Colocasia ‘Teacups’ struts prominent purple veined underside. Leaves are especially colorful in sun. Stems are strong and leaves are cupped to allow rainwater to collect in the cup! When it fills full, the stems bend just enough to pour out the water. This action is repeated — the leaf refills. Leaves are purple veined on their underside, especially colorful in the sun.

Both “action” varieties grow vigorously over the season, 3 to 6 feet high, growth rate depending on quality of the soil, irrigation frequency, and feeding rate. It grows best in full to partial sunlight (6 hours minimum) and thrive in moist soils.

In northern areas clumps are dug up and stored in a home garage with 40°F minimum temperature. In late winter or early spring clumps may be divided and repotted for the move outdoors once all danger of frost has passed.

Generally, elephant ears are free of disease and pest problems; occasionally aphids, whiteflies, spider mites, stem and root rots require attention.

Generally, elephant ears require low maintenance other than frequent irrigation during dry weather periods. Feed with a water soluble fertilizer such as Miracle-Gro™ and Jack’s™ and organic Espoma™ Plant Food. Halt feeding plants in late August.

Mallow Plant Breeders Developing Resistance To Hibiscus Sawfly

Posted by Hugh on July 16th, 2021

Mallows, hardy hibiscus, and perennial hibiscus (Hibiscus moscheutos) are vigorous shrub-like growers on sturdy 4-5 feet tall (and 2-4 feet wide) stems. The species is native to wetland areas from Ontario and Massachusetts south to Ohio, Indiana, Alabama and Florida.

Huge colorful 4-6(9) inch wide flowers have five overlapping petals with reddish-purple to dark crimson bases which form a sharply contrasting central eye. Flowers, your choice of white, creamy white, pink, and red, have a prominent and showy central staminal column of bright pale yellow anthers.

If site conditions are ideal, expect a long succession of large numbers of flowers, each bloom lasting only 1-2 days from July to September. New flowers open each day. Alternate, broad-ovate to lanceolate leaves (3-8 inches long) with toothed green margins above and white-hairy beneath. Most leaves exhibit 3-5 shallow lobes.

Hibiscus sawfly larvae (Photo by Dr. Alan Windham, Univ. of Tennessee, Nashville

Hibiscus sawflies can cause a lot of foliage damage in a short time. On a warm humid morning you will find the greenish larvae on the backside of leaves, chewing between veins. A sawfly adult is a primitive wasp-like insect. Adult females have a saw-like blade at the tip of the abdomen that is utilized to cut slits into plant tissue into which they deposit eggs.

Insecticides like permethrin, cararyl (Sevin®), Conserve®, and insecticidal soap provide good control if sprayed on the entire plant. Imidacloprid, a systemic insecticide, can be applied to the soil around the plant before feeding activity is noticed. Sawflies are relatively easy to control with foliar sprays, but because hibiscus sawflies produce up to six generations in one season, susceptible plants need to be sprayed on numerous occasions.

Hibiscus sawfly also attacks other ornamentals hollyhock (Alcea rosea), and other hibiscus species. The insect shows little or no interest in other economically important hibiscus relatives, including cotton, okra and rose of Sharon.

Plant breeders are developing resistant plants that are less susceptible to the ravenous appetites of the sawfly. Three genotypes show promise in breeding for hibiscus with resistance to the hibiscus sawfly: H. acetosella, H. aculeateus, and H. grandiflora. New resistant varieties are now arriving at garden centers now with lots more coming in the near future.

Growing Shasta Daisies

Posted by Hugh on July 11th, 2021

Shasta daisies (Leucanthemum x superbum) is a European native that has naturalized in most areas of North America (zones 5-9). Truly low care perennials, Shasta daisies come back every spring and bloom reliably from early summer into early fall (if deadheaded). Some varieties, ‘Becky’ for example, are multi-year top performers.

Shasta daisies tend to form clumps, 2 to 3 feet tall and 1 to 2 feet wide. They bear all-white daisy petals, yellow disk florets, along with glossy, dark green leaves. Shasta daisies make terrific cut flowers, and their blooms last a week or more in arrangements. As flowers fade, deadhead to extend the blooming season. After the first killing frost, cut stems back to 1-2 inches above the soil line.

Shasta daisies grow in average, well-drained soil. At planting time, work in lots of compost around the plants. Feed plants with a slow-release fertilizer like Osmocote™ if flowers numbers are low or small sized. Be careful, over-feeding can lead to an abundance of foliage and a lack of flowers. One-year old established Shasta daisies are drought tolerant, but weekly irrigation with an inch of water weekly over the summer.

Purchase disease resistant varieties. Divide clumps every 4-5 years to avoid crowding. Occasionally, plants may be troubled by aphids, leaf miners, powdery mildew, bacterial spots, gray mold (botrytis), and Japanese beetles.

Recommended varieties:

‘Becky’ – large flowers grow 3 – 3.5 feet tall; considered the “standard” among Shasta daisy varieties.

‘Cream Puff’ –lemon yellow buds, large 3-4 inch creamy flowers; creamy tight compact 14-16 inch tall.

‘Whoops-a Daisy’ – full 2-3 inch wide white blossoms; uniform compact plant habit (15 inches x 22 inches).

Caveat: Some varieties may spread from seed. Choose reliable hybrid varieties that don’t produce viable seed or remove flowers before they go to seed.

Growing Shasta Daisies

Summer Blooming Amur Maackia

Posted by Hugh on July 7th, 2021

Amur maackia (Maackia) is a small deciduous tree with a broad, rounded canopy. Typically, it grows in cultivation at a slow-to-moderate rate to a height of 20-30 feet (to 60 feet in wild). This compact growing tree is an ideal fit in smaller landscapes. A botanical member of the Pea family (Fabaceae), it grows in the region of the Amur River in Manchuria and Korea and eastern Russia and China (USDA hardiness zones 3 to 7).

Compound, odd-pinnate, dark olive green leaves (7-13 leaflets each) are attractive in summer. The deciduous compound leaves emerge silvery-green in spring changing to medium green in summer. Each compound leaf measures 8 to 12 inches long and open grayish-green and matures to dark green. Expect a very slight reddish leaf color change in autumn.

Maackia prefers in full sun to part shade and moist, well-drained soil that is either acidic or alkaline. Its roots enrich the soil by adding nitrogen. It grows in a wide range of soil conditions. Florida horticulturists report that maackia is highly drought tolerant. Maackia has no serious insect or disease problems.

Few landscape trees bloom in early summer. Its fragrant oft-white pea-like flowers start to open in mid-June (In Tennessee). Blooms are clustered in showy 4 to 6 inch bundles and lightly fragrant flowers are pollinated by bees. Flowers are followed by flat 2-3 inches long seed pods, legume pods look like redbuds (Cercis).

Mottled olive-green bark adds to winter interest. Bark is copper-brown and starts peeling with age, a winter asset.

Available Cultivars:

MaacNificent® (M. amurensis ‘JFS-Schichtel1’) – very cold hardy cultivar (zone 3) with a vase-shaped habit and yellow fall color; grows 30 feet high x 20 feet wide.

Summertime™ – a more cold hardy cultivar (zone 3) selected by University of Minnesota. A round form; grows 15 to 20 feet high x 12 to 15 feet wide.

subsp ‘Buergeri’ – 20 to 30 feet tall (zone 4 hardy)

Amur maackia

Black Snakeroot (Bugbanes) For Woodland Beauty

Posted by Hugh on July 1st, 2021

*Actaea racemosa* at Kingwood Center, Mansfield, OH

The bugbanes (Actae spp.) represent a varied botanical genus. In my opinion, the most attractive and easy to grow perennial form is black cohosh or snakeroot (Actaea racemosa), formerly (Cimicifuga racemosa). It is a tall growing U.S woodland native (USDA hardiness zones 4 – 8).

Bugbanes are beloved for their tall architectural floral spikes. Small, numerous, creamy white, fragrant flowers form on wiry stems. Tall floral spires (typically 1-2 feet long) arise above the foliage in June – July or in September depending on locality. Full height (foliage plus flowering spikes) is 4 to 6 feet, sometimes to 8 feet when the growing environment if ideal. Its lacy astilbe-like foliage may be either a deep green or dark purple, related to the cultivar chosen.

Bugbanes prefer rich moisture-retentive soils and partial to full shade. Abundant soil moisture is of key importance. Allow plants 1-2 years to establish after planting as bugbanes tend to be slow. Ideally, plants thrive in 2-3 hours of morning sun, although they prosper in shady areas where light is reduced. Flower spikes are less if soil is excessively dry and under dark shade. Plant in an area protected from strong and/or drying winds.

This plant offers a vertical floral look planted in the rear garden border or in a woodland setting. The leaves are attractive and the showy flowers are followed by cool seedheads, often utilized in floral arrangements. Flowers exude an unpleasant medicinal smell. It is attractive to wildlife.

Disease and insect troubles are rare. Rust and leaf spot are occasional problems. The taller flower spires sometimes may require staking support. Flower spires tend to twirl directionally toward the morning – afternoon light source. Leaf edges may scorch in dry soil or under low humidity.

Cultivar: ‘Atropurpurea’ – purple foliage, dark tint in high light areas.

Actae pachypoda and Actae simplex are related species. Both are equally garden worthy.

Seven Picks For Your Summer Shade Garden

Posted by Hugh on June 26th, 2021

1. Coleus (Solenostemon) are known for their colorful foliage in containers around trees or shrubs. For shady areas select the Kong Mosaic™ or Wizard™ series.

2. Begonias, as a group, represent lots of variety series. Most garden begonia varieties should do well in beds, planters and pots. Begonia types like the Rex and Angel Wing are grown primarily for colorful foliage and, secondarily, for flowers.

3. Impatiens are not just for shady garden spots anymore. Choose hybrid disease resistant cultivars of Sunpatiens, New Guinea, and Beacon™ series. Impatiens offer showy, season-long blooms and perform best in partly sunny to partially shaded areas.

4. Caladium are non-hardy tubers; they are often started indoors in late winter to extend their outdoor seasonal performance. They are grown for their colorful tropical foliage which brightens up shady areas.

5. Fuchsias are readily identifiable by their drooping, brightly colored flowers that bloom most in spring, late summer, and early fall. Summer heat slows down blooming. Select the trailing forms which offer better performance in flower beds or hanging baskets.

6. Wishbone flower (Torenia fournieri) bloom from late spring into early autumn. Summer Wave® series is the current favorite with heat tolerance and hold up to occasionally dry soils. Plants grow 6 – 10 inches tall and trail 24 – 30 inches wide.

7. Boston fern (Nephrolepis exaltata) are excellent shade plants, traditionally planted in hanging baskets and window boxes. Asparagus fern (Asparagus springeri) is also nice addition to a shady spot.

All seven shade annuals look great in the front of landscape beds or in large patio containers and hanging baskets. Plants are set out in spring when threats of frost have left your area. All prefer moist fertile soil garden soil and partial shade. They perform in summer heat and humidity and underperform in deep shade.

Avoid Mulch Volcanos

Posted by Hugh on June 22nd, 2021

Ever heard of a “mulch volcano? It is a load of mulch that is piled up around the base of a landscape shrub or tree. A common answer I get from homeowners guilty of this practice is that they see professional landscapers and city maintenance crews doing it.

Volcano mulch can also cause tree roots to encircle the tree trunk. Eventually, this develops stem-girdling roots associated with volcano mulch, particularly on shallow rooted species like elms and maples.

Mulch volcanoes do not occur in nature and are all man-made. In fact, the practice may cost 2-3 times because of the excess mulch materials and installation cost. Result: 1. trees don’t grow, 2. their life expectancy is greatly reduced, and/or 3. the tree dies. Thick mulch layers develops tree health problems —suffocation of roots, loss of the root systems, and trunk girdling.

The injurious effect of mulch volcanoes occurs over multiple years. Initially, tree growth appears abnormal. Tree structure is weakened and become a liability to pedestrians, autos, and property owners. Insects such as scale insects and borer make their homes in the decaying wood. Disease pathogens also have an easier time invading the trees via the wounds.

Piling mulch around tree trunks has been a bad practice for decades. As the mulch decomposes and dries out, it becomes hydrophobic, that is, the organic mulch dries out; or becomes hydrophobic. You can observe hydrophobicity of dry organic matter when you try to moisten a bag of dry peat moss.

Remedy: First, inspect the trunk itself by removing the decaying mulch. Expose the decayed area to the air and treat decaying areas with insecticides. If you are unsure how to proceed, contact a certified tree arborist in your area.

Attracting Hummingbirds

Posted by Hugh on June 16th, 2021

In early spring many area gardeners rush to set out hummingbird feeders filled with a sugary solution to encourage these feathery critters to visit. However, the sugary drink also attracts ants, bees, and wasps. The solution does not furnish vitamins, minerals, and carotenoids that hummingbirds pick up from pollinating flowers and eating insects. In addition, in
garden beds and containers, offer hummers garden spaces to nourish on their favorite pollinator plants.

Red cardinal flower (*Lobelia cardinali*s)

Favorite Hummingbird Plants:

Perennials:
Anise hyssop (Agastache spp.)
Foxglove (Digitalis purpurea)
Daylilies (Hemerocallis spp.)
Blazing Star (Liatris spicata)
Red cardinal flower (Lobelia cardinalis)
Great blue lobelia (L. siphilitica)
Lupine (Lupinus perennis)
Beebalm (Monarda spp.)
Catmint (Nepeta spp.)
Beardstongue (Penstemon spp.)
Garden phlox (Phlox paniculata)
Sage (Salvia spp.)

Woody plants:
Mimosa tree (Albizia julibrissin)
Trumpetvine (Campsis radicans)
Summersweet shrub (Clethra alnifolia)
Rose of Sharon (Hibiscus syriacus)
Coral honeysuckle (Lonicera sempervirens)
Rose of Sharon (Hibiscus syriacus)
Coral honeysuckle (Lonicera sempervirens)
Azaleas and rhododendrons (Rhododendron spp.)
Weigela (Weigela florida)

Annuals:
Cuphea, cigar plant (Cuphea)
Impatiens
Lantana
Flowering tobacco (Nicotiana)
Salvia (Salvia spp.)
Snapdragons (Antirrhinum)
Zinnia (Zinnia elegans)
Cypress vine (Ipomoea quamoclit)

Caveat: change the hummingbird feeding solution every 4-7 days during warm spring and summer weather. The sugary feeding solution gradually ferments and clouds up with bacteria which may be fatal to birds.