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

Fuzzy Bolivian Sage

Posted by Hugh on September 27th, 2021

The large and bright fuzzy blossoms of Bolivian Spearhead Sage (Salvia oxyphora), aka Fuzzy Bolivian Sage, should catch your eye in late summer and early autumn. Equally attractive is the plant’s lush tropical-like glossy green foliage.

Fuzzy Bolivian Salvia (*Salvia oxyphora*) at Longwood Gardens

This sage inhabits the edges of moist forests in the foothills of the Andes. It is grown as an annual in full sun in Northern climes during the summer. If grown in containers, you may opt to bring plant(s) indoors over the winter. It prefers midday shade in the hot summer climes in the southern U.S.

This vigorous growing salvia can reach 4 feet high by summer’s end along with deep green tropical-like foliage. Numerous velvety hairs, almost invisible, cover the foliage. Fuzzy deep pink tubular flowers emerge from short dense spikes atop the verdant foliage starting in late-spring.

Fuzzy Bolivian sage prefers a well-drained, rich loamy, mildly acidic pH soil, and in full to partial sun. Cut back stems once in late spring to develop better branched plants. If sown from seeds, start them indoors 6-8 weeks before last spring frost date. Plants are not commonly available for purchase at U.S. garden centers. Fertilize plants at planting time and once again in mid-summer.

Salvias are rarely troubled by very few serious disease and insect pests. Plants may be susceptible to downy and powdery mildew if the planting is crowded or poorly sunlit.

Salvia’s attractive tubular flowers are valued by hummingbirds, bees and butterflies for their pollen and nectar. If salvias appear tired in late summer, shear the plants lightly, including the removal of the spent flowering spikes in order to encourage new growth and flowering.

In the northern portions of its hardiness range (Zone 8), cover crowns (plant bases) with a loose (non-packing) winter mulch such as pine straw.

‘Goshiki’ Holly Tea Olive

Posted by Hugh on September 21st, 2021

Holly Tea Osmanthus, also called holly tea olive and false-holly (Osmanthus heterophyllus) is a large (15 feet tall), dense, upright, oval-rounded evergreen shrub. The species blooms in late fall and the tiny inconspicuous white flowers are sweetly fragrant. Small numbers of fruits ripen the following year, and often go unnoticed.

Osmanthus heterophyllus ‘Goshiki’ is a smaller compact, mound-forming evergreen variety that reaches up to 4-5 feet tall and 3-5 feet wide. It is a perfect choice in a small garden. Goshiki osmanthus flowers open in late September into October and their sweet fragrance fills the air from several feet away. The small (about ¼ inches across) white flowers are borne in clusters of 4 or 5 at the base of the leaf axils.

‘Goshiki’ stands out for its bright leaf variegation dotted with creamy white flecks against the dark green holly-like foliage. It can be utilized as a low hedge or front border evergreen shrub. Blue-black drupe fruits, only 3/8 to 1/2″ in size, are rarely seen in cultivation. Goshiki is not invasive and deer stay away. It was introduced from Japan by Barry Yinger.

Plant in full sun or a partially shaded area and in a humus-rich well-drained soil; it tolerates pH soil between 5.5 to 7.5. Hardy in zones 6-9, site in partial shade in southerly zones 8-9. New spring growth starts out pinkish bronze; the spiny mature leaves display a mix of green, gold, and cream. Relatively pest-free.

Landscape Use: Great plant for low borders and hedges. Slow growing by nature, makes Goshiki a wonderful addition to a dwarf shrub collection, in a rock garden, or in a large container.

Clump Type Ornamental Grasses Excel In Autumn

Posted by Hugh on September 16th, 2021

City gardeners want low maintenance. These ornamental grasses are what you’re looking for. They achieve their intended growth heights in summer, and produce flowers (inflorescence). Foliage of some change color as temps start cooling in late summer.

Five of six listed grass species are winter hardy and overwinter outside in large containers or tubs in most regions (USDA hardiness zones 4-9). Muhly grass is the exception in hardiness (zones 6-10). All six tolerate a wide range of soils and deer leave them alone.

Short List (6) of Ornamental Grasses:

Maiden grass, Eulalia grass (Miscanthus sinensis) are beautiful in the early autumn landscape. Several cultivars are very invasive in U.S. landscapes. My Fair Maiden™ (6 – 8 ft. tall x 4 ft. wide), ‘Rigoletto’, ‘Morning Light’, ‘Strictus, and ‘Zebrinus’ (Variegata’) produce very low amounts of sterile seed and are rated less invasive.

Switchgrass (Panicum virgatum) is a U.S. native prairie grass that is an exceptional performer. ‘Northwind’ switch grass grows 4 -5 ft. tall and 2.5 ft. wide and is tightly constricted at its base; airy panicles of feathery flowers in late summer. ‘Shenandoah’ forms a small 3 feet tall clump; summer foliage is dark purple cast on its tips dark, black-purple foliage in fall. ‘Cheyenne Sky’ emerges with blue-green leaves in late spring, forming a tidy and well-behaved mound. In late summer deep wine-red leaf tips and airy sprays of dark-red flowers.

Feather Reed Grass (Calamagrostis x acutifora ‘Karl Foerster’ has a strong upright habit and blooms with showy flowers that ripen to tawny seed heads that decorate the plant through the fall and winter months. Other cultivars are: ‘Overdam’ and ‘Avalanche’.

Muhlygrass (Muhlenbergia capillaries) produce a loose, airy inflorescence that is nothing less than spectacular pink clouds in early fall. Muhlygrass typically grows to 3 ft. tall x 3 ft. wide when in flower (USDA hardiness zones 6-10). Pink Muhly is the most popular form; ‘White Cloud’ sports white flowers and grows more upright than pink form.

Little bluestem (Schizachyrium scoparium) are popular native warm season grasses. ‘Carousel’ (2.5 ft.) has green and cream stripes. ‘The Blues’ (3 ft.) has blue leaf blades with red stem accents. ‘Standing Ovation’ (4 ft.) has blues, greens, pinks, and purples. Sturdy spiky stems mature in the fall with a brilliant display of oranges, reds, yellows and purplish-browns.

Prairie dropseed (Sporobolus heterolepis) is a warm season, clump-forming grass. Fine-textured, hairy, long green leaves (to 20 inches long and 1/16 inches wide) typically form an arching foliage mound to 15 inches tall and 18 inches wide. Foliage takes on a golden with orange hues in fall, and light bronze in winter. Open, branching flower panicles appear on slender stems which rise well above the foliage clump in late summer to 30-36 inches tall. Flowers have pink and brown tints, and a coriander fragrance in fall.

*Sporobolus* *heterolepis* in late October

Fall Planting – Hyacinths

Posted by Hugh on September 11th, 2021

For over 400 years hyacinths have been popular spring-flowering bulbs, beloved for their colorful blooms and delightful floral fragrance. Modern day varieties are hybrids of a single species (Hyacinthus orientalis) that grows wild in Turkey, Syria, and other regions in the eastern Mediterranean. Over 50 cultivars are listed by Dutch growers.

Centuries of breeding have given gardeners taller and larger floral spikes, mostly double florets that are tightly packed along the stem. Each hyacinth bulb produces a single 8 -12 inch tall flower stalk. Flowers open in mid-spring around the same time as daffodils and early tulips.

Shades of purples and blues are very common, including Blue Jacket (royal blue), Delft Blue (soft lilac blue), and Miss Saigon (deep lavender blue) Aida (violet-blue). Other color choices include Woodstock (burgundy), Jan Bos (hot pink), Carnegie (white), Gipsy Queen (salmon), and City of Haarlem (pale yellow).

Hyacinth bulbs are planted in mid to late fall. Choose a planting area with well-drained soil. Full sun is best, particularly if you desire bulbs to re-bloom for several years. Hyacinths will grow in light shade, but multi-year planting numbers gradually decline. For visual impact, plant the bulbs in groups of 5 or more, spaced about 5 inches apart on center and 5 to 8 inches deep.

In the mid-Atlantic and mid-South states, (zones 5-7), hyacinths grow well in outdoor containers or mixed with other spring bulbs. You may also force hyacinth bulbs in pots that are chilled outdoors, or in unheated garages/sheds, or in refrigerators. Bring pre-chilled bulbs in your home for floral display winter into spring.

Like tulips, newly planted hyacinths perform at their best the first planting year. Some gardeners will grow bulbs for 2-3 years and redo the planting bed. Botanical gardens sow hyacinths and tulips as annuals. Hyacinth bulbs may re-bloom for several years, but lose their vigor and flower size. Soil-borne diseases will also reduce their numbers.

Once flowers have wilted and faded in spring, clip off the flower stalks to re-energize bulbs for next spring. Allow the green foliage to grow until it dies back in late May or early summer. Bulbs enjoy a dry summer dormancy in ground.

Favorite Bulb Emporium: Brent and Becky’s Bulbs in Gloucester, VA. Shop on-line or mail order.

Goldenrods

Posted by Hugh on September 6th, 2021

Goldenrods (Solidago spp.) represent about 100 species of perennials that grow ubiquitously alongside U.S. roadsides, prairies, open woods, and riverbanks. (USDA hardiness zones 4-9). A few species are also native in South America and Eurasia. Goldenrods are grown for their bright yellow or golden flowers that form late in the summer. They are easy to grow, and the tiny yellow flowers are a bountiful source of nectar for bees and butterflies, including Monarchs; seeds are eaten by songbirds fall and winter.

Goldenrods, Asters and Ironweeds at Dawes Arboretum In Ohio

Goldenrods grow in almost any soil that is well-drained and in full sun. Removing spent flower clusters will encourage more blooms. Deadhead the old spent flowers to avoid prolific self-seeding. Every 3-4 years, divide plants in spring or fall.

Showy goldenrod (Solidago speciosa) is an eye-catching selection with abundant tiny, bright yellow terminal flower clusters atop stiff, narrow-leaved, reddish stems; 2 – 3 feet tall starting in mid- to late-summer.

Wreath goldenrod (Solidago caesia), aka blue stem goldenrod grows 1.5 – 3 feet tall on wiry, arching, glabrous, greenish-purple stems which are covered with a silver-white waxy coating (zones 4-8). Yellow clusters of tiny flowers bloom along the purplish stem in early autumn. Lance-shaped, medium green leaves (2 – 5 inches long) are toothed with sharply pointed tips.

‘Fireworks’ rough-stemmed goldenrod (Solidago rugosa) is probably the most popular variety, this 3 – 4 feet tall clump-forming plant is covered with stiff bright yellow inflorescences in early autumn, reminiscent of exploding fireworks.

‘Golden Fleece’ goldenrod (S. sphacelata ‘Golden Fleece’) grows 18 – 24 inches tall and 24 – 36 inches wide; forms showy sprays of golden yellow flowers from mid-September into October. Its heart-shaped leaves are semi-evergreen.

Ultra-dwarf varieties:

Little Lemon® (‘Dansolitlem’) – light yellow flowers on ultra-compact plants – 14 inches tall and 18 inches wide.
‘Cloth of Gold’ – deep yellow flowers on 18-24 inch tall stems.
‘Crown of Rays’ – bright yellow flowers on 2-3 feet tall stems.

‘Little Lemon’ Solidago (Photo courtesy of North Creek Nurseries)

No serious insect or disease problems trouble goldenrods and plants are moderately deer tolerant. Spot anthracnose, powdery mildew, rust, fungal spots are occasional problems if summer weather is unusually wet or the planting becomes too crowded.

Goldenrods make colorful companions with excellent additions to a perennial border or meadow favorites such as little bluestems (Schizachyrium scoparium), assorted fall asters (Symphyotrichum), beebalms (Monarda spp.), coneflowers (Echinacea), big bluestems (Andropogon gerardii), Joe Pye (Eupatorium), and Arkansas bluestar (Amsonia hubrichtii).

Fall Anemones

Posted by Hugh on September 1st, 2021

Japanese anemones (Anemone x hybrida) are popularly called “fall anemones”. These late summer-fall blooming perennials are long-lived and make fine additions to flower borders and open woodland areas (USDA hardiness zones 4 to 7). Many colorful varieties are available and their flowers are great additions to cut floral arrangements.

Showy 2-4 inch wide flowers stand 2-4 feet tall (depending on variety) for 4 to 5 weeks in autumn. Starting in late August flowers rise up atop long wiry stems from dark-green basal mounds. Each flower is composed of 6-9 overlapping white/pink petals with numerous yellow stamens in center. The dark green leaves are 3-lobed.

Fall anemones thrive in garden spaces with full or partial day sunlight and in moist, well-drained ground. At planting time, add lots of compost to a mildly acidic garden soil (pH 5.5 to 7.0 preferred). Fall anemones do poorly on dry sites and in heavy clay soil. Plants also fail in soggy clay soil over winter. Leaves tend to burn in hot, dry, sunny conditions. In warmer climes of zone 7, set fall anemones in morning sun and partial afternoon shade. When planted in too much shade, plants tend to be floppy and require staking.

Plants are mostly deer tolerant and have few disease and insect problems. Flowers attract numerous late season pollinators. From the Greek, the word anemone means “windflower”. Observe the flowers swaying in the gentle autumnal breezes, and do shelter plants on extremely windy sites.

Over time fall anemones tend to naturalize via creeping rhizomes and seed in freely. In the spring dig up extras to share with gardening friends.

5 Cultivars to plant:

‘Honorine Jobert’ (2-3 inch wide single pure white flowers on 3-4 feet tall stems) –heirloom plant introduced in the mid-19^th century and awarded the Perennial Plant of The Year in 2016

‘Queen Charlotte’ (3-inch semi-double rosy pink flower on 2-3 feet tall stems)

‘September Charm’ (3-inch single rose-pink flower on 3-4 feet tall stems)

‘Whirlwind’ (4-inch semi-double white flowers on 3-4 feet tall stems)

‘Serenade’ (3-inch double deep-pink blooms on 3-3.5 feet tall stems)

Lots of Choice With European Hornbeams

Posted by Hugh on August 26th, 2021

Seasonal foliage and nutlet capsule

European hornbeam (Carpinus betulus), aka ironwood and musclewood, is an underused tree that is an excellent urban street and park tree. (USDA hardiness zones 4-7). The tree develops a full, dense canopy and little maintenance requirements. The species typically grows 40-60 feet (less frequently to 80 feet) tall with a pyramidal to oval-rounded crown.

Its dense summer foliage is medium green, to 4 inches in length with little susceptibility to foliar diseases and insects. In the fall foliage turns yellow-orange. Some leaf retention over winter months is likely. Trunks have smooth gray bark and distinctive muscle-like fluting. Flowering catkins are visible in early spring before the foliage emerges. Male catkins are yellowish and female catkins are greenish. Fruits are small nutlets in 3-lobed bracts that appear in late summer.

The tree is commonplace in landscapes across Europe as a street tree, privacy screens and windbreaks, and in topiary forms. Hornbeam adapts to a wide variety of soils as is tolerates hot and dry conditions once established after 2 years. Full to partial sun is ideal, although tree will tolerate partial shade. The species tolerates drought and short term flooding. It prefers well-drained/loamy, sandy or clay soils with an acidic pH. Plant where the soil stays cool. Annual mulching is an added plus.

Dense, compact and narrow when young, developing an upright oval crown with maturity. Long, thick, corrugated dark green foliage is resistant to insects and diseases and turns a pleasing yellow in fall. Handsome gray fluted bark. An excellent choice for hedging and windbreaks.

Annual fertilization of young trees is recommended, not so much for older trees. Disease and pest free although powdery mildew. Japanese Beetles may slightly damage the foliage, but rarely needs pest control. Little or no pruning is generally required.

‘Fastigiata’ displays a narrow, columnar form to 35 – 40 feet tall and 25 – 30 feet wide. This cultivar is more available in U.S. nurseries than the species.

‘Columnaris’ is stately and extremely formal-looking, with a limbed-up trunk, strong central leader, and branches arranged tightly near the trunk.

‘Frans Fontaine’ is a narrowly columnar form that grows 35 feet high and 20 feet wide.

Columnar forms display strong upright architecture in winter

Kalimeris – Late Summer Flowering Perennial

Posted by Hugh on August 21st, 2021

Japanese asters (Kalimeris spp.) are synonymous with boltonias (Boltonia). It is native of China, Japan and Siberia. It superficially resembles Boltonia, but differs enough to be assigned to the genus Kalimeris in the 1990s.

Kalimeris incisa ‘Blue Star’ is a superior form. This clump-forming species is noted for its long summer bloom period featuring 1 ½ inch wide, daisy-like flowers of pale lavender rays and yellow centers. The flowers are very aster-like. (USDA hardiness zones 4-8). Plants typically grow 12-18 inches tall and wide. Oblong-lanceolate green leaves are 3-4 inches long.

Kalimeris is easily grown in average, medium moist, well-drained soils in full sun to part shade. Established plants tolerate droughty clay, provided the ground is not poorly drained. It stands up well to hot and humid summers. Foliage may be pinched back in early summer to stimulate more branching and increased bloom count. Shear stems after flowering to encourage re-bloom in early fall. Plants may self-seed in optimum growing conditions.

Japanese asters perform equally well in large containers. Plants require very little maintenance. It may be propagate by seed or cuttings. Space individual plants in a flower garden or group several together for mass plantings.

Another Japanese aster cousin, K. pinnatifida, is also popular. Semi-double daisy-like flowers are composed of 1-inch wide white ray petals and a pale yellow center disk. They bloom continuously from early summer to fall. The cultivar ‘Hortensis’ produces white double flowers.

Over the years plants tend to sucker and colonize among themselves and do not spread to other places in the garden. Divide older 3 to 4 year clumps in spring to maintain their overall vigor. Fertilize in early spring with a slow release fertilizer like Osmocote™ or Nutrikote™. Disease or pest problems are rare.

Smart Water Use In The Summer Garden

Posted by Hugh on August 17th, 2021

When the heat of the summer settles in, water is in high demand. Here is some practices to implement when planting a water-wise garden,
irrigating lawngrass, and better mulching practices to improve soil moisture levels:

Lawn grass species vary in their water needs. Cool season grasses like fescues and bluegrasses are moderately drought tolerant, turn off-color during dry periods (“their summer dormancy”), and recover when adequate rainfall returns. Warm season grasses like bermuda and zoysia grasses are more drought tolerant than fescues and bluegrasses.
Irrigate in the morning to reduce water loss to evaporation and minimize disease risks.
Plant more drought tolerant plants. For examples, cacti , euphorbias, and succulents are low water users. Many prairie flowers such purple coneflowers (Echinacea), black-eyed Susans (Rudbeckia), blanket flower (Gaillardia), yarrows (Achillea), hyssop (Agastache), Russian sages (Perovskia), lavenders (Lavandula), and sedums are some favorites.
Repair leaks in hoses and faucets.
Don’t use fine mist sprinklers and avoid watering on a windy day.
Drip or trickle irrigation systems are better water users than overhead sprinklers
Target sprinklers to irrigate plants and not driveways and walkways.
Collect rainwater in rain barrels or rain gardens.
Mulch using organic amendments such as pine bark, pine needles, and wood mulches will reduce surface evaporation. Newspapers, cardboard, and grass clippings serve as good mulches.
Summer pruning to reduce vegetative competition.

Deer Resistant Perennials

Posted by Hugh on August 11th, 2021

Most deer-resistant plants share several traits or characteristics: 1. Aromatic flowers / foliage; 2. thorny, bristly, or hairy (pubescent) leaves or stems; 3. toxic plants. If “deer pressure” (population) is exceptionally high, deer don’t heed plant lists like this one.

Available food resources, species of deer, seasonal weather are all factors. Flowers, foliage, fruits, and seeds of plants are not off-limits to other critters. Expect damage from native butterflies, moths, and beneficial insects. Design your garden to include plants that are not munched on. Otherwise, construct a tall fence to keep deer away.

Yarrow (Achillea)

Black cohosh (Actaea racemosa)

Anise Hyssop (Agastache foeniculum)

Bugleweed (Ajuga reptans)

Bluestar (Amsonia spp.)

Artemisia

Goatsbeard (Aruncus dioicus)

Butterfly weed (Asclepias tuberosa)

Baptisia (Baptisia australis)

Siberian bugloss (Brunnera macrophylla)

Karl Forester reed grass (Calamagrostis)

Calamintha nepeta subsp. nepeta