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

Marginal Plants For Wet Areas

Posted by Hugh on August 16th, 2020

Brunnera macrophylla ‘Variegata’

‘Gateway’ Joe Pye

Most perennials demand well-drained soil. They perform poorly or die out when in ground that is constantly wet and soggy. However, a small number of perennials tolerate and even thrive in moist soils. Most plants listed here are all hardy within zones 5-8, and grow best in moist, humus-rich, well-drained soil. Most are okay getting their feet (roots and crown) wet for short time periods in terms of days, but not weeks. The list includes some ornamental grasses that cope with short period of flooding.

Bog plants, cannas, cardinal flower (Lobelia cardinalis), goatsbeard (Aruncus dioicus), monkshead (Aconitum), spiderwort (Tradescantia andersoniana), bugleweed (Ajuga reptans), flag iris (Iris pseudoacorus), Louisiana iris (Iris x hybrida) excel in a continuously wet spot around the water garden or a feature. Papyrus (Cyperus papyrus). Shrubs like weigela (Weigela floridus), kerria (Kerria japonica), Virginia sweetspire (Itea virginica), smooth hydrangea (H. arborescens), winterberry holly (Ilex verticillata), Joe Pye (Eutrochium spp.), and shrub dogwoods (Cornus spp.).

Perennials to look out for include: Hosta, Siberian bugloss (Brunnera macrophylla), Queen of the Prairie (Filipendula rubra), Toadlily (Tricyrtis formosana), loosestrife (Lysimachia clethroides), plume poppy (Macleaya), Chinese astilbe (Astilbe chinensis), black snakeroot (Cimicifuga racemosa), meadow rue (Thalictrum aquilegifolium), swamp sunflower (Helianthus angustifolius), obedient plant (Physostegia virginiana), swamp milkweed (Asclepias incarnata), calla lilies (Zantedeschia aethiopica), rodgersia (Rodgersia aesculifolia), primula, rose campion (Lychnus coronaria), Japanese iris (Iris ensata), Indian pink (Spigelia marilandica), ligularias (Ligularia spp.), Farfugium (F. japonicum), swamp hibiscus (Hibiscus coccineus), mukdenia (Mukdenia rossii), and some ferns including cinnamon fern (Osmundastrum cinnamomeum), royal fern (Osmunda regalis), arborvitae fern (Selaginella braunii), and sensitive fern (Onoclea sensibilis).

Ornamental Grasses for moist sites include hakone grass (Hakonechloa macra), sweet flag (Acorus gramineus), muhly grass (Muhlenbergia capillaris), sea oats (Chasmanthium latifolium), big bluestem (Andropogon gerardii), feather reed grass (Calamagrostis x acutiflora), switchgrass (Panicum virgatum), Bowles’ golden sedge (Carex elata ‘Aurea), Gray’s sedge (Carex grayi), Morrow sedge (Carex morrowii cv.), and common rush (Juncus effusa).

Six Architecturally Tall Perennials

Posted by Hugh on August 11th, 2020

Here are six showy architectural gems to grow in your garden. All six are “big guys” and are valued for their bold presence, disease-free foliage, and their attractive flowers, that are also great pollinators.

*Filipendula rubra* at Kingwood Center, Mansfield, Ohio

Queen of the Prairie (Filipendula rubra) is a U.S. native perennial that mimics an astilbe on steroids. This tall, upright, clump-forming perennial typically grows 6-8 feet tall and features branched, terminal, astilbe-like, 6-9 inch wide panicles (corymbs) of tiny, fragrant, pale pink flowers in early to mid-summer. Deeply cut, bright green, 4-8 inch long compound leaves are composed of 7-9 lobed lance-shaped leaflets. Leaves are fragrant when crushed. (USDA hardiness zones 3 to 8).

Bronze Fennel (Foeniculum vulgare ‘Purpureum’) is a highly aromatic perennial herb. Fennel is widely cultivated for its edible, licorice-flavored leaves and seeds. The variety ‘Purpureum’, also known as Bronze Fennel, has dark “smoky” foliage that is very attractive planted along perennial borders or in wide annual containers (staking necessary). You may opt to keep plants from blooming so they don’t reseed. However, the yellow flower heads are attractive. Specific swallowtail butterflies utilize bronze fennel as a food source for their caterpillars. (Zones 4 to 9).

Giant sunflower (Rudbeckia maximum) grow tall and bold. Huge basal powder blue leaves on giant stalks rise straight up bearing deep golden coneflowers. The central flower cones of “Rudbeckia max” grow 4-6 inches high. The old bloom stalks attract goldfinches for the seed (Zones 4 to 9).

Fall flowering sunflower (Helianthus angustifolium) is a narrow leaf perennial sunflower that will thrive in moist soil with full sun to part shade. Plants grow 5- 7 feet tall with cutleaf dark green foliage attached to maroon stems. An explosion of 2-3 inch wide yellow flowers comes in September into November. (Zones 6 to 9).

*Helianthus angustifolius* var. salicifolius

Scarlet Rose Mallow (Hibiscus coccineus) is a vigorous, woody-based 3-6 feet tall perennial. Stems bear showy 3-5 inch wide, 5-petaled, bright scarlet red flowers from mid-summer to early fall for a long bloom season. Palmately palmately compound, deep green leaves are very hemp-like, (5-6 inches wide). (Zones 6 to 11).

*Hibiscus coccineus* at NC Arboretum, Asheville, NC

Rosinweed (Silphinum spp.) is a native sunflower-like meadow plant. It typically grows on coarse erect stems to 4-8 feet tall and is identified by its square/quadrangular stems, coarsely-toothed foliage, and pairs of cup-forming leaves. Flower heads (to 3 inch diameter) feature light yellow rays (20-40) and darker yellow center disks bloom in summer on the upper part of the plant. Over wet spells, leaf cups collect dew and rain water. (Zones 4 to 8).

*Silphium* at NC Arboretum, Asheville, NC

Six Tall Architectural Statuesque Perennials

Celebrate Summerific® Rose Mallow (Hibiscus) Week

Posted by Hugh on August 6th, 2020

Perennial hibiscus (Hibiscus moscheutos) is commonly known as rose mallow or dinner plate size hibiscus. Blooms measure a huge 7-9 inches across. Plants are exceptionally hardy, and can withstand winters as cold as zone 4 (-20°F to -30°F) in Minnesota (zone 4) and the heat of zone 9 (20°F -30°F) in Florida. Each flower lasts only one day.

Summerific® Spinderella (Photo courtesy of Walters Gardens, Inc

Summerific® rose mallows are a huge improvement. Older varieties tended to produce flower buds only at the tips of the branches and bloomed for just a few weeks. Plants produced fewer flower buds.

Newer varieties in the Summerific series produce flower buds all up and down the stems, including the top. Newer Summerific varieties are bred to bloom for months, 3 times longer than older varieties.

Rose mallows need water and lots of it. Plants can actually grow in standing water. Grow them within reach of a hose or sprinklers and irrigate on a regular schedule. Whether you are growing in average soil or in a good garden loam, do not allow plants to wilt and dry out. Badly wilted plants will drop their lower leaves and flower buds.

Give them room to grow. Rose mallows are very robust growers that fill their space in the garden. Read the plant label about variety spacing. Dwarf varieties grow at least 3 feet tall and wide, and standard-sized rose mallows grow 4-6 feet tall and wide.

Bring on the sun. Full sun (6+ hours) is imperative. Dark leaf varieties develop a more intense dark purple foliage color in a sunny garden. Full sun equals more flowers. In partial shade, plants produce fewer flowers and dark leaf varieties appear more greenish.

Summerific® French Vanilla (photo courtesy of Walters Gardens, Inc)

Spring-Summer Perennial Hibiscus Care Tips:

Cut back rose mallow in the spring. Cut down the dormant woody stems to about 6 inches tall. Rose mallows tend to be one of the last plants to emerge, sometimes as late as early June in northern areas. Newly emerging shoots will grow rapidly, about an inch a day.
Once spring growth arises, sprinkle slow release plant food such as Espoma™ Plant-tone^® or an equivalent slow release organic fertilizer around the root zone (according the package directions. In early summer, follow-up with a water-soluble plant food like Miracle-Gro™ or Jacks™ just as flower buds are beginning to form.

Seven Late Summer Perennial Gems

Posted by Hugh on August 1st, 2020

‘Hot Lips’ turtlehead (Photo from North Creek Nursery, Landenburg, PA

The following seven (7) perennials provide gorgeous floral color in mixed perennial beds in late summer and into fall. Flowers attract pollinators, including lots of bees, butterflies, and an occasional hummingbird.

‘Blue Fortune’ Giant Hyssop (Agastache x ‘Blue Fortune’) offers lavender-blue flowers during a long hot summer extending into early fall. Leaves emit a minty-anise fragrance and adds flavor cold drinks. Dead-heading extends bloom time. Deer resistant. (USDA hardiness zones 5-9)

‘Little Spire’ Russian Sage (Perovskia atriplicifolia ‘Little Spire’) – compact and erect sub-shrub. It flaunts silvery aromatic foliage and striking light blue to violet floral color. This compact woody perennial grows only 2-3 feet high (versus the 6-7 feet tall species) and is drought tolerant. Deer Resistant. (zones 5-9)

‘Autumn Bride’ Heuchera (Heuchera villosa ‘Autumn Bride’) is a 2-foot-tall by 3-foot-wide native perennial that forms a dense mound of large fuzzy green leaves. The plant spreads by underground rhizome and holds up to moderate dry shade partial dry shade. Heucheras with villosa bloodline grow in either partial shade to full sun. Deer Resistant. (zones 3-8)

‘Hot Lips’ Pink Turtlehead (Chelone lyonii‘Hot Lips‘) produces attractive late-summer pink flowers that look like a turtle’s head. It prefers moist well-drained soils. This 2 to 3 foot-tall perennial has handsome dark green foliage. Deer Resistant. (zones 3-8)

‘Hillside Sheffield Pink’ Chrysanthemum – an old fashioned shrubby garden mum which grows 2-to 3 feet high and wide. Pinch in June to keep plants compact and bushy; divide plants every 2 or 3 years in spring to maintain vigor. Deer Resistant. (zones 3-8)

‘October Skies Aromatic Aster (Symphyotrichum oblongifolium ‘October Skies’) – one of our finest native asters. This 2-foot-tall by 2-foot-wide plant is covered up with dark blue flowers with yellow button centers. The plant forms a lush mound of foliage and should be pinched back by one-half in late June to develop a compact form. Deer Resistant. (zones 3-8)

Leadwort (Ceratostigma plumbaginoides), also called plumbago, is a low-growing dependable 8-10 inch high ground cover for sunny to partly shaded spots. Plumbago is filled with cobalt-blue flowers in late August; dark green leaves begin to turn red 4-5 weeks before abscising later in autumn. (zones 5-9)

General Care: all plants perform in partial to full sun and in well-drained soil. More sun means more flowers. All are moderately drought-tolerant after their first growing season. After blooming, plants don’t need to be cut back until late winter. For best look, set 3 or more plants in garden beds or containers.

Lovely Fruit Capsules Fill Sweetheart Tree In Late Summer

Posted by Hugh on July 26th, 2020

Korean sweetheart tree (Euscaphis japonica) is a large flowering shrub or small deciduous tree that is native to mountain valleys, open forests and thickets in China, Korea and Japan (USDA hardiness zones 6 to 8). Dr. J. C. Raulston discovered Korean sweetheart tree in 1985 on the Korean Peninsula during a plant expedition. Yet, it is still relatively unknown in American gardens. Sweetheart tree belongs to the bladdernut (Staphyleaceae) family

It typically matures to 12 to 20 feet tall, occasionally upwards to 30 feet and a spread of 8 to10 feet wide. Leaves are opposite pinnately compound, a single leaf 6-10 inches long. Each leaf is composed of 7-11 thick, leathery, finely toothed, glossy, dark green leaflets, 2-4 inches long. The deciduous leaves turn mahogany-purple hue in the fall.

This durable tree thrives in a variety of soils, preferably moist, for sweetheart tree to bloom and bear numerous fruits. The tree should be planted in partial to full sun. The yellowish-white flowers (each to 1/4” diameter) appear in spring (May-June) in 6-9 inch long terminal panicles and go by mostly unnoticed. It tolerates brief periods of drought, and performs best in moist soils. Avoid areas of the U.S. where summers are extremely hot and droughty.

The smooth purplish-brown gray bark is lined with white striations for winter interest. Its pinnately compound foliage displays an interesting textural character. The late summer fruits shaped like tiny heart-shaped red capsules, hence the name “sweetheart tree”.

Without question, plant collectors grow sweetheart tree for its showy clusters of heart-shaped fruits. Starting in early August, ripening fruits morph from green to pink to red. In early to mid-October capsules split open revealing a tiny, shiny, black seed. The jet black seeds hang from the tree branches. Wildlife attraction to the fruits is not known.

No serious insect or disease problems trouble this highly ornamental small tree. The tree is sold by specialty nurseries found on-line.

Korean Sweetheart Tree (*Euscaphis japonic*a)

Favorite Native Shrub Pollinators

Posted by Hugh on July 21st, 2020

These eight (8) shrubs amaze me by the numbers of bees and other pollinators that their flowers attract when blooming.

Virginia sweetspire (Itea virginica) is an erect, rounded, broad-spreading, deciduous shrub with arching branches. Itea grows 3-4 feet (less frequently to 5 feet) tall with similar spread. Fragrant, tiny white flowers borne in cylindrical, drooping racemes (3-6 inches long) cover the shrub from late spring to early summer. Oval, dark green leaves (1-4 inches long) turn varying shades of red, orange and gold in autumn. (USDA Hardiness Zones 5-9).

Elderberry (Sambucus canadensis) are known for their creamy white blooms against the glossy green foliage. Laceleaf and purple colored leaves are very ornamental. Elderberries attract great numbers of bees and other pollinators. They prefer a moist well-drained soil. (Zones 3-9).

Bottlebrush buckeye (Aesculus parviflora) spectacular 8-12 foot tall and 12-15 feet wide suckering summer flowering shrub in partial sunny areas; 8-12 inch white bottle brush flowers with showy red anthers and pinkish filament sand attractive dark green palmate leaves that turn bright yellow in the fall. (Zones 5-8).

Summersweet (Clethra alnifolia) grows 3-8 feet high. depending on cultivar. Sweetly fragrant white 2-6 inch long flower panicles attract hundreds of bees and butterflies in July. Flowers give way to dark brown seed capsules (1/8 inches diameter) which may persist into winter. Glossy dark green leaves (3-4 inches long) transition to shades of golden yellow in fall. (Zones 3-9).

Coralberries (Symphoricarpus spp.), represent several low ground cover shrubs. They produce tiny summer flowers which are browsed by many pollinators and fruits persist well into winter along arching stems. (Zones 2-7).

Bluebeard (Caryopteris spp.), aka blue mist shrub, is covered with brilliant blue blooms in late summer into fall and bees and butterflies come to them. (Zones 5-9).

Red Chokeberry (Aronia arbutifolia) grows 6-10 feet tall with spring blooms. Chokeberry grows in a stiff, upright vase shape habit and exhibits a fibrous rootsystem that suckers freely. Fruits are eaten by birds and other animals. (Zones 4-9).

Black chokeberry (Aronia melanocarpa) is another May blooming upright spreading, suckering shrub. It grows 3-6 feet tall with 5-6 flower clusters of white 5-petals which leads to tart, almost bitter black berries and purple/red fall leaf color in late summer. (Zones 3-8).

Beebalm (Monarda) Varieties Attract Hummingbirds, Butterflies And Moths

Posted by Hugh on July 16th, 2020

In 2016 Mt. Cuba Center in Greenville DE enlisted a team of trained volunteers to monitor the visitation of hummingbirds, moths, and butterflies in the 40 cultivar beebalm (Monarda) trial. Their goal was to systematically observe and note the cultivars that were most frequently visited by these pollinators. Below is a listing of the five most-visited selections by hummingbirds and moths/butterflies.

MT Cuba plant scientists report: “One of the first things we learned from this data is that hummingbirds visit large-flowered, red cultivars almost to the exclusion of everything else. This is most likely due to the fact that hummingbirds require a larger flower size in order to access the nectar. Despite the floral similarities among the hummingbird-visited selections, ‘Jacob Cline’ was much more favored than any other cultivar.

They report: “It is hard to pinpoint an exact cause, but one possible explanation may be that ‘Jacob Cline’ is the tallest of these cultivars and therefore may be easier for the hummingbirds to visit. Just as hummingbirds favored a certain type of flower, so too did moths and butterflies. They were most frequently observed visiting selections that produced the largest abundance of 2-3 inch wide flowers.”

Beebalm (Monarda) Varieties Attract Hummingbirds, Butterflies And Moths The data demonstrate that there are horticulturally desirable characteristics of cultivars (i.e. improved flower production and longer bloom times) that can have a positive impact on ecological function. For example, M. fistulosa ‘Claire Grace’ is a top performer horticulturally as well as a favorite among moths and butterflies.

Attracting Hummingbirds

1. M. didyma ‘Jacob Cline’

2. M. ‘Gardenview Scarlet’

3. M. ‘Cambridge Scarlet’

4. M. didyma

5. M. ‘Raspberry Wine’

Moth/Butterfly

1. M. fistulosa ‘Claire Grace’

2. M. ‘On Parade’

3. M. ‘Violet Queen’

4. M. ‘Peter’s Purple’

5. M. ‘Colrain Red’

Caveat: you should not conclude from a one year study that 2 or 3 varieties were the best. Hummingbird and insect activity may vary with the choice of varieties and the summer time period. Beebalms are also able to support an incredible number of bee and wasp species.

Indian Pinks Generate Garden Fireworks

Posted by Hugh on July 11th, 2020

Indian Pinks Generate Garden Fireworks

Indian pink (Spigelia marilandica) is a strikingly beautiful native wildflower native to the Southern Appalachian region. However, this perennial grows well in most parts of the country (Zones (5b)6-9). Plants emerge quite late in the spring. Sometime in June, depending on locality, their bright red tubular flowers flare open, crowned by five sharply pointed pale yellow reflexed lobes. By the 4^th of July flowers will produce floral fireworks in your garden.

Indian pink prospers around a rich moist open woodlands or shade garden. They grow equally well in mixed containers. Plant in a well-drained, mildly acidic soil that is generously amended with compost or humus. A partially sunny site in full morning to dappled sunlight is perfect. Irrigate during dry periods and do not allow plants to stand in water.

In older plantings vigorous plants will grow 2 to 3 feet tall. Leaves are
are arranged opposite on the stem, attached directly to the main stem (no petioles), ass well as an entire (toothless) margin. Plants stand erect and are rarely branched.

New plantings of Indian pink often start off slowly, taking 2-3 years to reach maximum flowering. Create a dazzling display by setting five or more plants en masse. Over the years in good humus-rich soil, Indian pinks often naturalize and look stunning. Flowering time is extended over several months by swift removal of the old spent flowers (deadheading).

The brightly colored flowers attract numerous pollinating insects and hummingbirds. No disease and pest problems cause Indian pink any troubles.

The popularity of Indian pinks continues to increase. In recent years, the U.S. native plant industry have been bulking up plant inventories. Tissue culture labs are also producing them. ‘Little Redhead’ is a superior vegetatively propagated strain that grows very uniformity.

Attracting Hummingbirds

Posted by Hugh on July 6th, 2020

This time of year many gardeners are setting out bird feeders, including those filled with a sugar solution to encourage hummingbirds to visit your garden. Unfortunately, the sugary drink will also attracts numerous ants, bees, and wasps. When warm spring and summer weather arrives, the solution clouds up with bacteria which ferments or perhaps fatal to the birds. In addition to adding feeders, plant several woody trees and shrubs, perennials, and annuals to your landscape, raised beds and containers.

The kinds of flowers that attract hummers are tubular in shape and red in color, although they’re frequently seen visiting orange, yellow, purple or even blue flowers, offering you plenty to choose from. Avoid considering double-flowered forms which are poor nectar producers and aren’t attractive to pollinators.

Here are some of my 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.)

Annuals:

Snapdragons (Antirrhinum spp.)

Cuphea, cigar plant (Cuphea spp.)

Impatiens (Impatiens spp.)

Lantana (Lantana spp.)

Cypress vine (Ipomoea quamoclit)

Flowering tobacco (Nicotiana spp.)

Salvia (Salvia spp.)

Zinnia (Zinnia spp.)

Woody plants:

Mimosa tree (Albizia julibrissin)

Trumpetvine (Campsis radicans)

Rose of Sharon (Hibiscus syriacus)

Coral honeysuckle (Lonicera sempervirens)

Azaleas and rhododendrons (Rhododendron spp.)

Weigela (Weigela florida)

Torch Lilies (Kniphofia)

Posted by Hugh on July 1st, 2020

Torch lilies (Kniphofia spp.) are easy to grow long-lived perennials from South Africa that are remarkably (USDA hardiness zones 5-9). They go by a number of common names including red hot poker and tritoma. The colorful floral spikes (and a little imagination) resemble fiery torches or sizzling pokers, visited often by hummingbirds, bees and butterflies.

New cultivars are mostly hybrids and vary in plant height and flower color. One or more floral spikes arise 18 inches to 4 feet in height, depending on the cultivar(s) planted. Color choices include off-whites, yellows, oranges, reds, and blends of two or more tints. From May thru October additional re-blooming follows soon after the spent floral scapes have been pruned off (deadheaded).

Torch lily excels when planted in average well-drained soil. Full to partial (6 hours minimum) sunlight is ideal. Most, but not all, cultivars are cold hardy in the Southern Appalachian region (USDA zones 6 and 7). The sharp edged grass-like foliage is evergreen and tends to take a beating in rough winters. Prune back the entire plant near the soil line in late winter for a fresh start.

Modern varieties tend to grow shorter (under 20 inches) compared to the species, K. uvaria, which grows 3 feet and higher. Terra Nova Nurseries, an Oregon wholesale nursery, offers two series of dwarf Kniphofia that are bred for the both the container and perennial garden market. The Poco® series has 4 color variations and the Popsicle® series comes in 7 hues. Late blooming ‘Fire Glow’ is a lovely 14-inch dwarf Kniphofia with large bi-color orange and red flower spikes that flower later from August to October. The Echo® Series, offered by Itsaul Nursery in Atlanta Georgia, grow 30-48 inches high, depending on cultivar. Echo Duo (reddish-orange), Echo Mango (apricot), and Echo Rojo (orange-creme) are popular choices.

A 2-year and older plant clump is both heat and drought tolerant. Every 3-4 years rhizomes are dug and divided either in early fall or late winter. Torch lily has few serious disease and insect problems. Root rot may become a significant problem when planted in a poorly drained soil.