Plants of the Week by Natalie Ipock, Summer Horticulture Intern

Rhododendron prunifolium ‘Hohman’ – plumleaf azalea

Blooming bright red on the edge of our Rhododendron Collection, you’ll find Rhododendron prunifolium ‘Hohman’. The cultivar ‘Hohman’ highlights the beautiful red blooms with a hint of orange. Growers commonly use Rhododendron prunifolium to develop late-blooming azalea cultivars. Usually, the bloom time for rhododendrons ends by June, but this species helps extend the blooming season to September. 

Rhododendron prunifolium is only found in the Chattahoochee River Valley between Georgia and Alabama. Because of its scarcity, it is one of the rarest azaleas in the eastern United States. In 1918 Arnold Arboretum – located in Boston, MA – became the first to grow this azalea outside of its native range. 

When choosing a planting location, make sure the soil is acidic and well drained. It is a deciduous shrub that prefers partial to full shade. This species is great for attracting pollinators during the summer and can grow about 8-12 feet tall. You can find this azalea off the pathway to the Amphitheater in front of the Scott Map House. 

Poliothyrsis sinensis – pearl-bloom tree

In 1993 J. C. Raulston gifted six pearl-bloom tree seedlings to the Scott Arboretum & Gardens. While only two remain, they’ve grown into magnificent, blooming trees and are a must-see on a mid-summer visit to the Arboretum. The gorgeous, pale yellow flowers perfectly outline the old observatory on the Cunningham House. 

The pearl-bloom tree gets its common name due to the flower buds, which do not fully open, appearing pearl-like. Poliothyrsis sinensis is native to central and eastern China on deciduous mountainsides and is the only plant in its genus. It can grow up to 40 feet high with a 25-foot spread. 

Lagerstroemia indica ‘Whit III’ – Pink Velour® common crapemyrtle 

Lagerstroemia indica ‘Whit III’ is a deciduous tree that thrives in a full sun environment. It blooms a magenta pink color from July through September and has textured exfoliating bark year-round. This common crapemyrtle’s spread and height can reach up to 12 feet, but in the deep southern US, it may exceed 12 feet and need to be cut back. In the fall, this cultivar’s leaves turn orange-brown in color. 

Although many Lagerstroemia suffer from powdery mildew, the Pink Velour® common crapemyrtle is resistant to such diseases. Dr. Carl E. Whitcomb was the original breeder for this plant and patented it in 2020. You can find these Lagerstroemia indica ‘Whit III’ along the western wall of Parrish Hall.

The post Plants of the Week: July 23 appeared first on Scott Arboretum & Gardens.

Plants of the Week by Caelon Shugrue, Public Horticulture Intern

Eryngium yuccifolium – rattlesnake master

With stunning spiked globes for flowers, Eryngium yuccifolium is sure to catch your eye – it sure caught mine as I was strolling through the Whittier meadow. While it may look similar to a thistle, rattlesnake master is a member of the carrot family, containing many of the same oils and secondary compounds found in parsley, carrot, and parsnip. Break and crush a leaf and you smell the similarities!

Rattlesnake master can grow up to 6 feet tall in optimal sites. It is drought tolerant and thrives in full sun with sandy soils. Growing rattlesnake master in your garden would provide an interesting variation in texture. As an herbaceous perennial, it can be planted in shrub borders and also fits well in meadow plantings.

Vernonia baldwinii – Baldwin’s ironweed

Buzzing with pollen-covered bees, Veronia baldwinii sports deep purple flowers clustered in corymbs. These blooms last from late summer to early fall and attract bees, butterflies, and curious plant-enthusiasts. Once the flowers are done, they give way to rusty-colored seed clusters. These rusty-colored seeds, in addition to the rusty tinge in the fading flowers and the tough stems, give the plant certain “iron-like” qualities, hence the common name “ironweed.”

Also found in the Whittier meadow, Baldwin’s ironweed can grow in most conditions, whether moist or dry. It is native to Missouri where it can be found across the state in woods, meadows, prairies, glades, fields, and disturbed areas. It is very successful in self-seeding and is thus easily grown from seed.

Lagerstroemia ‘Hopi’ – hybrid crapemyrtle

Found tucked away in the Lilac Collection, this hybrid crapemyrtle stands out due to its stunning, hot pink blooms. Wild crapemyrtles are red or rose-colored, but many cultivated varieties have been developed with new flower colors including white, pink, mauve, purple, and lavender. Originally native to the Himalayas, crapemyrtles have been naturalized in the U.S. as far as Florida and Arkansas. In addition to its impressive flowers, crapemyrtles have interesting multicolored, exfoliating bark. 

The ‘Hopi’ cultivar is one of many mildew-resistant hybrids developed by the National Arboretum in Washington D.C., which named these cultivars after Native American tribes. The Hopi tribe has a reservation in Hopitutskwa, located in northeastern Arizona.

The post Plants of the Week: July 15 appeared first on Scott Arboretum & Gardens.

Plants of the Week by Kaiden Lytle, Summer Education Intern

If you’ve ever wished you could add plants to your garden that make it look like alien life has taken hold, then stay tuned for this week’s ‘Plants of the Week’ selections!

Allium ‘Millenium’ – ornamental onion

First off is a spiky, globular, blooming perennial that will make passersby stop and marvel at its unique shape. I am talking about Allium ‘Millenium’, otherwise known as ornamental onion. This plant is often used in garden borders as the purple color and planetary shape is eye-catching. Each bloom is large and packed with little star-shaped florets, and in a drift or group can look akin to floral fireworks.

Easy to establish in your garden and drought tolerant, this plant grows best in well-drained soil and full sun, where it will naturalize readily and return year after year as a hardy bulbous perennial. Gardeners also favor Allium ‘Millenium’ as a temporal gap-filler: it will bloom to fill the season between spring bulbs and early summer perennials. Within the Scott Arboretum & Gardens, you can currently find this plant in the Dean Bond Rose Garden, Cut-Flower Display Garden, gravel culture beds, John W. Nason Garden, and around the entrance of the McCabe Library. 

Cynara cardunculus ‘Florist Cardy’ – cardoon 

For those gardeners that prefer varied textures in their garden, you might be excited by the next featured plant this week: Cynara cardunculus ‘Florist Cardy’, commonly known as cardoon or artichoke thistle. Closely related to globe artichokes, and similarly edible, this is an extremely fun plant all around. Unlike the artichoke, however, it is not the fruit or flowers that are edible but rather the blanched leaf stalks! When established in your garden, Cynara cardunculus ‘Florist Cardy’ presents as thick stalks with silvery foliage, and in the summer season, this plant boasts dramatic spiky blooms in varying shades of violet.

This perennial is native to the Mediterranean region, and thrives in warm, sunny, dry conditions, but can still grow in colder regions as an annual or less-hardy perennial. Within the Scott Arboretum & Gardens, you can currently find Cynara cardunculus ‘Florist Cardy’ within the Entrance Garden, outside of the Cunningham Building. 

Colocasia esculenta ‘Illustris’ – elephant ear

Unlike the other two showcased flowering plants, this last featured plant is not planted for its blooms, but rather the striking foliage. I am talking about Colocasia esculenta ‘Illustris’, of course, commonly known as elephant ear or taro. While it can bloom briefly in summer, producing small yellow flowers, the blooms are infrequent and sparse, even in the best of conditions. The real show-stopper, the leaves, are huge and heart shaped (up to 3 ft. long), drooping artfully from the long petioles. The leaves are dark purple to almost black, with electric green coursing through each vein. This plant is a head-turner!

As a tropical perennial, it will thrive in sunny to part-shade areas with rich, moist soils. Be careful of planting too far away from other plants, as the leaves are sensitive to wind gusts, and can break easily without nearby shelter. Regarding height and cohesiveness in your garden, the above-mentioned plants are quite tall, and add a lot of vertical texture and color to the top layers of your garden. If you feel you need a nice medium-height addition, Colocasia esculenta ‘Illustris’ will help to add some balance within the mid layers of your garden. Within the Scott Arboretum & Gardens, you can currently find this plant interspersed within the Terry Shane Teaching Garden.

The post Plants of the Week: July 9 appeared first on Scott Arboretum & Gardens.

Plants of the Week by Natalie Ipock, Summer Horticulture Intern

Lilium ‘Montreux’ – Asiatic lily

Lilium ‘Montreux’ is a stunning lily that can be found in the Tree Peony Collection outside the Hormel-Nguyen Intercultural Center. This lily’s flowers are pink in color with brown dots towards the center, along with brown anthers protruding from the center. As is the case for many Asiatic hybrid lilies, this plant is winter hardy, not fragrant, and readily reproducing. Although on the taller end for Asiatic hybrids, ‘Montreux’ still requires minimal overall maintenance.

Lilium ‘Montreux’ is a perennial that can reach about 3 feet tall and blooms in May through June. When considering a location to plant these lilies, make sure they are in full sun to partial shade and the soil can drain excess water. Lilium ‘Montreux’ could be just the pop of color your mid-summer garden needs. 

Heliopsis helianthoides var. scabra ‘Bleeding Hearts’ – false sunflower 

Heliopsis helianthoides var. scabra ‘Bleeding Hearts’ is native to North America and can be found in the Harry Wood Garden entrance. This perennial’s blooms last throughout the entire summer in ideal conditions, from late June to the first frost. False sunflower forms in clumps and is drought tolerant. With such vibrant colors, bees and butterflies love to swoop by and pollinate these magnificent plants. 

What I find most fascinating about Heliopsis helianthoides is what sets it apart from true sunflowers. These false sunflowers are composed of ray and disc florets, with both flower parts able to seed. However in a true sunflower, the ray florets  – the distinct yellow “petals” – are unable to seed. Beyond its physiological features, the striking orange-red color of the Heliopsis helianthoides var. scabra ‘Bleeding Hearts’ is sure to catch your eye. 

Hydrangea arborescens ‘Abetwo’ – Incrediball™ smooth hydrangea 

Another plant currently attracting pollinators is the deciduous shrub Hydrangea arborescens ‘Abetwo’. The height and spread of this impressive plant can reach about 4-5 feet, and it blooms throughout the whole summer. This Hydrangea can be found in the Hydrangea Collection outside Whittier Hall.

This smooth hydrangea was bred to fix the weak stem of Hydrangea arborescens ‘Annabelle’, previously featured in last week’s Plants of the Week article. Not only does Hydrangea arborescens ‘Abetwo’ have thicker stems holding up the blooms, but its blooms are slightly bigger as well.

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Plants of the Week by Caelon Shugrue, Public Horticulture Intern

Echinacea ‘Cheyenne Spirit’ – coneflower

Blooming in a variety of colors, Echinacea ‘Cheyenne Spirit’ flower can be purple, pink, red, orange, yellow, cream, or white. This specific cluster at the entrance of the Pollinator Garden – found between Cornell Library of Science & Engineering and Martin Hall – attracted me due to its wide range of hues from dusty orange to bright purple. The dried cones can remain into the winter and are often visited by birds such as goldfinches that feed on the seeds. In addition to birds, deer have also been known to snack on the new growth. 

Echinacea ‘Cheyenne Spirit’ is relatively easy to grow, enjoying full to partial shade and dry to medium moisture. As herbaceous perennials, it is tolerant of drought, heat, humidity, and poor soil conditions. These Echinacea can be planted in rock gardens, perennial borders, or almost any garden with sun. They are quite attractive when planted in groups; however, they can reseed themselves and often become overcrowded.

Hydrangea arborescens ‘Annabelle’ – smooth hydrangea

Walking through campus, Hydrangea arborescens ‘Annabelle’ immediately caught my eye due to its huge, round, stark-white blooms. These flower structures (called corymbs) can bloom for up to two months in the summer, sometimes featuring a repeat bloom in the fall. The ‘Annabelle’ cultivar is characterized by having larger flowers than the straight species. This cultivar is a naturally occurring cultivar that was discovered in the wild near the town of Anna, Illinois.

Hydrangea arborescens ‘Annabelle’ grows best in partial shade with medium moisture, and while it tolerates full sun it would require constant moisture. These specimens are located between Parish Hall and the Lang Performing Arts Center and bask in the shade of the dawn redwoods. Flowers bloom on new wood, so to promote an ideal form plants can be pruned back almost to the ground in late winter. Hydrangea arborescens ‘Annabelle’ looks best in mass or group plantings making up a shrub border or as a background for a perennial border.

Hypericum × inodorum ‘Allgrandeur’ – Miracle^® Grandeur St. John’s wort

The deciduous shrub Hypericum × inodorum ‘Allgrandeur’ struck my fancy due to the vibrant yellow flowers and bright red berries that stick out against its dark green foliage. Planted at the entrance of the Harry Wood Garden, the mass of foliage, bright yellow flowers, and glowing berries draw visitors into the garden. While this plant is very attractive for birds and butterflies, it does not attract deer, who have no interest in the plant.

Hypericum × inodorum ‘Allgrandeur’ grows in full to partial shade and does best in dry to average moisture. It is drought tolerant and will die in standing water. Hypericum × inodorum ‘Allgrandeur’ is also tolerant of most soil pH levels and is tolerant of pollution, allowing it to thrive in city landscapes. It can get quite tall (over two feet) and therefore it is best used in mass plantings, as hedges, or in containers. If growing Hypericum × inodorum ‘Allgrandeur’ in a container, it may require more frequent watering.

The post Plants of the Week: June 24 appeared first on Scott Arboretum & Gardens.

Why do my beech tree leaves have stripes? Join Assistant Horticulture Supervisor Beck Armstrong as she discussing Beech Leaf Disease and how it is moving through the beech trees in our area.

Tune into the Gardener’s Almanac to learn what we are doing in the garden at this moment. Learn from Scott Arboretum staff which plants we are pruning, planting, weeding and which pests we are monitoring and removing right now. This virtual almanac is a great reference guide for gardeners.

The post Gardener’s Almanac: Beech Leaf Disease appeared first on Scott Arboretum & Gardens.

Plants of the Week by Kaiden Lytle, Summer Education Intern

Clematis (Early, large-flowered Group) ‘Jerzy Popiełuszko’ – clematis

Popular for its large white blooms (13-15 cm diameter), this clematis adds a bit of elegance to any garden. This variety is fond of climbing and will climb both living and non-living structures nearby (trellises, fences, shrubs, etc). The leaves of this plant are large as well and are tripartite and heart-shaped. In regard to care, ‘Jerzy Popiełuszko’ prefers sunny sites in USDA Zones 4-9, with well-drained, fertile soils. In these conditions, it will bloom happily from May through October. 

This clematis cultivar was originally bred in Poland by Dr. Szczepan Marczyński, and released to the public in 2004. Notably, the following year, it won a gold medal at the 2005 Plantarium arboriculture trade fair, and again in the Gardenia 2011 exhibition in Poznań. The variety name bears reference to the historic Polish-Catholic priest, Father Jerzy Popiełuszko (1947–1984).

On the grounds of the Scott Arboretum & Gardens and Swarthmore campus, one can find Clematis ‘Jerzy Popiełuszko’ on the west side of the historic Dean Bond Rose Garden, or within the Isabelle Cosby Courtyard. 

Asclepias tuberosa – butterfly weed 

One might be more familiar with these bright orange clusters of flowers (and their usual winged clientele). Asclepias tuberosa, more commonly known as butterfly weed, frequents many a home garden, adding texture, color, and a hardy native nectar source for pollinators. 

Native to the lower 48 states and parts of Canada, this bushy perennial boasts flat-topped pops of showy bright orange flowers that are sure to add vibrant color to any garden it’s planted in. Once established, expect this plant to grow up to 1.5-2 ft. tall, with stiff, dark green stems and alternate, pointed leaves. 

This plant will help entice native pollinator species to one’s garden, boosting plant fertilization and improving native species biodiversity. Not only utilized by butterflies and bees, this Asclepias species is used by goldfinches and other songbirds as well, who will use the plant’s seed pod fibers as a food source and as nesting material.

Asclepias tuberosa can be found across Scott Arboretum & Gardens, including in the Entrance Garden, the Pollinator Garden, outside of Singer Hall and Whittier Hall (around the meadows), and the Harry Wood Garden. 

Astilbe ‘Straussenfeder’ (or ‘Ostrich Plume’) – astilbe

Lastly, but certainly not least, is Astilbe ‘Straussenfeder’, also commonly referred to as false spirea. First cultivated in 1952, and notable for its tall plumes of light pink flower panicles, this herbaceous perennial is also referred to interchangeably as Astilbe ‘Ostrich Plume’. (It’s worth noting that the German word ‘Straussenfeder’ translates to ostrich feather in English!) The Astilbe genus, however, is native to eastern Asia and eastern North America, with the ‘Straussenfeder’ cultivar being of Japanese origin. 

Great for any gardener looking to add a bit of light spring-ish color or depth to their garden, this Astilbe variety grows in fern-like clumps (up to 20 in. in height) and produces erect and arching stems that can reach up to 2.5-3 ft. tall. Blooms are light pink, loose-packed, and often trailing or otherwise flowy, and many gardeners favor this plant by a water feature for this reason. Within the Scott Arboretum & Gardens, Astilbe ‘Straussenfeder’ can be found in the Terry Shane Teaching Garden in a sole planter next to the fish pool.

Blooms occur in late spring and into early summer and leave dried seed heads on the ends of the stalks. These seed heads are often favored decoratively by gardeners and left throughout the summer to add ornamental interest to one’s garden. The blooms are also attractive to pollinators, and one might consider this variety for pollinator gardens! 

The post Plants of the Week: June 17 appeared first on Scott Arboretum & Gardens.

Plants of the Week by Natalie Ipock, Summer Horticulture Intern

Spigelia marilandica ‘Little Redhead’ – Indian pink

Found at the western entrance to the Glade Garden, Spigelia marilandica ‘Little Redhead’ is a gorgeous flower you should make sure to check out on your visit to Scott Arboretum & Gardens. Blooming May through July, it is a perennial that prefers moister environments, such as a stream bank.

Spigelia marilandica ‘Little Redhead’ is native to the southeastern US and naturally forms in clumps. It is best grown in full sun to partial shade. Indian pink’s flower has a beautiful red base with a five-point yellow star of petals protruding from it. When in bloom, hummingbirds love to stop by and pollinate this magnificent plant.

Geranium ‘Azure Rush’ – cranesbill 

With striking patches of lavender flowers, Geranium ‘Azure Rush’ is sure to catch your eye throughout the entire summer. It has a floral scent and attracts many pollinators to its countless flowers. When considering a location to plant, cranesbill prefers full sun to partial shade.

This perennial blooms from late spring to early fall making it an ideal summer ground cover. It grows about 1-1.5 feet high and has a spread of about 2-2.5 feet. Not to mention, Geranium ‘Azure Rush’ is cold-hardy, deer resistant, and requires low maintenance. Make sure to check out this beautiful plant on the north side of Kohlberg Hall.

Clematis (Integrifolia Group) ‘Rooguchi’ – clematis 

Another perennial that attracts many pollinators is Clematis (Integrifolia Group) ‘Rooguchi’. A cross between Clematis integrifolia and Clematis × durandii, it inherits cute indigo bell-shaped flowers that dangle from its stem. With vine-like tendencies, it needs the support of another plant or a trellis to help it reach 6-8 feet tall.

Clematis prefers to be in locations with full sun to partial shade, and does not like damp environments. Found outside the Science Center, this Clematis (Integrifolia Group) ‘Rooguchi’ provides a nice pop of color to the area.

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Plants of the Week by Caelon Shugrue, Public Horticulture Intern

Aesculus chinensis var. wilsonii – Wilson’s horsechestnut

Native to northern China, Aesculus chinensis var. wilsonii has stunning branched clusters (also known as panicles) of white, slightly aromatic flowers. Wilson’s horsechestnut is mostly grown ornamentally. In fact, its seeds were collected and distributed due to these showy blooms. They first arrived in the United States when British botanist William Purdom sent saplings to the Arnold Arboretum in Boston from seeds collected in Beijing.

After the panicles of flowers –which can be as large as 16 inches long– bloom from May to June, dry dehiscent fruits form. At maturity, the husks of these fruits open (or dehisce) in early fall to release 1-inch nuts. Beware, these nuts are slightly poisonous due to the abundance of saponins, which can be successfully leached out through a rigorous process of cooking or washing. These nuts have historically been used in traditional Chinese medicine to treat shortness of breath and abdominal pain.

In China, Aesculus chinensis var. wilsonii grows in forests, thickets, slopes, ravines and roadsides. Thus, this tree is planted in places where it enjoys full sun to partial shade and well-draining soils. It can be used as a shade tree in many gardens or a street tree, but cleaning up after its nuts may seem tedious. This specific specimen is planted on the quad between Sharples Commons and Clothier Hall, where it basks in partial shade. Its eye-catching flowers and nuts add an interesting texture and feel to the landscape.

Deutzia x hybrida ‘Magicien’ – hybrid deutzia

Also with large clusters of flowers, this hybrid deutzia produces showy pink and white flowers from late spring to early summer. Adored by Scott Arboretum & Gardens horticulturists, visitors, and bees alike, this beautiful Deutzia has gorgeous, star-shaped flowers. It caught my eye because around this time of year it seems as though the Deutzia has more flowers than leaves. 

This hybrid is a cross between two Asian species of Deutzia: D. longifolia and D. discolor. Rapidly growing and with beautiful, showy flowers and bright, green foliage, this plant is ideal for planting along shrub borders or mass plantings. This specimen is found on the edge of the path by the Cunningham House – calling visitors to the entrance garden or perhaps wishing them farewell. 

Most flowers are produced when the plant is in full sun to partial shade with nutrient rich, moist soils. This shrub typically grows as tall as four to six feet with a similar spread, but regular prunings are recommended to keep it from looking unkempt. The hanging clusters of flowers are eye-catching in bloom, and the fall foliage is a pleasant red. Perfect for a shrub border or a hedge, this Deutzia is sure to spruce up any garden.

Kalmia latifolia – mountain-laurel

The state flower of Pennsylvania and Connecticut, the mountain-laurel blooms in late spring to early summer with striking geometric flowers. With many cultivars available, its flowers can range from pink to white to red or all three! The anthers in the flowers have an interesting pollen dispersal adaptation – when touched by a bee, the anthers spring out of their pockets in the petals and fling dustings of pollen on the pollinator.

As a member of the Ericaceae family, Kalmia latifolia is best grown in acidic soils. Native to eastern North America, this plant is found in a variety of landscapes such as rocky or sandy woods, meadows, and mountain slopes. In planted landscapes, this shrub is often used in shrub borders as it can spread vigorously. Its flowers are quite showy, and as an evergreen shrub, it has excellent year round foliage. Eaten in abundance, the leaves are poisonous but that doesn’t stop deer from enjoying a bite or two.

Kalmia latifolia has dramatic, gnarly branches adding an interesting dimension to any landscape. One of its common names “spoonwood” is a reference to the fact that woodworkers today and in the past have used this wood to make spoons or bowls. Often identified by its branches, Kalmia latifolia bark is rigid with pieces plaited and often hanging or peeling off.

The post Plants of the Week: June 4 appeared first on Scott Arboretum & Gardens.

Summer Education Intern Moss Graves teaches us about the difference between soil and dirt as well as how to conduct a soil separation experiment.

Tune into the Gardener’s Almanac to learn what we are doing in the garden at this moment. Learn from Scott Arboretum staff which plants we are pruning, planting, weeding and which pests we are monitoring and removing right now. This virtual almanac is a great reference guide for gardeners.

The post Gardeners Almanac: Soil Separation Science Experiment appeared first on Scott Arboretum & Gardens.