Plant Profile – Zizia aurea

Zizia in the garden

Zizia aurea has the common name Golden Alexanders. It is an easy to grow native plant that no native plant garden should be without. It has lovely umbels of bright yellow flowers that bloom for a long time in spring to early summer – when many of our native plants are just starting to think about flowering.

The flowers are important to a number of short-tongued native bees and other insects that are able to easily reach the nectar in the small yellow flowers.

Swallowtail caterpillar hiding in the Zizia

Zizia aurea is also a host plant for Black Swallowtail butterfly caterpillars.

Zizia can grow in considerable shade but will flower better in full sun to light shade.  Plants look best in a grouping. They can grow to 3 feet with the flowers, but flower stalks can be trimmed back after flowering to control height. While perennial, Zizia can be short lived so allow some reseeding to make sure it stays in your garden.

Want to know more? Here are a few links.

Missouri Botanical Garden – Zizia aurea

Lady Bird Johnson Wildflower Center – Zizia aurea

Plant Profile: Baptisia

A perennial with presence

Baptisia australis flowers

Baptisia is a tough, deer and rabbit resistant group of herbaceous perennial plants that provide beautiful spires of flowers in spring and handsome, disease and pest resistant foliage the rest of the season.

Baptisia is commonly known as false indigo or wild indigo because a blue dye can be made from some species. Dye made from Baptisia was exported from the colonies to England in the 1700’s.

Baptisia australis

Baptisia australis, a blue flowering species, is native to Pennsylvania. Other Baptisia species have flowers in white (Baptisia alba) and yellow (Baptisia sphaerocarpa). These different species have been crossed to create many beautiful and robust garden perennials.

Baptisia flower best in full sun and pretty much any average garden soil – they are not pH sensitive. Because of their extensive tap root they shrug off drought, but this also makes them difficult to move once established. They create sizable, shrub-like plants when they mature so be sure to take note of the chosen cultivar’s size and leave room for growth. The seed pods can be attractive in winter, but if desired plants can be trimmed after flowering to control size and prevent any flopping on to neighbors. Baptisia will push out new leaves after trimming to cover any rough cut stems.

Baptisia ‘Decadence® Lemon Meringue’

It’s generally better to plant Baptisia in the fall in our warmer climate, but it can be planted anytime. Just be sure to give it some water its first summer if you plant in spring.

Because Baptisia grow to shrub size every year, they appreciate a top dressing of compost or a dose of slow release fertilizer. Be careful working around the plants in spring because breaking off the new growth will eliminate flower buds.

Baptisia can be slow to get started in the garden because it’s busy underground building its root system, but be patient and you will be rewarded with a beautiful, dependable, long-lived plant. Bet on Baptisia – you won’t be sorry.

Want more information? Here are some links:

Mt. Cuba Botanical Garden Baptisia Trials report

Missouri Botanical Garden Plant Finder – Baptisia australis

Clemson Cooperative Extension – Baptisia

No Longer Impatient for Impatiens

By A Glodman

Welcome back old friend!  The ubiquitous annual that all shade gardeners loved is back and ready to create season-long color.  Impatiens are what we are discussing. 

Beacon Impatiens – photo courtesy of Ball Seed

Impatiens walleriana were attacked by Impatiens Downy Mildew (IDM). This disease caused defoliation and eventual death of impatiens well before the growing season ended. The disease was difficult to control; and airborne and overwintering soil spores re-infected new plants. This disease essentially ended sales of the once common annual.

Other annuals came to the shade gardener’s rescue; Begonia, Torenia, Coleus, New Guinea impatiens, and Caladiums but some things can never be duplicated. 

Through a collaboration of plant breeders and extensive plant trials in Washington State, Michigan, Colorado, Texas, Minnesota, England, Australia, South Africa and here in Pennsylvania at Penn State, two varieties were deemed to be worthy and will be introduced for sale in 2020. 

Beacon and Imara are the two brand names these new impatiens will be sold under.  The Penn State trials that were overseen by Sinclair Adam revealed Beacon to be slightly better in Pennsylvania gardens.  Both Beacon and Imara are hardy and vigorous for your garden but with any plant, conditions may favor one variety over the other.  Color variety is not as extensive as previously but I am sure with time we will have many more to choose from.

Keep an eye out this spring for the reintroduction of this hardworking, floriferous, easy care annual. 

Meet Sweet Box

By C StClair

Are you familiar with the plant commonly known as “Himalayan Sweet Box” (Sarcococca hookeriana var. humilis)?  This is one of those plants I dearly love, especially this time of the year.

Sweet Box is actually a shrub, but it is very low growing and spreads, creating a ground cover. No worries about a horticultural invasion.  It spreads slowly – you’ll actually wish it spread faster than it does.

It does need some shade – especially during hot afternoons.  If it gets too much sun in winter, the leaf tips might brown a bit.  But once it is established, it can tolerate dry, shady soils – even those under established trees. It looks fresh, green and tidy all season.

The common name “Sweet Box” is very fitting. It maintains it shiny green leaves like a boxwood (although they are larger and pointy), but it gets small, intensely fragrant flowers in very early spring (in my garden – about the same time as the snow crocus). Brought inside, the flowers can subtly perfume the entire room.

One caution though, Sarcococca hookeriana is susceptible to boxwood blight so if you know you have boxwood blight on your property this may not be the best plant choice.

Pennsylvania Gold Medal Plants for 2020

By C StClair

Every year the Pennsylvania Horticultural Society recommends a selection of plants that they feel will be outstanding performers in the mid-Atlantic home landscape.

The selections are made by a committee of growers, nursery owners, landscape designers and other horticulturalists who have had the opportunity to observe the plants over time. They are chosen for their hardiness, pest and disease resistance, ease of growing and maintenance – as well as appearance of course.

This year, they have singled out one tree, 2 shrubs and 3 herbaceous perennials.

The tree is Carpinus caroliniana, commonly known as American Hornbeam but sometimes called Ironwood or Musclewood. It is an understory tree so its smaller size can be useful in home landscapes. It is slow growing to about  20-30 feet and has orange- yellow fall foliage. This tree is native to the mid-Atlantic.

One of the chosen shrubs is Aronia melanocarpa ‘Viking’, also known as Black Chokeberry. This native shrub has fragrant white flowers in spring that turn into glossy black berries in late summer. The berries are edible (although astringent) and can be cooked into pies and jam – or left as a food source for birds. The glossy leaves have good red fall color. ‘Viking’ is a cultivar selected for greater fruit production. This shrub grows 3-6 feet tall and wide. It can tolerate part shade, but flowering and fruiting are best in full sun.

Image courtesy of Northcreek Nursery

The second shrub is Hydrangea arborescens ‘Haas’ Halo’, a cultivar of our native Smooth Hydrangea. This shrub has large lacecap flowers with sturdy stems that don’t droop after a rain. The lacecaps can be as much as 14 inches in diameter and are sturdy enough to provide winter interest. The flower heads include both showy, sterile flowerets and fertile flowers so they provide more pollen and nectar for insects than the more common ‘Annabelle’ hydrangea. Haas’ Halo also appears to be more drought tolerant (once established) than ‘Annabelle’.  This shrub grows 3-5 feet tall and wide in part to full sun.

Coreopsis verticillata ‘Zagreb’ is a compact herbaceous perennial with a light, airy texture. The bright yellow flowers cover the plant from early through mid-summer, with a re-bloom in fall if the plant is cut back to half after flowering slows. ‘Zagreb’ is useful for the front of a border or in pots. It can tolerate poor soils and drought. It does need good soil drainage to prevent crown rot. This perennial is compact (12-18 inches tall and wide), long flowering and long lived.

The second perennial selected is Geranium X cantabrigiense ‘Biokovo’, commonly known as Cranesbill Geranium due to the shape of the seed pods. This plant is low growing and compact, about 6-12 inches tall. It flowers in spring with white flowers tinged slightly with pink. Although somewhat slow growing, it can create a groundcover over time.  It grows best in full sun to part shade. While it can tolerate some drought, it may go dormant in late summer in dry conditions. It performs and spreads better in consistently moist, well drained soils.

Although technically a woody sub-shrub, the last selection chosen is usually grown as an herbaceous perennial. Perovskia atriplicifolia ‘Little Spire’  (commonly known as Russian Sage) is a compact selection growing to about 2 feet tall versus 4 feet tall for the species. ‘Little Spire’ grows best in full sun and medium to dry soil moisture. It is drought tolerant, deer resistant and has attractive silvery foliage. The spires of blue to violet flowers bloom for a long period over the summer.

Plant Profile: Amsonia hubrichtii

Amsonia hubrichtii has the common name Bluestar or Threadleaf Bluestar. It is a hardy, long-lived perennial native to Arkansas, Oklahoma and Missouri.

This Amsonia has lovely, feathery foliage that adds a unique, billowy texture to the garden. It blooms in spring with light blue, star-like flowers – but this plant really shines in the fall with brilliant golden-yellow foliage.

Amsonia hubrichtii is easy to grow in average, well-drained soil . With time it can grow quite large, 3-4 feet tall and wide with a shrub-like appearance.  This perennial starts slow and may need a couple years to fill out but once established it is hardy, dependable and rarely needs division. A polite grower, it does not spread by rhizomes and is not known to aggressively self-seed. Amsonia hubrichtii is deer and rabbit resistant and has no serious pests or diseases.

The flowering and fall color is best in full sun, but it will tolerate some shade.  If grown in too much shade or very rich soil, its habit will be open and floppy. Cutting it back about 6 inches after blooming will help prevent flopping.  

Want more information? Here are some links:

Missouri Botanical Garden  Plant Finder

Lady Bird Johnson Wildflower Center

Plant Profile: Rudbeckia laciniata

A tall, native coneflower

Rudbeckia laciniata is commonly known as cut leaf coneflower or green headed coneflower.  It is a stately native perennial that can reach 9 feet tall under the right conditions but generally grows 5-7 feet tall. Its preferred location is full to part sun in moist soil. It naturally occurs in moist woodland clearings or along stream beds. It is adaptable to average garden soil, but may wilt during periods of drought without supplemental water.

Like many plants, there are both pros and cons to adding Rudbeckia laciniata to your garden.

On the positive side, this rudbeckia provides plenty of sunny flowers and has a long 2 month bloom time – July through September.  The size and bright coloration of this plant creates a strong accent in the garden at a time when some other perennials are starting to wane.

The flowers are attractive to bees (both native and domesticated) and butterflies, providing a late season nectar source.  They have attractive seed heads and the flower seeds provide food for finches in the fall.  This coneflower is generally pest and disease resistant and can handle hot, humid summer weather.  It is considered deer and rabbit resistant.

Because of its tolerance for moist soil and periodic flooding, it is a good plant for flood prone areas or rain gardens. Given space, it can create a (very tall!) groundcover. The root structure provides good erosion control.

However (here come the cons), in moist sunny areas this coneflower can spread somewhat aggressively by underground rhizomes. Plants should be edged or divided in spring to control the spread.

In fertile soils, more shade or windy areas the plants will probably need staking to keep it upright. 

While the plants will probably survive drought, the lower leaves will droop and brown. Drought stress can occasionally result in powdery mildew.

If you can give this plant a bit of moisture and some room to grow, it might be a great addition to a pollinator friendly landscape.

Want more information? Here are some links:

Missouri Botanical Garden plant profile – Rudbeckia laciniata

Ladybird Johnson Wildflower Center –  Rudbeckia lancinata

Plant Profile: Echinacea purpurea

a native pollinator favorite

Echinacea pupurea

Echinacea purpurea has the common name Purple cone flower.  It is a lovely herbaceous perennial that is native to eastern North America. Its showy blossoms usually appear in late June to early July and can rebloom through August. The blooms are very attractive to bees and butterflies making Echinacea a great addition to a pollinator friendly garden.  Gold finches will also visit the flower heads as they ripen to eat the seeds.

Echinacea grows best in full sun, but will take some shade. It requires well drained soil and is tolerant of drought and poor soil. It grows 2 to 5 feet tall depending on the cultivar and for the most part is self-supporting, but may need some support if grown in rich soil or too much shade.

Echinacea generally will continue to bloom whether spent blossoms are removed or not, but removing spent blossoms early in the season may make the plant look more tidy. Consider leaving some spent blossom seed heads over the winter as a food source for birds, but be prepared for some self-seeding around the base of the plant.  I consider this a bonus, and simply move the volunteer seedlings where I want them in the spring. Echinacea is also used as an herbal supplement to boost the immune system.

Echinacea flower

While called purple coneflower, the common version is more of a pinkish-purple and it has been hybridized into a variety of different colors including white, yellow, orange, red and even bi-colors. Some varieties are quite fragrant.

There are also coneflowers that have been hybridized with double or triple the petals to create a “pom-pom” effect, but note that these doubles and triples are not useful to pollinators because the hybridization process eliminates nectar sources.  These hybrids are also mainly sterile, so they do not provide seeds for birds.

Echinacea can be susceptible Aster Yellows. This is a disease caused by infection by a microorganism called a phytoplasma. The infected plant’s flowers will remain green and the cones will be distorted with leaf like projections.   The disease can be spread from an infected plant to a healthy one by leafhopper insects as they feed on different plants so it is important to remove any infected plants you find. There is no cure for Aster Yellows.

Echinacea are sometimes bothered by Japanese beetle which chew the flower petals but they usually out-grow “beetle season” and continue flowering.   

Want a little more information on Echinacea? Here are some links:

Ladybird Johnson Wildflower Center profile

Penn State Extension – Echinacea Diseases

Iowa State Extension: Yellows Disease of Purple Coneflower

National Institute of Health of Echinacea Herbal Properties